In vitro antiplasmodial activity of selected plants from the Colombian North Coast with low cytotoxicity.

Background: Plants are an important option in the treatment of malaria, especially in endemic regions, and are a less expensive and more accessible alternative with a lower risk of toxicity. Colombia has a great diversity of plants, and evaluation of natural extracts could result in the discovery of new compounds for the development of antimalarial drugs. The purpose of this work was to evaluate the in vitro antiplasmodial activity and the cytotoxicity of plant extracts from the Colombian North Coast against Plasmodium falciparum. Materials and Methods: The antiplasmodial activity of 12 plant species from the Colombian North Coast that are used in traditional medicine was evaluated through in vitro cultures of P. falciparum, and the cytotoxicity of extracts of these species to human cells was determined. Plant extracts with high antiplasmodial activity were subjected to preliminary phytochemical screening. Results: Extracts from five plants had promising antiplasmodial activity. Specifically, Bursera simaruba (Burseraceae) (bark), Guazuma ulmifolia Lam. (Malvaceae) (whole plant), Murraya exotica L. (Rutaceae) (leaves), Hippomane mancinella L. (Euphorbiaceae) (seeds), and Capparis odoratissima Jacq. (Capparaceae) (leaves). Extracts presented 50% inhibitory concentration values between 1 and 9 µg/ml. Compared to no extract, these active plant extracts did not show cytotoxic effects on mononuclear cells or hemolytic activity in healthy human erythrocytes. Conclusions: The results obtained from this in vitro study of antiplasmodial activity suggest that active plant extracts from the Colombian North Coast are promising for future bioassay-guided fractionation to allow the isolation of active compounds and to elucidate their mechanism of action against Plasmodium spp.

A screening of plants used in Colombian traditional medicine revealed the anti-inflammatory potential of Physalis angulata calyces.

The use of natural products by communities from the Colombian Caribbean region to treat health issues, together with biodiversity and geographical features, constitute a great scenery to develop new therapies based on ethnopharmacological heritage. Here, we investigated the anti-inflammatory potential of 10 commonly used plants in Colombian folk medicine, evaluating their effect on nitric oxide (NO) production by LPS-stimulated RAW 264.7 macrophages. The most active plant was evaluated in vivo using 12-O-tetradecanoyl-phorbol-13-acetate (TPA)-induced mouse ear edema, along with its effect on the production of pro-inflammatory mediators in vitro. The extract of Physalis angulata L. calyces showed the highest activity. This extract was fractionated and its dichloromethane fraction (DF) was the most active in vitro, inhibiting the production of NO, prostaglandin E2 (PGE2), interleukin (IL)-1ß, IL-6, tumor necrosis factor (TNF)-α and monocyte chemotactic protein (MCP)-1 (CCL2). In vivo, DF showed a significant inhibition of ear edema and myeloperoxidase (MPO) activity, with evident reduction of the leukocyte infiltration into tissue. Our results support the ethnopharmacological use of the selected plants in folk medicine. P. angulata dichloromethane fraction represents a promising source of pharmacological compounds with great potential therapeutic use to treat inflammatory illness.

Anthrone and oxanthrone C-glycosides from Picramnia latifolia collected in Peru.

Cytotoxicity-based, bioassay-guided fractionation of the chloroform-soluble extracts of both the roots and leaves of Picramnia latifolia led to the isolation of two new anthrone C-glycosides, picramniosides G (1) and H (2), two new oxanthrone C-glycosides, mayosides D (3) and E (4), and a new benzanthrone natural product, 6,8-dihydroxy-10-methyl-7H-benz[de]anthracen-7-one (5), together with 10 known compounds, 6,8-dihydroxy-4-methyl-7H-benz[de]anthracen-7-one (6), nataloe-emodin (7), chrysophanein, chrysophanol, 1,5-dihydroxy-7-methoxy-3-methylanthraquinone, pulmatin, 7-hydroxycoumarin, 7-hydroxy-6-methoxycoumarin, beta-sitosterol, and beta-sitosterol glucoside. The structures of 1-5 were established by spectroscopic methods, including 1D and 2D NMR, HRMS, and CD data interpretation. The cytotoxic activity of all isolates was evaluated in a small panel of human cancer cell lines. Compound 7 exhibited significant in vitro cytotoxic activity in the tested cell lines, but no significant activity was observed with an in vivo hollow fiber model at doses of 6.25, 12.5, 25, and 50 mg/kg/injection.

Cytotoxic flavone analogues of vitexicarpin, a constituent of the leaves of Vitex negundo.

Bioassay-guided fractionation of the chloroform-soluble extract of the leaves of Vitex negundo led to the isolation of the known flavone vitexicarpin (1), which exhibited broad cytotoxicity in a human cancer cell line panel. In an attempt to increase the cytotoxic potency of 1, a series of acylation reactions was performed on this compound to obtain its methylated (2), acetylated (3), and six new acylated (4-9) derivatives. Compound 9, the previously unreported 5,3'-dihexanoyloxy-3,6,7,4'-tetramethoxyflavone, showed comparative cytotoxic potency to compound 1 and was selected for further evaluation. However, this compound was found to be inactive when evaluated in the in vivo hollow fiber assay with Lu1, KB, and LNCaP cells at the highest dose (40 mg/kg/body weight) tested, and in the in vivo P-388 leukemia model (135 mg/kg), using the ip administration route.