Description:
Field of the Invention
The present invention relates to a preservative blend comprising lactic acid, salicylic acid, triethylene glycol and 1,3 propanediol, intended for use in diverse products like cosmetic, pharmaceutical, and personal care products.
Background of the Invention
Preservatives play a critical role in inhibiting microbial growth and extending the shelf life of various products, specifically aqueous products. Anhydrous and non-aqueous products, like lip balms and body butters, do not require preservatives due to their resistance to microbial growth. However, products that may encounter water during manufacturing and use, like body scrubs and cleansing balms, as well as all products containing water, require a broad-spectrum preservative.
Traditional preservatives present challenges in safety, efficacy, and consumer acceptance. Parabens, formaldehyde-releasing agents, and phenoxyethanol, the commonly used conventional preservatives, have been associated with skin irritation and allergies, especially in sensitive skin types. Moreover, some of these preservatives pose health risks by disrupting endocrine function or by acting as carcinogens; for instance, parabens disrupt hormones, while formaldehyde-releasing agents are carcinogenic in nature. Environmental concerns may also arise as conventional preservatives can harm aquatic life when washed off and may accumulate in water bodies. Thus, their production and disposal can contribute to environmental pollution. Also, conventional preservatives like phenoxyethanol have not been found suitable for sensitive skin due to redness, itching or burning sensation caused. Cumulative exposure through same or multiple products containing such preservatives may cause drying of the skin, which can exacerbate skin sensitivity. Prolonged use of these preservatives can also lead to microbial resistance, diminishing their effectiveness and necessitating higher concentrations or alternative options. With growing consumer preference for natural products, cosmetics with conventional preservatives face scepticism. Many opt for products with milder preservatives, or those where the amount of preservatives is low.
Natural preservatives, derived from naturally occurring substances, safeguard consumer products against microbial contamination, while also providing safer alternatives. Various molecules with antimicrobial properties exist in nature, such as benzoic acid (naturally found in strawberries and cayenne pepper), sorbic acid (derived from rowanberry), ethanol (produced via microbial fermentation of sugars by yeast), or benzyl alcohol (present in jasmine and ylang-ylang essential oils). Despite their natural origins, commercial preservatives are preferred due to energy and cost efficiencies, compared to isolation methods for natural products.
While many essential oils possess antimicrobial properties, achieving effective protection would necessitate use of extremely high concentrations, potentially leading to skin irritation and sensitization. Additionally, the overpowering aroma of essential oils renders them unsuitable for cosmetics. Vitamin E, often mistaken as a preservative, functions as an antioxidant, preventing oils from becoming rancid, but offering no protection against microbial growth in water-containing products. Thus, there is a need for a preservative system that is suitable for all skin types, especially including sensitive skin types, which is effective over a broad range of organisms, and is soluble in water as well as oil.
To this day there is no official regulatory definition for natural and organic cosmetics. There are private standards, but they mention that the baseline requirement is for products to first comply with Regulation (EC) No 1223/2009 of the European Parliament and of the Council of 30 November 2009 on cosmetic products. Organic ingredients are regulated under the Council Regulation (EC) No 834/2007 of 28 June, 2007 with respect to organic production and labelling of organic products. Further, the production of cosmetics with natural products poses numerous challenges due to the complexity of their formulations and due to the essential aspects linked to the sourcing and production of natural ingredients, such as environmental protection, sustainability, biodiversity promotion, and the like. Apart from aspects linked to the production, the formulation of natural cosmetics involves complex processes in which the number of modifications and chemical processes that raw materials are subjected to, directly influence the natural and organic qualities of the final ingredients, as well as the cost. Standard technical guides such as COSMOS and NATRUE (The International Natural and Organic Cosmetics Organisation) that maintain lists of permitted preservatives for natural and organic cosmetics, are therefore, merely helpful in providing a list of the ingredients that could possibly be used.
The prior art is replete with examples of various strategies focused on developing effective preservative systems. Zemea® Propanediol, produced through a proprietary fermentation process using plant-derived glucose instead of petroleum-based feedstock, serves as a preservative-boosting humectant. Its exceptional performance extends across various industries including cosmetics, personal care, food, laundry, household cleaning products, pharmaceuticals, and dietary supplements. Studies, such as those conducted by Pinto et al., Scientific Reports volume 11, Article number: 8695 (2021) have explored the impact of commonly used cosmetic preservatives on skin resident microflora dynamics. In their research, a variety of preservatives were tested in different combinations, including sodium benzoate, phenoxyethanol, ethylhexylglycerin, gluconolactone, hydroxyacetophenone, phenylpropanol, propanediol, caprylyl glycol, tocopherol, sodium anisate, 1,2-hexanediol, tetrasodium glutamate diacetate, benzyl alcohol, benzoic acid, dehydroacetic acid, o-cymen-5-ol, PPG-3 benzyl ether myristate, tropolone, levulinic acid, sodium levulinate, ammonium acryloyldimethyltaurate/vp copolymer, and potassium sorbate, with suggested percentages of usage, wherein Zemea® Propanediol level was varied from 0-6%. The combinations containing hydroxyacetophenone, phenylpropanol, propanediol, caprylyl glycol, tocopherol, and tetrasodium glutamate diacetate were identified as the most effective for restoring pre-existing dysbiosis. These combinations demonstrated moderate inhibition of C. acnes and strong inhibition of S. aureus without simultaneously inhibiting the growth of S. epidermidis. Further, the Cosmetic Toiletry and Fragrance Association (CTFA) Preservative Challenge Testing has validated that Zemea® Propanediol enhances the efficacy of preservatives in formulations, underscoring its value as a versatile ingredient in cosmetic and personal care products.
