Two new steroidal alkaloids from the rhizomes of Veratrum nigrum L. and their anti-TYLCV activity.

Two new steroidal alkaloids (1–2), together with seven known related steroidal alkaloids (3–9), were isolated from the rhizomes of Veratrum nigrum L. Their structures were elucidated by extensive spectroscopic analysis, and by comparison with literature data. Compound 1 possessed a rare 1, 3-oxazolidine unit within varazine-type alkaloids, and 2 was a 9-hydroxy-4-one derivative of 3-veratroylgermine. All isolates were evaluated inhibit tomato yellow leaf curl virus (TYLCV) activity. Compounds 5 and 7 (40 μg/mL) showed a significant anti-TYLCV activity in the host Nicotiana benthamiana with inhibition rates 74.6% and 63.4%, respectively, which are higher than that of the positive control ningnanmycin (51.4%). Nine steroidal alkaloids (1 – 9) including two new ones, 1 and 2 , were isolated from the rhizomes of Veratrum nigrum L.. Their anti- tomato yellow leaf curl virus (TYLCV) activity was evaluated for the first time and compound 5 showed remarkable antiviral activity against TYLCV replication in tobacco. The results indicated steroidal alkaloids could be served as a promising lead for development of new anti-TYLCV agents. Unlabelled Image • Nine steroidal alkaloids (1 – 9) including two new ones were isolated from the rhizomes of Veratrum nigrum L. • Compound 1 possessed a rare 1, 3-oxazolidine unit within varazine-type alkaloids. • Alkaloids (1 – 9) against tomato yellow leaf curl virus (TYLCV) were evaluated for the first time. • Compound 5 showed remarkable antiviral activity against TYLCV. [ABSTRACT FROM AUTHOR]