Description:Field of the Invention
The present invention relates to a preservative blend comprising lactic acid, 1,2 hexanediol, and gluconolactone, 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 use, like body scrubs and cleansing balms, 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 contributes 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 without preservatives altogether.
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 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.
To this day there is no official regulatory definition for natural and organic cosmetics. There are private standards, but they need to mention that the baseline requirement is that products must 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 on organic production and labelling of organic products. Further, the production of natural cosmetics 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 development, 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. 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 guidance for selection of the ingredients.
The prior art is replete with examples of various strategies focused on developing effective preservative systems.
US20080139672A1 discloses advanced or synergistic preservative systems designed for use in topical compositions, including cosmetic and dermatological formulations, containing (1) 50-90 weight % of oil miscible glycols selected from pentylene glycol, neopentyl glycol, caprylyl glycol, benzyl glycol, 1,2 hexanediol, ethyl hexanediol, or any combinations thereof, and (2) 10-50 weight % of a preservative selected from at least one organic acid, organic acid derivative, inorganic acid, inorganic acid derivative, or any combinations thereof. However, the elevated concentration of oil-miscible glycols in this preservative system may lead to skin irritation, rendering it unsuitable for sensitive skin types, and may also pose environmental concerns. Further, the disclosure is silent about the pH of the preservative blend, and/or its impact on the pH of the final formulation, which is important in view of the impact it can have on various skin types, such as by causing irritation. There is certainly no teaching, motivation or suggestion in this disclosure to use the specific combination being suggested herein, and a person of skill in the art could not have predicted or visualised the amount of each of these components required to provide a synergistic preservative effect without causing sensitisation of the skin.
KR1020090097406 discusses the utilization of a plant extract obtained using 1,2-hexanediol as the solvent for extraction, enabling the formulation of cosmetics suitable for long-term storage without the need for chemical preservatives known to cause irritation. This disclosure certainly does not provide any motivation or suggestion to use 1,2-hexanediol as a component of a preservative blend. Nothing herein discloses the use of the specific preservative blend being claimed herein, and its unique preservation properties.
US20190216085A1 discloses a preservative composition for wet wipes, comprising gluconolactone, a benzoic acid or salt thereof, and a preservative enhancing agent, the preservative enhancing agent comprising a phenolether, an organic acid, or a salt of an organic acid, the organic acid or the salt of an organic acid having a carbon chain length of from about 6 carbon atoms to about 8 carbon atoms, the organic acid or the salt of an organic acid being either cyclic or acyclic. While benzoic acid demonstrates primary effectiveness against yeasts and molds, its efficacy against bacteria is limited, often prompting the need for combination with other preservatives to enhance the antimicrobial action. Further, the performance of benzoic acid relies on pH of the composition, the performance being optimal at pH values below 4.0, thereby restricting its application in skincare products for fear of sensitivity reactions and skin irritation. Further, this reference does not disclose the specific combination being suggested herein for use as a preservative blend, nor does it motivate the use of the specific components being claimed herein.
WO2016162326A1 describes a preservative solution comprising carboxylic acid (0.1 to 35 wt %), which may include lactic acid; alkanediol (40-95 wt %), such as 1,2-hexanediol; and 0.1 to 35 wt % of carboxylic salt. The disclosure emphasizes the simultaneous presence of carboxylic acid and at least one carboxylic salt in the preservative solution. Furthermore, it specifies that the carboxylic acid salt (C6-C9) and carboxylic acid must be present in particular ratios to ensure minimal pH changes in aqueous formulations upon addition of the solutions outlined in the invention. Additionally, it is noteworthy that the invention employs a notably high amount of 1,2-hexanediol. Nothing herein teaches, suggests or motivates a person of skill in the art to use the preservative blend being described and claimed in the present application.
DE10341179A1 discloses the use of hydroxy acids, such as lactic acid, within a total concentration ranging from 0.1 to 10% by weight, and one or more alkane-1,2-diols, such as decane-1,2-diol, within a total concentration of 0.1 to 5% by weight, as an active ingredient in dermatological preparations. Additionally, it discusses formaldehyde donors as preferred preservatives. Notably, the patent does not detail the combination of lactic acid, 1,2-hexanediol, and gluconolactone being described and claimed herein.
While websites such as www.Surfachem.com and www.happi.com disclose a preservative composition of lactic acid, 1,2-hexanediol, and gluconolactone (Saliguard LAG), 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. The formulation of the preservative blend involves careful consideration of several factors, including the specific product application, pH requirements, microbial susceptibility, and regulatory standards. The precise proportions of 1,2-hexanediol, lactic acid, and gluconolactone 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 is a constant need for innovative preservative that is safer and gentler on the skin, that is environment friendly, effective, 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 consumer-centricity.

