Quest for antibacterial alkaloids from Rauhia multiflora through bioassay complementary-guided fractionation.

The clinical efficacy of many existing antibiotics is currently threatened by the emergence of microbial resistance. This recognized worldwide situation prompts to greater efforts to discover antimicrobial agents of natural origin, including plant sources. The objective of this work was to evaluate the antimicrobial activities of extracts, fractions and pure compounds from Rauhia multiflora using a bioguided complementary fractionation, contributing also to explain some traditional uses of this genus. Some subfractions showed antimicrobial activity against the Gram-negative and Gram-positive bacteria. Galantamine was identified and isolated as the main alkaloid, together with two additional structures of the same skeleton. Characterization by GC-MS revealed the presence of twelve galantamine-type and four crinane-type compounds. The tentative structure of one of the galantamine-type skeletons is proposed here for the first time. Altogether, these results support the use of Rauhia genus to inhibit bacterial growth.

Withanolides from the genus Exodeconus (Solanaceae). Chemotaxonomical considerations.

Five Exodeconus species were phytochemically analyzed. From the aerial parts of E. pusillus, the 7α,27-dihydroxy-1-oxo-22R-witha-2,5,24-trienolide and three other previously unreported normal-type withanolides were isolated. All the studied species had normal type and/or ring-D aromatic withanolides, and some had already been isolated from other Solanaceae genera, and therefore, these compounds are not chemotaxonomic markers at the generic level. The chemical composition of an undescribed Exodeconus species analyzed here supports the designation of this taxon as a new entity. The integral chemical profile of Exodeconus can be evaluated for its taxonomic implication when a more robust phylogeny of Solanaceae is available that allows the phylogenetic relationships with its closest genera to be clarified.

Four new species of Capsicum (Solanaceae) from the tropical Andes and an update on the phylogeny of the genus.

Four new species of Capsicum (Capsiceae, Solanaceae) from Andean tropical forests in South America are described. Capsicum benoistii Hunz. ex Barboza sp. nov. (incertae sedis) is endemic to a restricted area in south-central Ecuador and is most similar to the more widespread C. geminifolium (Dammer) Hunz. (Colombia, Ecuador, and Peru). Capsicum piuranum Barboza & S. Leiva sp. nov. (Andean clade) is found in northern Peru (Department Piura) and is morphologically most similar to C. caballeroi M. Nee of the Bolivian yungas (Departments Santa Cruz and Cochabamba) but closely related to C. geminifolium and C. lycianthoides Bitter. Capsicum longifolium Barboza & S. Leiva sp. nov. (Andean clade) occurs from northern Peru (Departments Amazonas, Cajamarca, and Piura) to southern Ecuador (Province Zamora-Chinchipe), and is morphologically most similar to C. dimorphum (Miers) Kuntze (Colombia, Ecuador, and Peru). Capsicum neei Barboza & X. Reyes sp. nov. (Bolivian clade) is endemic to southeastern Bolivia (Departments Chuquisaca and Santa Cruz) in the Boliviano-Tucumano Forest, is morphologically most similar to another Bolivian endemic species C. minutiflorum Rusby (Hunz.), and is closely related to C. caballeroi. Complete descriptions, illustrations, distributions and conservation assessments of all new species are given. Chromosome numbers for C. piuranum and C. longifolium are also provided. Three of the new species were included in a new phylogenetic analysis for Capsicum; their positions were strongly resolved within clades previously recognized in the genus.

Phytochemical Study of the Genus Salpichroa (Solanaceae), Chemotaxonomic Considerations, and Biological Evaluation in Prostate and Breast Cancer Cells.

Twelve Salpichroa taxa have been phytochemically analyzed. From the aerial parts of S. scandens, four known salpichrolides A, C, I, S, and an unreported withanolide named salpichrolide V (1), were isolated. In S. dependens, S. gayi, S. glandulosa subsp. glandulosa, S. glandulosa subps. weddellii, S. leucantha, S. micrantha, S. microloba, S. proboscidea, S. ramosissima, S. tristis var. tristis, and S. weberbauerii, no withanolides were found. The chemical content of ca. 85% of the Salpichroa taxa is in agreement with molecular studies, which suggest that Salpichroa and Jaborosa, a genus considered morphologically close to Salpichroa, are distant in the systematic of the Solanoideae subfamily. Moreover, the in vitro cytotoxic activity of a set of natural salpichrolides and derivatives was examined against two prostate carcinoma cell lines (PC3 and LNCaP) and two human breast cancer cell lines (MCF-7 and T47D). Several compounds showed moderate activity (IC50  = 64.91 - 29.97 µm).

Withanolides with antibacterial activity from Nicandra john-tyleriana.

Eleven new withanolides (1-11) were isolated and characterized from the aerial parts of Nicandra john-tyleriana. Five of these withanolides have an unmodified skeleton (1-5), two are acnistins (6, 7), and four are withajardins (8-11). These new isolates were fully characterized using a combination of spectroscopic techniques (including multidimensional NMR) and mass spectrometry. All compounds were evaluated for their antibacterial activity against Bacillus, Enterococcus, Escherichia, Listeria, Pseudomonas, and Staphylococcus strains.