Pesticidal, antibacterial, and cytotoxic alkaloids from Stephania kwangsiensis

Four previously undescribed alkaloids designated as kwangsine A ( 1 ), sinoacutine- O -pulchine ( 2 ), 4-hydroxylpalmatrubine ( 3 ), and 4- O -methylcolumbamine ( 4 ), together with nine known analogues, were isolated from the tubers of Stephania kwangsiensis . The structures of the new compounds ( 1–4 ) were elucidated via comprehensive MS and NMR spectroscopic analysis. Their absolute configurations were determined by comparing experimental and calculated ECD spectra or by DFT calculations. Thirty compounds, including the 13 isolates from this study and 17 previously obtained ones, were assessed for pesticidal, antibacterial, and cytotoxic activities. Bioassay results showed that thaicanine N -oxide ( 23 ) exhibited strong pesticidal activity against Diaphorina citri , achieving a corrected mortality rate of over 80 % at a concentration of 50 ppm. (6 S ,6a S ,7 R )-sukhodianine α- N -oxide ( 14 ) exhibited potent antibacterial activity against Bacillus cereus TKL1–3H with an MIC value of 32 μg/mL. Liriodenine ( 11 ) showed cytotoxic activity against MCF-7 cells, with IC 50 values of 9.68 ± 0.36 μM.