Description:Field of the Invention
The present invention discloses a novel preservative blend comprising a combination of Lactic Acid, Triethylene Glycol and Undecylenic Acid. This blend not only serves as an effective preservative but also acts as a permeation enhancer in topical formulations. The preservative blend has broad industrial applications across various cosmetic, pharmaceutical and personal care products, providing a safer and more efficacious alternative to conventional preservatives.
Background of the Invention
Inadequately preserved personal care products pose severe risks, including skin irritation, infections, blindness, and even fatalities. A notable incident occurred in 2006 at a Barcelona hospital, where five intensive-care patients contracted life-threatening infections from Burkholderia cepacia. Investigations linked the infections to a moisturizing body milk used in patient care. The bacterium was found in unopened bottles of the body milk, highlighting the critical importance of proper product preservation.
The term "preservative" encompasses substances used to inhibit microbial growth in products like food, medications, and personal hygiene items. Whether natural or artificial, they protect against contamination and spoiling, maintaining product integrity. Preservatives are crucial for extending shelf life, especially in aqueous products. Anhydrous products, such as lip balms, don't need preservatives, but those prone to water exposure, and those containing water, like body scrubs, require broad-spectrum preservatives.
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 contributes to environmental pollution. Also, conventional preservatives like phenoxyethanol have not been found suitable for sensitive skin due to redness, itching and/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 in the product, potentially leading to skin irritation and sensitization. Additionally, the overpowering aroma renders them unsuitable for cosmetics. Vitamin E, often mistaken as a preservative, functions as an antioxidant, preventing oils from becoming rancid, but offers 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, and which is effective over a broad range of organisms.
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.
Cosmile Europe (https://cosmileeurope.eu/inci/detail/16724/undecylenic-acid/) recognizes Undecylenic acid as a versatile ingredient in cosmetic products, serving various functions including antimicrobial, preservative, surfactant-cleansing/emulsifying, and fragrance. It is also known for treating fungal diseases. However, the site does not disclose its use and/or its effects when used with other preservatives, nor does it provide information regarding the quantity of undecylenic acid to be used for use as a preservative.
JP2000204039 discloses a cosmetic formulation suitable for sensitive skin, containing pentanediol and undecylenic acid monoglyceride, with antiseptic effect against Escherichia coli and/or bacteria of the genus Pseudomonas. The disclosed usage of pentanediol is between 1 to 10% by weight, with a preferred range of 2 to 5% by weight. Further, the preferred content of Undecylenic acid monoglyceride is specified to be between 0.1 to 5% by weight, with an optimal range of 0.3 to 3% by weight. This precise range is disclosed to be crucial as insufficient amounts may compromise the antiseptic effect, while excessive amounts may lead to a plateau in effectiveness, potentially hindering the flexibility of other ingredients in the formulation. However, nothing herein discloses the specific combination of agents beings used as the preservative blend with superior properties.
JP2002114669 pertains to a skin cleanser composition having exceptional antibacterial qualities against Trichophyton, Propionibacterium acnes, Pityrosporum ovale, or the like, while causing minimal skin irritation. The invention offers a remarkable antibacterial product that combines Photosensor No. 201 with one or more ingredients selected from undecylenic acid, its salts, and derivatives, and hinokitiol or its salts, respectively. Hinikitiol is a natural tropolone derivative compound and an essential oil component first identified in the heartwood of cupressaceous plants. The composition was found to provide a rapid improvement in common skin illnesses. While this reference discloses combination of undecylenic acid with hinokitiol, there is no teaching, suggestion or motivation to use undecylenic acid in combination with other agents as preservatives in skincare products.
CN116183829A discusses a method for testing moisturizing effect of cosmetic raw materials. The reference discloses 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. While use of the one or more components is disclosed as humectant, there is no disclosure about using these as preservative.
While websites such as www.Surfachem.com and www.happi.com disclose a preservative composition of lactic acid, triethylene glycol and undecylenic acid (Saliguard LAU), only qualitative aspects of the composition have been described. The quantitative details of such a combination are unknown, and so is the efficacy of such a combination or blend. In the absence of quantitative composition, it is difficult to predict the properties, and therefore the use of such a blend. 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. It is certainly not envisaged or visualised from the qualitative disclosures on these sites. 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 lactic acid, triethylene glycol and undecylenic acid must be meticulously determined to ensure maximum efficacy and safety, without compromising product stability and safety of use. The presently described preservative blend has been arrived at after significant research to achieve a harmonious balance between safety and efficacy, that surpasses conventional preservative solutions.
There exists a continuous demand for new preservatives that enhance antimicrobial effectiveness while maintaining stability and compatibility within diverse formulations. Moreover, there is a growing requirement for preservatives that are not only safe and gentle on the skin but also environmentally friendly, effective, and adaptable to various formulations. The preservative blend described herein presents a novel solution, addressing both, the need for superior microbial protection and the consumer's desire for safer and more effective products.
SUMMARY OF THE INVENTION
The present invention discloses a unique preservative blend comprising lactic acid (LA), triethylene glycol (TEG) and undecylenic acid (UA). 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, Triethylene Glycol; and Undecylenic Acid, wherein Lactic acid is present in the range of about 5 wt% to about 70 wt%, Triethylene Glycol is present in the range of about 5 wt% to about 70 wt% and Undecylenic Acid or a pharmaceutically acceptable salt thereof is present in the range of about 0.5 wt% to about 30 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, thereby allowing use of low amount of the blend for providing effective preservation of the composition in which it is used.

