Phytotoxic and antimicrobial constituents of Argyreia speciosa and Oenothera biennis.

The antifungal activity of hexadecanyl p-hydroxycinnamate (1), scopoletin (2) isolated from Argyreia speciosa roots and gallic acid (3) from Oenothera biennis roots was evaluated against three fungi. Compound 1 and 2 were found to be highly potent against Alternaria alternata compared to 3. The phytotoxicity in terms of root growth inhibition of germinating wheat seeds was observed in all the three test materials. At 250 ppm concentration the inhibition caused by 3, was 85.63%; 1, 79.42%; and 2, 91.57%. At higher concentrations (1000 ppm) the root growth of the wheat was completely inhibited. The structures of these compounds were established using spectral and chemical methods.