Separation And Activity Evaluation Of Antioxidant And Antitumor Components From Alpinia Oxyphylla Miq

Fructus Alpinia oxyphylla is the dry ripe fruit of Alpinia oxyphylla Miquel (Zingiberaceae), mainly distributed in Hainan, Guangdong and Guangxi Provinces in China, which is one of the important traditional Chinese medicine with a history of thousands of years. Previous pharmacological studies have indicated that the extracts of Fructus Alpinia oxyphylla exhibit neuroprotective, antioxidant, antitumor, anti-inflammatory, antianaphylactic and insecticidal activities.In present study, the ethanol extracts of Alpinia oxyphylla from different regions were investigated for their in vitro antioxidant and antitumor activities, using DPPH, ABTS radical scavenging methods, reducing power test and SRB (sulforhodamine B) assay, respectively. As a result, the ethanol extract of Alpinia oxyphylla from Guangxi Province showed the most significant antioxidant and antitumor activities, which was selected for further study.Through bioassay-guided fractionation, the ethanol extract of Alpinia oxyphylla was extracted with different solvents, and three different polar fractions were obtained. Bioassay results showed that the ethyl acetate fraction exhibited the strongest antioxidant and antitumor effects in vitro. Subsequently, the ethyl acetate fraction was further separated by silica column technique, using petroleum ether and ethyl acetate as elution solvents, to obtain four subfractions including petroleum ether:ethyl acetate (v:v,4:1,1:1,1:3and0:1). The same bioactive assays indicated that the subtraction of petroleum ether:ethyl acetate (v:v,4:1) showed the most potent antioxidant and antitumor activities in vitro and was selected for the isolation and identification of major bioactive compounds. And seven compounds including nootkatone (1), chrysin (2), protocatechuic acid (3), Oxyphyllol B (4), Oxyphyllenodiol B(5), teuhetenoneA (6) and (4R,6R,10S)-4,10-dimethyl-6-(1’-hydroxyisopropyl)-1-en-3,4,5,6,7,8-hexahydronaphthalen-2-one(7) were isolated and determined. Among them, compound7were firstly found from this plant.Biological tests revealed that compounds3,4,5,6and7had antioxidant activity. Among them, compound3exhibited the highest scavenging effects on DPPH and ABTS radicals, which was comparable with ascorbic acid (VC). Compared with the positive control5-FU, compound1showed stronger antitumor activity towards HepG2and MNK-45cells, while compound2exhibited very higher antitumor ability against HepG2, HeLa and MNK-45cells, and compound3displayed more remarkable antitumor effect on HeLa and MCF-7cells. Therefore, these compounds probably responsible for the antioxidant and antitumor activities of the ethyl acetate fraction of Fructus Alpinia oxyphylla.