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 another aspect of the invention, there is provided a unique preservative blend comprising LA and TEG in the ratio of about 0.1:1 to about 10:1.
In yet another aspect of the invention, there is provided a unique preservative blend comprising LA and UA 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 UA 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 TEG and UA 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 TEG and UA in the ratio of about 1:1 to about 10:1.
In another aspect of the invention, there is provided a unique preservative blend, wherein the blend comprises Lactic acid: Triethylene glycol: Undecylenic acid in a ratio of about 8:9:3.

In yet another aspect of the invention, there is provided a unique 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 herein 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 homogeneous 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.
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 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.
The preservative blend described herein comprises LA, TEG and UA, 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, 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 novel and innovative. 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.
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, to 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 the 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.
Undecylenic acid or Undecylenate is a naturally occurring unsaturated fatty acid derived from castor oil or coconut oil. It is also found naturally in the human sweat. It is used as a precursor in the manufacture of aromatic chemicals, polymers and modified silicones. Salts of undecylenate are found in topical over-the-counter or combination products as antifungal agents. Zinc undecylenate is an example of a topical antifungal agent that treats skin infections such as athlete’s foot and relieves itching, burning, and irritation associated with the skin condition. Undecylenic acid works by disrupting the cell membranes of fungi, leading to their death or inhibition of growth. It is often formulated into creams, powders, and solutions for application to the skin or nails affected by fungal infections. Undecylenic acid is generally regarded as safe and is approved by regulatory authorities for use in various over-the-counter antifungal products.
Without wanting to be bound to any theory, the present inventors believe that Lactic acid disrupts bacterial cell membranes, causing protein disruption and loss of chemiosmotic control, leading to cell death. Triethylene glycol reduces water activity and dissolves bacterial cell wall proteins. Undecylenic acid disrupts both bacterial and fungal cell membranes, inhibiting enzymatic activity and their ability to replicate and divide, thus inhibiting bacterial and fungal growth. Thus, the blend of lactic acid, triethylene glycol and undecylenic acid presents a comprehensive approach against microorganisms. When carefully combined in optimal proportions, they form a preservative system with heightened efficacy suitable for various formulations, including cosmetics, pharmaceuticals and personal care products.
The preservative blends discussed offer a multitude of benefits for skincare formulations. They are soluble in organic solvents, providing versatility across various skincare products. A number of products, including those intended for neonates, children, adults and the elderly, can be made with the preservative blend of the present invention since it is free of harmful chemicals such as parabens, methylisothiazolinone, chloro-methylisothiazolinone (MIT-CMIT), phenoxyethanol, and formaldehyde-releasing agents. The blend serves not only as preservative but also as moisturizer and chemical exfoliant, enhancing skin texture and tone while exhibiting anti-acne and anti-aging properties. Importantly, the blend does not compromise the color or viscosity of formulations, remaining biodegradable and compatible with most ingredients, including metal ions. The innovative preservative blend is gentle yet a potent blend comprising undecylenic acid and lactic acid, offering natural alternatives to synthetic preservatives. The blend is particularly effective as a phenoxyethanol-free formulation for anti-acne, anti-aging, and scalp care products. Adhering to EP and ISO standards, the blend can be added at any phase of formulation, at a temperature below 60°C, with prototypes maintaining a desired pH below 6.5, reflecting sustainability through the use of biodegradable ingredients.
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 triethylene glycol 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 undecylenic acid in the range of about 0.5 wt% to about 30 wt%, or from about 0.5 wt% to about 25 wt%, or from about 0.5 wt% to about 20 wt%, or from about 0.5 wt% to about 19 wt%, or from about 0.5 wt% to about 18 wt%, or from about 0.5 wt% to about 17 wt%, or from about 0.5 wt% to about 16 wt%, or from about 0.5 wt% to about 15 wt%, or about 14 wt%, or about 13 wt%, or about 12 wt%, or about 11 wt%, or about 10 wt%, or about 9 wt%, or about 8 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.
One embodiment of the present disclosure provides a unique preservative blend comprising LA and TEG in the ratio of about 1:1 to about 1:10. In another embodiment the preservative blend comprises LA and TEG in the ratio of about 0.1:1 to about 10:1. In another embodiment the preservative blend comprises LA and TEG in the ratio of about 1:10 to about 10:1.
One embodiment of the present disclosure provides a unique preservative blend comprising LA and UA in the ratio of about 1:1 to about 1:10. In another embodiment the preservative blend comprises LA and UA in the ratio of about 1:1 to about 10:1. In another embodiment the preservative blend comprises LA and TEG in the ratio of about 1:10 to about 10:1.
One embodiment of the present disclosure provides a unique preservative blend comprising TEG and UA in the ratio of about 1:1 to about 1:10. In another embodiment the preservative blend comprises TEG and UA in the ratio of about 1:1 to about 10:1. In another embodiment the preservative blend comprises LA and TEG in the ratio of about 1:10 to about 10:1.
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 which is entirely soluble in organic solvent and harmonizes well with non-aqueous products.
One embodiment of the present disclosure provides a unique preservative blend comprising LA:TEG:UA in 8:9:3 ratio which demonstrates a low MIC against diverse organisms, enabling the utilization of minimal amounts of the blend for preserving formulations, thereby highlighting its potency.
In yet another embodiment of the invention, the unique preservative blend demonstrates a minimum inhibitory concentration (MIC) of less than 0.10% against at least one Gram-negative bacterium. In yet another embodiment of the invention, the unique preservative blend 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.
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.
In yet another embodiment of the invention, skin care 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, skin care products suitable for sensitive skin conditions such as acne, tanned skin, dry skin, sun-burnt skin, psoriasis, and other types of damage, can be prepared using the preservative blend of the present disclosure.
In yet another embodiment of the 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 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 all products related to nail care and similar formulations.
In yet another embodiment of the 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 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 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 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 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 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%, or about 0.4 wt%, or about 0.3 wt%, or about 0.2 wt%, or about 0.1 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 described above.
The present disclosure is further illustrated by reference to the following examples which is for illustrative purposes only, and not intended to impose any limitations on the scope of the present disclosure.

