Antibacterial, Antioxidant, and Cytotoxic Flavonoid Compound from Sterculia Quadrifida Leaves

Abstract

Sterculia quadrifida is empirically used as a medicinal plant. The leaves of the plant are reported to have anti-infective, antioxidant, and anti-cancer activities. This study aims to identify active compounds from the plant leaves by bioassay-guided isolation. S. quadrifida leaves were extracted with 80% methanol, then partitioned with n-hexane, chloroform, ethyl acetate, n-butanol, and insoluble n-butanol fractions by liquid-liquid partition. Purification of compounds was done using preparative HPLC, identification and structure elucidation were by comprehensive spectroscopic analyses. The in vitro antioxidant assay of the isolated compound was investigated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), nitric oxide (NO), and hydrogen peroxide (H2O2) radical scavenging methods. The in vitro antibacterial assay was done using the microdilution method. The in vitro cytotoxic effect of the compound was investigated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The isolation results from the n-butanol fraction found a new aurone compound named (2E)‐2‐[(3,4-dihydroxy phenyl)(hydroxy)methylidene]‐4,6‐dihydroxy‐2,3‐dihydro‐1-benzofuran‐3‐one. The antioxidant assay results showed IC50 values of 46.36, 38.41, 37.85, and 20.50 μg/mL in the DPPH, ABTS, NO, and H2O2 assays, respectively. The antibacterial assay results showed IC50 values of 23.38, 26.22, 58.45, 100.92, 103.14, and 193.98 μg/mL against P. aureginosa, H. pylori, S. bovis, S. aureus, S. thypi, E. coli, respectively. The cytotoxicity assay showed IC50 values of 4.05, 12.53, 15.38, and 25.91 μg/mL against breast cancer cell lines (4T1, MCF7, MDA-MB-435, and T47D). The aurone compound could be developed as a potential antibacterial, antioxidant, and cytotoxic agent.