Marine natural products polycarpine, polycarpaurines A and C, and their derivatives were designed, synthesized, and characterized on the basis of (1)H NMR and mass spectroscopy. The antiviral and antiphytopathogenic fungus activities of these alkaloids were first evaluated. Polycarpine derivative 1g displayed excellent in vivo antiviral activity against TMV (inactivation inhibitory effect, 57%/500 μg mL(-1) and 19%/100 μg mL(-1); curative inhibitory effect, 62%/500 μg mL(-1) and 23%/100 μg mL(-1); and protection inhibitory effect, 56%/500 μg mL(-1) and 29%/100 μg mL(-1)), which is evidently higher than the activity of ribavirin (inactivation inhibitory effect, 37%/500 μg mL(-1) and 9%/100 μg mL(-1); curative inhibitory effect, 36%/500 μg mL(-1) and 13%/100 μg mL(-1); and protection inhibitory effect, 39%/500 μg mL(-1) and 17%/100 μg mL(-1)), thus emerging as a new lead compound for antiviral research against TMV. Fungicidal testing in vitro showed that most of the compounds displayed good fungicidal activity against plant pathogenic fungi. Further in vivo fungicidal testing indicated that compounds 6a, 6f, and 8a-c displayed good fungicidal activity. Current results provide support for the development of polycarpine alkaloids as novel agrochemicals.
Keywords: anti-TMV; antifungal activity; marine natural products; polycarpine.