EXAMPLES
Example 1
Table 1
Ingredient Quantity (%)
Lactic acid 40
Undecylenic Acid 15
Triethylene glycol 45

Triethylene glycol and undecylenic acid were weighed and mixed first for about 5 to 10 minutes. The lactic acid was then weighed and added to this mix to obtain the blend.

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 <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 8.7 x 102 1.4 x 105
28th day <10 <10 <10 <10 4.0 x 104

8.0 14th day <10 <10 <10 <10 6.8 x 104

28th day <10 <10 <10 <10 2.2 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 1.4 x 105 to 4.0 x 104 at pH 6.5, and from 6.8 x 104 to 2.2 x 104 at pH 8, from day 14 to day 28 , 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 5.29, whereas for A. niger it stands at 1.68. Comparatively, the log reduction of C. albicans at pH 8.0 is approximately 5.33, whereas for A. niger it stands at 1.98, suggesting effectiveness of the blend over a broad 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 0.3% 0.8% 0.025% 0.2% 0.5%
E. coli ATTC 8739 0.3% 0.3% 0.2% 0.1% 0.1%
P. aeruginosa ATCC 9027 0.3% 0.3% 0.2% 0.5% 0.6%
C. albicans ATCC 10231 0.3% 0.5% 0.2% 0.2% 0.3%
A.brasiliensis ATCC 16404 0.7% 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 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 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
Stearth 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 preservative blend of Example 1. 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 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 blend was held at room temperature for a period of no less than 28 days. The product was then evaluated at specific intervals within the 28-day period. At each contact time, the inoculated product 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 5.38. These results indicate a robust antimicrobial efficacy of the preservative blend as per the standards outlined in the USP General Chapter 51.
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

C Colour Q.s
Fragrance Q.s
Saliguard LAU 0.7

The weighed quantities of components of phase A were taken in a vessel and heated to 65oC, and mixed. The components of phase B were then added to this mix. Finally, components of phase C were added to obtain the blend.
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 5.43, indicating a robust antimicrobial efficacy of the preservative blend, as per the standards outlined in the USP General Chapter 51.
Table 9 describes a face wash cosmetic formulation comprising the preservative blend of Example 1 in an amount of 1.2% by total weight of the formulation.
Table 9
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
Kaolin 0.5
B
Sodium Laureth Sulphate (and) Cocamidopropyl Betaine (and) Glycol Stearate (and) Cocamide MEA 30
Saliguard LAU 1.2
C Colour Qs
Fragrance Qs

The weighed quantities of components of phase A were taken in a vessel and heated to 65oC, and mixed. The components of phase B were then added to this mix. Finally, components of phase C were added to obtain the blend.
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 10 below.

Table 10

The face wash containing 1.2% of 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 5.39, indicating a robust antimicrobial efficacy of the preservative blend, as per the standards outlined in the USP General Chapter 51.

, Claims:1. A preservative blend comprising
(i) Lactic Acid,
(ii) Triethylene Glycol; and
(iii) Undecylenic Acid,
wherein Lactic acid is present in the range of about 5 wt% to about 70 wt%, Triethylene Glycol is present in the range of about 5 wt% to about 70 wt% and Undecylenic Acid or a pharmaceutically acceptable salt thereof is present in the range of about 0.5 wt% to about 30 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: Triethylene glycol: Undecylenic acid in a ratio of about 8:9:3.
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.