Antifungal and Phytotoxic Activities of Isolated Compounds from Stems.

The identification of natural and environmentally friendly pesticides is a key area of interest for the agrochemical industry, with many potentially active compounds being sourced from numerous plant species. In this study, we report the bioassay-guided isolation and identification of phytotoxic and antifungal compounds from the ethyl acetate extract of stems. We identified eight compounds, consisting of two coumarins and six alkaloids. Among these, a new alkaloid, 2-hydroxy-3,6,7-trimethoxyquinoline-4-carbaldehyde (), was elucidated, along with seven known compounds. The phytotoxicity of purified compounds was evaluated, and chalepin () was active against at 1 mM with 50% inhibition of seed germination and it reduced (duckweed) growth by 50% (IC) at 168 μM. Additionally, we evaluated the antifungal activity against the fungal plant pathogen using a thin-layer chromatography bioautography assay, which revealed that three isolated furoquinoline alkaloids (flindersiamine (), kokusagenine (), and maculine ()) among the isolated compounds had the strongest inhibitory effects on the growth of at all tested concentrations. Our results indicate that these active natural compounds, i.e., (), (), (), and (), could be scaffolds for the production of more active pesticides with better physicochemical properties.