In vitro antioxidant, antibacterial and anti-tumor activities of total flavonoids from Elsholtzia densa Benth

Purpose: To investigate the in vitro antioxidant, antibacterial and anti-tumor activities of total flavonoids from Elsholtzia densa Benth of Sichuan Province, China. Methods: The total flavonoids of Elsholtzia densa Bent were extracted utilizing the ultrasonic extraction method, and purified by D101 macroporous adsorption resin. An in vitro antioxidant test, 3-(4,5dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay and iCELLigence system were used to evaluate their antioxidant, antibacterial and anti-tumor activities. Results: The results showed that the total flavonoids exhibited good scavenging ability in hydroxyl radical (center dot OH), DPPH free radical (DPPH center dot), and super oxide anion radical (O-2(-)center dot). Antioxidant activity was higher than for control (ascorbic acid). Their antibacterial activity was good with minimum inhibitory concentration (MIC) of 2, 4 and 14 mu g/mL against Escherichia coli, Staphylococcus aureus and Bacillus subtilis, respectively. Anti-proliferation data from the iCELLigence system studies showed that the total flavonoids significantly inhibited the growth of five types of cells, including a normal human hepatocytes cell line (L02), two human hepatocellular carcinoma cell line (SMMC-7721 and HepG-2), a human cervical cancer cell line (Hela) and a Baby Hamster Syrian Kidney cell line (BHK-21) (p < 0.05). AO/EB staining indicate that the total flavonoids might cause apoptosis of Hela cells. Conclusion: The results suggest that the total flavonoids from Elsholtzia densa Bent are potential natural antioxidants and antimicrobial agent, with anti-cancer properties.