140 PRESERVATIVES
in these extreme environments are unique. Lichens synthesize and accumulate a wide variety of phenolic secondary compounds, such as usnic acid, as mechanisms of defence. Lichen’s secondary metabolites can be a
source of energy for soil microorganisms and, at the same time, they can inhibit the growth of surrounding competitive lichens, mosses, and vascular plants.1
In most lichen species, those
compounds are found in the medulla and may also give some antibiotics and antioxidants properties.2 Although secondary metabolites are not
necessary for lichen survival and growth, research on these substances has revealed numerous possible advantages. The lichens and their secondary metabolites seem to be effective natural antimicrobial agents, according to published studies. Additionally, because of their phenolic content, numerous lichen extracts have been claimed to have antioxidant capabilities.3 Reactive oxygen species, which can lead to damaging diseases, are inhibited and prevented by antioxidants. Since natural antioxidants are now preferred over many synthetic antioxidants, this might be considered as a chance to include a naturally derived antioxidant ingredient in cosmetic formulations.
Usnic acid sourced from reindeer lichen Usnic acid is one of more than a thousand secondary metabolites that lichens make. The lichen metabolite usnic acid exhibits various types of biological activity, most notably antimicrobial activity against plant and human pathogens, including inhibitory activity against bacterial strains resistant to antibiotics. Unique to lichens, usnic acid is particularly prevalent in the species Alectoria, Cladonia, Usnea, Lecanora, Ramalina, and Evernia. Cladonia rangiferina, also called and known
as reindeer lichen, is a fruticose that grows in the boreal forests. The name is coming from the fact that it serves as pasture for reindeer, moose, caribou, and musk oxen.4
Covering large
areas, this lichen is able to grow in both hot and cold environments.
E.coli ■ P. aeruginosa ■ S. aureus ■
A.brasiliensis ■
C.albicans ■
1.00E+07 1.00E+06 1.00E+05 1.00E+04 1.00E+03 1.00E+02 1.00E+01
1.00E+00 0 7 14 21 20 0 7 14 21
28
Figure 2: Challenge test results for Generic Cream Formula with 1% Phytocide Lichen, pH 7 following the PCPC method. Inoculated on Day 0 and reinoculated on Day 28. Results show log reduction in viable microorganisms
They often dominate the ground in boreal
pine forests and open, low-alpine sites in a wide range of habitats, from humid, open forests to rocks and heat sand, forming an important part of the winter diet of reindeer. Humans have long utilized lichens as food, medicine, and dye; Cladonia rangiferina has been used for decades to treat conditions like colds, arthritis, and fever, among others. Commercial pharmaceutical drugs based on lichen compounds have been produced in numerous nations. Usnic acid, for instance, was utilized in antiseptic products in Germany.5
Proven antimicrobial activity The ability of the investigated ingredient, PhytoCide Lichen, to inhibit the growth of a variety of bacteria and fungi was determined using the Minimum Inhibitory Concentration
ORAC PhytoCide Lichen
250 200 150 100 50 0
196 200
(MIC) test. The results are illustrated, showing that this material provides broad-spectrum antimicrobial protection (Table 1). The positive MIC screening results warranted
further testing to confirm its ability to provide product preservation. Fifty grams of a generic O/W cream formula containing 1% PhytoCide Lichen was weighed into five individual containers. Each container was inoculated with one of the five test organisms (E. coli, P. aeruginosa, S. aureus, C. albicans, and A. brasiliensis). The inoculated samples were evaluated at 0,
7, 14, 21, and 28 days after the initial inoculation to determine quantitatively the number of viable microorganisms remaining. On the 28th day of testing, the samples were re-inoculated and evaluated at 7, 14, 21, and 28 days after the second exposure to determine the number of viable microorganisms (Figure 2).
124 64 14 200µM Trolox® 12.5µM Trolox® Figure 3: Antioxidant capacities PERSONAL CARE April 2024
PhytoCide Lichen
5%
PhytoCide Lichen
2.5%
PhytoCide Lichen
1.25%
Antioxidant activity To evaluate the antioxidant capability of PhytoCide Lichen, an oxygen radical absorbance capacity (ORAC) experiment was performed. A common technique for determining the antioxidant capacity of physiological fluids, meals, beverages, and natural products is the ORAC assay. The assay quantifies a sample’s capacity to
neutralize free radicals that could interact with and damage cellular components. The ability of PhytoCide Lichen to act as an antioxidant has been evaluated. This test quantifies its capacity to reduce free radicals that could interact with and damage cellular components. This assay is based upon the effect of
peroxyl radicals generated from the thermal decomposition of 2, 2’-azobis- 2-methyl- propanimidamide dihydrochloride (AAPH) on the signal intensity from the fluorescent probe,
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Antioxidant Capacity (µMTE)
Inoculum Concentration (cfu/ml)
Days
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