Resumo Devido ao aumento da incidência da radiação ultravioleta na superfície da Terra causada pelo esgotamento do ozônio estratosférico, a pele humana se torna mais suscetível à danos, como eritema, queimaduras solares e câncer, principalmente em países tropicais. Assim, em todo o mundo os esforços de conscientização estão aumentando, assim como o uso de produtos de proteção solar. No entanto, filtros UV sintéticos têm sido associados a efeitos deletérios, como a fotossensibilização. Os produtos de origem natural foram usados por culturas antigas para diversos fins, incluindo a proteção da pele contra a radiação solar. Contudo, até hoje há uma dúvida se é uma fotoproteção real ou apenas um simples bronzeamento da pele. O fato é que as espécies vegetais apresentam mecanismos de autoproteção e produzem metabólitos secundários para se proteger da radiação UV. Porém, as substâncias de origem vegetal podem proteger a pele humana? A presente revisão discute o efeito paradoxal dos filtros químicos UV e a influência dos metabólitos secundários de origem vegetal nos testes de fotoproteção in vitro e in vivo.

Abstract Due to increased UV radiation on the Earth’s surface, caused by depletion of the stratospheric ozone, people have become more susceptible to different types of skin damage, such as erythema, sunburns, and cancer; this is especially of concern in tropical countries. Thus, efforts to improve awareness as well as the use of sunscreen are increasing worldwide. However, synthetic UV filters have been associated with deleterious effects such as photosensitization. Natural products have been used by ancient cultures for several purposes, including protecting the skin from the sun. However, there is still doubt today whether photoprotection is a real phenomenom or whether it is simply tanning of the skin. Plants have self-protective mechanisms and produce secondary metabolites that can protect themselves from UV radiation. Yet, can phytochemical compounds protect human skin? This review discusses the paradoxical effect of chemical UV filters and the influence of phytochemicals in in vitro and in vivo tests of photoprotection.

Based on previous studies, it has been found that goji berry (GB), popularly known as a ‘miracle fruit’, has excellent antioxidant potential and can be used in the treatment of skin disorders associated with ageing. This study aimed to incorporate GB into a structured cosmetic in order to optimise its penetration. Stability studies of the formulation, determination of the antioxidant activity of the extract and of the formulation, rheological measurements, SAXS, polarised light microscopy and bioadhesion analyses were performed. The results indicated the antioxidant activity of the extract, which can be incorporated into an emulsified cosmetic formulation. The emulsified formulation containing the extract remained stable, even after being submitted to thermal and luminous stresses for 30 days. In addition, rheological tests revealed that the addition of the GB soft extract reduced the viscosity of the formulation, increasing thixotropy and deformation. These systems were characterised by SAXS as a lamellar phase, which was confirmed by polarised light microscopy. These highly organised structures indicate their excellent stability. In vitro bioadhesion experiments revealed that these formulations exhibited skin adhesion strength statistically similar to commercial anti-ageing formulation. These results suggest that this formulation has excellent potential to be used as a topical treatment for ageing.

ABSTRACT Guava (Psidium guajava L.) is a native fruit of the American tropics with commercial applications for its taste, flavor and aroma. Numerous pharmacological uses have been described for it, such as the antiseptic effect of its leaves, the use of the fresh fruit and tea from its leaves for the treatment of diarrhea, dysentery, diabetes mellitus, and others. However, considering its rich composition, the guava also is a potential source of antioxidants to be used in the development of new formulations for cosmetic and/or dermatological applications, the main focus of this research. Herein, we describe the study of the phytochemical composition and the antioxidant activity of a guava extract prepared with non-toxic solvents aiming its use at biological applications. High performance liquid chromatography and mass spectrometry were employed to identify the major components, while thermoanalytical measurements and hot stage microscopy were used to assess the chemical stability of guava fruit extract. The antioxidant activity was also evaluated assessing the SOD-like activity and ABTS free radical scavenger. The results show that the extract is a rich source of phenolic compounds, such as quercetin, kaempferol, schottenol, among many others. All of the components found in guava extract exhibit biological effects according to the literature data, mainly antioxidant properties.