Int J Pharm Pharm Sci, Vol 12, Issue 3, 94-99Hypothesis Article

YOGURT; A NOVEL EXCIPIENT (WITH ITS LYSED BACTERIA, AMINO ACIDS, VITAMINS, FATTY ACIDS, AND MINERALS) FOR “TOPICAL DERMATOLOGICAL PRODUCTS” AND FOR “SKIN MICROBIOTA”

M. ORHAN VAIZOGLU

ORVA Ilac A. S. and SEZA Kimyevi Ltd, AOSB, 10047 Sokak, No. 3, Cigli/Izmir/Turkey
Email: orhmuh@sezakimyevi.com.tr

Received: 25 Dec 2019, Revised and Accepted: 29 Jan 2020

ABSTRAC

In recent years various Microbiomes (Skin, Gut Lumen) of the human body have attracted the attention of different research groups. In the meantime it has been shown that the conventional therapy of different diseases by making use of antibiotics and similar antibacterial treatments may disturb the harmony of the Skin Microbiome, resulting in dysbiosis. There are efforts of using “live” or “tyndallized (lysed)” probiotics in order to treat different diseases of the skin. It is also known that amino acids are one of the important key elements of the skin. In this paper, a hypothesis for the utilization of yogurt as an excipient for various topical dermatological products will be proposed. Yogurt contains significant amounts of; Probiotics (starter cultures), Amino Acids, Vitamins, Minerals and various Fatty Acids (saturated, monounsaturated and polyunsaturated). Besides, it has been shown that Antimicrobial Peptides (Bacteriocins) are also present in yogurt. Yogurt could eventually be used as an excipient for the production of various topical dermatological products in order to deliver some of the above-mentioned constituents to the Stratum Corneum (Skin) locally.

Keywords: Yogurt, Excipient, Dermatological, Topical, Microbiota

© 2020 The Authors. Published by Innovare Academic Sciences Pvt Ltd. This is an open-access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)
DOI: http://dx.doi.org/10.22159/ijpps.2020v12i3.36704. Journal homepage: https://innovareacademics.in/journals/index.php/ijpps

INTRODUCTION

After exploration of the importance of Probiotic microorganisms like Lactobacillus species, Bifidobacterium species and their importance for “Human Gut Lumen Microbiota” and for “Skin Microbiota”, scientific work upon this field is growing in an exponential manner. Because of the importance of probiotics for gut microbiota, and the importance of gut microbiota for human health and the immune system, probiotics attract the attention of many groups [1-10]. Different articles report interesting results, i.e. anti-cancer properties of bioactive peptides from synbiotic yogurt [5], antibacterial activity of bacteriocin isolated from lactobacillus bulgaricus [6], one article contemplates the probiotics as undervalued conquerors [8], one review article reports about the anti-aging properties of probiotics [9], another article reports about the role of gut microbiota in lipid metabolism, cholesterol levels and the positive effect of probiotics in infants with atopic dermatitis [10]. Since yogurt also contains probiotics, it can eventually be an important candidate as an excipient for various topical dermatological products. As an example of utilizing yogurt as a major excipient for topical dermatological products, we are working on a topical ointment using yogurt as one of the main excipients, in excess of 50%. Besides yogurt, Dexpanthenol, Olive Oil, Almond Oil and other necessary ingredients for emulsion formation and antimicrobial agents are being used. The resulting ointment has acceptable organoleptic, microbiological, physical-chemical properties and stability (unpublished results). It has been reported by different authors, that probiotic bacteria are lysed by heat at elevated temperatures (70–100 °C). Following the lysation of probiotic bacteria, favorable cell contents for the skin microbiome, including Antimicrobial Peptides (Bacteriocins) are excreted [4-6]. Recent studies report that Antimicrobial Peptides (Bacteriocins) are also present in yogurt, which seem to be stable at elevated temperatures, i.e. 80 °C [6]. It has also been shown by different publications and patents that the “lysates” of probiotics are at least as effective as their “live” forms in inhibiting various pathogenic bacteria, either in the gut lumen and/or skin surface [7, 11-14]. The conventional method of manufacturing topical dermatological products is performed at elevated temperatures (i.e. 80 °C) and under turbulent homogenization. Considering the fact that probiotic bacteria would be lysed at elevated temperatures, it is highly probable that the probiotics in yogurt, when yogurt is used as an excipient for topical dermatological products, should also be in the lysed form following the production of the corresponding ointment. Besides, the added antimicrobial agents would also be contributing to this lysation process. Not to be forgotten is the fact that yogurt is not only rich in probiotics. Besides probiotic bacteria, yogurt is rich in Amino Acids (amino acids make up 40% of the skin’s Natural Moisturizing Factor/NMF) [15], Vitamins, Fatty Acids, and Minerals [16]. It can be assumed that only very small fractions of Amino Acids, Vitamins, Fatty Acids and Minerals will reach the skin surface following systemic application of these ingredients in various dosage forms. In case the skin, i.e. the Stratum Corneum is directly targeted, yogurt could eventually be used as an excipient for various topical dermatological products, for supplying the skin with; Lysed Probiotic Bacteria, Amino Acids, Vitamins, Fatty Acids and Minerals, locally. It seems as if there is quite some work to be done upon this field.

