Manikkam Rajalakshmi

Insulin mimetic impact of Catechin isolated from Cassia fistula on the glucose oxidation and molecular mechanisms of glucose uptake on Streptozotocin-induced diabetic Wistar rats

Diabetes mellitus is the most common and serious metabolic disorder among people all over the world. Many plants have successfully been used to overcome this problem. Cassia fistula, an ethnomedicnal plant, is widely used in Indian medicine to treat diabetes. Methanol extract of stem of plant, reduced the blood glucose levels in Streptozotocin-induced diabetic rats. Bioassay guided fractionation was followed to isolate Catechin from methanol extract. Catechin was administered to Streptozotocin (60mg/kg b.w.)-induced diabetic male Wistar rats at different doses (5, 10, 20mg/kg b.w.) for 6 weeks to assess its effect on fasting plasma glucose. The plasma glucose was significantly (p<0.05) reduced when compared to the control. Oral administration of Catechin (20mg/kg b.w.) markedly increased tissue glycogen, and (14)C-glucose oxidation without any change in plasma insulin and C-peptide. Catechin restored the altered Glucokinase, glucose-6 Phosphatase, Glycogen Synthase and Glycogen Phosphorylase levels to near normal. GLUT4 mRNA and protein expression were enhanced after Catechin treatment. The results of this experimental study indicated that Catechin possesses hypo-glycemic, Glucose oxidizing and insulin mimetic activities and hence it could be used as a drug for treating diabetes.

A database for the predicted pharmacophoric features of medicinal compounds

Pharmacophore feature is defined by a set of chemical structure patterns having the active site of drug like molecule. Pharmacophore can be used to assist in building hypothesis about desirable chemical properties in drug molecule and hence it can be used to refine and modify drug candidates. We predicted the pharmacophoric features of 150 medicinal compounds from plants for anti-cancer, anti-carcinogenic, anti-diabetic, anti-microbial, and anti-oxidant. Estimation of pharmacophoric feature is necessary to ensure the optimal supramolecular interaction with a biological target and to trigger or block its biological response. We subsequently make this data available to open access using a database at the URL: http://www.hccbif.info/index.htm Availability The database is available for free at http://www.hccbif.info/index.htm

Virtual Screening of Potential Inhibitor Against FtsZ Protein from Staphylococcus aureus

The gram-positive bacterium Staphylococcus aureus, responsible for a wide variety of diseases in human involve all organ systems ranging from localized skin infections to life-threatening systemic infections. FtsZ, the key protein of bacterial cell division was selected as a potent anti bacterial target. In order to identify the new compounds structure based screening process was carried out. An enrichment study was performed to select a suitable scoring function and to retrieve potential candidates against FtsZ from a large chemical database. The docking score and docking energy values were compared and their atomic interaction was also evaluated. Furthermore molecular dynamics simulation were also been performed to check the stability and the amino acids interacted towards the FtsZ. Finally we selected C ID 16284, 25916, 15894, 13403 as better lead compounds. From these results, we conclude that our insilico results will provide a framework for the detailed in vitro and in vivo studies about the FtsZ protein activity in drug development process.

Metabolism-dependent cytotoxicity of citrinin and ochratoxin A alone and in combination as assessed adopting integrated discrete multiple organ co-culture (IdMOC)

Citrinin (CTN) and ochratoxin A (OTA) can be present as co-contaminants in cereals, foods and feed commodities, and can affect human health. Metabolism-dependent toxicity of these two mycotoxins, separately as well as in combination, is not yet understood. To fill this gap we adopted integrated discrete multiple organ co-culture (IdMOC) technique, which obviates animal experiments from the perspectives of species difference as well as animal welfare concerns. IdMOC facilitates co-culture of a metabolically competent cell (HepG2) and a metabolically incompetent cell (3T3) that are physically separated but provides for extracellular product(s) from one cell to interact with the other. After ascertaining that HepG2 is metabolically competent and 3T3 is not, adopting luciferin-IPA metabolism assay, CTN and OTA were tested separately and in combination in the co-culture set-up, when both proved to be metabolism-dependent cytotoxic agents. Hepatocytes metabolize CTN into a diffusible product that is cytotoxic to 3T3 cells but the cytotoxicity of OTA appears to be limited to the hepatocytes, i.e., local acting. As a combination at a concentration of 20% of IC50 of each, CTN forms a reactive metabolite that diffuses out of HepG2 to cause cytotoxicity to 3T3 cells synergistically with OTA parent molecule. The CYP isoenzymes involved in the metabolism OTA and CTN were identified adopting in silico methods which indicated that OTA and CTN can bind CYP proteins at specific sites.

