AIM To study the chemical constituents from the root tubers of Stephania kwangsiensis H.S.Lo and their tyrosinase inhibition and insecticidal activities.METHODS The 70％ ethanol extract from root tubers of S.kwangsiensis was isolated and purified by Sephadex LH-20,MCI,ODS,semi-prepative HPLC and HSCCC,then the structures of obtained compounds were identified by physicochemical properties and spectral data.The tyrosinase inhibitory activities were determined by using levodopa as substrate,and the insecticidal activities were evaluated by the control effect of Diaphorina citri.RESULTS Twelve compounds were isolated and identified as tetrahydropalmatine ( 1 ),dehydrocrebanine ( 2 ),crebanine ( 3 ),stephanine ( 4 ),liriodenine ( 5 ),piperumbellactam A ( 6 ),sinoacutine ( 7 ),(+)-salutaridine N-oxide ( 8 ),bisnorargemonine ( 9 ),(+)-corytuberine (10),sebiferine (11) and palmatrubine (12).The IC50 values of compounds 5-7 to tyrosinase were (0.1702±0.0101),(0.7663±0.0331) and (0.5193±0.0075) mg/mL,respectively.The control effects of compounds 2-5,7,8,10-12 against D.citri ranged from ( 19.33±0.57 )％ to ( 77.15±0.45 )％.CONCLUSION Compounds 2,5,6,and 8-12 are isolated from this plant for the first time,6 and 9 are first obtained from genus Stephania.Compounds 5-7 displayed significant tyrosinase inhibition activities.Compounds 7,8 and 10 show strong insecticidal activities.

AIM To study the chemical constituents from the root tubers of Stephania kwangsiensis H.S.Lo and their tyrosinase inhibition and insecticidal activities.METHODS The 70％ ethanol extract from root tubers of S.kwangsiensis was isolated and purified by Sephadex LH-20,MCI,ODS,semi-prepative HPLC and HSCCC,then the structures of obtained compounds were identified by physicochemical properties and spectral data.The tyrosinase inhibitory activities were determined by using levodopa as substrate,and the insecticidal activities were evaluated by the control effect of Diaphorina citri.RESULTS Twelve compounds were isolated and identified as tetrahydropalmatine ( 1 ),dehydrocrebanine ( 2 ),crebanine ( 3 ),stephanine ( 4 ),liriodenine ( 5 ),piperumbellactam A ( 6 ),sinoacutine ( 7 ),(+)-salutaridine N-oxide ( 8 ),bisnorargemonine ( 9 ),(+)-corytuberine (10),sebiferine (11) and palmatrubine (12).The IC50 values of compounds 5-7 to tyrosinase were (0.1702±0.0101),(0.7663±0.0331) and (0.5193±0.0075) mg/mL,respectively.The control effects of compounds 2-5,7,8,10-12 against D.citri ranged from ( 19.33±0.57 )％ to ( 77.15±0.45 )％.CONCLUSION Compounds 2,5,6,and 8-12 are isolated from this plant for the first time,6 and 9 are first obtained from genus Stephania.Compounds 5-7 displayed significant tyrosinase inhibition activities.Compounds 7,8 and 10 show strong insecticidal activities.