Geogard® ECT is a broad-spectrum preservative blend developed for cosmetics and personal care products. It is composed of benzyl alcohol, salicylic acid, glycerin, and sorbic acid. Geogard® ECT is reported to be effective against bacteria, yeast and mold, providing protection and stability to a variety of formulations. It is considered a natural preservative and is often used in products that aim to avoid traditional synthetic preservatives. Benzyl alcohol serves as a preservative in over 500 formulations, spanning injections, topical, oral, and otic applications. However, it carries several disadvantages when used in skincare products, such as potential skin irritation and limited long-term preservative efficacy. Notably, its use in neonates is cautioned against, and in children older than four weeks it should be administered with care. This caution arises from the risk that accumulation of benzyl alcohol metabolites, notably benzoic acid, could surpass the detoxification capacity of immature liver and kidneys.
WO2011028110A1 describes a composition containing between 0.5% and 30% by weight of salicylic acid and/or a physiologically acceptable ester or salt, along with at least one physiologically acceptable C1-C4 alkyl ester of a carboxylic acid as a carrier. This composition has shown improved efficacy in addressing various skin conditions such as acne, warts, corns and calluses, psoriasis, and keratosis pilaris. The effectiveness of the blend stems from the skin-softening properties of salicylic acid, which are further enhanced by the inclusion of the C1-C4 alkyl ester of a carboxylic acid as a carrier, facilitating deeper penetration of salicylic acid or its derivatives into the skin. Notably, the document does not suggest the use of salicylic acid or lactic acid as preservative, but underscores the enhanced skin softening effect achieved through the combination of salicylic acid and a C1-C4 ester of a carboxylic acid, preferably lactic acid.
CN116183829A discusses a humectant comprising either one or a combination of at least two of the following: 1,3-propanediol, glycerol, butanediol, methyl propanediol, lactic acid, sodium lactate, mannose, sorbitol, or trehalose. Specifically, the combinations include 1,3-propanediol and glycerol, glycerol and butanediol, or lactic acid and sodium lactate, among others. Ideally, the mass fraction of the humectant in the aqueous solution ranges from 1% to 10%. Nothing herein teaches, motivates or suggests the use of the combination as a preservative for use in skincare compositions. Further, while it discloses the use of a combination of lactic acid and sodium lactate, there is no teaching on the use of lactic acid without the salt thereof.
While websites such as www.Surfachem.com and www.happi.com disclose a preservative composition of Lactic acid, salicylic acid, triethylene glycol and 1,3-Propanediol (Saliguard LAS), only qualitative aspects of the composition have been described. The quantitative details of such a combination are unknown, and so is the utility and efficacy of such a combination or blend. In the absence of additional details, it is difficult to come up with a quantitative composition with superior preservative properties, and therefore the use of such a blend in skincare products. In fact, significant experimentation would be required to decide the quantities of each of the components to be used in order to obtain meaningful preservative efficacy, and without any side effects. It is certainly not envisaged or visualised from the qualitative disclosures. The formulation of the preservative blend involves careful consideration of several factors, including the specific product application, pH requirements, microbial susceptibility, and regulatory standards, all of which govern the quantity of each of the components to be used. The precise proportions of each of lactic acid, salicylic acid, triethylene glycol and 1,3-Propanediol must be meticulously determined to ensure maximum efficacy and safety, without compromising product stability and safety of use. The presently claimed preservative blend has been arrived at after significant research to achieve a harmonious balance between safety and efficacy, that surpasses conventional preservative solutions.
There is a constant need for innovative preservatives that are safer and gentler on the skin, are environment friendly, effective over a broad range, and compatible with a variety of formulations. The presently described preservative blend is an innovative approach that not only ensures superior microbial protection, but also addresses consumer need for safer and more efficacious products. It is a promising candidate in the realm of cosmetic preservation, with a focus on efficacy, sustainability and the consumer.
SUMMARY OF THE INVENTION
The present invention discloses a unique preservative blend comprising lactic acid (LA), salicylic acid (SA), triethylene glycol (TEG) and 1,3 propanediol (PDO). This blend demonstrates remarkable effects in inhibiting microbial growth and preserving product integrity.
According to a first aspect of the present invention, there is provided a preservative blend comprising Lactic acid, Salicylic acid, Triethylene glycol; and 1,3-Propanediol wherein the Lactic acid is present in the range of about 5 wt% to about 70 wt%, Salicylic acid is present in the range of about 2.5 wt% to about 25 wt%, Triethylene glycol is present in the range of about 5 wt% to about 50 wt% and 1,3 Propanediol is present in the range of about 5 wt% to about 50 wt% of the total weight of the preservative blend.The unique combination allows formulation of a preservative blend that has a low Minimum Inhibitory Concentration (MIC) against various microorganisms and allows use of low amount of the blend, providing effective preservation of the composition in which it is used.
In yet another aspect of the invention, there is provided a unique aqueous preservative blend comprising LA and SA in the ratio of about 1:1 to about 1:10.
In another aspect of the invention, there is provided a unique aqueous preservative blend comprising LA and SA in the ratio of about 1:1 to about 10:1.
In yet another aspect of the invention, there is provided a unique preservative blend comprising LA and TEG in the ratio of about 1:1 to about 1:10.
In yet another aspect of the invention, there is provided a unique preservative blend comprising LA and TEG in the ratio of about 1:1 to about 10:1.
In yet another aspect of the invention, there is provided a unique preservative blend comprising LA and PDO in the ratio of about 0.1:1 to about 1:10.
In yet another aspect of the invention, there is provided a unique preservative blend comprising LA and PDO in the ratio of about 0.1:1 to about 10:1.
In yet another aspect of the invention, there is provided a unique aqueous preservative blend comprising SA and TEG in the ratio of about 1:1 to about 1:10.
In another aspect of the invention, there is provided a unique aqueous preservative blend comprising SA and TEG in the ratio of about 1:1 to about 10:1.
In yet another aspect of the invention, there is provided a unique aqueous preservative blend comprising TEG and PDO in the ratio of about 1:1 to about 1:10.
In another aspect of the invention, there is provided a unique aqueous preservative blend comprising TEG and PDO in the ratio of about 1:1 to about 10:1.
In yet another aspect of the invention, there is provided a unique aqueous preservative blend wherein the blend comprises Lactic acid: Salicylic acid: Triethylene glycol: 1,3-Propanediol in a ratio of about 4:3:8:5.
In another aspect of the invention, there is provided a unique aqueous preservative blend wherein the pH of the blend ranges from about 5.5 to about 7.0.
In yet another aspect of the invention, there is provided a unique preservative blend having a minimum inhibitory concentration (MIC) less than 0.10 % against at least one Gram-positive bacterium and/ or fungi.
