Antimalarial Activity of Anacardium occidentale Leaf Extracts Against Plasmodium falciparum Transketolase (PfTK).

BACKGROUND: 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 IC50 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. CONCLUSION: 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.

Identification of novel PTP1B inhibitors by pharmacophore based virtual screening, scaffold hopping and docking.

Design and synthesis of protein tyrosine phosphatases-1B (PTP1B) inhibitors are important for the drugs targeted to treat diabetes and obesity. The pharmacophore modeling, docking and scaffold hopping techniques have been applied to discover the novel PTP1B inhibitors. The ten prioritized compounds (115-119, 120-121, 127, 130-131) from the library of 86 compounds were synthesized and found positive in the micro molar range for PTP1B in-vitro inhibitory assays as compared to Suramin (IC50 9.5 µM). Among these five active compounds (115-119) were tested in STZ-s induced diabetic rat model and the most active compound 115 in this test, was further tested in C57BL/KsJ-db/db mice where it significantly improved OGTT along with the fasting and random blood glucose level. The treatment by the compound 115 significantly improved the insulin resistance and insulin signaling by restoring the insulin level and normalizing the serum lipid profile. Compound 115 also augmented the insulin action by modulating the expression of genes involved in insulin signaling like IRS 1-2, PI3K, PTPN1, Akt2, AMPK and PPAR-α. Western blot analysis of both skeletal muscle and liver demonstrated that proteins and intermediate enzymes of insulin signaling were also increased as compared to control group. The compound 115 was also investigated for anti-adipogenic effect on 3T3L-1 cells. The compound 115 inhibited MDI induced lipid accumulation in a dose-dependent manner. The oral bioavailability of compound 115 was ∼10.29% after 30 mg/kg oral dosing assessed in rat.

Lipid lowering and antioxidant effect of miglitol in triton treated hyperlipidemic and high fat diet induced obese rats.

Miglitol, an anti-diabetic drug, has been shown to reduce plasma lipids and inhibit free radical generation. The anti-hyperlipidemic and antioxidant effects of miglitol were studied in triton-induced hyperlipidemic rats and high fat diet-fed obese rats. Plasma cholesterol and triglycerides levels were significantly lowered by miglitol at 100 mg/kg body weight doses. Miglitol inhibited generation of superoxide anion and hydroxyl free radicals by 14 and 31 % in enzymatic systems and 19 and 25 % in non-enzymatic systems, respectively. The in-vitro effect of the drug on adipogenesis using 3T3-L1 preadipocytes at 2-, 5- and 10-µM concentrations showed significant inhibition of adipogenesis (34.2 %) at 10-µM concentration. High fat diet-fed rat model was used to investigate anti-hyperlipidemic, anti-obesity and antioxidant effect of miglitol. Miglitol increased the activities of lecithin-cholesterol-acyltransferase (19 %), post heparin lipolytic activity (26 %), lipoprotein lipase (26 %) and triglyceride lipase (31 %) which result in a decrease in plasma lipid levels. The antioxidant enzymes viz., catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase and thioredoxin reductase were increased by the drug in the treated animals. The antihyperlipidemic and antioxidant effect of miglitol can be correlated to its effect on different enzymes and it can be used for inhibiting the development of cardiovascular diseases.

Hypolipidemic and antioxidant activity of Anthocephalus indicus (Kadam) root extract.

The present study was carried out to explore the anti-diabetic, anti-dyslipoproteinemic and anti-oxidant activities of Anthocephalus indicus root extract in alloxan-induced (150 mg/kg body wt.) diabetic rats. A marked increase in plasma levels of glucose and lipid peroxides accompanied with an elevation in the lipids and apoprotein levels of serum very low density lipoprotein (VLDL) and low density lipoprotein (LDL) following decrease in lipid and protein constituents of high density lipoprotein (HDL) were observed. The alterations in lipoprotein pattern was associated with inhibition of lipolytic and antioxidant enzymes. Oral administration of root extract (500 mg/kg body wt.) for 30 days in dyslipidemic animals resulted in significant decrease in plasma glucose, total cholesterol, phospholipids, triglyceride and lipid peroxides. The decrease of lipids and apoprotein levels of VLDL and LDL were followed by stimulation of plasma post-heparin lipolytic activity and lecithin cholesterol acyltransferase as well as hepatic superoxide dismutase and catalase activities. Lipid and apoprotein levels of HDL were also recovered partially on treatment with root extract.

Lipid Lowering Activity of Anthocephalus indicus Root in Hyperlipidemic Rats.

The lipid lowering activity of Anthocephalus indicus (family Rubiaceae; Hindi name Kadamba) root extract has been studied in triton WR-1339 induced hyperlipidemia in rats. In this model, feeding with root extract (500 mg kg(-1) b.w.) lowered plasma lipids and reactivated post-heparin lipolytic activity in hyperlipidemic rats. Furthermore, the root extract (50-500 µM) inhibited the generation of superoxide anions and hydroxyl radicals, in both enzymic and non-enzymic systems, in vitro. The results of the present study demonstrated both lipid lowering and antioxidant activities in root extract of A. indicus, which could help prevention of hyperlipidemia and related diseases.

Hypolipidemic activity of Hibiscus rosa sinensis root in rats.

The hypolipidemic activity of Hibiscus rosa sinensis (family Malvaceae) root extract was studied on triton and cholesterol-rich high fat diet (HFD) induced models of hyperlipidemia in rats. In triton WR-1339-induced hyperlipidemia, feeding with root extract (500 mg/kg body wt/day p.o.) exerted lipid-lowering effect, as assessed by reversal of plasma levels of total cholesterol (TC), phospholipids (PL) and triglycerides (TG) and reactivation of post-heparin lipolytic activity (PHLA) of plasma. The other model was fed with cholesterol-rich HFD and root extract (500 mg/kg body wt/ day p.o.) simultaneously for 30 days. This also caused lowering of lipid levels in plasma and liver homogenate and reactivation of plasma PHLA and hepatic total lipoprotein lipase activity. The hypolipidemic activity of Hibiscus rosa sinensis root was compared with a standard drug guggulipid (200 mg/kg body wt/day p.o.), a known lipid- lowering agent in both models. Histopathological findings in rat liver supported the protective role of H. rosa sinensis root extract in preventing cholesterol-rich HFD-induced hepatic steatosis.