Summary of the Invention
The present invention discloses a unique preservative blend comprising lactic acid (LA), gluconolactone (GL) and an enhancer. This blend demonstrates remarkable synergistic effects in inhibiting microbial growth and preserving product integrity.
According to a first aspect of the present invention, there is provided a synergistic preservative blend comprising Lactic acid (LA), Gluconolactone (GL) and an enhancer, wherein the Lactic acid is present in an amount of about 5 wt% to about 70 wt%, glucanolactone is present in an amount of about 2.5 wt% to about 20 wt%, and enhancer is present in an amount of about 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 and allows use of low amount of the blend, providing effective preservation of the composition in which it is used.
In another aspect of the present invention, the preservative blend may further contain a suitable carrier.
In yet another aspect of the present invention, the carrier is water.
In another aspect of the invention, the enhancer is selected from a group comprising propanediol and derivatives, 1,2- hexanediol, propylene glycol, decylene glycol, 1,2-pentanediol, 1,5-pentanediol, pentylene glycol, 1,3-propanediol, butanediol and mixtures thereof.
In further aspect of the invention, the enhancer is 1,2-hexanediol.
In yet another aspect of the invention, the pH of the blend ranges from about 5.5 to about 7.0. More preferably pH of the blend is about 6.5.
In another aspect of the invention, there is provided a preservative blend wherein blend comprises Lactic acid: Gluconolactone: 1,2-hexanediol: water in 1:1:1:2 ratio.
In yet another aspect of the invention, there is provided a unique aqueous preservative blend comprising LA and water 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 water 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 HD 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 HD 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 GL 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 GL 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 GL and water in the ratio of about 1:1 to about 1:10.
In yet another aspect of the invention, there is provided a unique aqueous preservative blend comprising GL and water 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 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 an aspect of the invention, there is provided a product comprising the 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.
In another aspect of the invention, 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 “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 "blend", as used herein, 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.
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, GL and HD, optionally with a carrier, which effectively addresses the shortcomings of the prior art. This distinctive preservative blend, particularly in its aqueous form, 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. These advantages include broad-spectrum antimicrobial properties of the preservative blend, demonstrating a low MIC value, compatibility with pH levels suitable for dermatological purposes, and for 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, and therefore qualifies as a sustainable and green preservative blend. Moreover, as discussed above, the innovative aspect of this invention is the quantitative aspect of the preservative blend. It is worth emphasizing that the preservative blend has application in cosmetic formulations tailored for sensitive skin conditions such as acne, tanned 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. The following source describes sodium lactate as a versatile additive for flavor preservation and safety in food: (Source: 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). However, while Lactic acid has been used in skincare products for pH adjustment, there have been no attempts to use it as a primary preservative in these products. 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, so that skin damage is reduced. However, the role of lactic acid in pH adjustment and its potential skin benefits like exfoliation and hydration are well-known, thereby requiring careful formulation and testing for safety and efficacy. 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.
Gluconolactone is a sugar derived polyhydroxy acid. It is a naturally occurring substance found in various fruits, honey, and wine. Gluconolactone is widely used in cosmetic and skincare products for its exfoliating, moisturizing, and antioxidant properties. The use of Gluconolactone in the preservative blend of the current invention is based on the hypothesis that it works by chelating metal ions that are essential for microbial growth, and by maintaining the pH of the formulation within a range that is unfavourable for microbial proliferation. This dual action is expected to help prevent the growth of bacteria, fungi, and other microorganisms in cosmetic products, thus preserving their quality and safety for consumer use.