In yet another aspect of the invention, there is provided a unique preservative blend having a minimum inhibitory concentration (MIC) less than 0.10 % against at least one Gram-negative bacterium and/ or fungi.
In another aspect of the invention, there is provided a product comprising a preservative blend wherein the said preservative blend is present in the said product in an amount of about 0.5 wt% to about 2 wt% based on the total weight of the product. The product is selected from cosmetic, pharmaceutical, and personal care products.
DETAILED DESCRIPTION OF THE INVENTION
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
Unless the context indicates otherwise, it is specifically intended that the various features of the invention described herein can be used in any combination.
Moreover, the present invention also contemplates that in some embodiments of the invention, any feature or combination of features set forth herein can be excluded or omitted.
All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety for all purposes.
As used herein, “a,” “an,” or “the” can mean one or more than one.
Furthermore, the term “about,” as used herein, when referring to a measurable value such as an amount of a compound or agent of this invention, dose, time, temperature, and the like, is meant to encompass variations of ±10% of the specified amount.
The term "blend" refers to a mixture or combination of different substances, elements, or components. In various contexts, blending involves the process of combining two or more ingredients, materials or entities to create a unified or homogenous mixture.
The term “carrier” refers to a substance or medium or a combination of known excipients that serves as a base or vehicle for the preservative blend of the present invention.
Minimum Inhibitory Concentration (MIC) refers to the lowest concentration of the preservative blend that inhibits the growth of a microorganism after a specific incubation period.
The term composition(s), product(s), preparation(s) and formulation(s) have been used interchangeably.
The term “sustainable” and “green” have been used together and/or alternatively to indicate the low or no impact on environment, i.e. involving the use of natural products and energy in a way that does not harm the environment.
A preservative blend refers to a mixture of different preservative agents designed to safeguard products against microbial contamination, spoilage, and/or deterioration. In certain instances, the preservative blend may also incorporate a preservative enhancer and/or carrier, which could be either aqueous or organic in nature.
The preservative blend described herein comprises LA, SA, TEG and PDO, with or without a carrier, which effectively addresses the shortcomings of the prior art. This distinctive preservative blend offers several benefits, such as its suitability for inclusion in diverse cosmetic, pharmaceutical and personal care items, while catering to various skin types and age groups. The advantages include broad-spectrum antimicrobial properties of the preservative blend, a low MIC value, compatibility with pH levels suitable for dermatological purposes, and increased consumer appeal. Further, the preservative blend of the present invention has a natural index of 1 as per ISO 16128 standards (Guidelines on technical definitions and criteria for natural and organic cosmetic ingredients and products), and is also compliant with EP and USP standards, thereby qualifying as a sustainable and green preservative blend. Moreover, as discussed above, the quantitative aspect of the preservative blend is truly novel. It is worth emphasizing that the preservative blend has application in cosmetic formulations tailored for sensitive skin conditions such as acne, tanned skin, sun-burnt skin, dry skin, psoriasis, and other types of damaged skin.
Lactic acid, a naturally occurring organic acid, is widely acknowledged for its preservative properties in food. Particularly, its salt form, sodium lactate is preferred as a preservative for a variety of foods. Several sources describe sodium lactate as a versatile additive for flavor preservation and safety in food (for example: https://www.arshinefood.com/Industry-information/sodium-lactate-in-food-a-versatile-additive-for-flavor-preservation-and-safety). Furthermore, the FDA's food additive status list identifies lactic acid as a buffer and neutralizing agent (B&N). It is recognized under the designation Lactic acid - B&N, GRAS/FS - 184.1061, Part 136 for Bakery Products; Part 133 for Cheese; Part 135 for Frozen Desserts; Part 150 for Fruit Butters, Jellies & Preserves; and under animal feed practices - 582.1061. (Source: https://www.fda.gov/food/food-additives-petitions/food-additive-status-list#ftnL). Lactic acid has been used in skincare products for pH adjustment, but there have been no attempts to use it as a primary preservative in these products. Further, it is not typically classified as a preservative for skin preparations by EU and USFDA guidelines. Lactic acid can cause skin irritation due to its acidic nature, necessitating its use alongside humectants in formulations when used as a pH-adjusting agent, so that skin damage is reduced. While the role of lactic acid in pH adjustment and its potential skin benefits like exfoliation and hydration are well-known, careful formulation and testing for safety and efficacy is warranted. One hypothesis regarding the preservative effect of Lactic acid is that it disrupts the microbial cell membrane integrity by interacting with proteins and the lipid bilayer, interfering with cellular functions, and ultimately leading to microbial death or inhibition of growth.
Salicylic acid is a monohydroxy benzoic acid. It is used as a food preservative, a bactericide, and an antiseptic. Salicylic acid is known to be used in the production of other pharmaceuticals, including 4-aminosalicylic acid, sandulpiride, and landetimide (via salethamide). Under 21 CFR 333, Subpart D, salicylic acid is listed as an active ingredient for use in Topical Acne Drug Products, in a concentration range of 0.5-2 percent. However, there is no teaching on use of salicylic acid, alone or in combination with other agents, as a preservative in skincare compositions.
Triethylene glycol (TEG), also known as triglycol, is a low-vapor-pressure liquid higher glycol primarily employed in industrial applications. It demonstrates a remarkably low level of acute toxicity via various exposure routes, including intravenous (iv), intraperitoneal (ip), oral ingestion, dermal contact, and inhalation (both vapor and aerosol). Additionally, it does not elicit primary skin irritation. This compound boasts two hydroxyl groups and two ether linkages, contributing to its notable traits such as high-water solubility, hygroscopic nature, solvent characteristics, and reactivity with various organic substances. Traditionally, it has found application in numerous fields similar to diethylene glycol. However, it is increasingly preferred over diethylene glycol due to its lower toxicity. Triethylene glycol serves as a widely utilized humectant in industries ranging from tobacco, composition cork, textile fibers, paper, leather and adhesives. Furthermore, Triethylene glycol has earned approval in Council Directive 82/229/EEC as a sanctioned softening agent for regenerated cellulose film intended for food contact. The directive permits its usage at levels of up to 27% by weight, calculated on the basis of quantity of anhydrous regenerated cellulose film. However, there are no express teachings in the art on use of triethylene glycol, alone or in combination with other agents, as a preservative in skincare compositions.