Hypothesis

Yogurt

The word “yogurt” is a Turkish word. It is believed to have come from the word “yoğurmak” which means to thicken, coagulate and curdle [17, 18]. Yogurt is a fermented milk product. Following fermentation, the main structure of yogurt consists of a casein gel. In between, there are empty spaces filled with a liquid phase known as whey, which is the liquid part of milk left after fermentation. Some of these spaces are filled with starter bacteria [1]. The main starter cultures/bacteria which are used for the production of yogurt are; “Streptococcus thermophilus” and “Lactobacillus bulgaricus”. S. thermophilus is an aerobic and L. bulgaricus an anaerobic bacterium [1, 2, 17, 18]. Both bacteria cooperate for the fermentation of milk. As a result, from lactose in milk, lactic acid is produced. The pH will be more acidic, where the growth of other bacteria is unfavored. During this cooperation, S. thermophilus produces pyruvic acid, formic acid and carbon dioxide, which in turn stimulate the growth of L. bulgaricus. L. bulgaricus produces peptides and amino acids which promote the growth of S. thermophilus [19]. According to FAO/WHO, these two bacteria fulfill the definition of probiotic bacteria. FAO/WHO defines Probiotics as; “live microorganisms, which when administered in adequate amounts, confer a health benefit on the host” [3]. According to Guarner et al. [20], taken here “word by word” from the corresponding publication; “a number of human studies have clearly demonstrated that yoghurt containing viable bacteria (Streptococcus thermophilus and Lactobacillus delbrueckii sp. Bulgaricus) improve lactose digestion and eliminate symptoms of lactose intolerance. Thus, these cultured bacteria clearly fulfill the current concept of probiotics”.

Nutrient composition of yogurt

USDA National Nutrient Database for Standard Reference [16], has reported the nutrient composition of “Plain Yogurt/Whole Milk” in its “4/1/2019 Release”. The relevant nutrients, excluding the ones under the title “Others”, are presented in table 1. Besides nutrients, yogurt contains probiotics like “S. thermophilus” and “L. bulgaricus”. Antimicrobial Peptides (Bacteriocins) are also identified in yogurt, which seems to be stable at elevated temperatures, i.e. 80 °C [4-6].

