Skin Antioxidant Activity Research Articles

Topical formulation containing natural oligomeric proanthocyanidins (OPCS) reduces UV-induced oxidative stress in skin as assessed by ultra-weak photon emission (UPE)

Background OPCs are natural phytonutrients of the flavanol family. The dietary supplement ingredient MASQUELIER's ® OPCs has been demonstrated to exhibit antioxidant, anti-inflammatory and vasculo-protective properties in humans, which suggested potential benefits as a topical formulation for skin health. Exposure of skin to UV triggers oxidative stress in skin tissue that can lead to erythema, skin aging or even cancer. Our previous studies have shown that a specific topical formulation (cream containing MASQUELIER's ® OPCs) can significantly reduce UV-induced erythema in skin of human subjects and in animals, indicating it has antioxidant activity in skin. Objective This study was undertaken to further establish antioxidant activity of the specific OPCs cream formulation in human skin by measuring ultra-weak photon emission (UPE) of skin. UPE measurement in skin is a non-invasive, fairly-sensitive and convenient technique for continuously monitoring oxidative stress (Sauermann, 1999). Methods The study was an open-label study in 25 healthy volunteers. Measurement of skin UPE was performed on the dorsal surface of the subjects’ hands before (spontaneous UPE) and after exposure to UV (UV-induced UPE). The effects of the OPCs cream on spontaneous and UV-induced UPE were measured using a fractionated UV exposure protocol. Results Within each subject, spontaneous UPE of the right and left hand were found to be significantly correlated ( r =0.9; p =0.000). UV-induced UPE of the right and left hand were also significantly correlated ( r =0.87; p =0.000). UV exposure resulted in a long-term (>80 min) increase of spontaneous UPE. This is likely due to depletion of antioxidant capacity of skin, which is quantifiable by the fractionated UV-exposure protocol. Application of the OPCs cream immediately after UV exposure resulted in a significant (approx. 30%) decrease in UV-induced UPE. Topical OPCs application also reduced UV-induced long-term increase in spontaneous UPE, indicating prevention depletion of antioxidant capacity of skin by UV. Conclusions This study indicates that the specific OPCs cream formulation significantly decreases UV-induced oxidative stress in human skin based on UPE measurement, thereby suggesting that regular use of this OPCs cream might protect skin from harmful effects of UV.

Antioxidant activity in astringent and non-astringent persimmons

SummaryCatechins, ascorbic acid and -cryptoxanthin concentrations during fruit development and the antioxidant activity in skin and flesh were investigated in astringent ‘Saijyo’ and non-astringent ‘Fuyu’ persimmons (Diospyros kaki Thunb.). The IC50 values (a midpoint of 50% between zero and full inhibition of diazo dye formation) of superoxide (O2–)-scavenging activity remained low in the skin throughout fruit development.The IC50 values of the activity increased with d after full bloom (DAFB) in the flesh of the non-astringent type, whereas values remained low until harvest in the astringent type. However, IC50 values increased sharply after the removal of astringency with ethanol spray. Catechin concentrations in the flesh also decreased after the removal of astringency, whereas the concentrations in the skin did not decrease. Ascorbic acid concentrations in the skin and flesh were high at the beginning and middle of fruit development, but -cryptoxanthin in the skin and flesh increased toward harvest. However, -cryptoxanthin concentrations in the skin and flesh were lower than catechins and ascorbic acid. In addition, IC50 in the flesh of the non-astringnet type was high despite the increase of -cryptoxanthin at harvest.These results suggest that catechins and ascorbic acid influence O2-scavenging activity at the beginning and middle of fruit development, and catechins are associated with the O2-scavenging activity at ripening. Changes in 1-diphenyl-2-picrylhydrazyl (DPPH)-radicalscavenging activity with fruit developmental stage were similar to that for O2–. That is, IC50 values of DPPH-radical-scavenging activity decreased rapidly after the removal of astringency. -cryptoxanthin did not eliminate the DPPH-radicals. Therefore, the DPPH-radicals in persimmons may be eliminated primarily by catechins and ascorbic acid. The utilization of tannins before the removal of astringency is discussed.

Antioxidant Activity of Methanolic Extracts from Peanut Skin

Antioxidant activity of skin from runner peanut was performed on sunflower refined oil. The skin was obtained from industrial blanching process. The oil was oxidized at 60ºC. The methanolic extracts show antioxidant activity in relation to the oil (without additives). However these extracts do not reach the activity level from BHT.

Noninvasive in vivo evaluation of skin antioxidant activity and oxidation status

The method described here allows noninvasive quantification of reducing LMWA or the lipid hydroperoxide present on the surface of the skin. Quantification of reducing antioxidants can be achieved because they are secreted from the skin surface into a well containing an extraction solution. Analysis of the reducing equivalents released indicates the presence of uric acid and ascorbic acid. Other LMWA released from the skin are as yet unidentified. The secretion of the LMWA reaches a plateau following 20-30 min of incubation. Therefore, a 30-min incubation period was chosen as the optimal time for the extraction solution to be present in the well and in contact with the skin. This extraction procedure can be repeated after 24 hr. This period of time is needed for regeneration of the LMWA to their initial levels. Direct measurement allows continuous determination of the release of LMWA and their interaction with the iron chelate. The reaction is completed after 25-35 min, at which time the final potential can be recorded. When organic peroxides on the surface of the skin are determined, it is important that the glassy carbon electrode be in close contact with the skin, since the reaction occurs on the surface of the electrode and the bound peroxide on the outer layer of the skin. Furthermore, close contact is needed to avoid interference of reducing equivalents secreted from the skin into the well.

Reducing equivalents in the aging process.

Reducing equivalents may play a major role in the aging process. These metabolites are responsible for the endogenous redox potential in the living cell which is kept under tight regulation. Among their various roles is the ability to donate electrons to reactive oxygen species and by doing so to scavenge them. Most of the reducing equivalents in the cell are molecules with low molecular weights, such as glutathione and NADH which are synthesized by the cell. Other members of this group, such as uric acid are produced as waste products, while others, such as ascorbic acid and tocopherol, are derived from the diet. We studied the role of these equivalents in the aging process in various rat tissues. We demonstrated that the reducing power of a tissue may reflect its antioxidant activity. We used cyclic voltammeter methodology in order to evaluate the overall reducing power of tissue homogenates and other biological fluids. It was found that reducing power changes during the aging process in a bell-shaped manner in liver, lungs and kidneys, but not in heart and brain. We also showed that skin possesses strong reducing power which decreases dramatically with age. A non-invasive procedure to evaluate the oxidation status and the antioxidant activity of skin was developed. Using this method we demonstrated that there is an accumulation of organic peroxide in old skin compared to young skin, supporting the free radical hypothesis of aging.

Antioxidant Activity of Wine Pomace

Extractable polyphenols and antioxidant activity of white and red grape pomaces were determined. Total extractable polyphenols assayed by the Folin-Ciocalteu method in white grape pomace (6.5%), skins (5.3%), and seeds (9.2%) were higher than those in red grapes: 2.2%, 2.1%, and 2.1%, respectively. Red grape skin antioxidant activity determined by the ferric thiocyanate method was the strongest; however, it was 1.5 to 2 times lower than that of red wine. Red grape pomace and seeds, and white grape pomace did not exhibit any antioxidant capacity at concentration of 0.25% (w/v). Polyphenolic content of the samples did not seem to be the only factor determining the antioxidant activity.