1,3-Propanediol is a widely favored ingredient, renowned in cosmetic and skincare formulations. 1,3-propanediol, presenting as a clear, odorless liquid, carries exceptional effectiveness and boasts a cost-effective profile. Its versatility as an emollient and humectant reveals its adaptability, protecting the skin from losing moisture, thereby boosting moisture levels. Furthermore, because of its exceptional solvent properties, other compounds can be added to the formulation with ease, ensuring maximum effectiveness.
It is important to note that 1,3-propanediol and triethylene glycol are not categorized as preservatives or preservation enhancers for skincare products. Instead, they are frequently used in formulations for cosmetics and personal care products as humectants, solvents, and viscosity regulators. But the current inventors have discovered an unanticipated finding that a combination of lactic acid and salicylic acid, along with triethylene glycol and 1,3-propanediol in defined ratios, exhibits a preservation effect that increases stability and efficacy of a formulation. This strategic blend not only reinforces the formula but also establishes a noteworthy alternative in the realm of preservatives within the industry.
The preservative blend of the present disclosure offers several advantages. It is soluble in organic solvents, making it versatile for use in various skincare formulations. A number of products, including those intended for neonates, children, adults, and the elderly, can be made with it since it is free of harmful chemicals such as parabens, methylisothiazolinone, chloro-methylisothiazolinone (MIT-CMIT), phenoxyethanol, and formaldehyde (FA). It is gentler compared to other organic acid-based preservatives, and therefore, can also be used in sensitive and/or damaged skin. The preservative blend is compatible with most ingredients typically used in skincare products, including metal ions. In addition to its preservative function, it serves as a moisturizer and chemical exfoliant, effectively dissolving dead, dry cells on the skin's surface and enhancing texture and tone. Furthermore, it exhibits anti-acne and anti-aging properties. Importantly, it does not alter the color or viscosity of the final formulations and is biodegradable. This innovative preservative blend can be incorporated at any stage of formulation below 60° C, thereby providing ease of manufacturing.
The preservative blend of the present disclosure comprises lactic acid, in the range of about 5 wt% to about 70 wt%, or from about 5 wt% to about 65 wt%, or from about 5 wt% to about 60 wt%, or from about 5 wt% to about 55 wt%, or from about 5 wt% to about 50 wt%, or from about 5 wt% to about 45 wt%, or from about 5 wt% to about 40 wt%, or from about 5 wt% to about 35 wt%, or from about 5 wt% to about 30 wt%, or from about 5 wt% to about 25 wt%, or from about 5 wt% to about 20 wt%, or from about 5 wt% to about 19 wt%, or from about 5 wt% to about 18 wt%, or from about 5 wt% to about 17 wt%, or from about 5 wt% to about 16 wt%, or from about 5 wt% to about 15 wt%, or from about 5 wt% to about 14 wt%, or from about 5 wt% to about 13 wt%, or from about 5 wt% to about 12 wt%, or from about 5 wt% to about 11 wt% , or from about 5 wt% to about 10 wt% based on the total weight of the preservative blend.
The preservative blend of the present disclosure comprises salicylic acid, in the range of about 2.5 wt% to about 25 wt%, or from about 2.5 wt% to about 24 wt%, or from about 2.5 wt% to about 23 wt%, or from about 2.5 wt% to about 22 wt%, or from about 2.5 wt% to about 21 wt%, or from about 2.5 wt% to about 20 wt%, or from about 2.5 wt% to about 19 wt%, or from about 2.5 wt% to about 18 wt%, or from about 2.5 wt% to about 17 wt%, or from about 2.5 wt% to about 16 wt%, or from about 2.5 wt% to about 15 wt%, or from about 2.5 wt% to about 14 wt%, or from about 2.5 wt% to about 13 wt%, or from about 2.5 wt% to about 12wt%, or from about 2.5 wt% to about 11 wt%, or from about 2.5 wt% to about 10 wt%, or from about 2.5 wt% to about 9 wt%, or from about 2.5 wt% to about 8 wt%, or from about 2.5 wt% to about 7 wt%, or from about 2.5 wt% to about 6 wt%, or from about 2.5 wt% to about 5 wt%, or from about 2.5 wt% to about 4 wt%, or from about 2.5 wt% to about 3 wt%, or about 2.6 wt% or about 2.7 wt% or about 2.8 wt% or about 2.9 wt% based on the total weight of the preservative blend.
The preservative blend of the present disclosure comprises triethylene glycol in the range of about 5 wt% to about 50 wt%, or from about 5 wt% to about 45 wt%, or from about 5 wt% to about 40 wt%, or from about 5 wt% to about 35 wt%, or from about 5 wt% to about 30 wt%, or from about 5 wt% to about 25 wt%, or from about 5 wt% to about 20 wt%, or from about 5 wt% to about 15 wt%, or from about 5 wt% to about 10 wt%, or about 9 wt%, or about 9.5 wt%, or about 8.5 wt%, or about 8 wt%, or about 7.5 wt%, or about 7 wt%, or about 6.5 wt%, or about 6 wt%, or about 5.5 wt%, or about 5 wt% based on the total weight of the preservative blend.
The preservative blend of the present disclosure comprises 1,3 propanediol in the range of about 5 wt% to about 50 wt%, or from about 5 wt% to about 45 wt%, or from about 5 wt% to about 40 wt%, or from about 5 wt% to about 35 wt%, or from about 5 wt% to about 30 wt%, or from about 5 wt% to about 25 wt%, or from about 5 wt% to about 20 wt%, or from about 5 wt% to about 15 wt%, or from about 5 wt% to about 10 wt%, or about 9 wt%, or about 9.5 wt%, or about 8.5 wt%, or about 8 wt%, or about 7.5 wt%, or about 7 wt%, or about 6.5 wt%, or about 6 wt%, or about 5.5 wt%, or about 5 wt% based on the total weight of the preservative blend.
The preservative blend of the present disclosure optionally comprises a carrier in a quantity sufficient to make up the volume to 100%. The carrier is preferably organic in nature. Typically, the carrier is a mixture of triethylene glycol and 1,3-propanediol, and helps in providing an effective manner of preparing, storing and using the blend.
One embodiment of the present disclosure provides a unique aqueous preservative blend comprising LA and SA in the ratio of about 1:1 to about 1:10. In another embodiment the aqueous preservative blend comprises LA and SA in the ratio of about 1:1 to about 10:1. In another embodiment the aqueous preservative blend comprises LA and SA in the ratio of about 1:10 to about 10:1.
One embodiment of the present disclosure provides a unique aqueous preservative blend comprising LA and TEG in the ratio of about 1:1 to about 1:10. In another embodiment the aqueous preservative blend comprises LA and TEG in the ratio of about 1:1 to about 10:1. In another embodiment the aqueous preservative blend comprises LA and TEG in the ratio of about 1:10 to about 10:1.
In yet another embodiment of the invention, there is provided a unique preservative blend comprising LA and PDO in the ratio of about 0.1:1 to about 1:10. In another embodiment of the invention, there is provided a unique preservative blend comprising LA and PDO in the ratio of about 0.1:1 to about 10:0.1. In another embodiment of the invention, there is provided a unique preservative blend comprising LA and PDO in the ratio of about 0.1:10 to about 10:0.1.
