Phenolic Compound Profiles, Cytotoxic, Antioxidant, Antimicrobial Potentials and Molecular Docking Studies of Astragalus gymnolobus Methanolic Extracts

Abstract

Since Astragalus is a genus with many important medicinal plant species, the present work aimed to investigate the phytochemical composition and some biological activities of Astragalus gymnolobus. The methanolic fractions of four organs (stems, flowers, leaves, root and whole plant) were quantified and identified by Liquid Chromatography Electrospray Ionization Tandem Mass Spectrometry (LC-ESI-MS/MS) analysis. Hesperidin, hyperoside, p-hydroxybenzoic acid, protocatechuic acid and p-coumaric acid were identified as main compounds among the extracts. Among all cells, leaf methanol (Lm) extract had the highest cytotoxic effect on HeLa cells (IC₅₀ = 0.069 μg/mL). Hesperidin, the most abundant compound in A. gymnolobus extract, was found to show a strong negative correlation with the cytotoxic effect observed in HeLa cells according to Pearson correlation test results and to have the best binding affinity to targeted proteins by docking studies. The antimicrobial activity results indicated that the most susceptible bacterium against all extracts was identified as Streptococcus pyogenes with 9-11 mm inhibition zone and 8192 mg/mL MIC value. As a result of the research, it was suggested that A. gymnolobus could be considered as a promising source that contributes to the fight against cancer.

Keywords: Astragalus; antimicrobial; antioxidant; apoptosis; cytotoxicity.

Figure 1

Effect of methanolic extracts on multicaspase activity in cancer cells. (A) A549 cells were treated with Fm and Rm extracts at IC₅₀ concentration for 24, 48 and 72 h. (B) HeLa cells were treated with Fm, Rm, Lm and WPm extracts at IC₅₀ concentration for 24, 48 and 72 h. (C) MDA-MB-231 cells were treated with Fm, Rm, Sm and Lm extracts at IC₅₀ concentration for 24, 48 and 72 h. The statistical analysis of the data was carried out by Student t-test. * p < 0.05, ** p < 0.01 and *** p < 0.001 were considered to indicate a statistically significant differences compared to control group.

Figure 2

Effect of methanolic extracts on DNA fragmentation of cancer cells. (A) A549 cells were treated with Fm and Rm extracts at IC₅₀ concentration for 24, 48 and 72 h. (B) HeLa cells were treated with Fm, Rm, Lm and WPm extracts at IC₅₀ concentration for 24, 48 and 72 h. (C) MDA-MB-231 cells were treated with Fm, Rm, Sm and Lm extracts at IC₅₀ concentration for 24, 48 and 72 h. The statistical analysis of the data was carried out by Mann-Whitney test and the results were expressed as mean ± SEM.

Figure 3

Heatmap analysis of the correlation coefficient matrix between the changes in the amounts of phytochemicals in the A. gymnolobus methanol extract and the IC₅₀ doses of the extracts applied in A549 (lung cancer cell line), HeLa (cervical cancer cell line) and MDA-MB-231 (breast cancer cell line) by Pearson correlation analysis. The correlation heatmap was prepared bidirectionally. Red and blue color labels indicate positive and negative correlations, respectively. The color label represents the value of the Pearson correlation coefficient, while those with “*” indicate significant values (**, p < 0.01; *, p < 0.05). Since the IC₅₀ dose of the extract could not be determined in MDA-MB-231 cells in 24 h of incubation, it was excluded from the evaluation.

Figure 4

Visualization of the 2D and 3D protein-ligand interaction profile of hesperidin. (A) BCL2-Hesperidin, (B) CDK1-Hesperidin, (C) HDAC2-Hesperidin, (D) TNFα-Hesperidin, (E) PBP2α-Hesperidin.