Biochemical Studies and Virtual Screening of Phytochemical Reservoir from Northeastern Indian Plants to Identify Anti-Cancer Agents

Abstract

In the present study, medicinal phytochemicals found in plants of north-eastern India were virtually screened against the C1b regulatory domain of Protein Kinase C (PKC), an important enzyme in cancer cell-biology. Amongst the few top hits, the molecules Gallic acid (GA) and Epigallocatechin gallate (EGCG) were identified through an agonist competition assay. Both phytochemical are non-toxic and non-mutagenic. An in vitro PKC binding assay confirmed that GA and EGCG were strong ligands of PKC. Both the phytochemicals formed numerous hydrogen bonding and hydrophobic interactions with the amino acids lining the ligand binding pocket of the C1b domain of PKC. They were able to induce translocation of PKC to the plasma membrane in MDAMB-231 breast cancer cells. Furthermore, GA and EGCG dose-dependently reduced the viability of breast cancer cells by arresting the cell-cycle. Eventually, mitochondrial pathway of apoptosis was identified as the mechanism of loss of breast cancer cellular viability. Thus, our study has revealed that tea phytochemicals GA and EGCG exhibit anti-cancer activity by acting as strong ligands of PKC. This study encourages the further identification of newer novel and even more potent such PKC-directed phytochemicals from natural herbs & beverages as a part of herbal anti-cancer therapy.