Inhibition activity of 4-O-α-thevetopyranosyldiphyllin on Spirogyra communis and its effect on chloroplast ultrastructure

Objective The inhibition activity of 4-O-α-thevetopyranosyldiphyllin(TSC-3), extracted from Taiwania flousiana, on Spirogyra communis and its effect on S. communis chloroplast were investigated.

Method The IC₅₀ of 4-O-α-thevetopyranosyldiphyllin on chlorophyll and carotenoids in S. communis were determined by the ethanol extraction-spectrophotometric method. The effects of 4-O-α-thevetopyranosyldiphyllin on the microstructure and ultrastructure of S. communis were observed using microscopy and transmission electron microscopy.

Result The IC₅₀ of 4-O-α-thevetopyranosyldiphyllin on the contents of carotenoids, chlorophyll a, chlorophyll b and total pigments of S. communis after 7 d treatment were 3.41, 31.50, 47.34 and 29.30 mg·L⁻¹, respectively. Further investigation showed that 4-O-α-thevetopyranosyldiphyllin could destroy the cells of S. communis, inducing broken cell wall, disappeared cell membrane, disintegrated chloroplast, completely disappeared thylakoids, dispersed starch granules, degraded and fragmented pyrenoids.

Conclusion 4-O-α-thevetopyranosyldiphyllin can reduce the contents of chlorophyll a, chlorophyll b and carotenoids in S. communis. The inhibition rate of carotenoids was higher than those of the other pigments. 4-O-α-thevetopyranosyldiphyllin mainly acts on the chloroplasts and cell walls. This study provides a basis for further study of the molecular herbicidal mechanism of the plant-derived herbicidal chemical 4-O-α-thevetopyranosyldiphyllin, and also provides a theoretical basis for the control of aquatic algae.