Leaf alkaloid contents of Tabernaemontana pachysiphon as influenced by endogenous and environmental factors in the natural habitat

Variation in Phenolic Compounds Content and Antioxidant Activity of Different Plant Organs from Rumex crispus L. and Rumex obtusifolius L. at Different Growth Stages

The study investigated the accumulation of phenolic compounds and the antioxidant activity of extracts of various parts of R. crispus and R. obtusifolius, collected at the flowering stage and the fruiting stage. Half of the collected plants were divided into root, stem, leaves, and reproductive organs (inflorescence). The other half was used to study the vertical distribution of biologically active components and antioxidants throughout the plant. The samples were analyzed for total catechins content, total proanthocyanidins content, total phenolic content, and total antioxidant activity (1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'azinobis(3)ethylbenzthiazoline-6-sulfonic acid (ABTS), and ferric reducing antioxidant power (FRAP) assays). All analyses were performed in four replicates. In general, a similar trend was observed in the distribution of phenolic compounds in the studied species. The maximum content of these secondary metabolites was noted in the reproductive organs, both in the flowering and fruiting period. Stems were characterized by a minimum content of the studied classes of substances. The antioxidant activity of the sorrels studied parts can be arranged in the following order: the generative part (flowers, seeds) > leaves > root > stem (for flowering and fruiting stages). It was found that parts of the root closer to the stem differed in higher activity.

Variation of leishmanicidal activity in four populations of Urechites andrieuxii

Urechites andrieuxii Muell.-Arg. (Apocynaceae) is widely used in the Yucatan Peninsula for the treatment of cutaneous leishmaniasis. The influence of the environment in the variability of the leishmanicidal activity of the plant was evaluated using crude methanol extracts of roots from individuals belonging to four natural populations growing in the Yucatan Peninsula. The results of the growth inhibition test using three Leishmania spp. promastigotes showed a stronger leishmanicidal activity in populations of U. andrieuxii growing in more humid environments. Further evaluation against four human cancer cell lines and in the brine shrimp bioassay of both extracts from various parts of the plant and from the most active methanol root extracts, suggested that while the leaf extract appears to have selective toxicity against Leishmania parasites, the strong leishmanicidal activity detected in the root extracts of the plant might be due to its cytotoxicity.