In yet another embodiment of the invention, there is provided a unique preservative blend comprising SA and TEG in the ratio of about 0.1:1 to about 1:10. In another embodiment of the invention, there is provided a unique preservative blend comprising SA and TEG in the ratio of about 0.1:1 to about 10:0.1. In another embodiment of the invention, there is provided a unique preservative blend comprising SA and TEG in the ratio of about 0.1:10 to about 10:0.1.
In yet another embodiment of the invention, there is provided a unique preservative blend comprising TEG and PDO in the ratio of about 0.1:1 to about 1:10. In another embodiment of the invention, there is provided a unique preservative blend comprising TEG and PDO in the ratio of about 0.1:1 to about 10:0.1. In another embodiment of the invention, there is provided a unique preservative blend comprising TEG and PDO in the ratio of about 0.1:10 to about 10:0.1.
One embodiment of the present disclosure provides a unique preservative blend which is entirely soluble in water and harmonizes well with water-based products.
One embodiment of the present disclosure provides a unique preservative blend comprising LA:SA:TEG:PDO in a ratio of 4:3:8:5 which demonstrates a low MIC, i.e. high potency against diverse organisms, enabling the utilization of minimal amount of the blend for preserving formulations.
In yet another embodiment of the invention, the unique preservative blend of the present disclosure demonstrates a minimum inhibitory concentration (MIC) of less than 0.10 % against at least one Gram-negative bacterium and/or fungi. In yet another embodiment of the invention, the unique preservative blend of the present disclosure demonstrates a minimum inhibitory concentration (MIC) of less than 0.9%, more preferably less than 0.8%, more preferably less than 0.7%, more preferably less than 0.6%, more preferably less than 0.5% against at least one Gram-positive bacterium and/or fungi.
In yet another embodiment of the present invention, a unique preservative blend demonstrates a minimum inhibitory concentration (MIC) of less than 0.10 % against at least one Gram-negative bacterium and/or fungi. In yet another embodiment of the invention, the unique preservative blend of the present disclosure demonstrates a minimum inhibitory concentration (MIC) of less than 0.9%, more preferably less than 0.8%, more preferably less than 0.7%, more preferably less than 0.6%, more preferably less than 0.5% against at least one Gram-negative bacterium and/or fungi.
The unique preservative blend of the current disclosure performs a role beyond preserving the composition in which it is used – it contributes to pH regulation, enhances stability of the formulation and promotes a desirable cosmetic elegance.
In one embodiment of the invention, the aqueous preservative blend is formulated for inclusion in cosmetic preparations, encompassing, but not limited to, skincare products, hair care products, color cosmetics, fragrances, and personal care products. It must be noted that skincare products encompass a range of items including, but not limited to, lotion, cream, gel, ointment, scrubs and the like. Examples extend to facial cleansers, moisturizers, sunscreens, serums, toners, exfoliants and similar formulations. More particularly, skincare products suitable for sensitive skin conditions such as acne, tanned skin, sun-burnt skin, dry skin, psoriasis, and other types of skin damage, can be prepared using the preservative blend of the present disclosure without any concern of skin irritation and/or damage.
In yet another embodiment of the present invention, hair care products that can use the preservative blend of the present disclosure encompass a range of items including, but not limited to, shampoo, conditioner, serum, hair sprays, mousses, styling gels, putties, pomades, oils, hair coloring agents and similar formulations.
In yet another embodiment of the present invention, color cosmetics that can use the preservative blend of the present disclosure encompass a range of items including, but not limited to, lipsticks, lip gloss, blush, eye shadow, eye liner, mascara, nail polish, gloss, and products related to nail care and similar formulations.
In yet another embodiment of the present invention, fragrances that can use the preservative blend of the present disclosure encompass a range of items including, but not limited to, perfumes, colognes, body splashes, body sprays which are aerosol versions of colognes, and similar formulations.
In yet another embodiment of the invention personal care products that can use the preservative blend of the present disclosure encompass a range of items including, but not limited to, tooth paste, shaving products, mouthwash, hand wash, whitening products, deodorants and anti-perspirants and similar formulations.
In yet another embodiment of the invention, the unique preservative blend of the present disclosure is formulated for inclusion in liquid dosage forms encompassing, but not limited to solutions, suspensions, elixirs, syrups and similar formulations. In yet another embodiment of the present invention, the unique preservative blend is formulated for inclusion in semisolid dosage forms encompassing, but not limited to creams, gels, ointments, pastes, lotions, and similar formulations.
In one embodiment of the present invention, the unique preservative blend is formulated for inclusion in personal care products encompassing, but not limited to, personal hygiene products like hand sanitizers, wet wipes, feminine hygiene products (tampons, pads, menstrual cups), intimate washes and similar formulations.
In one embodiment of the present invention, the unique preservative blend is formulated for inclusion in personal care products encompassing, but not limited to, oral care products like toothpaste, mouthwash, dental floss, teeth whitening products, breath fresheners and similar formulations.
In one embodiment of the present invention, the unique preservative blend is formulated for inclusion in personal care products encompassing, but not limited to, body care products like body washes, soaps, body lotions, body scrubs, deodorants, antiperspirants and similar formulations.
In one embodiment of the present invention, the unique preservative blend is formulated for inclusion in the range of about 0.05 wt% to about 5 wt%, or from about 0.05 wt% to about 4.5 wt%, or from about 0.05 wt% to about 4 wt%, or from about 0.05 wt% to about 3.5 wt%, or from about 0.05 wt% to about 3 wt%, or from about 0.05 wt% to about 2.5 wt%, or from about 0.05 wt% to about 2 wt%, or from about 0.05 wt% to about 1.5 wt%, or from about 0.05 wt% to about 1 wt%, or about 0.9 wt%, or about 0.8 wt%, or about 0.7 wt%, or about 0.6 wt%, or about 0.5 wt% calculated based on the total weight of the final preparation. Such preparations include, but are not limited to, cosmetic, pharmaceutical, and personal care formulations, as described above.
The present disclosure is further illustrated by reference to the following examples which have been included for illustrative purposes only, and are not intended to impose any limitations on the scope of the present disclosure.

