In vitroevaluation of the efficacy of commercial green tea extracts in UV protection

Antioxidant Effects of Catechins (EGCG), Andrographolide, and Curcuminoids Compounds for Skin Protection, Cosmetics, and Dermatological Uses: An Update

Here we have chosen to highlight the main natural molecules extracted from Camellia sinensis, Andrographis paniculata, and Curcuma longa that may possess antioxidant activities of interest for skin protection. The molecules involved in the antioxidant process are, respectively, catechins derivatives, in particular, EGCG, andrographolide, and its derivatives, as well as various curcuminoids. These plants are generally used as beverages for Camellia sinensis (tea tree), as dietary supplements, or as spices. The molecules they contain are known for their diverse therapeutic activities, including anti-inflammatory, antimicrobial, anti-cancer, antidiabetic, and dermatological treatment. Their common antioxidant activities and therapeutic applications are widely documented, but their use in cosmetics is more recent. We will see that the use of pharmacomodulated derivatives, the addition of co-antioxidants, and the use of various formulations enable better skin penetration and greater ingredient stability. In this review, we will endeavor to compile the cosmetic uses of these natural molecules of interest and the various structural modulations reported with the aim of improving their bioavailability as well as establishing their different mechanisms of action.

Research progress on the potential delaying skin aging effect and mechanism of tea for oral and external use

Skin aging is characterized by the gradual loss of elasticity, the formation of wrinkles and various color spots, the degradation of extracellular matrix proteins, and the structural changes of the dermis. With the increasingly prominent problems of environmental pollution, social pressure, ozone layer thinning and food safety, skin problems have become more and more complex. The skin can reflect the overall health of the body. Skincare products for external use alone cannot fundamentally solve skin problems; it needs to improve the overall health of the body. Based on the literature review in recent 20 years, this paper systematically reviewed the potential delaying effect of tea and its active ingredients on skin aging by oral and external use. Tea is the second-largest health drink after water. It is rich in tea polyphenols, l-theanine, tea pigments, caffeine, tea saponins, tea polysaccharides and other secondary metabolites. Tea and its active substances have whitening, nourishing, anti-wrinkle, removing spots and other skincare effects. Its mechanism of action is ultraviolet absorption, antioxidant, anti-inflammatory, inhibition of extracellular matrix aging, inhibiting the accumulation of melanin and toxic oxidation products, balancing intestinal and skin microorganisms, and improving mood and sleep, among other effects. At present, tea elements skincare products are deeply loved by consumers. This paper provides a scientific theoretical basis for tea-assisted beauty and the high-end application of tea in skincare products.

Effect of grape seed extract on skin fibroblasts exposed to UVA light and its photostability in sunscreen formulation

BACKGROUND

Grape seed extract (GSE) is rich in polyphenolic compounds, particularly (+)-catechin (C) and (-)-epicatechin (EC). Strong antioxidant activity of these compounds makes GSE to be value-added to the cosmetics with anti-aging properties. However, a lack of stability in different environmental conditions makes GSE challenging for the development of photostable cosmetic sunscreen products.

AIMS

To evaluate photoprotective effects of GSE on human dermal fibroblasts irradiated with UVA light and assess photostability of catechins in cream formulations containing GSE alone or in combination with octyl methoxycinnamate (OMC).

METHODS

MTT assay was used to assess protective effects of GSE on fibroblasts irradiated with UVA light. A photostability of C and EC in GSE and in cream formulation containing GSE was investigated using high-performance liquid chromatography and confirmed by reflection and transmission spectrophotometry using Transpore™ tapes and polymethacrylate (PMMA) plates as substrates.

RESULTS

High UVA doses damaged fibroblast structure and inhibited their growth. However, GSE increased cell viability and effectively protected them from UVA damage. Photostability of C and EC was achieved by combination of GSE and OMC that also improved absorption capacity of UV filter and increased overall efficacy of formulation. PMMA plates showed better applicability for in vitro photostability testing of sunscreen formulations. However, despite the instability of Transpore® tape under heat from UV exposure, it can still be economically a substrate of alternative choice for screening.

CONCLUSIONS

GSE can be used as an effective and sustainable natural resource for prevention of UV-induced skin damage providing long-term protection against premature skin aging.

DNA damage in human skin and the capacities of natural compounds to modulate the bystander signalling

Human skin is a stratified organ frequently exposed to sun-generated ultraviolet radiation (UVR), which is considered one of the major factors responsible for DNA damage. Such damage can be direct, through interactions of DNA with UV photons, or indirect, mainly through enhanced production of reactive oxygen species that introduce oxidative changes to the DNA. Oxidative stress and DNA damage also associate with profound changes at the cellular and molecular level involving several cell cycle and signal transduction factors responsible for DNA repair or irreversible changes linked to ageing. Crucially, some of these factors constitute part of the signalling known for the induction of biological changes in non-irradiated, neighbouring cells and defined as the bystander effect. Network interactions with a number of natural compounds, based on their known activity towards these biomarkers in the skin, reveal the capacity to inhibit both the bystander signalling and cell cycle/DNA damage molecules while increasing expression of the anti-oxidant enzymes. Based on this information, we discuss the likely polypharmacology applications of the natural compounds and next-generation screening technologies in improving the anti-oxidant and DNA repair capacities of the skin.

