Molecular modelling, docking and network analysis of phytochemicals from Haritaki churna: role of protein cross-talks for their action.

Phytochemicals are bioactive agents present in medicinal plants with therapeutic values. Phytochemicals isolated from plants target multiple cellular processes. In the current work, we have used fractionation techniques to identify 13 bioactive polyphenols in ayurvedic medicine Haritaki Churna. Employing the advanced spectroscopic and fractionation, structure of bioactive polyphenols was determined. Blasting the phytochemical structure allow us to identify a total of 469 protein targets from Drug bank and Binding DB. Phytochemicals with their protein targets from Drug bank was used to create a phytochemical-protein network comprising of 394 nodes and 1023 edges. It highlights the extensive cross-talk between protein target corresponding to different phytochemicals. Analysis of protein targets from Binding data bank gives a network comprised of 143 nodes and 275 edges. Taking the data together from Drug bank and binding data, seven most prominent drug targets (HSP90AA1, c-Src kinase, EGFR, Akt1, EGFR, AR, and ESR-α) were found to be target of the phytochemicals. Molecular modelling and docking experiment indicate that phytochemicals are fitting nicely into active site of the target proteins. The binding energy of the phytochemicals were better than the inhibitors of these protein targets. The strength and stability of the protein ligand complexes were further confirmed using molecular dynamic simulation studies. Further, the ADMET profiles of phytochemicals extracted from HCAE suggests that they can be potential drug targets. The phytochemical cross-talk was further proven by choosing c-Src as a model. HCAE down regulated c-Src and its downstream protein targets such as Akt1, cyclin D1 and vimentin. Hence, network analysis followed by molecular docking, molecular dynamics simulation and in-vitro studies clearly highlight the role of protein network and subsequent selection of drug candidate based on network pharmacology.Communicated by Ramaswamy H. Sarma.

Extraction, phytochemical characterization and anti-cancer mechanism of Haritaki churna: An ayurvedic formulation.

Haritaki churna (HC), a single herb ayurvedic formulations is known to be prescribed for various gastro-intestinal disorders in Ayurveda. Haritaki churna aqueous extract (HCAE) has anti-cancer activity against different types of cancer cells with an IC50 in the range of 50-97 µg/ml. Bioavailability of Haritaki Churna is very high in digestive track and treatment of colorectal cancer cells HCT-116, DLD1, HT-29 with HCAE reduces its cellular viability with anti-cancer IC50 70µg/ml. HCAE consumption is safe for human as it didn't affect the cellular viability of primary human PBMCs or non-cancerogenic HEK-293 cells. Haritaki churna was found to be stable in biological gastric fluids and bioactive agents are not losing their anti-cancer activity under such harsh conditions. The HPLC Chromatogram of HCAE is giving 13 major peaks and 11 minor peaks. Exploiting LC-MS, IR and NMR spectroscopic techniques, a total of 13 compounds were identified from HCAE namely Shikimic acid, Chebulic acid, gallic acid, 5-hydroxymethylfurfural, Protocatechuic acid, 4-O-galloyl-shikimic Acid, 5-O-galloyl-shikimic Acid, Methylgallate, corilagin, 1, 2, 6, Tri-O-galloyl ß-D-glucose, chebulagic acid, chebulinic acid, and Ellagic acid. Reconstitution and subtraction of phytochemicals from the mixture indicate that Ellagic acid significantly contribute into anti-cancer effect of HCAE. Cancer cells treated with ellagic acid from HCAE were incapable of completing their cell-cycle and halted the cell-cycle at DNA synthesis S-Phase, as demonstrated by decreased cyclin A2 expression levels with increasing ellagic acid concentration. Halting of cells at S-phase causes induction of apoptosis in cancer cells. Cancer cells exhibiting DNA fragmentation, changes in expression of several apoptotic proteins such as Bcl2, cytochrome-c and formation of cleaved products of caspase 3 and PARP-1 suggests ellagic acid induces cell death via mitochondrial pathway of apoptosis.

Manikya Bhasma is a nanomedicine to affect cancer cell viability through induction of apoptosis.

BACKGROUND: Ayurveda is an ancient medicine system practiced in the Indian sub-continent. Ayurvedic Bhasma is incinerated herbo-metallic/mineral preparations that consist of the particles in the range of nano/micrometers with therapeutic effects against different diseases. Manikya Bhasma (MB) is composed of purified ruby, orpiment, and purified arsenic sulfide. OBJECTIVE: This study was conducted to identify the potential of MB as a nanomedicine that can be used for the treatment of cancer. MATERIALS AND METHODS: Biophysical characterization to determine the morphology and composition of bhasma particles was done using several techniques such as DLS, FTIR, FETEM, FESEM, EDX, and XRD. Cell viability assays were conducted to identify the cytotoxic effect of MB against different cancer cell lines and also to determine the mode of death caused by MB. RESULTS: The biophysical characterization of MB indicates that it is crystalline with a particle size of 70 nm. MB exhibits anticancer activity against MDAMB-231, HeLa, HCT-116, DLD-1, MG-63 cancer cells with an IC50 in the range of 105-155 µg/mL. MB induces oxidative stress in cancer cells, which in turn affects their cell-cycle with an accumulation of cells in the G1-phase. Also, apoptosis induced by MB involves loss of mitochondrial membrane potential, the release of Cyt c, activation of caspases, and DNA degradation. CONCLUSION: Our study highlights the dual potential of MB as a nano-carrier to deliver the drugs and exerting cytotoxic effects against cancer cells.

