Bioautography, synergistic effect and HPTLC-MS and SEM analysis of antimicrobial and antioxidant compounds of inflorescence extract of Sphaeranthus indicus

Abstract

Abstract Background Sphaeranthus indicus L. is a well-known medicinal plant in folk medicine. A variety of biological activities and chemical substances in this plant have been reported. The phytochemical content and activity may vary according to geographic location. This study aims to determine the geographical significance, the analysis of the synergistic effect of phytochemicals, the identification of active compounds, and the determination of the action mechanism of S. indicus inflorescence methanolic extract against Staphylococcus aureus and Klebsiella pneumonia. Results The bands with Rf values of 0.92 and 1.0 showed antimicrobial activity, while all bands showed antioxidant activity. The first fraction showed the highest antimicrobial activity, and the pool of the second fraction showed the highest antioxidant activity. The kinetics of the antioxidants differed among the fractions. Analysis of synergistic effects showed that several compounds were involved in the activities. The bands with Rf 0.45, 0.55, 0.68, 0.79, and 0.85 were active components of the extract. Leakage of cell contents was detected at 260 and 280 nm wavelengths. Six different proteins and one nucleic acid band were detected after electrophoresis. The SEM analysis showed that the phytochemicals caused severe membrane damage. Conclusion  The study revealed that the photochemical present in methanol extract of the inflorescence of S. indicus has a synergistic effect and acts on bacterial cell envelope. The five compounds were identified as active molecules belonging to the class of terpenoids. The result also signified the geographical area since thymol was identified for the first time in this plant at this location. Graphical abstract