ABSTRACT
The polyether antibiotic maduramicin and its methyl ester derivative inhibited photophosphorylation and proton uptake in isolated spinach chloroplasts. Both compounds also enhanced basal and phosphorylating electron transport and stimulated Mg(2+)-dependent ATPase activity, therefore, they behave as uncouplers of photophosphorylation being the methyl ester derivative more potent than the parent compound. On the other hand, maduramicin inhibited germination and radicle elongation of several crop and weed species. In addition, the antibiotic caused phytotoxic injury and fresh weight reduction to 4-to-6 week old seedlings of two weed and two crop species when applied at 10(-4) M by foliar application in the greenhouse.
Subject(s)
Anti-Bacterial Agents/pharmacology , Chloroplasts/metabolism , Lactones/pharmacology , Photophosphorylation/drug effects , Photosynthesis/drug effects , Plant Development , Anti-Bacterial Agents/chemistry , Chloroplasts/drug effects , Electron Transport/drug effects , Lactones/chemistry , Molecular Structure , Plants/drug effects , Spinacia oleracea/metabolism , Structure-Activity RelationshipABSTRACT
31 crude extracts derived from 28 plants highly valued as anti-infective agents in Mexican folk medicine have been screened for antimicrobial activity against four bacteria, a yeast and two molds. The results of the quantitative study indicated that the extracts derived from five species (Malmea depressa, Heliopsis longipes, Datura lanosa, Cnidosculus tehuacanensis and Helianthella quinquenervis) possessed significant antiseptic properties, therefore supporting the ethnomedical uses of these species. The cytotoxic activity was assayed against three cell lines HT-29 (Colon adenocarcinoma), MCF-7 (Breast carcinoma), A-549 (Lung carcinoma) and only the extract of Helianthella quinquenervis possessed significant activity against the MCF-7 cell line.
