Many cosmetics that are marketed nowadays often contain antioxidants as the active ingredients. It is known that oxidation reactions could produce free radicals, which can start chain reactions that will damage skin cells. Increasing the amount of free radicals could initiate the wrinkling, photoaging, elastosis, drying, and pigmentation of the skin. Topical antioxidants could terminate the chain reactions by removing the free radical intermediates and inhibit other oxidation reactions by being oxidized themselves; this could defend the skin against the environmental stress caused by free radicals. It is well known that plants can produce natural antioxidant compounds that could control the oxidative stress caused by sunlight and oxygen. Many patents and commercial cosmetic products have various combinations of plant extracts. The cosmetic formulations usually contain various combinations of many plant extracts, for example, green tea, rosemary, grape seed, basil grape, blueberry, tomato, acerola seed, pine bark, and milk thistle. These plants extracts contain natural antioxidants, that is, polyphenols, flavonoids, flavanols, stilbens, and terpenes (including carotenoids and essential oils). Some commercial products contain pure natural compounds such as quercetin, kojic acid, and resveratrol in their formulation. The choice of the right active plant extracts or compounds, the confirmation of their activity, and their stability and synergistic effects in cosmetic products are the important factors for the formulation of an effective product.

Natural Antioxidants in Cosmetics

The skin as the largest part of human body is one of the main targets for ultraviolet radiation, environmental pollution, toxic chemicals and some metal ions, which share responsibility for the formation of free radicals. The resulting free radicals, both oxygen and nitrogen species are one of the main causes of aging due to impaired regulation of cell respiratory metabolism involving incomplete oxygen reduction in mitochondria and production a superoxide anion, hydroxyl radicals et al. In modern cosmetology to minimize the adverse effects of free radicals, antioxidants, which inhibit free radical reactions, mainly autoxidation processes are used. Currently, not only many cosmetic products containing antioxidants are available, but a large diversity of methods for determination of cosmetics antioxidant activity is also accessible. These methods can be divided into three main groups: in vitro, in vivo, and ex vivo as reported herein. Due to lack of standardization and validation it is necessary to use a variety of methods as well as conditions for those purposes, which are presented to the context.

Methods for evaluation of cosmetic antioxidant capacity

Food-waste is produced throughout all the food supply chain, with a large part already achieved at farm level. In fact, fruits and vegetables, which do not satisfy aesthetic demands, cannot be marketed, but their recovery could favour their valorisation for the obtainment of highly qualified goods. In this context, faulty zucchini fruits (cultivar ‘Lungo Fiorentino’), intended for disposal, were rescued as effective, inexpensive and bio-sustainable source for cosmeceutical purposes. Zucchini fruits underwent extraction and fractionation to obtain ZLF-O and ZLF-A extracts, which were chemically characterized by UHPLC-HRMS. ZLF-A extract, rich in flavonols and flavones, scavenged massively DPPH• and ABTS•+, and was not cytotoxic at doses up to 200 μ g/mL. Thus, ZLF-A was incorporated into a base cream formula. Zucchini-based emulsion was deeply screened for its antiradical properties and cytotoxicity towards human keratinocytes and fibroblasts. ZLF-A-enriched cream, whose chemical stability was assessed over time and mimicking different storage conditions, was further tested on reconstructed epidermis disks (EpiskinTM). The recovery of valuable chemical substances from zucchini agro-food waste, complying with the principles of valorisation and sustainable development, can represent a new market force for local farmers. Data acquired were eager to convey a suitable reuse of nutraceuticals rich zucchini waste.

https://www.mdpi.com/1420-3049/24/8/1479/pdf

Recovering Cucurbita pepo cv. 'Lungo Fiorentino' Wastes: UHPLC-HRMS/MS Metabolic Profile, the Basis for Establishing Their Nutra- and Cosmeceutical Valorisation.

Topical compositions comprising grape seed and at least three of folic acid, biotin, Bifidobacterium longum extract and Echinacea purpurea.

Topical preparations comprising grape seed, folic acid, biotin, bifidobacterium longum and echinacea purpurea

Publisher Summary This chapter presents a procedure to perform rapid direct electrochemical measurements in dermocosmetic creams on unmodified electrode materials and to follow the variation of the properties of the emulsion, disposed in mass or in layer to evaluate the stability of the cream. To evaluate the stability of the cream, the product is disposed in an air-tight cell during a controlled period; then, a cyclic voltammogram is immediately performed. For each period, a new amount of cream is used. Influences of dioxygen and natural light are studied: the cream is exposed or protected from natural light and a flow-meter Brooks controls the flux of dinitrogen or air. The variation of the oxido-reduction properties of the cream can be recorded as a function of the time, in different conditions: with an atmosphere of air or nitrogen, exposed or protected from light. The reductive properties of the product decrease in each experiment; light seems to have the most important influence.

Procedure 9 Direct electrochemical measurements in dermo-cosmetic creams

The aim of this study was to develop a technique to assay for the activity of antioxidants in a finished cosmetic product. This was accomplished by adapting the Randox Assay for Total Antioxidant Status kit so that diluted samples could be evaluated by kinetic as well as end-point determinations. Using this technique, we found that a finished product had an IC(50) of 0.07 gm of product and a relative antioxidant activity concentration of 52.7 nmoles/mg.

D Dicanio

Papers

A test for antioxidant activity in cosmetic formulations