Photoprotective and antiglycation activities of non-toxic Cocos nucifera Linn. (Arecaceae) husk fiber ethanol extract and its phenol chemical composition

Abstract Underutilized parts of some abundant crops can be valuable and the search for additional uses, mainly in healthy and for social purposes are very attractive. This is the case of Cocos nucifera Linn., an important source of phenolic compounds and a native plant of tropical countries, widely distributed in the Northeast and North of Brazil. The objectives of this study were to determine the phenolic chemical composition, the photoprotection capacity, represented by sun protector factor (SPF), of the ethanol extract of coconut (Cocos nucifera) husk fiber of the yellow dwarf variety (EEYD) against UVB rays and after its incorporation into sunscreen formulations. Antiglycation activity [represented by bovine serum albumin (BSA) – glucose/fructose, Collagen – glucose/fructose and BSA-Methylglyoxal (MG) assays], using aminoguanidine (AG) as a positive control, and cytotoxic effects toward macrophages, were also evaluated. The identification of non-toxic antiglycation agents holds great promise in the development of alternative therapies for diseases, such as diabetes and their complications and is not often, reported in the literature. The determination of the SPF of the EEYD together with its sunscreen formulations was performed by in vitro method. A total of seven phenolic compounds, quercetin, catechin, epicatechin, vanillic, caffeic, 4-hydroxybenzoic and chlorogenic acids were identified by high performance liquid chromatography (HPLC)-UV/Vis and ultra high performance liquid chromatography - tandem mass spectrometer UHPLC-MS/MS. The present extract (EEYD) presented photoprotective activity with SPF values equivalent to the standards, benzophenone-3 and quercetin. The formulations prepared in different concentrations of the extract (5–20 % w/w) showed maximum SPF values of 15.94. The extract presented promising antiglycation activity, higher than the positive control, the pure compound aminoguanidine (AG), except for BSA/MG, with values for BSA/glucose/fructose of 9.61 μg/mL (vs.AG 18.30 μg/mL); for collagen/glucose/fructose of 4.50 μg/mL (vs.AG 82.87 μg/mL) and 34.76 μg/mL (vs.AG,13.19 μg/mL). The present ethanol extract does not decrease macrophage viability and presents a plethora of biologically active compounds. The combined results have shown the possibility of using non-toxic EEYD, as an active ingredient in sunscreen formulations and in the nutrition/medicinal areas, giving extra value to an environmental-unfriendly residue, with strong prospects for success.