Table 1: Nutritional value of plain, whole milk yogurt. From USDA. Composition of Yogurt/nutrients in 100g

Proximates 100g Amino acids 100g Reference
Water 87,90g Tryptophan 0,020g [16]
Protein 3,47g Threonine 0,142g
Total Lipid (Fat) 3,25g Isoleucine 0,189g
Carbohydrate 4,66g Leucine 0,350g
Sugars 4,66g Lysine 0,311g
Methionine 0,102g
 Minerals 100g  Cystine 0,032g
Calcium, Ca 121 mg Phenylalanine 0,189g
Iron, Fe 0,05 mg Tyrosine 0,175g
Magnesium, Mg 12 mg Valine 0,287g
Phosphorus, P 95 mg Arginine 0,104g
Potassium, K 155 mg Histidine 0,086g
Sodium, Na 46 mg Alanine 0,148g
Zinc, Zn 0,59 mg Aspartic acid 0,275g
Copper, Cu 0,009 mg Glutamic acid 0,679g
Manganese, Mn 0,004 mg Glycine 0,084g
Selenium, Se 2,2µg Proline 0,411g
Fluroride, F 12µg Serine 0,215g
Vitamins 100g Lipids 100g
Vit C (total Ascorbic acid) 0,5 mg Fatty acids, total saturated 2,096g
Thiamin, Vit B1 0,029 mg 4:0 0,096g
Riboflavin 0,142 mg 6:0 0,066g
Niacin 0,075 mg 8:0 0,042g
Panthotenic acid 0,389 mg 10:0 0,093g
Vit B6 0,032 mg 12:0 0,111g
Folate Total 7µg 14:0 0,343g
Carotene, beta 5µg 16:0 0,886g
Choline Total 15,2 mg 18:0 0,317g
Vit B12 0,37µg Fatty acids, total monounsaturated 0,893g
Retinol 27µg 16:1 0,071g
Vit A, RAE 27µg 18:1 0,743g
Vit E, (alpha-tocopherol) 0,06 mg 20:1 0
Vit D (D2+D3) 0,1µg 22:1 0
Vit D3 (cholecalciferol) 0,1µg
Vit D 2 IU Fatty acids, total polyunsaturated 0,092g
Vit K (phylloquinone) 0,2µg 18:2 0,065g
18:3 0,027g
18:4 0
20:4 0
20:5 n-3 (EPA) 0
22:5 n-3 (DPA) 0
22:6 n-3 (DHA) 0
Cholesterol 13 mg

Considering yogurt as an excipient for various topical dermatological products from the aspect of amino acids, vitamins, and minerals

As an example of utilizing yogurt as an excipient for topical dermatological products, we are working on a topical ointment using yogurt as the main excipient, in excess of 50%. Besides Yogurt, Dexpanthenol, Olive Oil, Almond Oil, and Antimicrobial Agents, other necessary ingredients for emulsion formation are being used. The resulting ointment has acceptable organoleptic, physical-chemical, microbiological properties and stability (unpublished results). For the sake of simplicity, let us consider that we use, besides other necessary ingredients for emulsion formation and antimicrobials, 50%/50g yogurt in a 100g ointment. We can then, depending on table 1, calculate the amount of amino acids, vitamins, minerals and lipids which would be present in such a formulation (excluding the lipids coming from the other ingredients). In table 2, the amount of nutrients in 50g yogurt are also calculated depending on the data of USDA [16]. Since we aim at using 50%/50g yogurt in our hypothetical formulation, the nutrients which are present in 50g yogurt should be present in our 100g hypothetical formulation. In our preliminary studies, we were able to reassess the amount of amino acids in our finished topical formulation, which was proportional to the amounts of amino acids in the yogurt sample used (unpublished results). We have “not” done similar studies for the vitamins, minerals and lipids. In the corresponding columns of table 2, depending on the data of USDA [16], the amount of amino acids, minerals, vitamins, and lipids which would be present in 1g of the above mentioned hypothetical 100g ointment are calculated. 1g ointment also corresponds to 2 Finger Tip Units (FTU). The details for FTU for an adult male fingertip is given below [21]:

Table 2: Amount of nutrients in 50g yogurt and in 1g (2 FTU) of a hypothetical ointment containing 50%/50g yogurt. The amounts are calculated depending on the yogurt data of USDA, from table 1

