Impact of Acid ("Progressive Brush") and Alkaline Straightening on the Hair Fiber: Differential Effects on the Cuticle and Cortex Properties.

Background: Glyoxylic acid has emerged as a safe alternative to formol (formaldehyde) use as a hair straightener/relaxer. However, the possible damage to the hair fiber after its application is low known and/or published in the literature. Aims: This work aims to characterize hair locks treated with glyoxylic acid compared to traditional alkaline straighteners such as sodium and guanidine hydroxide and ammonium thioglycolate. Materials and Methods: The morphology of the hair cuticles was observed by scanning electron microscopy. Protein loss was assessed by the Lowry method modified by Peterson and as mechanical properties that were expressed in terms of tensile strength. Results: All products (sodium and guanidine hydroxides and ammonium thioglycolate) caused protein loss of about 2.5 µg/g, except glyoxylic acid that caused the worst damage (3.5 µg/g), in relation to the untreated (virgin) hair (1.12 µg/g), indicating that the chemical treatments can cause hair damage in both cuticles and cortex. The force to break the fibers treated with traditional straighteners based on sodium hydroxide, guanidine hydroxide, and ammonium thioglycolate was statistically the same. Conclusion: The treatment with glyoxylic acid showed rupture tensile statistically equivalent to the alkaline straighteners. The mechanism of action of glyoxylic acid does not appear to be based on breaking and rearrangement of disulfide bridges, but altered them, that influenced the hair strength. However, it is also essential to consider other factors relevant: technical application technique, reaction time, and interval of reapplication of the product, as this can change the pattern of the results obtained.

Potential use of essential oils in cosmetic and dermatological hair products: A review.

BACKGROUND: Essential oils have great interest among the increasing demand for herbal cosmetics in the market. They are natural sources of biologically active ingredients due to the wide application of such compounds as well as their particular chemical composition. Several researches have evaluated the effectiveness of these bioactive ingredients for use in cosmeceuticals, mainly in both hair scalp and shaft hair damage repair. Thus, the amounts and their associations define the properties of these compositions with interest for hair cosmetic use, such as antioxidant, inflammatory, and antimicrobial activities. Because they are complex compounds, their actions on the skin, hair scalp, and shaft are not yet fully understood. AIMS: The purpose of this review is to highlight the relevant researches and findings on essential oils in hair care. METHODS: In order to achieve this objective, the present work comprises an updated bibliographic review related to essential oils used in hair care. RESULTS: It was possible to observe that cosmeceuticals containing essential oils applied to the scalp are preferable for topical activity. Also, it was noticed that there are few reports regarding their use in hair shaft. However, it was found that some oils are used to intensify the brightness and fix the hair color. CONCLUSIONS: This work demonstrated that the use of essential oils in both cosmetic products (industrial application) and those associated with oils carriers (as individual protocols) may lead to satisfactory results in the treatment of some scalp dysfunctions.

In vivo SPF from multifunctional sunscreen systems developed with natural compounds-A review.

BACKGROUND: The use of sunscreens is mandatory, especially in countries with high ultraviolet (UV) incidence. In consequence, there has been a growing interest in using compounds from natural sources to develop new multifunctional products that protect human skin from the consequences of UV exposition. Even though there are in vitro methods to determine anti-UV efficacy, it is still required to test photoprotection activity on human skin to validate product performance. AIM AND METHODS: In this review, we summarized all reported clinical studies about sun protection factor (SPF) measurements of sunscreens with natural compounds. We also discussed the probable action mechanism of those actives. RESULTS: Herein, we provided an overview on recent studies concerning photoprotection activity of compounds from natural sources, for example, rutin, ferulic acid, caffeine, shea butter, and plant extracts, mainly presented in sunscreen systems with efficacy clinically established by SPF. CONCLUSION: Our review suggested that even when the in vivo SPF evaluation has inherent difficulties, it is essential to assure the real efficacy of sunscreens. Furthermore, the incorporation of natural compounds could enhance the in vivo SPF values of such sunscreens by different mechanisms. Finally, some compounds derived from natural resources with skin benefits could be used as "green"/natural UV filters that provide broad-spectrum sunscreens with further upgrading of the multifunctional dermocosmetic formulation to enhance aesthetics and even skin health.