anti-leishmanial effects of herbal monoterpenes

Leishmaniasis, the third most important disease transmitted by vectors, is caused by protozoan parasites of the genus leishmania (1). chemotherapy of leishmaniasis has several limitations. medicinal plants are rich resources containing valuable and accessible materials. as a subset of volatile plant compounds, monoterpenes have been attributed to many biological and pharmacological actions of plant products in recent years (2). one of the main members of monoterpenes is herbal monoterpenes (mt) (3). this study investigated the biological effects of mt on leishmania, antileishmanial effect, cytotoxicity, apoptosis induction and gene expression changes. herbal monoterpene was probed for its antileishmanial potentials using the mtt biochemical colorimetric assay and a model macrophage cell. annexin-v/pi staining by flow cytometry was used for evaluation of apoptosis. its immunomodulatory properties were assessed by analyzing their effect on the transcription of cytokines related to th1 and th2 responses. the mt showed significant inhibitory effects against l. major promastigotes and amastigotes. the apoptotic effect of herbal monoterpenes against l. major promastigotes was increased concentration-dependently. herbal monoterpenes ability to attenuate the transcriptional expression of il-12p40, jak1, inos, il-10, and tgf-β genes and to enhance the metacaspase gene at mrna level was evidenced. the present study confirmed that mt was a suitable candidate compound to interfere with the growth of l. major in a eukaryotic cell model by moderate scavenging activities. this study was the first to investigate the performance of mt as a pure compound against l. major stages, whereas, previous studies have elaborated using terpenes obtained from plants.