Phenolic content and antibacterial activity of extracts of Hamelia patens obtained by different extraction methods

Abstract Hamelia patens, is a plant traditionally used to treat a variety of conditions among the Huastec people of Mexico. The objective of this study is to characterize the phenolic content and critically examine the antimicrobial activity of leaf extracts H. patens, obtained by maceration, Soxhlet and percolation, using ethanol as 70% solvent. Phenolic compounds are characterized by liquid chromatography, coupled to a High Resolution Mass Spectrometry, and the antimicrobial activity was studied from the inhibitory effect of each extract for Escherichia coli, Staphylococcus aureus, Salmonella typhi and S. paratyphi, and by the Minimum Bactericidal Concentration, the percentage of activity and the Index of Bacterial Susceptibility of each extract. The phenolic compound identified in different concentrations in the three extracts was epicatechin. The extracts obtained by the three methods had antimicrobial activity, however, there was no significant difference (p < 0.05) between the Minimum Bactericidal Concentration of the extracts obtained by maceration, percolation and Soxhlet. The results of this study contribute to the body of knowledge on the use of extracts in controlling microorganisms with natural antimicrobials.

Toxicity and antinociceptive effects of Hamelia patens

Abstract Many medicinal herbs are used in folk medicine without taking into account their toxicity. Hamelia patens Jacq. (Rubiaceae), a Mexican endemic species, is used for the empirical treatment of pain. The aim of this work was to evaluate the toxicity and antinociceptive effects of ethanolic extracts of H. patens leaves. The toxicity of H. patens leaves (500–5000 mg/kg) was evaluated in acute (14 days) and subacute (28 days) assays. In the subacute assay, a blood analysis (both hematology and chemistry) was carried out. The antinociceptive effects of H. patens leaves (50–200 mg/kg) were evaluated using thermal-induced nociception (hot plate) and the chemical-induced nociceptive tests (acid acetic and formalin). In the acute toxicity test, the LD50 estimated for H. patens leaves was 2964 mg/kg i.p. and >5000 mg/kg p.o., whereas in the subacute test HPE did not affect hematological or biochemical parameters. In chemical-induced nociception models, H. patens (100 and 200 mg/kg p.o.) showed antinociceptive effects with similar activity than 100 mg/kg naproxen. In the hot plate test, HPE at 100 mg/kg (17%) and 200 mg/kg (25%) showed moderate antinociceptive effects. HPE could be a good source of antinociceptive agents because of its good activity and low toxicity.

In vitro and in vivo antifungal activity, liver profile test, and mutagenic activity of five plants used in traditional Mexican medicine

Berberis hartwegii Benth., Berberidaceae, Hamelia patens Jacq., Rubiaceae, Dendropanax arboreus (L.) Decne & Planch., Araliaceae, Erythrina herbacea L., Fabaceae, and Zanthoxylum caribaeum Lam., Rutaceae, acetone extracts were selected on the basis of their use in traditional Mexican medicine to treat scabies or skin diseases. Anti-dermatophyte activity in vitro was evaluated using the agar dilution assay, and the therapeutic efficacy of B. hartwegii and Z. caribaeum were tested against experimental tinea pedis. The infected animals were treated intragastrically daily for seven days with 2.5 and 5 mg/kg of acetone extracts. The acetone extract of H. patens exhibited 100% growth inhibition against T. mentagrophytes and E. floccosum at 100.0 and 50.0 µg/ml, respectively, and B. hartwegii inhibited growth of M. canis and T. mentagrophytes at 100.0 µg/ml. Effective treatments with 2.5 mg/kg of Z. caribaeum and B. hartwegii extract were comparable with 1 mg/kg of clotrimazole in mice. Liver profile tests and histological analyses did not exhibit any signs of toxicity and the Ames test indicated that both extracts were safe when evaluated in strains TA98, TA100 and TA102. Our results suggest the potential for the future development of new antifungal drugs from B. hartwegii or Z. caribaeum.