Minerals 50g 1g Ointment (2FTU) Amino acids 50g 1g Ointment (2 FTU) Reference
Calcium, Ca 60,5 mg 605µg Tryptophan 0,010g 100µg [16]
Iron, Fe 0,025 mg 0.25µg Threonine 0,71g 7100µg
Magnesium, Mg 6 mg 60µg Isoleucine 0,0945g 945µg
Phosphorus, P 47,5 mg 475µg Leucine 0,175 1750µg
Potassium, K 77,5 mg 775µg Lysine 0,1555g 1555µg
Sodium, Na 23 mg 230µg Methionine 0,051g 510µg
Zinc, Zn 0,295 mg 2.95µg Cystine 0,016g 160µg
Copper, Cu 0,0045 mg 0.045µg Phenylalanine 0,0945g 945µg
Manganese, Mn 0,002 mg 0.02µg Tyrosine 0,0875g 875µg
Selenium, Se 1,1µg 0.011µg Valine 0,1435g 1435µg
Fluroride, F 6µg 0.06µg Arginine 0,052g 520µg
Vitamins 50g 1g Ointment (2 FTU) Histidine 0,043g 430µg
Vit C (total Ascorbic acid) 0,25 mg 2.5µg Alanine 0,074g 740µg
Thiamin, Vit B1 0,0145 mg 0,145µg Aspartic acid 0,1375g 1375µg
Riboflavin 0,071 mg 0.71µg Glutamic acid 0,3395g 3395µg
Niacin 0,0375 mg 0,375µg Glycine 0,042g 420µg
Panthotenic acid 0,1945 mg 1.945µg Proline 0,2055g 2055µg
Vit B6 0,016 mg 0,16µg Serine 0,1075g 1075µg
Folate Total 3,5µg 0,035µg Lipids 50g 1g Ointment (2 FTU)
Folic acid 0 0 Fatty acids, total saturated 1,048g 10480µg
Choline 7,6 mg 76µg 4:0 0,048g 480µg
Vit B12 0,185µg 0,00185µg 6:0 0,033g 330µg
Retinol 13,5µg 0,135µg 8:0 0,021g 210µg
Vit A, IU 49,5 IU 0,495 IU 10:0 0,0465g 465µg
Vit E, (alpha-tocopherol) 0,03 mg 0,3µg 12:0 0,0555g 555µg
Vit D (D2+D3) 0,05µg 0,0005µg 14:0 0,1715g 1715µg
Vit D3 (cholecalciferol) 0,05µg 0,0005µg 16:0 0,443g 4430µg
Vit D 1 IU 0,01 IU 18:0 0,1585g 1585µg
Vit K (phylloquinone) 0,1µg 0,001µg Fatty acids, total monounsaturated 0,4465g 4465µg
16:1 undifferentiated 0,0355g 355µg
18:1 undifferentiated 0,3715g 3715µg
20:1 0 0
22:1 undifferentiated 0 0
Fatty acids, total polyunsaturated 0,046g 460µg
18:2 undifferentiated 0,0325g 325µg
18:3 undifferentiated 0,0135g 135µg
18:4 0 0
20:4 undifferentiated 0 0
20:5 n-3 (EPA) 0 0
22:5 n-3 (DPA) 0 0
22:6 n-3 (DHA) 0 0
Cholesterol 6,5 mg 65µg

The quantity of cream in a Finger Tip Unit (FTU) varies with age [21]:

The necessary FTU for different body areas are given below [21]:

Supposing that we would like to use the hypothetical ointment for the treatment of “One Adult Foot”.

We would then need 2 FTU=1g ointment, as expressed above. The corresponding amount of nutrients that would be delivered by the hypothetical 1g ointment are shown in table 2.

Questions about the fraction of an amino acid dose reaching the stratum corneum following systemic application

Amino acids are, among others, breakdown products of filaggrin which is important for proper epidermal differentiation and skin barrier function.

The amino acids and the other byproducts of filaggrin contribute to the formation of the Natural Moisturizing Factor (NMF) [22] as shown in table 3 [15]. The Confocal Raman Spectroscopy depth measurements indicate that the NMF concentration is higher in the whole Stratum Corneum of the human skin [23].