Hexanediol, particularly, 1,2-Hexanediol is a glycol (with two hydroxy groups on 1 and 2 positions and six carbon atoms), which is a multifunctional ingredient used as a solvent, emollient, moisturizing agent, and preservative in skin and hair care applications. 1,2-Hexanediol in its pure form is nearly devoid of odor, making it well-suited for formulations with minimal or no fragrance. 1,2-Hexanediol acts as a preservative enhancer by effectively penetrating the cell wall of the organism. This characteristic enables the seamless passage of preservatives through pathogen cells, enhancing their germ-killing efficacy. Additionally, 1,2-Hexanediol demonstrates intrinsic antimicrobial properties, further contributing to its ability to combat pathogens. Employed as an emollient, it aids in stabilizing emulsions and facilitating the solubilization of additional active components.
Alternative preservative enhancers that could be used in the preservative blend of the present disclosure include propanediol and its derivatives, propylene glycol, decylene glycol, 1,2-pentanediol, 1,5-pentanediol, pentylene glycol, 1,3-propanediol, and butanediol. These compounds are all soluble in water and facilitate the creation of a transparent aqueous solution, enabling compatibility with diverse water-based formulations. They are easily washable and environmentally sustainable.
The employment of water-soluble solvent like 1,2-hexanediol as a preservative enhancer enables the effective utilization of the blend within the pH spectrum of 5.5-7.0, which is a desirable pH range for skincare compositions that need pH in the neutral to slightly acidic range. In the absence of 1,2-hexanediol (or the penetration enhancer), the blend could potentially have a pH level below 4 due to the presence of lactic acid, thereby making it unsuitable for skincare formulations. The term preservative enhancer and penetration enhancer can be used interchangeably.
The preservative blend of the present disclosure offers several advantages. It is both water-soluble and soluble in organic solvents like ethyl alcohol, 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 paraben, 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. 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, is biodegradable and is compatible with most ingredients including metal ions. This innovative preservative blend can be incorporated at any stage of formulation below 60°C.
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 gluconolactone in the range of 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 1,2 hexanediol in the range of 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 8 wt%, or about 7 wt%, or about 6 wt%, or about 5 wt% based on the total weight of the preservative blend. Generally, the penetration enhancer may be used in the ranges mentioned above.
The preservative blend of the present disclosure comprises a carrier in a quantity sufficient to make up the volume to 100%. The carrier is preferably aqueous in nature. Typically, the carrier is water, 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 water in the ratio of about 1:1 to about 1:10. In another embodiment the aqueous preservative blend comprises LA and water in the ratio of about 1:1 to about 10:1. In another embodiment the aqueous preservative blend comprises LA and water 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 HD in the ratio of about 1:1 to about 0.1:10. In another embodiment of the invention, there is provided a unique preservative blend comprising LA and HD in the ratio of about 1:1 to about 10:0.1. In another embodiment of the invention, there is provided a unique preservative blend comprising LA and HD in the ratio of about 1:10 to about 10:0.1.
In yet another embodiment of the invention, there is provided a unique preservative blend comprising LA and GL in the ratio of about 1:2 to about 0.1:10. In yet another embodiment of the invention, there is provided a unique preservative blend comprising LA and GL in the ratio of about 2:1 to about 10:0.1. In yet another embodiment of the invention, there is provided a unique preservative blend comprising LA and GL in the ratio of about 1:0.1 to about 0.1:1.
In yet another embodiment of the invention, there is provided a unique aqueous preservative blend comprising GL and water in the ratio of about 1:2 to about 0.1:10. In yet another embodiment of the invention, there is provided a unique aqueous preservative blend comprising GL and water in the ratio of about 2:1 to about 10:0.1. In yet another embodiment of the invention, there is provided a unique aqueous preservative blend comprising GL and water in the ratio of about 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:GL:HD:water in 1:1:1:2 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.
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, 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, oil, 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 the other 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, 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% calculated based on the total weight of the final preparation. Such preparations include, but are not limited to, cosmetic, pharmaceutical, and personal care formulations.
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 20
Gluconolactone 20
1,2-hexanediol 20
Water Qs 100

