Estudo fitoquímico e avaliação in vitro da atividade antioxidante do resíduo agrícola da melancia (Citrullus lanatus)

Abstract

Watermelon (Citrullus lanatus) is a fruit belonging to the Cucurbitaceae family, being one of the most produced fruits in the world and considered of great economic and food importance. Brazil is one of the main watermelon producers in the world, part of this production is destined for the foreign and domestic market. Therefore, there is a significant generation of organic waste resulting from the harvesting of this fruit. Based on the above, the present work aimed to evaluate the biological activity of extracts and silver nanoparticles (AgNPs) obtained from watermelon leaves in order to minimize the disposal of agricultural waste. The leaves were collected in Juazeiro/BA. The species was dried and ground, the extracts were obtained by Soxhlet from the solvents hexane (hex), ethyl acetate (AcOEt), ethanol (EtOH) and hydroalcoholic solvents (EtOH/H2O, 1:1). The determination of the phytochemical profile was carried out by Thin Layer Chromatography (TLC). Subsequently, flavonoids were quantified followed by total tannins and antioxidant activity was performed using the DPPH, ABTS, reducing power, phosphomolybdenum and iron and copper chelating activity methods. The synthesis route for silver nanoparticles was selected and the antioxidant activity was again performed. The phytochemical profile presented the classes coumarins, flavonoids, tannins and terpenes. In the quantification of flavonoids and tannins, the AcOEt extract showed the highest concentration. In the antioxidant activity of extracts and silver nanoparticles, the EtOH extract stood out with 53.58% scavenging of the DPPH radical, samples containing AgNPs and EtOH/H2O extract scavenged 80.81% of the ABTS radical cation, the ethyl acetate extract showed 58.49% iron chelating activity and the sample containing AgNPs and EtOH extract showed 83.04% copper chelating activity. The reducing power and phosphomolybdenum method did not show significant results. It is relevant that new studies are carried out to isolate the active metabolites of the Citrullus lanatus species. Therefore, it is clear that the watermelon leaf has promising potential and can be used in both the pharmaceutical and food industries