Bauhinia variegata leaf extracts exhibit considerable antibacterial, antioxidant, and anticancer activities

Abstract

The present study reports the phytochemical profiling, antimicrobial, antioxidant, and anticancer activities of Bauhinia variegata leaf extracts. The reducing sugar, anthraquinone, and saponins were observed in polar extracts, while terpenoids and alkaloids were present in nonpolar and ethanol extracts. Total flavonoid contents in various extracts were found in the range of 11-222.67 mg QE/g. In disc diffusion assays, petroleum ether and chloroform fractions exhibited considerable inhibition against Klebsiella pneumoniae. Several other extracts also showed antibacterial activity against pathogenic strains of E. coli, Proteus spp. and Pseudomonas spp. Minimum bactericidal concentration (MBC) values of potential extracts were found between 3.5 and 28.40 mg/mL. The lowest MBC (3.5 mg/mL) was recorded for ethanol extract against Pseudomonas spp. The antioxidant activity of the extracts was compared with standard antioxidants. Dose dependent response was observed in reducing power of extracts. Polar extracts demonstrated appreciable metal ion chelating activity at lower concentrations (10-40 μg/mL). Many extracts showed significant antioxidant response in beta carotene bleaching assay. AQ fraction of B. variegata showed pronounced cytotoxic effect against DU-145, HOP-62, IGR-OV-1, MCF-7, and THP-1 human cancer cell lines with 90-99% cell growth inhibitory activity. Ethyl acetate fraction also produced considerable cytotoxicity against MCF-7 and THP-1 cell lines. The study demonstrates notable antibacterial, antioxidant, and anticancer activities in B. variegata leaf extracts.

Figure 1

Reducing power assay of B. variegata leaf extracts. The extracts were prepared in PE, BZ, CH, EA, AC, ET, and AQ as described in Section 2. Reducing power of extracts was measured at different concentrations, and absorbance was recorded at 700 nm. Data represent mean ± SEM of three replicates (P < 0.05).

Figure 2

Metal ion chelating ability of B. variegata leaf extracts. Phytochemicals present in sample were extracted with PE, BZ, CH, EA, AC, ET and AQ as described in Section 2. Chelating activity of extracts was measured at different concentrations (10–40 μg/mL), and absorbance was recorded at 562 nm. The results are expressed as mean ± SEM of three replicates (P < 0.05).

Figure 3

Beta carotene bleaching assay of B. variegata leaf extracts. Phytochemicals present in sample were extracted with petroleum ether (PE), benzene (BZ), chloroform (CH), ethyl acetate (EA), acetone (AC), ethyl alcohol (ET), and water (AQ) as described in Section 2.Beta carotene bleaching assay of extracts was measured at 100 μg/mL concentrations, and absorbance was recorded at 700 nm. The results are expressed as mean ± SEM of three replicates (P < 0.05).

Figure 4

Cytotoxic effect of B. variegata leaf extracts against cancer cell lines using SRB assay. Percentage growth inhibition of DU-145 (prostate), HOP-62 (lung), IGR-OV-1 (ovary), MCF-7 (breast), and THP-1 (leukemia) cancer cell lines was assayed at 100 μg/mL concentration of extracts as described in Section 2. Abbreviations: PE—petroleum ether, BZ—benzene, CH—chloroform, EA—ethyl acetate, AC—acetone, ET—ethanol, and AQ—water. ACD—Anticancer drugs (mitomycin-C (10 μM) against prostate, Paclitaxel (10 μM) against lung and breast, Adriamycin (1 μM) against ovary and 5-Flurouracil (20 μM) against leukemia human cancer cell lines). Data represent mean ± SD of three replicates (P < 0.05).

Figure 5

Relationship between % MIC (metal ion chelating ability) and total flavonoid content (mg QE/g) of B. variegata leaf extracts.

Figure 6

Relationship between RPA (reducing power ability) and total flavonoid content (mg QE/g) of B. variegata leaf extracts.