Chouhan Garima, Islamuddin Mohammad, Want Muzamil Y, Ozbak Hani A, Hemeg Hassan A, Sahal Dinkar, Afrin Farhat
Parasite Immunology Laboratory, Department of Biotechnology, Faculty of Science, Jamia Hamdard (Hamdard University) New Delhi, India.
Department of Medical Laboratories Technology, Faculty of Applied Medical Sciences, Taibah University Medina, Saudi Arabia.
Front Microbiol. 2015 Dec 8;6:1368. doi: 10.3389/fmicb.2015.01368. eCollection 2015.
Visceral leishmaniasis (VL) is a life-threatening protozoal infection chiefly impinging the rural and poor population in the tropical and sub-tropical countries. The deadly affliction is rapidly expanding after its association with AIDS, swiftly defying its status of a neglected disease. Despite successful formulation of vaccine against canine leishmaniasis, no licensed vaccine is yet available for human VL, chemotherapy is in appalling state, and the development of new candidate drugs has been painfully slow. In face of lack of proper incentives, immunostimulatory plant preparations owing antileishmanial efficacy bear potential to rejuvenate awful antileishmanial chemotherapy. We have earlier reported profound leishmanicidal activity of Piper nigrum hexane (PNH) seeds and P. nigrum ethanolic (PNE) fractions derived from P. nigrum seeds against Leishmania donovani promastigotes and amastigotes. In the present study, we illustrate that the remarkable anti-promastigote activity exhibited by PNH and PNE is mediated via apoptosis as evidenced by phosphatidylserine externalization, DNA fragmentation, arrest in sub G0/G1 phase, loss of mitochondrial membrane potential and generation of reactive oxygen species. Further, P. nigrum bioactive fractions rendered significant protection to L. donovani infected BALB/c mice in comparison to piperine, a known compound present in Piper species. The substantial therapeutic potential of PNH and PNE was accompanied by elicitation of cell-mediated immune response. The bioactive fractions elevated the secretion of Th1 (INF-γ, TNF-α, and IL-2) cytokines and declined IL-4 and IL-10. PNH and PNE enhanced the production of IgG2a, upregulated the expression of co-stimulatory molecules CD80 and CD86, augmented splenic CD4(+) and CD8(+) T cell population, induced strong lymphoproliferative and DTH responses and partially stimulated NO production. PNH and PNE were devoid of any hepatic or renal toxicity. These encouraging findings merit further exploration of P. nigrum bioactive fractions as a source of potent and non-toxic antileishmanials.
内脏利什曼病（VL）是一种危及生命的原生动物感染，主要影响热带和亚热带国家的农村贫困人口。在与艾滋病关联后，这种致命疾病正在迅速蔓延，迅速摆脱了其被忽视疾病的地位。尽管已成功研制出针对犬利什曼病的疫苗，但目前尚无用于人类VL的许可疫苗，化疗状况不佳，新候选药物的研发进展极其缓慢。面对缺乏适当激励措施的情况，具有抗利什曼活性的免疫刺激植物制剂有可能使糟糕的抗利什曼化疗恢复活力。我们之前报道过，胡椒黑籽己烷提取物（PNH）和从胡椒黑籽中提取的胡椒乙醇提取物（PNE）对杜氏利什曼原虫前鞭毛体和无鞭毛体具有显著的杀利什曼活性。在本研究中，我们证明PNH和PNE所表现出的显著抗前鞭毛体活性是通过凋亡介导的，这可通过磷脂酰丝氨酸外化、DNA片段化、亚G0/G1期阻滞、线粒体膜电位丧失和活性氧生成来证明。此外，与胡椒属植物中存在的已知化合物胡椒碱相比，胡椒生物活性提取物对感染杜氏利什曼原虫的BALB/c小鼠具有显著的保护作用。PNH和PNE的巨大治疗潜力伴随着细胞介导免疫反应的激发。这些生物活性提取物提高了Th1（INF-γ、TNF-α和IL-2）细胞因子的分泌，并降低了IL-4和IL-10的水平。PNH和PNE增强了IgG2a的产生，上调了共刺激分子CD80和CD86的表达，增加了脾脏CD4(+)和CD8(+) T细胞群体，诱导了强烈的淋巴细胞增殖和迟发型超敏反应，并部分刺激了一氧化氮的产生。PNH和PNE没有任何肝毒性或肾毒性。这些令人鼓舞的发现值得进一步探索胡椒生物活性提取物作为强效且无毒抗利什曼药物来源的可能性。
