Department of Neglected Tropical Diseases and Translation Research, ICMR-National Institute of Traditional Medicine, Nehru Nagar, Belagavi, Karnataka, 590010, India.
Department of Biochemistry, CSIR-Central Drug Research Institute, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow, Uttar Pradesh, 226031, India.
Acta Parasitol. 2023 Dec;68(4):832-841. doi: 10.1007/s11686-023-00718-6. Epub 2023 Oct 13.
As per estimates by WHO in 2021 almost half of the world's population was at risk of malaria and > 0.6 million deaths were attributed to malaria. Therefore, the present study was aimed to explore the antimalarial activity of extracts derived from the leaves of the plant Anacardium occidentale L., which has been used traditionally for the treatment of malaria. Different extracts of A. occidentale leaves were prepared and tested for their inhibitory activity against recombinant P. falciparum transketolase (rPfTK) enzyme, in vitro. Further, growth inhibitory activity against cultivated blood stage P. falciparum parasites (3D7 strain), was studied using SYBR Green fluorescence-based in vitro assays. Acute toxicity of the hydro alcoholic extracts of leaves of A. occidentale (HELA) at different concentrations was evaluated on mice and Zebra fish embryos. HELA showed 75.45 ± 0.35% inhibitory activity against the recombinant PfTk and 99.31 ± 0.08% growth inhibition against intra-erythrocytic stages of P. falciparum at the maximum concentration (50 µg/ml) with IC of 4.17 ± 0.22 µg/ml. The toxicity test results showed that the heartbeat, somite formation, tail detachment and hatching of embryos were not affected when Zebra fish embryos were treated with 0.1 to 10 µg/ml of the extract. However, at higher concentrations of the extract, at 48 h (1000 µg/ml) and 96 h (100 µg/ml and 1000 µg/ml, respectively) there was no heartbeat in the fish embryos. In the acute oral toxicity tests performed on mice, the extract showed no toxicity up to 300 mg/kg body weight in mice.
The hydro-alcoholic extract of leaves of A. occidentale L. showed potent antimalarial activity against blood stage P. falciparum. Based on the observed inhibitory activity on the transketolase enzyme of P. falciparum it is likely that this enzyme is the target for the development of bioactive molecules present in the plant extracts. The promising anti-malarial activity of purified compounds from leaves of A. occidentale needs to be further explored for development of new anti-malarial therapy.
根据世界卫生组织（WHO）在 2021 年的估计，世界上几乎有一半的人口面临疟疾风险，疟疾导致的死亡人数超过 60 万。因此，本研究旨在探索从植物鳄梨（Anacardium occidentale L.）的叶子中提取的物质的抗疟活性，该植物传统上用于治疗疟疾。制备了鳄梨叶的不同提取物，并在体外测试其对重组恶性疟原虫转酮醇酶（rPfTK）酶的抑制活性。进一步使用 SYBR Green 荧光体外测定法研究了对培养的恶性疟原虫血阶段寄生虫（3D7 株）的生长抑制活性。在不同浓度下，用急性毒性评估叶子的水醇提取物（HELA）对小鼠和斑马鱼胚胎的毒性。HELA 对重组 PfTk 的抑制活性为 75.45±0.35%，在最大浓度（50μg/ml）时对恶性疟原虫红内期的生长抑制率为 99.31±0.08%，IC 为 4.17±0.22μg/ml。毒性试验结果表明，当斑马鱼胚胎用 0.1 至 10μg/ml 的提取物处理时，心跳、体节形成、尾部分离和孵化不受影响。然而，在更高浓度的提取物（48 小时（1000μg/ml）和 96 小时（100μg/ml 和 1000μg/ml）时，鱼胚胎没有心跳。在对小鼠进行的急性口服毒性试验中，提取物在 300mg/kg 体重以下对小鼠没有毒性。
鳄梨叶的水醇提取物对恶性疟原虫血期具有很强的抗疟活性。基于对恶性疟原虫转酮醇酶的抑制活性，该酶可能是植物提取物中生物活性分子的作用靶点。需要进一步探索鳄梨叶中纯化化合物的抗疟活性，以开发新的抗疟疗法。
