Evaluation of in vitro and in vivo safety of the by-product of Agave sisalana as a new cosmetic raw material: Development and clinical evaluation of a nanoemulsion to improve skin moisturizing

Agave sisalana (sisal) is the important global source of hard fiber, which is widely used in the production of wires, ropes, and handicrafts. The decortication process of the A. sisalana leaf produces large amounts of by-product that is discarded and can cause environmental damage. Studies have shown the potential of the by-product of A. sisalana in different applications. The aim of this study was to obtain a polysaccharide-enriched fraction (EF) from the by-product of A. sisalana, assess its safety in vitro and in vivo, to develop a cosmetic nanoemulsion and to evaluate its moisturizing clinical efficacy. EF was obtained and total sugar, total phenolic, and protein content were quantified. The safety of EF was determined using in vitro and in vivo assays. Nanoemulsions were developed and their stability evaluated for 90 days at different temperature conditions. The clinical moisturizing efficacy was evaluated by biophysical techniques using capacitance measurement and transepidermal water loss. The fraction exhibited high concentrations of sugar (65.49 ± 0.51%) and the presence of phenolic compounds (2.53 ± 0.04%) as well as protein (0.04 ± 0.01%). The EF did not exhibit potential cytotoxic or phototoxic effects and did not present the potential to induce skin irritant reaction in clinical tests. Nanoemulsion containing 40% oil phase, 50% aqueous phase and 10% surfactants, added fraction or not (vehicle), was stable for 90 days. The nanoemulsion containing 0.5% of the fraction increased the water content of stratum corneum by 10.13% vs. vehicle and by 19.28% vs. baseline values and maintained skin barrier function after 5 h of a single application. The EF obtained from the industrial by-product of A. sisalana demonstrated a promising profile as a moisturizing cosmetic raw material. This is important because it shows the possibility to increase the commercial value to the industrial by-product of sisal, and thus reduce the environmental impact caused by the disposal of this material.