Background and objective: The waste products of the tamarind canning industry have been discarded; however, it has potential health benefits. Herein, the study was carried out HPLC profiling of phenolic constituents of Tamarindis indica pericarp and seeds. Furthermore, the cytotoxic activity against HUH-7 cells was evaluated and assessed with molecular docking study on angiogenesis-related VEGF kinase proteins in addition to evaluating the level of released VEGF in treated HUH-7 cells by ELISA.
Materials and methods: Folin-ciocalteu and AlCl3 assays were used for quantification of total phenolics (TPC) and total flavonoids (TFC) contents, respectively. Molecular docking study was done on VEGF kinase proteins.
Results: TPC and TFC of pericarp and seeds were 0.35±0.02 g GAE g-1 DE and 0.12±0.009 g CE g-1 DE, 0.39±0.01 g GAE g-1 DE and 0.03±0.006 g CE g-1 DE, respectively. In pericarp, 8 phenolics were tentatively identified, where (+)-catechin was the major (27,386.04 μg g-1 DE) followed by gallic acid and naringenin (931.47, 500.42 μg g-1 DE) respectively. While in seeds, 11 phenolics were tentatively identified, where naringenin was the major (95,305.47 μg g-1 DE) followed by (+)-catechin and rutin (54,930.29, 15,361.66 μg g-1 DE) respectively. Aqueous and methanol seeds extracts exhibit cytotoxic effect with IC50 27.4±1.81 and 13.4±0.94 μg mL-1, respectively, it was more potent than aqueous and methanol pericarp extracts which had IC50 132±5.82 and 61.6±3.16 μg mL-1. The tested phenolics were fit on the active sites of VEGF kinase targets with varied degree of interactions. The cytotoxic and anti-angiogenic activities were confirmed in light of phenolics docking interactions.
Conclusion: Results demonstrate for the first time that phenolics could inhibit angiogenesis via inhibiting kinase proteins, which could therefore be developed as antiangiogenic drugs.
Keywords: Cytotoxicity; HUH-7 cells; Tamarindis indica; VEGF; phenolics.