Studies On Chemical Constituents Of Ophiorrhiza Exigua And Bauhinia Glauca

In this study,nine compounds are isolated from the whole plant of Ophiorrhiza exigua.They are identified as friedelin(OE-1),sitgmast-4-en-3-one(OE-2),lawsaritol A(OE-3),isoscopoletin(OE-4),9-hydroxy-3-methoxy-6H-pyrido[1,2-a]pyrazin-6-one(OE-5),ethyl linoleate(OE-6),octadecyl phenylpropanoate(OE-7),drechslerol-B(OE8),and bis-(2-ethylhexyl)terephthalate(OE-9),based on their spectral data.These secondary metabolites possess different structural types.Among them,compound OE-1 is triterpenoid,compounds OE-2 and OE-3 are steroids,compound OE-4 is phenylpropanoid,compound OE-5 is alkaloid,and compounds OE-6-OE-9 are fatty acids.Compounds OE-2-OE-5 are reported from the genus Ophiorrhiza for the first time,while all compounds are obtained from O.exigua firstly.In this study,four compounds are isolated from the stem of Bauhinia glauca.They are identified as 2’-hydroxy-4,4’-dimethoxychalcone(BG-1),3,3’,4’,7tetramethoxyflavone(BG-2),bis-(2-ethylhexyl)terephthalate(BG-3),and n-tetratriacont20,23-dienoic acid(BG-4),based on their spectral data.Among them,compounds BG-1 and BG-2 are flavonoids,and compounds BG-3 and BG-4 are fatty acids.Compounds BG-1 and BG-2 are reported from the genus Bauhinia for the first time,while all compounds are obtained from B.glauca firstly.In the antioxidant bioassay,the scavenging ability of several extracts of B.glauca and O.exigua against DPPH and ABTS+free radicals are investigated.The results show that the scavenging ability of DPPH and ABTS+ radicals by each extract of B.glauca is in the order of ethyl acetate>total ethanol extract>residual aqueous extract>dichloromethane extract.Of which,ethyl acetate extract showed the strongest scavenging activity against DPPH and ABTS+radicals with IC50 of 0.011 mg/mL and 0.010 mg/mL,respectively,and its scavenging ability is similar to that of ascorbic acid(IC50 of 0.017,0.015 mg/mL,respectively).The results show that the scavenging ability of DPPH and ABTS+ radicals by each extract of O.exigua is in the order of ethyl acetate>total ethanol extract>residual aqueous extract>dichloromethane extract>petroleum ether extract.Of which,ethyl acetate extract showed the strongest scavenging activity against DPPH and ABTS+radicals with IC50 of 0.337 mg/mL and 0.134 mg/mL,respectively,and its scavenging ability is similar to that of ascorbic acid(IC50 of 0.051,0.035 mg/mL,respectively).Meanwhile,the inhibition of all the extracts and thirteen compounds from two plants against α-glucosidase are evaluated.In the antidiabetic bioassay,the experiment with enzymes as the evaluation index,and the inhibitory activity of each extract of B.glauca against α-glucosidase is in the order of ethyl acetate extract>total ethanol extract>residual aqueous extract>dichloromethane extract.Among them,the ethyl acetate extract exhibits the most significant inhibitory activity against α-glucosidase,with IC50 of 0.003 mg/mL,which is the same as that of acarbose(IC50 of 0.003 mg/mL).However,the inhibitory ability against α-glucosidase by each extract of O.exigua is in the order of dichloromethane extract>petroleum ether extract>ethyl acetate extract>total ethanol extract>residual aqueous extract.Of which,dichloromethane extract showed the strongest inhibitory activity with IC50 of 0.178 mg/mL.For the test compounds,OE-5,OE-7 and OE-9 exhibited potential inhibitory activity against α-glucosidase with inhibition rates>60%.In conclusion,the chemical compositions and biological activities of O.exigua and B.glauca are studied.Their chemical components are purified using normal-phase silica gel and Sephadex LH-20 chromatographic techniques.Thirteen compounds are identified by analysis of NMR,UV and MS spectral data and comparison of literature data.All of them are isolated for the first time from the two title plants.Their structural features are diverse,involving terpenoids,steroids,phenylpropanoids,flavonoids and fatty acids.The bioassays showed that all the extracts of B.glauca and O.exigua possess antioxidant and hypoglycemic activities to some extent,indicating the two plants have potential antiaging and anti-wrinkle and therapeutic effects on diabetes.While compounds OE-5,OE7 and OE-9 have certain hypoglycemic activity,and showing potential efficacy on diabetes.