Antioxidant Activity and Phytochemical Profile in Sequential Solvent Extract of Faloak (Sterculia quadrifida) Leaves and Stem Bark

Faloak (Sterculia quadrifida R.Br) is an endemic plant of East Nusa Tenggara Island. This plant was found in the East Nusa Tenggara archipelago, including Timor, Sumba, Flores, Alor and Rote Islands. Traditionally, the community used this plant for a variety of therapeutic purposes. Faloak demonstrate numerous biological activities, primarily attributable to its secondary metabolite compounds. The presence of phenolic compounds and flavonoids renders it a good candidate for the development of a novel natural antioxidant resource. Faloak possesses several biological activities related to its high antioxidant content. However, research on antioxidant, phenolic, and flavonoids content of Faloak leaves and stembark in different solvent remains limited. This study aims to investigate the antioxidant activity of Faloak leaves and stembark the ABTS (2, 2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) and DPPH (2, 2-diphenyl-1- (2, 4, 6-trinitrophenyl) hydrazyl) radical scavenging assay in different solvents. Measurement of phenolic and flavonoids levels, together with thin layer chromatography (TLC) bioautography, is performed to predict the related antioxidant compounds. The results showed that ethanol, as a polar solvent, produced the highest output, indicating that Faloak mostly comprises a polar compound. Leaves have a higher concentration of phenolic and flavonoid compounds than stembark. Leaves and stembark have significant antioxidant activity. Thin layer chromatography (TLC) combined with bioautography confirmed the presence of polyphenols and flavonoids, which are likely responsible for the antioxidant activity in the Faloak fractions. Bioautography also yielded active compounds with antioxidant activity. The stembark and leaves of Faloak possess antioxidant properties; nevertheless, the leaves demonstrate significant potential as a candidate for diverse pharmacological treatments due to their robust antioxidant activity and sustainability.