Chemical investigation of Cyperus distans L. and inhibitory activity of scabequinone in seed germination and seedling growth bioassays.

Chemical investigation of the rhizomes of Cyperus distans (Cyperaceae) led to the identification of α-ciperone, cyperotundone and scabequinone, besides other common constituents. Complete assignment of the (13)C NMR data of scabequinone is being published for the first time. The inhibitory effects of C. distans extracts and scabequinone on the seed germination and seedling growth of Mimosa pudica, Senna obtusifolia and Pueraria phaseoloides were evaluated. Seed germination inhibition bioassay revealed that S. obtusifolia (52-53%) was more sensitive to the hexane and the methanol extracts at 1% than M. pudica (0-10%). Scabequinone at 250 mg L⁻¹ displayed seed germination inhibitions more than 50% and radicle growth reduction of more than 35% of the test species S. obtusifolia and P. phaseoloides, while the hypocotyl growth of M. pudica was significantly affected (>50%) by the quinone at the same concentration. These results demonstrate that scabequinone contributes to the overall inhibitory activities of C. distans.

Chemical constituents and allelopathic and antioxidant activities of Alchorneopsis floribunda Müll. Arg. (Euphorbiaceae).

Chemical investigation of extracts from the stems and leaves of Alchorneopsis floribunda Müll. Arg., collected in the Amazon region, was performed. The main isolated compounds were triterpenes (α-amyrin, ß-amyrin, lupeol, betulin, betulinic acid, uvaol, erythrodiol and oleanolic acid) and phenolic acid derivatives from 4-hydroxybenzoic acid (gallic and protocatechuic acids and isocorilagin). In the germination assays, high inhibitory allelopathic effects of the extracts and isocorilagin were observed and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity of isocorilagin was higher than those of the standards used (Trolox and butylated hydroxyanisole). This is the first chemical study of the genus Alchorneopsis (Euphorbiaceae).