Asian Research Thesis Index

Abstract

Medicinal plants cater healthcare needs of about 80% of world population particularly in developing countries. Bistorta amplexicaulis belongs to the genus Polygonum (Polygonaceae), and is found in temperate regions of the world. The plant is extensively used as herbal medicine in North Pakistan, India and China and has proven antioxidant and antitumor activities with high phenolic contents. Plant phenolics being quantitatively highest in the extract and are most bioactive, suffer from low cellular uptake due to their hydrophilic nature. The in vivo activity of phenolics is often limited due to stability, low bioavailability and cellular uptake. This translates to using a higher dosage of the extract for effective intracellular concentrations which in turn limits the affectivity and increases side effects. So the researchers are focusing on approaches that can improve the cellular uptake of these compounds to enhance their activity. Keeping in view, the current study was designed for nano-liposomal encapsulation of B. amplexicaulis extracts for increased anti-cancer activity due to increased cellular uptake. Plant extract was prepared using maceration technique, analyzed for its phytochemical constituents using Ultra performance liquid chromatography (UPLC) with C18 columns and screened for its anticancer activity against HCT-116 Human Colon cancer cell lines. Liposomes were prepared using thin film method with DPPC, PEG2000DSPE and Cholesterol in a ratio of 1.85:0.15:1 with 2mg/mL and 4mg/mL ethanolic extract of B. amplexicaulis respectively. Prepared liposomes were characterized using Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) and Size was determined using dynamic light scattering (DLS) whereas charge was determined using Zeta sizer. Encapsulation efficiency was estimated using spectrophotometer and UPLC. A cytotoxicity comparison was established between encapsulated and un-encapsulated extract through in-vitro MTS cell proliferation assay using Hepatocellular carcinoma cell lines (HepG2) and breast cancer cell lines (MCF-7). Furthermore, encapsulated and un-encapsulated extract was also tested for cytotoxicity to normal Human Umbilical Vein Endothelial Cells. The UPLC analysis identified gallic acid, caffeic acid, chlorogenic acid, catechin and epicatechin in ethanolic rhizome extract. Liposomes encapsulating rhizome extract were characterized having zeta potential of -19.8 mV and -16.9mV, size of 155nm and 143nm with PDI of 0.09 and 0.16 for 2mg/mL and 4mg/mL ethanolic extract formulations respectively. Encapsulation efficiency was in a range of 71-81% for both formulations. The HepG2 cells were found most sensitive against free extract with IC50 of 27mg/mL as compared to MCF-7 with IC50 of 67mg/mL. The rhizome extract loaded liposomes as compared to free extract has shown to improve anticancer activity by 30% against HepG2 cells. However, in normal Human Umbilical Vein Endothelial Cells (HUVEC) the LD50 value of free extract was 13 mg/mL compared to liposomes encapsulated extract having LD50 54.0 mg/mL and LD50 65.9 mg/mL for 2mg/mL and 4mg/mL ethanolic extract formulations respectively. The increased LD50 values of liposomes encapsulated extract against HUVEC cells indicates that its toxicity is decreased to the normal cell whereas liposomal encapsulation of extract has enhanced its anticancer activity. Hence, Nano-liposomal encapsulation could be used as a mean of targeting the B. amplexicaulis rhizome extract to the cancer cells to enhance its anticancer potential avoiding cytotoxicity to the normal cells. To our knowledge this is the first report of the liposomal encapsulation of an extract, enhanced uptake of extract and an improved activity against hepatocellular carcinoma (HepG2).

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