Table 3: Chemical composition of the Natural Moisturizing Factor/NMF

Free Amino Acids 40% Reference [15]
Pyrrollidone carboxylic acid 12%
Lactate 12%
Sugars 8,5%
Urea 7%
Chloride 6%
Sodium 5%
Potassium 4%
Ammonia, uric acid, glucosamine and creatine 1,5%
Calcium 1,5%
Magnesium 1,5%
Phosphate 0,5%
Citrate, formate 0,5%

As far as our surveys about the data in the scientific literature are concerned, we do not know what fraction of a systemically applied amino acid dose would reach the Skin/Stratum Corneum. For many drugs, the term Volume of Distribution (pharmacokinetics) is used as a calculation factor to approximately calculate the amount of drug in the body at any time, by making use of i.e. plasma concentrations. As an example, let us take the Volume of Distribution of the amino acid Arginine, which is given to be around 24 liters, assessed in humans. The authors [24] have infused 3g of L-Arginine to humans and have measured “peak plasma concentrations” of approximately 400 µmoles/liter, which corresponds to approximately 70µg/ml for L-Arginine.

The U. S. Food and Nutrition Board has published the Recommended Dietary Allowances for various amino acids for adults. Depending on the type of amino acid, the amounts vary between 8–14 mg per kg of body weight [25]. If we consider an average value of 10 mg/kg allowance for a certain amino acid, for an average person of 75 kg body weight, the total dietary allowance would be around 0,75g. As cited above, after an infusion of 3g L-Arginine, the peak plasma concentrations are measured to be approximately 70µg/ml [24]. After systemic application of 0,75g amino acid, the plasma concentrations should be considerably lower (assuming 100% bioavailability and no “first-pass-effect” following peroral application). It can be assumed that only very small fractions of the amount present in the plasma would reach the Skin Surface/Stratum Corneum.

Looking at table 2, it can be seen that relative significant amounts of amino acids can be delivered locally to the stratum corneum by utilization of yogurt as an-excipient in a topical dermatological product.

Amino acids make up 40% of the skin’s Natural Moisturizing Factor/NMF. The other constituents of the NMF besides amino acids are given in table 3 [15]. One could eventually achieve significant moisturization of the skin by delivering amino acids, minerals, and the humectant lactic acid (which is one of the major constituents of yogurt) by means of a topical yogurt containing ointment locally.

As shown in table 1, besides amino acids, yogurt also contains significant amounts of vitamins, minerals, and lipids. We have not studied the fate and proportional transfer of vitamins, minerals, and lipids from the yogurt samples used. They may or may not have been degraded during the manufacturing process. There seems to be quite some work to be done upon this field.

Considering yogurt as an excipient for topical dermatological products from the aspect of lysed probiotics

The skin Microbiome

Since the Skin Microbiome is the main scope of this paper, various other Microbiomes of the human body will not be discussed.

In their very interesting paper, Grice and Segre [26], have presented the schematic of the skin histology in a cross-sectional form. Microorganisms, like viruses, bacteria, and fungi are schematized on the surface of the skin, which also reside in sweat glands, sebaceous glands, hair and hair shaft. Rod-shaped and round bacteria, like Proteobacteria and Staphylococcus spp., commensal fungi like Malassezia spp. and skin mites (i.e. Demodex folliculorum, Demodex brevis) are also schematized for the reader in a brilliant and very understandable scheme. All these microorganisms live in communities and in close association with each other. Major examples of the 19 phyla which are known to be part of the skin microbiome are; Actinobacteria (51, 8%), Firmicutes (24, 4%), Proteobacteria (16,5%) and Bacteriodetes. The major genera are Corynebacterium, Propionibacterium, and Staphylococcus [27]. The skin is an ecosystem of, microorganisms and host, existing in balance and harmony. The disturbance of this homeostasis may lead to different diseases [26, 27]. On the other hand, this homeostasis may also be misbalanced by exogenous agents, used for the treatment of various dermatological disorders. This should perhaps lead us to re-evaluate our understanding of treating various diseases, i.e. the unnecessary use of antibiotics, which may disturb the microbiome balance and harmony, resulting in dysbiosis. In such cases, it may take long periods for the microbiome to recover [27, 28].

