Topical application of baby- and adult-aloe on ultraviolet B irradiated mouse skin with metabolite profiling

Topical application of extracts frombaby aloe shoot (immature aloe with shoot length <10 cm) containing high levels of chromone derivatives, and adult aloe shoot (mature aloe with shoot length >50 cm) showing high levels of anthraquinone derivatives, suppressed ultraviolet (UV) B irradiation-induced skin damage, including increased epidermal thickness and matrix metalloproteinase-1 expression, decreased procollagen type I and involucrin expression, and changes in collagen fibers. Additionally, we applied mass spectrometry-based techniques with multivariate statistical analysis to UVB-exposed skin and showed that several types of skin metabolites, including amino acids, organic acids, nucleobases, fatty acids, sterols, carbohydrates, and glycerophospholipids, were altered in the epidermal and dermal layers by topical application of Aloe vera shoot extracts. In particular, four nucleobases (hypoxanthine, uridine, inosine, and cytidine) and cholesterol were significantly influenced by treatment with extracts from adult and baby aloe shoots, respectively. The alterations in skin metabolites induced by A. vera extracts in UVB-irradiated skin were generally greater in the epidermis than in the dermis. These metabolites represent biomarkers that indicate the effects of A. vera extracts on UVB-irradiated skin and will guide future studies. Our results suggest that the topical application of A. vera is capable of mitigating changes in the skin induced by UVB irradiation.