Anticancer and antioxidant effects of extracts from different parts of indigo plant

Abstract

The water, methanol and ethanol extracts of flowers, leaves, stems, and seeds from indigo (Polygonum tinctorium Lour.) were tested in vitro to verify cytotoxic effects on human renal cell line (HEK 293) and inhibitory effects on the proliferation of colon cancer cell line (HCT-116), cervical carcinoma cells (HeLa), liver carcinoma cells (Hep3B), breast carcinoma cells (MCF-7), laryngeal cancer cell line (SNU-1066), and gastric cancer cell line (SNU-601), in order to further increase the use of the indigo plant. Significant differences were found in polyphenols and flavonoids in extracts of different parts of indigo. The highest amount of total polyphenols (22.94±2.18 and 22.81±2.04mgGAE/g DW) were found in methanol extracts of leaves and flowers and flavonoids (4.02±0.43, 3.70±0.34 and 3.28±0.26mgCE/gDW) – in methanol extracts of leaves, flowers and seeds. The highest antioxidant capacities by ABTS+ (99.12±9.18 and 96.35±8.75μMTE/gDW) and CUPRAC (78.37±7.86 and 86.22±8.43μMTE/gDW) were also found in methanol extracts of leaves and flowers. The correlation coefficient (R2) between antioxidant capacities and polyphenols of indigo parts in different extracts varied from 0.7142 to 0.9765, showing the highest correlation for leaves and flowers in methanol extracts. The survival rates at a concentration of 800mg/L for human renal cell line (HEK 293) in indigo plant water extracts from flowers and stems were 17.58%±9.29 and 61.78%±11.00 and in methanol extract of leaves and seeds estimated as 36.47%±18.70 and 28.7%±16.68, respectively. The extracts of stem prolonged the overall survival of cancer cells. The survival rates at a concentration of 800mg/L of colon cancer cell line (HCT-116) and cervical cancer cell line (HeLa) in the ethanol extract of indigo flowers were 5.10%±0.32 and 8.85%±0.11, respectively, and in seeds on HeLa cells was 16.93%±3.09. The survival rates of HeLa and HCT-116 in methanol extracts of indigo leaves at a concentration of 800mg/L were 6.89%±0.53 and 13.22%±8.51, respectively. Proliferative and antioxidant activities were correlated. The highest R2 between the antioxidant capacities and survival rates was in methanol extracts of leaves on HeLa cells. Therefore, investigation in vitro revealed that the extracts of the indigo plant were found to be effective in suppressing the proliferation of cancer cells, although the results varied depending on the different parts of P. tinctorium Lour., the concentrations of solvent and extracts, the antioxidant activities and the types of cancers.