Use of lysed probiotics and their effect on the skin

It has been shown by different publications and patents that the “lysates” of probiotics are at least as effective as their “live” forms in inhibiting various pathogenic bacteria, either in the Gut Lumen and/or Skin Surface [7, 11-14, 29, 30].

Since it is not the scope of this paper to discuss the effects of “live probiotics” on the skin microbiome, solely the effect of “lysed probiotics” will be discussed. As already implemented above, FAO/WHO defines Probiotics as; “live microorganisms, which when administered in adequate amounts, confer a health benefit on the host” [3]. According to Guarner et al. [20], taken here from the corresponding publication “word by word”; “a number of human studies have clearly demonstrated that yoghurt, containing viable bacteria (Streptococcus thermophilus and Lactobacillus delbrueckii sp. Bulgaricus), improve lactose digestion and eliminate symptoms of lactose intolerance. Thus, these cultured bacteria clearly fulfill the current concept of probiotics”.

Pique et al. mention different methods for the inactivation/lysation of probiotic bacteria. The mentioned methods are; heat (70–100 °C), chemicals like formalin, gamma or ultraviolet rays and sonication. The preferred method being heat inactivation. Inactivation ruptures the cell walls of the probiotic bacteria, thereby releasing the cytoplasmic contents, i.e.; DNA and cell wall components like Peptidoglycans, Lipoteichoic acids or heat-labile Pilli. They cite that the excreted components play key immunomodulating roles, i.e. production of IgA by “S. thermophilus lysates” and anti-inflammatory responses mediated by metabolites and cell surfaces of “L. delbrueckii”. The authors cite that the lysate components of heat-killed probiotics would inhibit pathogens and also release Antimicrobial Peptides (Bacteriocins) which are effective against Gram-positive and Gram-negative bacteria [11]. Lew and Liong cite that the cell wall fragments of probiotic bacterial extracts, their metabolites and the dead probiotic bacteria as such, can improve skin barrier functions and regulate immune responses. One of the components of lysed S. thermophilus, the Sphingomyelinase enzyme, when applied in cream was able to increase the ceramide levels on the volar forearm of healthy human volunteers significantly (p<0.05) within a week. Other cell components, like Lipoteichoic acid, increases dermal cellular defense against bacterial infection and Peptidoglycan plays an important role in defending the skin against pathogens [12].

Shigwedha et al. name the “probiotical cell fragments (PCFs)” of probiotics as “parabiotics” since they do not represent intact bacteria. They also cite that the cell components of such bacteria, i.e. Peptidoglycan, Lipoteichoic acid, cell wall-associated Polysaccharides, Muramyl peptide, Muramyl dipeptide, when applied intestinally would exert beneficial effects. They mention that these cell fragments inhibit the adhesion of C. perfringens, E. coli, S. thyphimurium, C. difficile, Shigella sp. and Salmonella sp. to mucus and/or intestinal epithelial cells in a competitive way [7].

Di Marzio et al. have shown that sonicated (lysed) S. thermophilus strains, “which is one of the starter bacteria for yogurt”, when applied topically to patients suffering from atopic dermatitis, increased the level of ceramides in the stratum corneum thereby improving barrier function [29].

In one patent application [30], the inventors describe the use of lysed probiotic bacteria against skin infections. Lysates of Lactobacillus rhamnosus GG, was shown to inhibit Staphylococcus aureus infection by preventing the adhesion of St. aureus to cells. They also cite that these lysates can be administered in different dosage forms, including liposomes and other microparticulate dosage forms.

In a thesis submitted to the University of Manchester Medical Faculty, it is cited that lysates of Lactobacillus rhamnosus GG was effective against the adhesion of St. aureus to keratinocytes thereby counteracting infections. It has also been shown that L. rhamnosus GG lysates also enhance the re-epithelization of wounds, favoring keratinocyte terminal differentiation. The study cites that L. rhamnosus GG lysates can be used as a therapeutic agent to enhance wound healing [13].