Nimbolide inhibits androgen independent prostate cancer cells survival and proliferation by modulating multiple pro-survival signaling pathways

BACKGROUND Prostate cancer is the most prominent cancer in men, experiencing a relapse in disease often express high serum TNF-α levels. It has been correlated with increased cell survival and proliferation of prostate cancer cells. Previous studies reported that nimbolide, a terpenoid derived from the leaves and flowers of neem tree inhibits cancer growth through selective modulation of cell signaling pathways linked to inflammation, survival, proliferation, angiogenesis and metastasis. METHODS The present study aimed to examine the effect of nimbolide at 1 and 2μM concentrations on TNF-α/TNFR1 mediated signaling molecules involved in cell survival and proliferation in PC-3 cell line via NF-κB and MAPK pathways by real time PCR and western blot. Protein and compound interaction were performed by Molecular docking analysis. RESULTS Our results indicate that nimbolide treatment suppressed expression of TNF-α, SODD, Grb2, SOS mRNA and modulated TNF-α/TNFR1 regulated NF-κB and MAPK signaling molecules in PC-3 cells. Additional molecular dynamics simulation studies confirmed the stability of nimbolide and signaling molecules binding interactions. Binding pose analysis revealed the significance of hydrogen bond interactions for effective stabilization of virtual ligand protein complexes. CONCLUSION Nimbolide inhibited prostate cancer cell survival and proliferation via NF-κB and MAPK pathways.

Effects of dihydroxy gymnemic triacetate (DGT) on expression of apoptosis associated proteins in human prostate cancer cell lines (PC3)

Abstract Prostate cancer is the most common malignancies among men. The present study is aimed at the investigation of dihydroxy gymnemic triacetate (DGT) from Gymnema sylvestre on mitochondrial apoptotic pathway and cell cycle arrest. Treatment of DGT resulted in a dose-dependent inhibition of growth of PC-3 cells. The cell cycle arrest was observed at the G2/M phase and accumulation of apoptotic cells was observed in DGT-treated prostate cancer cell lines. The occurrence of apoptosis in these cells was observed by DNA fragmentation. These events were associated with increased levels of pro-apoptotic proteins Bax, Bad and reduced levels of the antiapoptotic proteins Bcl-2, Bcl-xL and Mcl-1. DGT also induces the activation of caspase-9 and caspase-3. The above results, clearly, suggest that DGT induces apoptosis by the intrinsic pathways which could be very useful for the treatment of prostate cancer.

Chemopreventive effect of saponin isolated from Gymnema sylevestre on prostate cancer through in silico and in vivo analysis

Prostate cancer is one of the frequently diagnosed cancers in men. In prostate cancer, initiation to the appearance of symptoms is a very long period. Due to its high latency period it paved the way for the chemoprevention. Chemopreventive drugs quickly and effectively eliminate pre-malignant cells by inducing apoptosis. In this context, the present study utilized an integrated approach of in silico and in vivo analysis to find an effective chemopreventive drug, which induces apoptosis. Three phytocompounds from Gymnema sylvestre were screened against anti-apoptoic proteins (Bcl-2 and Bcl-xl) through in silico analysis and the best compound was identified as dihydroxy gymnemic triacetate. Its chemopreventive activity was analyzed in the N-methyl-N-nitrosourea and Testosterone-induced Sprague-Dawley rats. The result indicates that anti-apoptotic proteins (Bcl-2, Bcl-xl) level were significantly increased in cancer-induced animals compared to control whereas treatment with dihydroxy gymnemic triacetate supplementation significantly maintained the protein expression in par with control rats. This study suggests that dihydroxy gymnemic triacetate may act as a potential chemopreventive agent in targeting the prostate cancer. Thus, these findings may open novel prospective in cancer chemoprevention.