Proximal chemical analysis and secondary metabolites in Washingtonia robusta fruit (Arecaceae): relevance for the feeding of wildlife and human

Abstract

Background: Washingtonia robusta fruits are a staple for birds, small and medium-size mammals, and humans. However, quantitative data of their nutritional contribution has remained unknown. This is the first report on the phytochemical components found in fruit pulp and seeds. Questions: Does pulp compounds favor its consumption and contribute with nutrients for wildlife and humans? Do seed contents favor ecological interactions for germination and plantlet development? Species study: Washingtonia robusta H. Wendl. Study site and dates: Sierra El Aguaje, Sonora, Mexico, February - April 2016 Methods: Chemical and secondary metabolite analyses were carried out from extracts via phytochemical coloring tests and ultra-resolution liquid chromatography. Antioxidant activity was analyzed by DPPH. Results: Washingtonia robusta seeds contain 73 % sugars, 7.4 % protein, 8.4 % humidity, 4.3 % ashes, 8.7 % fat and 0.2 % calcium, while cyanogenic glycosides content was 0.8 mu g/g. Pulp has 71 % sugars, 10.8 % protein, 1.6 % humidity, 5.5 % ashes, 9.4 % fat and 1.5 % calcium, and cyanogenic glycosides reached 0.2 mu g/g. Alkaloids, tannins, saponins, phenols, and flavonoids were more abundant in seeds than in pulp. The DPPH assay expressed in Trolox equivalents indicated antioxidant capacity. Conclusions: Washingtonia robusta pulp is an important source of sugars and natural antioxidants for wildlife and human consumption. Occurrence of secondary metabolites prevents pathogens in seeds, also they could be beneficial for germination and initial plantlet development.