EXAMPLES
Example 1
Table 1
Ingredient Quantity (%)
Lactic acid 20
Salicylic acid 15
Triethylene glycol 40
1,3-propanediol 25

The ingredients were weighed in the indicated quantity and salicyclic acid and triethylene glycol were mixed to obtain the blend by heating at 50oC for 10 minutes. 1,3-propanediol was then added to this mixture and mixed under heating for 5 minutes. Lactic acid was finally added and mixed well to obtain a clear solution.

Example 2
The anti-microbial properties of the preservative blend of Example 1 were tested against various organisms. Standard tests for preservative effectiveness, as outlined in USP Chapter <51> "Antimicrobial Effectiveness Test," were conducted to assess the ability of the blend to control microbial growth over a one-month duration. Table 2 below provides data for the same at different pH conditions, at day 14 and day 28 of the test.
Table 2
pH Test interval E. coli ATCC 8739 (CFU/mL) P.aeruginosa ATCC 9027
(CFU/mL) S. aureus ATCC 6538
(CFU/mL) C.albicans ATCC 10231
(CFU/mL) A. niger ATCC 16404
(CFU/mL)
3.0 14th day <10 <10 <10 <10 <10
28th day <10 <10 <10 <10 <10
6.5 14th day <10 <10 <10 1.1 x 103 1.95 x 105
28th day <10 <10 <10 <10 5.9 x 104

