Antibacterial and antioxidant activities and phytochemical composition of Stereospermum kunthianum root bark

Abstract

A new glycoiridoid (1) together with seven (7) known compounds were isolated from the methanol crude extract of the root bark of Stereospermum kunthianum using chromatography methods. Their structures were elucidated using HR-ESI-MS, 1 D- & 2 D-NMR spectroscopies in comparison with previous literature. The antioxidant activity was investigated by using FRAP, DPPH, ABTS and HRSA methods while the antibacterial activity was assays on Escherichia coli (ATCC25922) and Salmonella typhimurium (ATCC14028) strains. The results showed that the isolated compounds had significantly (p < 0.01) high radical scavenging (IC₅₀) and reducing power activity. All bacteria strains showed important minimal inhibitory concentration activity against isolated compounds started at 5 mg/mL with an inhibition zone of 6 mm. Thus, the isolated compounds in S. kunthianum justify the use of the plant in traditional medicine for the treatment of various diseases in humans. These isolated compounds can be used for formulation of new drug discovery to treat infectious diseases.

Graphical Abstract

Keywords:

• Stereospermum kunthianum
• Bignoniaceae
• antibacterial activity
• antioxidant activity
• iridoid

Acknowledgements

The authors are indebted to Department of General, Organic Chemistry and Biomedical, Laboratory of NMR and molecular Imaging, University of MONS, Belgium.

Disclosure statement

The authors declare no potential conflict of interest for this paper.

Funding

The author(s) reported there is no funding associated with the work featured in this article.