We assessed the biological activity of a crude extract, a mixture of several fractions, and a pure compound obtained from Piper ovatum Vahl against promastigote and amastigote forms of Leishmania amazonensis. The medicinal plant P. ovatum is used popularly as an anesthetic and anti-inflammatory. This study included the extraction process and bioassay-guided fractionation by the adsorption chromatography and Sephadex LH-20 method. A progressive increase in the antileishmanial effect was observed in the course of fractionation. The 50% inhibitory concentration (IC 50) for dichloromethane-ethyl acetate (1:1 v/v) fraction was 2.1 µg/ml and 24 µg/ml; mixture of piperovatine: piperlongumune (2:3) 0.9 µg/ml and 24 µg/ml; piperovatine (1) 9.5 µg/ml and 10 µg/ml; and piperlonguminine (2) 2.5 µg/ml and 9.0 µg/ml, for promastigote and amastigote forms, respectively. Cytotoxicity analysis indicated that these toxic concentrations were much higher for J774G8 macrophages and Vero cells than for the protozoans. The mixture of piperovatine: piperlongumune (2:3) showed important antiprotozoal activity against the amastigote and promastigote forms of L. amazonensis, and it produced morphological changes in promastigotes and amastigotes at 0.9 µg/ml and 24 µg/ml (50% growth inhibition concentration), respectively, including intense cytoplasmic vacuolization, mitochondrial swelling, and mitochondrial damage, as revealed by transmission electron microscopy.

Abstract:The chemical composition of the essential oil obtained from the leaves of Piper ovatum Vahl by hydrodistillation was analyzed by GC-MS. The main constituents found were δ-amorphene (16.5 %), cis-muurola-4(14),5-diene (14.29 %) and γ-muurolene (13.26%). The crude extracts and isolated compounds were screened for their antimicrobial activity. Hydroalcoholic extracts of different parts of Piper ovatum Vahl, essential oil and amides isolated from leaves were tested against Gram-positive and Gram-negative bacteria and Candida species. All extracts and amides were active against Bacillus subtilis and Candida tropicalis, including clinical strains. Essential oil was active against C. tropicalis. These amides showed an inhibitory effect on the adherence of C. tropicalis ATCC 28707 on cover glasses at 10 µg/mL, but did not show morphological alterations at the tested concentrations. Amides were identified as piperovatine and piperlonguminine, and showed MIC values of 15.6 and 31.2 µg/mL to B. subtilis and 3.9 µg/mL to C. tropicalis, and low toxic effects to Vero cells and macrophages.