Quantitative analysis and biological activities of Bauhinia vahlii Wight & Arn. growing in Nepal

The genus Bauhinia consists of about 300 species and is widely distributed in most tropical countries of the world.

The antioxidant, antibacterial, antidiabetic, and quantitative analysis of stem, leaf, and seed extracts of B. vahlii (the synonym name of Phanera vahlii) were investigated.

The antioxidant activity of the crude extracts and fractions was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging assay. The antidiabetic activity was investigated by α-amylase inhibition assay. The toxicity of plant extracts was assessed by brine shrimp lethality assay (BSLA) using Artemia salina as a biological test organism.

The aqueous fraction of the leaf showed a high total phenolic content of 168.47 ± 1.94 mg GAE/g. The total flavonoid content was found maximum in an aqueous fraction of leaf with 158.51 ± 2.99 mg QE/g. The stem extract showed potent antioxidant activity with IC50 1.91 ± 0.33 µg/ml as compared to the standard quercetin IC50 3.46 ± 0.40 µg/ml. The DCM (Dichloromethane) fraction of the leaf exhibited noteworthy α-amylase inhibition properties with IC50 112.70 ± 2.0 µg/ml as compared to the standard acarbose of 9.34 ± 2.0 µg/ml. The antimicrobial results showed that the methanolic extract of stem and seed exhibited the zone of inhibition against Staphylococcus aureus, Bacillus subtilis, and Klebsiella pneumoniae but failed against E. coli. The methanol and aqueous extract of the leaf showed toxicity against brine shrimp nauplii with LC50 257.63 µg/ml and 100 µg/ml, respectively.

This study showed Bauhinia vahlii is rich in flavonoid and phenolic content and the plant may be a rich source of natural antioxidants and antidiabetic agents that could be isolated as the drug candidate.