Gueniche et al., cite that lysates of Bifidobacterium longum spp. would improve sensitive skin. Skin sensitivity was assessed by the stinging test. Following barrier disruption, skin recovery was evaluated by measuring the Trans-Epidermal Water Loss (TEWL), in a double-blind, randomized, placebo-controlled trial, where a 10% cream of B. longum spp. lysate was applied. The results show that the volunteers who used the extract in a cream form had a significant drop in skin sensitivity and a significant decrease in skin dryness at the end of the treatment [14].

Tufail et al., isolated Bacteriocins (Antimicrobial Peptides) from Lactobacillus bulgaricus (which is one of the starter cultures of yogurt) and tested the inhibitory activity against B. subtilis, E. coli, S. typhi, St. aureus, V. cholerae by use of the agar diffusion method. They cite that the isolates have antibacterial potential against the mentioned pathogens [6].

To give the reader a picture about the amount of “L. bulgaricus and S. thermophilus” in yogurt, which are the main probiotics (starter bacteria) for yogurt production, the viable bacterial counts in yogurt are given below in table 4.

Table 4: The viable bacterial counts in Yogurt [2, 31]

Yilmaz-Ersan L, Kurdal E. Reference [2]
S. thermophilus 9,01 (log cfu/ml)
L. bulgaricus 8,42 (log cfu/ml)
Sarvari F, Mortazavian AM, Fazeli MR Reference [31]
S. thermophilus 8,72 (log cfu/ml)
L. bulgaricus 8,48 (log cfu/ml)

CONCLUSION

The utilization of yogurt as an excipient for various topical dermatological products is discussed. If such an ointment, where yogurt is used as an excipient, is manufactured by conventional methods (elevated temperatures and turbulent homogenization), under such conditions the major probiotic bacteria used for yogurt production (in this case S. thermophilus and L. bulgaricus) should be in the lysed state following the production of the ointment. In addition to heat and turbulent homogenization, the added antimicrobial agent(s) would also support this lysation process.

Many groups have shown that “lysed probiotics” exert favorable effects on the skin. These effects were shown to be at least as favorable as the “live forms” of the corresponding probiotics. Apart from using S. thermophilus and L. bulgaricus as starter cultures for yogurt production, different probiotics (starter cultures) may also be used. The corresponding yogurt samples (with different starter cultures) could perhaps be used in ointments, depending on the targeted effect to be achieved. Using yogurt as an excipient for a certain topical dermatological product could be promising for the future, since such a formulation may deliver significant amounts of; “Lysed Probiotics”, “Amino Acids (amino acids make up 40% of the skin’s Natural Moisturizing Factor/NMF)”, “Vitamins and fatty acids (it needs to be assessed whether the vitamins and the fatty acids are transferred from yogurt to the final formulation without degradation)” and “Minerals” to the Stratum Corneum, locally.

OVERVIEW

The utilization of yogurt as an excipient for various topical dermatological products is discussed. Yogurt contains live probiotics as such, which are shown to be exerting favorable effects in the human body. On the other hand, as cited in the above text, many groups have also shown that “lysed probiotics” also exert favorable effects in the human body and the skin locally. Using yogurt as an excipient for a certain topical dermatological product could be promising, since such a formulation may also deliver significant amounts of; Lysed Probiotics, Amino Acids (amino acids make up 40% of skin’s Natural Moisturizing Factor/NMF), Fatty Acids, Minerals and Vitamins to the stratum corneum locally. We were able to reassess the proportional corresponding amounts of amino acids in the final topical formulation that were present in the yogurt samples used (unpublished results). But no further studies were done in order to determine if all the Vitamins and Fatty Acids in the yogurt sample are transferred to the ointment intact, without degradation. Further studies are needed in order to investigate the utilization of yogurt as an excipient in topical dermatological products and its corresponding clinical implications.

FUNDING

Nil

AUTHORS CONTRIBUTIONS

All the authors have contributed equally.

CONFLICT OF INTERESTS

The author reports no conflict of interest.

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