The Stenocereus griseus species complex (SGSC) has long been considered taxonomically challenging because the number of taxa belonging to the complex and their geographical boundaries remain poorly understood. Bayesian clustering and genetic distance-based methods were used based on nine microsatellite loci in 377 individuals of three main putative species of the complex. The resulting genetic clusters were assessed for ecological niche divergence and areolar morphology, particularly spination patterns. We based our species boundaries on concordance between genetic, ecological, and morphological data, and were able to resolve four species, three of them corresponding to S. pruinosus from central Mexico, S. laevigatus from southern Mexico, and S. griseus from northern South America. A fourth species, previously considered to be S. griseus and commonly misidentified as S. pruinosus in northern Mexico showed significant genetic, ecological, and morphological differentiation suggesting that it should be considered a new species, S. huastecorum, which we describe here. We show that population genetic analyses, ecological niche modeling, and morphological studies are complementary approaches for delimiting species in taxonomically challenging plant groups such as the SGSC.
The lichen Pseudocyphellaria coriifolia is a species endemic to southern South America. From the lichen thallus, methyl evernate, tenuiorin and three hopane triterpenoids were isolated and identified as the main lichen constituents. Their trypanocidal effects were screened against epimastigotes of Trypanosoma cruzi. The results of the biological test showed that some hopane terpenoids exhibit antiparasitic properties.
The synthesis of a newangular analog 11 of cyclozonarone was achieved via Diels-Alder reaction between a sesquiterpene-1,3-diene and 1,4-benzoquinone. The cytotoxic activity of ent-cyclozonarone [(+)-10] and the angular (−)-cyclozonarone analog 11 has been determined in three human cancer cell lines and in normal fibroblasts using the sulforhodamine B assay. The analyzed isomers induce cell death in different cancer cell lines by eliciting nuclear condensation and fragmentation, decreasing mitochondrial membrane permeability and increasing caspase-3 activity, all traits indicating apoptosis, with the effects of (+)-10 being stronger than those of 11 in all cases.
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