Bioactive Composition, Antioxidant Activity, and Anticancer Potential of Freeze-Dried Extracts from Defatted Gac (Momordica cochinchinensis Spreng) Seeds

Abstract

Background: Gac (Momordica cochinchinensis Spreng) seeds have long been used in traditional medicine as a remedy for numerous conditions due to a range of bioactive compounds. This study investigated the solvent extraction of compounds that could be responsible for antioxidant activity and anticancer potential. Methods: Defatted Gac seed kernel powder was extracted with different solvents: 100% water, 50% methanol:water, 70% ethanol:water, water saturated butanol, 100% methanol, and 100% ethanol. Trypsin inhibitors, saponins, phenolics, and antioxidant activity using the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and the ferric reducing antioxidant power (FRAP) assays; and anticancer potential against two melanoma cancer cell lines (MM418C1 and D24) were analysed to determine the best extraction solvents. Results: Water was best for extracting trypsin inhibitors (581.4 ± 18.5 mg trypsin/mg) and reducing the viability of MM418C1 and D24 melanoma cells (75.5 ± 1.3 and 66.9 ± 2.2%, respectively); the anticancer potential against the MM418C1 cells was highly correlated with trypsin inhibitors (r = 0.92, p < 0.05), but there was no correlation between anticancer potential and antioxidant activity. The water saturated butanol had the highest saponins (71.8 ± 4.31 mg aescin equivalents/g), phenolic compounds (20.4 ± 0.86 mg gallic acid equivalents/g), and antioxidant activity, but these measures were not related to anticancer potential. Conclusions: Water yielded a Gac seed extract, rich in trypsin inhibitors, which had high anticancer potential against two melanoma cell lines.

Keywords: Gac; Momordica cochinchinensis; anticancer; antioxidant; extraction; freeze dried extract; phenolics; saponins; seeds; trypsin inhibitors.

Figure 1

Procedure for producing freeze dried (FD) crude extracts from defatted Gac seed kernel powder.

Figure 2

Effect of solvent on the trypsin inhibitor activity (TIA) of the FD crude extracts. The values are the means ± SD of three replicate extractions for each solvent. Columns not sharing the same letter are significantly different at p < 0.05.

Figure 3

Effect of solvent on the total saponin content (TSC) extraction from Gac seed. The values were the means ± SD of three replicate extractions for each solvent. Columns not sharing the same letter were significantly different at p < 0.05.

Figure 4

Effect of solvent on the total phenolic content (TPC) of the FD Gac seed crude extracts. The values were the means ± SD of three replicate extractions for each solvent. Columns not sharing the same letter were significantly different at p < 0.05. GAE, Gallic acid equivalents.

Figure 5

Effect of solvent on the antioxidant capacity of the FD crude extracts. The values were the means ± SD of three replicate extractions for each solvent. Columns not sharing the same superscript letter were significantly different at p < 0.05. * indicated the highest antioxidant activity. TE, Trolox equivalents.

Figure 6

Effect of the FD crude extracts prepared with the different solvents on the cell viability of normal (HaCat) and melanoma (D24 and C1) cell lines after 48 h treatment. The values were the means ± SD of three replicate extractions for each solvent. Columns not sharing the same letter were significantly different at p < 0.05.

Figure 7

Morphological effects of different extraction solvents of Gac seed on HaCat (control) and melanoma D24 and C1 cell lines observed under a phase contrast microscope after 48 h treatment. Cytotoxicity is indicated by red arrows pointed to condensation and detached cells; blue arrows pointed to apoptotic bodies. Magnification: 100×.

Figure 8

Correlations between extraction yields (red lines), bioactive compounds (blue lines), antioxidant activity (green lines), and cell viability (black lines) from Gac seed crude extracts.