Docking and virtual screening to identify PKC agonists: potentials in anticancer therapeutics.

Protein kinase C (PKC) is down-stream to most of the G-protein coupled receptor or tyrosine kinase receptors mediated signaling events from the cell surface. PKC C1 domain has a hydrophobic region with a polar groove to facilitate 1,2-diacyl-glycerol (DAG) binding or other agonist molecule for PKC activation. Post activation, a partial or complete blocking of hydrophilic groove makes the DAG binding site completely hydrophobic and facilitates easier penetration of the PKC into the membrane. Phorbol ester, a strong PKC agonist, uses this mechanism to induce tumor formation. A total of 300 heterocyclic compounds with 70% similarity to phorbol 12-myristate 13-acetate (PMA) were selected, and virtual docking was performed with PKC-α as target. An initial screening indicated that most of the molecules fit well into the C1 domain and had better binding energy than PMA. Further analysis in a PMA competition experiment identified five molecules, Zc 67913417, Zc 68601770, Zc 25726447, Zc 35376386 and Zc 49785214 as potent PKC agonists. In addition, as these compounds showed better binding than PMA, more interaction with PKC residues (hydrogen bonding and hydrophobic), and the top five hit molecules was potent enough to abolish carcinogenic effects of PMA. Searching the top heterocyclic compounds into the drug database gave a number of approved drugs. Testing two candidate drugs, nandrolone decanoate and budesonide, reduced cellular viability of HT1080 in a dose-dependent manner with an IC50 values of 96.8 nM and 200nM respectively. An in silico toxicity analysis indicated that top hit molecules are non-toxic, non-mutagenic in cellular and bacterial system, and have no tumorigenic potentials in a single cell or animal model. Hence, a virtual screening, agonist competition assay, and in silico toxicity assessment allowed us to identify five new PKC agonist molecules for future drug discovery against cancer.

Pro-stimulatory role of methemoglobin in inflammation through hemin oxidation and polymerization.

Inflammation or vascular occlusion by parasitized red blood cell contributes to the pathogenesis of cerebral malaria. The current study aimed to characterize the role of major pro-oxidant factor methemoglobin present in the malaria culture supernatant contributing in inflammation during malaria. Heme and heme polymer stimulate macrophage to secrete large amount of reactive oxygen species into the external micro-environment. The addition of methemoglobin along with heme or heme polymer amplifies production of ROS from macrophages several folds. Methemoglobin mediated stimulatory effect is not due to release of iron, enhanced production of H2O2 or mutual interaction of reaction components. Spectroscopic studies show that methemoglobin accepts heme as a substrate and oxidizes it through a single electron transfer mechanism. Heme oxidation product is a heme polymer with similar chemical and structural properties to synthetic ß-hematin. Phenyl N-t-butylnitrone inhibits heme polymerization (IC50=30 nM) and indicates the absolute necessity of heme oxidation and heme free radical generation for heme polymerization. Methemoglobin produced heme polymer is a potent pro-inflammatory factor to release ROS into external microenvironment. Interestingly, methemoglobin not only produces pro-inflammatory heme polymer, but it also amplifies the potential of heme or preformed heme polymer (haemozoin or ß-hematin) to produce several folds high ROS production from macrophages. This study illustrates the pro-inflammatory effect of methemoglobin, the underlying novel mechanism by which this occurs and a possible clinical intervention. Based on the results, we recommend methemoglobin directed peroxidase inhibitors as an adjuvant therapy during malaria.

A cell-free scintillation proximity assay for studies on lysosome-to-phagosome targeting.

Phagocytes, such as macrophages, neutrophils, and dendritic cells, play important roles in the innate immune system through their ability to engulf, kill, and digest invading microbes. In cooperation with the humoral adaptive immune system, coating of substrates with immunoglobulin G (IgG) antibodies enhances several aspects of phagocytosis, including the recognition of substrates by cell surface IgG (Fcgamma) receptors, particle internalization, generation of microbicidal oxygen species, and targeting of lysosomes to phagosomes. We describe a cell-free scintillation proximity assay developed to study the mechanisms of lysosome targeting to phagosomes and the regulation of this process by IgG. The approach involves the use of isolated phagosomes containing scintillant latex beads and lysosomes labeled with a tritiated marker. Scintillation results only when lysosomes and phagosomes come into immediate contact and requires supplementation of reactions with adenosine triphosphate and cytosol; addition of cytosol from IgG-conditioned cells enhances this signal. The method is useful for investigating the biochemistry and regulation of the early tethering and docking steps of lysosome and phagosome interactions.

Structure-based drug design: synthesis, crystal structure, biological evaluation and docking studies of mono- and bis-benzo[b]oxepines as non-steroidal estrogens.

Mono- and bis-benzo[b]oxepine derivatives have been rationally synthesized to meet the molecular requirement for interaction with estrogen receptor. Bis-benzo[b]oxepines (7 and 9) and mono-benzo[b]oxepine (10) acquire geometry with phenolic groups disposed in a fashion to stimulate estrogen receptor. Structure-based investigation, in vivo activity and docking studies have been described and correlated to demonstrate a practical approach for suitable ligand design.