The ingredients were weighed in the indicated quantity and mixed to obtain the blend. Specifically, 20 grams of gluconolactone was mixed with 40ml of water, followed by addition of 20 grams of 1,2- hexanediol to obtain a mixture. To the aforementioned mixture 20 grams of lactic acid was 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 <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 ATCC 16404 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 2.04, whereas for A. niger it stands at 0.52. Comparatively, the log reduction of A. niger at pH 8 is 0.41, suggesting greater effectiveness of the blend at pH 6.5 or lower.
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 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 0.3% 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 0.3% 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. 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 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 70 0C. 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 magnetic stirrer to obtain a mixture. Phase C ingredients, maintained at a temperature of about 40 0C, were then added to the final mixture to obtain the face cream formulation.
Table 4
Phase Ingredients Quantity (%)

A Cetostearyl Alcohol 3
Palmitic Acid 3
Glycol Distearate 3
Steareth 2 (Lakpol 72) 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 (Saliguard LAG) 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 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 blend 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. In fact, it surpassed a log reduction value of 5.45, indicating 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 (Ginamix CBP) 30
Preservative blend of Example 1 (Saliguard LAG) 0.7
C Colour Q.s
Fragrance Q.s

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 5.4, indicating a robust antimicrobial efficacy of the preservative blend, as per the standards outlined in the USP General Chapter 51.
3.3 Body lotion
Table 9 describes a body lotion cosmetic formulation comprising the preservative blend of Example 1 in an amount of 1% by total weight of the formulation.
Table 9
Phase Ingredients
Quantity



A

Sunflower Oil
2
Palmitic Acid
1
Cetearyl Olivate 1.5
Cetostearyl Alcohol
1.5
Ethylene Glycol Monostearate
1
Glycol Monostearate
1
Glycol Distearate
2
Ceteareth-6 Olivate 1
B Dimethyl Isosorbide 0.2
Sodium Ascorbyl Phosphate 0.3
N-butyl Resorcinol 0.2
Allantoin 0.5
1,3-Propanediol, Glycerine 2
Disodium EDTA 0.05
Sodium Pyrrolidone Carboxylate 1
Water
Qs 100
C Preservative blend of Example 1 (Saliguard LAG)
1
Color
Qs
Perfume
Qs

The preservative challenge test was conducted in accordance with United States Pharmacopoeia General Chapter 51 for the body lotion 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 5.42, indicating a robust antimicrobial efficacy of the preservative blend as per the standards outlined in the USP General Chapter 51.

, Claims:We claim:
1. A synergistic preservative blend comprising
(i) Lactic acid,
(ii) Gluconolactone; and
(iii) an enhancer,
wherein the Lactic acid is present in an amount of about 5 wt% to about 70 wt%, glucanolactone is present in an amount of about 2.5 wt% to about 20 wt%, and enhancer is present in an amount of about 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 blend may further contain a suitable carrier.
3. The preservative blend as claimed in claim 2, wherein the carrier is water.
4. The preservative blend as claimed in claim 1, wherein the enhancer is selected from a group comprising propanediol and derivatives, 1,2- hexanediol, propylene glycol, decylene glycol, 1,2-pentanediol, 1,5-pentanediol, pentylene glycol, 1,3-propanediol, butanediol and mixtures thereof.
5. The preservative blend as claimed in claim 4, wherein the enhancer is 1,2-hexanediol.
6. The preservative blend as claimed in claim 1 wherein the pH of the blend ranges from about 5.5 to about 7.0.
7. The preservative blend as claimed in claim 6, wherein the pH of the blend is about 6.5.
8. The preservative blend as claimed in claim 5, wherein the blend comprises Lactic acid: Gluconolactone: 1,2-hexanediol: water in 1:1:1:2 ratio.
9. 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.
10. 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.
11. The product as claimed in claim 10, wherein the product is selected from cosmetic, pharmaceutical, and personal care products.