Phytochemical composition, in vitro antioxidant and anticancer activities of quercetin from methanol extract of Asparagus cochinchinensis (LOUR.) Merr. tuber

Five compounds including quercetin (AC01), asparagine (AC02), sucrose (AC03), β-sitosterol-3-O-β-D-glucopyranoside (AC04) and β-sitosterol (AC05) were isolated from the methanol extract of Asparagus cochinchinensis (Lour.) Merr. tuber collected in Ba Ria–Vung Tau Province of Vietnam. Their structures were elucidated by NMR (1D and 2D-NMR). Quercetin (AC01) was subjected to the assay for antioxidant and anticancer activities. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging assay was employed for determining the antioxidant activity, while sulforhodamine B (SRB) method was applied for evaluating the anticancer activity against four selected human cancer cell lines. Quercetin had strong antioxidant activity with IC50 = 14.52 ± 2.12 µg/ml (as compared to standard vitamin C with IC50 = 10.49 ± 2.00 µg/ml). Meanwhile, quercetin (AC01) exhibited strong cytotoxicity against the HeLa, human cervical cancer cell line with IC50 = 5.78 ± 0.36 µg/ml, followed by lung cancer cell line (NCI–H460), lung cancer cell line with IC50 = 12.57 ± 1.19 µg/ml and liver cancer cell line (Hep-G2) liver cancer cell line with IC50 = 20.58 ± 0.85 µg/ml. The anticancer activity of quercetin against breast cancer cell line (MCF-7), breast cancer cell line was recorded with IC50 = 31.04 ± 3.14 µg/ml.   Key words: Asparagus cochinchinensis, 1,1-diphenyl-2-picrylhydrazyl (DPPH), sulforhodamine B (SRB), human cervical cancer cell line (HeLa), lung cancer cell line (NCI-H460), breast cancer cell line (MCF-7), liver cancer cell line (Hep-G2).