8.0 14th day <10 <10 <10 <10 1.2 x 105

28th day <10 <10 <10 <10 4.6 x 104

Table 2 illustrates that the concentration of each microorganism remained below 10 CFU/mL at pH 3 on both day 14 and day 28, indicating the effective inhibition of microbes by the preservative blend. The reduction in microbial count of A. niger from 1.95 x 105 to 5.9 x 104 at pH 6.5, and from 1.2 x 105 to 4.6 x 104 at pH 8, signifies a significant decrease in microbial population. A CFU/mL count below 10 indicates minimal viable microorganisms in the sample, suggesting that the preservative blend effectively hinders the growth of tested microbes, regardless of pH conditions and duration. Furthermore, the log reduction in the microbial count of C. albicans at pH 6.5 is approximately 5.30, whereas for A. niger it stands at 1.54, while the log reduction of C. albicans at pH 8.0 is approximately 5.27, whereas for A. niger it stands at 1.64, suggesting effectiveness of the blend over a wide pH range.
Determination of Minimum Inhibitory Concentration (MIC)
The Minimum Inhibitory Concentration was determined by using 96 well method. The preservative blend was prepared in different dilutions. The fungal and bacterial agents were inoculated in the nutrient media. The different dilutions of the blend were then transferred into the 96- well microtiter plate and inoculated with bacteria and fungus as shown in Table 3 and incubated for 18-24 hours at 37 degrees Celsius. Post incubation the MIC was determined by any known detection method, such as colorimetric method or spectrophotometer, to determine the turbidity of the solutions incubated. The lowest concentration of the blend that was capable of inhibiting the bacterial and fungal growth was determined as the minimum inhibitory concentration.
Table 3 below provides comparative data on the Minimum Inhibitory concentration (MIC) of the preservative blend of Example 1 vs conventionally used preservatives against various microorganisms.
Table 3
Preservative
Test Microbe Preservative blend Phenoxyethanol Benzyl Alcohol Sodium Benzoate Potassium Sorbate
S. aureus ATCC 6538 0.5% 0.8% 0.025% 0.2% 0.5%
S.epidermidis ATCC 12228 0.5% 0.3% 0.3% 0.5% 0.4%
E. coli ATTC 8739 0.5% 0.3% 0.2% 0.1% 0.1%
P. aeruginosa ATCC 9027 0.5% 0.3% 0.2% 0.5% 0.6%
C. albicans ATCC 10231 0.5% 0.5% 0.2% 0.2% 0.3%
A.brasiliensis ATCC 16404 0.5% 0.3% 0.5% 0.2% 0.5%

Table 3 indicates that the preservative blend of Example 1 is comparable to some of the conventionally used preservatives against all types of microbes, and is in fact more potent than Phenoxyethanol and potassium sorbate. As discussed in the specification above, the preservative blend of Example 1 has advantages in that it is suitable for sensitive skin, is water miscible and water soluble, and can be used in various cosmetic products.
Example 3
3.1 Face Cream
Table 4 describes a face cream cosmetic formulation comprising the preservative blend of Example 1, used in an amount of 0.7% by total weight of the formulation. The cream is used to provide smooth and supple skin texture. The cream has a milky white appearance with a pH of 5.5.
To formulate the face cream, ingredients listed in phase A of Table 4 were weighed in a main vessel and heated upto about 700C. Thereafter, phase B ingredients were weighed in another vessel and heated upto about 700C. Phase B ingredients were then added to Phase A ingredients with continuous mixing using a stirrer, such as a magnetic stirrer, to obtain a mixture. Phase C ingredients, maintained at a temperature of about 400C, were then added to the final mixture to obtain the face cream formulation.
Table 4
Phase Ingredients Quantity (%)

A Cetostearyl Alcohol 3
Hexadecanoic acid 3
Glycol Distearate 3
Steareth 2 3
Sunflower Oil 3
Glycol Monostearate 3
Ethylene Glycol Monostearate 3
Cetearyl Olivate 3
Ceteareth-6 Olivate 3