In Vitro Antioxidant, Antityrosinase, and Cytotoxic Activities of Astaxanthin from Shrimp Waste

Astaxanthin is a potent antioxidant compared with vitamins and other antioxidants. However, astaxanthin extract from shrimp processing waste has not yet been used in cosmetic products. This study aimed to explore the natural astaxanthin from shrimp shells for antioxidant and antityrosinase activities as well as potential toxicity. The antioxidant activities were performed with 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging, β-carotene bleaching, and singlet oxygen quenching assays. The results revealed that astaxanthin extract demonstrated potent antioxidant activities against DPPH and ABTS radicals, and prevented the bleaching of β-carotene and quenching of singlet oxygen (EC₅₀ 17.5 ± 3.6, 7.7 ± 0.6, 15.1 ± 1.9 and 9.2 ± 0.5 μg/mL, respectively). Furthermore, the astaxanthin extract could inhibit tyrosinase activity (IC₅₀ 12.2 ± 1.5 μg/mL) and had no toxic effects on human dermal fibroblast cells. These results suggested that shrimp astaxanthin would be a promising dietary supplement for skin health applications.

Effects of UV Rays and Thymol/Thymus vulgaris L. Extract in an ex vivo Human Skin Model: Morphological and Genotoxicological Assessment

Ultraviolet (UV) radiation is the major environmental factor affecting functions of the skin. Compounds rich in polyphenols, such as Thymus vulgaris leaf extract and thymol, have been proposed for the prevention of UV-induced skin damage. We compared the acute effects induced by UVA and UVB rays on epidermal morphology and proliferation, cytotoxicity, and genotoxicity. Normal human skin explants were obtained from young healthy women (n = 7) after informed consent and cultured at the air-liquid interface overnight. After 24 h, the samples were divided in 2 groups: the former exposed to UVA (16 or 24 J/cm2) and the latter irradiated with UVB (0.24 or 0.72 J/cm2). One hour after the end of irradiation, supernatants were collected for evaluation of the lactate dehydrogenase activity. Twenty-four hours after UVB exposure, biopsies were processed for light and transmission electron microscopy analysis, proliferation, cytotoxicity, and genotoxicity. UVB and UVA rays induced early inhibition of cell proliferation and DNA damage compared to controls. In particular, UVB rays were always more cytotoxic and genotoxic than UVA ones. For this reason, we evaluated the effect of either T. vulgaris L. extract (1.82 µg/ml) or thymol (1 µg/ml) on all samples treated for 1 h before UVB irradiation. While Thymus had a protective action for all of the endpoints evaluated, the action of the extract was less pronounced on epidermal proliferation and morphological features. The results presented in this study could be the basis for investigating the mechanism of thymol and T. vulgaris L. extract against the damage induced by UV radiation.

Dandelion Extracts Protect Human Skin Fibroblasts from UVB Damage and Cellular Senescence

Ultraviolet (UV) irradiation causes damage in skin by generating excessive reactive oxygen species (ROS) and induction of matrix metalloproteinases (MMPs), leading to skin photoageing. Dandelion extracts have long been used for traditional Chinese medicine and native American medicine to treat cancers, hepatitis, and digestive diseases; however, less is known on the effects of dandelion extracts in skin photoageing. Here we found that dandelion leaf and flower extracts significantly protect UVB irradiation-inhibited cell viability when added before UVB irradiation or promptly after irradiation. Dandelion leaf and flower extracts inhibited UVB irradiation-stimulated MMP activity and ROS generation. Dandelion root extracts showed less action on protecting HDFs from UVB irradiation-induced MMP activity, ROS generation, and cell death. Furthermore, dandelion leaf and flower but not root extracts stimulated glutathione generation and glutathione reductase mRNA expression in the presence or absence of UVB irradiation. We also found that dandelion leaf and flower extracts help absorb UVB irradiation. In addition, dandelion extracts significantly protected HDFs from H₂O₂-induced cellular senescence. In conclusion, dandelion extracts especially leaf and flower extracts are potent protective agents against UVB damage and H₂O₂-induced cellular senescence in HDFs by suppressing ROS generation and MMP activities and helping UVB absorption.

Active ingredients against human epidermal aging

The decisive role of the epidermis in maintaining body homeostasis prompted studies to evaluate the changes in epidermal structure and functionality over the lifetime. This development, along with the identification of molecular mechanisms of epidermal signaling, maintenance, and differentiation, points to a need for new therapeutic alternatives to treat and prevent skin aging. In addition to recovering age- and sun-compromised functions, proper treatment of the epidermis has important esthetic implications. This study reviews active ingredients capable of counteracting symptoms of epidermal aging, organized according to the regulation of specific age-affected epidermal functions: (1) several compounds, other than retinoids and derivatives, act on the proliferation and differentiation of keratinocytes, supporting the protective barrier against mechanical and chemical insults; (2) natural lipidic compounds, as well as glycerol and urea, are described as agents for maintaining water-ion balance; (3) regulation of immunological pathogen defense can be reinforced by natural extracts and compounds, such as resveratrol; and (4) antioxidant exogenous sources enriched with flavonoids and vitamin C, for example, improve solar radiation protection and epidermal antioxidant activity. The main objective is to provide a functional classification of active ingredients as regulatory elements of epidermal homeostasis, with potential cosmetic and/or dermatological applications.