B Allantoin 0.5
Disodium EDTA 0.05
Water Q.S 100%
Sodium PCA 1
C Preservative blend of Example 1 0.7

The antimicrobial effectiveness test of the face cream formulation was conducted using the challenge test in accordance with United States Pharmacopoeia General Chapter 51. The test employed 3 bacteria and 2 fungi for testing the efficacy of the face cream. Each of the microorganisms were selected such that they represent a wide range of microbial physiologies.
The preservative blend added product was separated out into 5 containers, each being challenged with one of the 5 method-specified microorganisms (S. aureus ATCC 6538, E. coli ATCC 8739, P. aeruginosa ATCC 9027, C. albicans ATCC 10231, S. epidermidis ATCC 12228 and A. niger ATCC 16404) at a concentration of >1×105CFU/g or ml. The initial concentration of each microorganism was determined by inoculating a control substance and using standard dilution and plating techniques. The inoculated product was held at room temperature for a period of no less than 28 days. The blend was then evaluated at specific intervals within the 28-day period. At each contact time, the inoculated blend was chemically neutralized and plated using standard dilution and plating techniques. After 48 hours of incubation, surviving microorganisms were counted, and the log reduction of each microorganism at each interval was reported.
The effectiveness of the preservative system was determined based on the USP <51> passing criteria, and the results are mentioned in Table 5 below.
Table 5

The face cream of Example 3.1 containing the preservative blend of Example 1 demonstrated a log reduction exceeding 2 for all microbial types on day14 and day 28. In fact, it surpassed a log reduction value of 5.41. These results indicate a robust antimicrobial efficacy of the preservative blend.
3.2 Liquid Face Wash
Table 7 describes a face wash cosmetic formulation comprising the preservative blend of Example 1 in an amount of 0.7% by total weight of the formulation.
Table 7
Phase Ingredients Quantity (%)

A Water To Make 100
N-Butyl Resorcinol 1
Allantoin 0.5
1,3-Propanediol, Glycerine 1
Disodium EDTA 0.05
Sodium Ascorbyl Phosphate 0.2
Sodium Pyrrolidone Carboxylate 1

B Kaolin 0.5
Sodium Laureth Sulphate, Cocamidopropyl Betaine, Glycol Stearate and Cocamide MEA 30
Saliguard LAS 0.7

C Colour Q.s
Fragrance Q.s

The components of phase A were weighed and taken in a vessel, followed by heating and mixing at 65oC. This was followed by addition of components of phase B to the vessel. Finally, color and fragrance was added to the mix.
The preservative challenge test was conducted in accordance with United States Pharmacopoeia General Chapter 51 for the liquid face wash composition of Example 3.2, and the results are included in Table 8 below.
Table 8

The face wash containing the preservative blend of Example 1 demonstrated a log reduction exceeding 2 for all microbial types. In fact, it surpassed a log reduction value of 5.38, indicating a robust antimicrobial efficacy of the preservative blend.

3.3 Face Toner
Table 9 describes an alcohol free face toner comprising the preservative blend of Example 1 in an amount of 2% by total weight of the formulation.
Table 9
Phase Ingredients Quantity (%)

A

Water To Make 100
Allantoin 0.5
Disodium EDTA 0.05
Sodium Ascorbyl Phosphate 0.5
N-Butyl Resorcinol 0.3
Dimethyl Isosorbide 0.5
Sodium PCA 1
1,3-propanediol, Glycerin 2
Glycerine 2
B Saliguard LAS 2
Propylene Glycol 3

The components of phase A were weighed, taken in a vessel and mixed well.. The weighed components of phase B were then added to this mix.
The preservative challenge test was conducted in accordance with United States Pharmacopoeia General Chapter 51 for the face toner composition of Example 3.3, and the results are included in Table 10 below.

Table 10

The body lotion containing the preservative blend of Example 1 demonstrated a log reduction exceeding 2 for all microbial types. In fact, it surpassed a log reduction value of 5.40, indicating a robust antimicrobial efficacy of the preservative blend as per the standards outlined in the USP General Chapter 51.
, C , Claims:We claim:
1. A preservative blend comprising
(i) Lactic acid,
(ii) Salicylic acid,
(iii) Triethylene glycol; and
(iv) 1,3-Propanediol
wherein the Lactic acid is present in the range of about 5 wt% to about 70 wt%, Salicylic acid is present in the range of about 2.5 wt% to about 25 wt%, Triethylene glycol is present in the range of about 5 wt% to about 50 wt% and 1,3 Propanediol is present in the range of about 5 wt% to about 50 wt% of the total weight of the preservative blend.
2. The preservative blend as claimed in claim 1 wherein the pH of the blend ranges from about 5.5 to about 7.0.
3. The preservative blend as claimed in claim 1, wherein the blend comprises Lactic acid: Salicylic acid: Triethylene glycol: 1,3-Propanediol in a ratio of about 4:3:8:5.
4. The preservative blend as claimed in claim 1, wherein the minimum inhibitory concentration of the blend is less than 0.10 % against at least one Gram-positive bacterium, Gram-negative bacterium and/or fungi.
5. A product comprising a preservative blend as claimed in claim 1, wherein the said preservative blend is present in the said product in an amount of about 0.5 wt% to about 2 wt% based on the total weight of the product.
6. The product as claimed in claim 5, wherein the product is selected from cosmetic, pharmaceutical, and personal care products.