Identification of Metabolites from Catharanthus roseus Leaves and Stem Extract, and In Vitro and In Silico Antibacterial Activity against Food Pathogens

Abstract

The plant produced powerful secondary metabolites and showed strong antibacterial activities against food-spoiling bacterial pathogens. The present study aimed to evaluate antibacterial activities and to identify metabolites from the leaves and stems of Catharanthus roseus using NMR spectroscopy. The major metabolites likely to be observed in aqueous extraction were 2,3-butanediol, quinic acids, vindoline, chlorogenic acids, vindolinine, secologanin, and quercetin in the leaf and stem of the Catharanthus roseus. The aqueous extracts from the leaves and stems of this plant have been observed to be most effective against food spoilage bacterial strains, followed by methanol and hexane. However, leaf extract was observed to be most significant in terms of the content and potency of metabolites. The minimum inhibitory concentration (20 µg/mL) and bactericidal concentrations (35 g/mL) of leaf extract were observed to be significant as compared to the ampicillin. Molecular docking showed that chlorogenic acid and vindolinine strongly interacted with the bacterial penicillin-binding protein. The docking energies of chlorogenic acid and vindolinine also indicated that these could be used as food preservatives. Therefore, the observed metabolite could be utilized as a potent antibacterial compound for food preservation or to treat their illness, and further research is needed to perform.

Keywords: Catharanthus roseus; NMR; antibacterial; food preservation; indole alkaloids; secondary metabolites.

Figure 1

Typical 1 H-NMR spectra of the metabolites of the different sections of C. roseus: (1) leaves and (2) stems. Key metabolites: Branch chain amino acids (BCAA), 2,3 butanediol, quinic acids, vindoline, lactate, alanine, pyruvate, glutamate, malic acid, glucose, vindoline, chlorogenic acids, fumaric acid, vindolinine, secologanin, quercetin, respectively.

Figure 2

Antibacterial effect of water, methanol, and hexane extracts of C. roseus leaves against meat-isolated bacterial pathogens (1, 3 Gram-negative streptobacilli and 2, 4 Gram-positive Streptococcus). The significant values were expressed as *** p value 0.0001.

Figure 3

Solvent effect on extraction of metabolites and antimicrobial activity of leaf extract of C. roseus. The hexane extract was likely observed to have the least growth inhibitory effect on the bacterium in a medium with methanol, while the optimum extraction had a strong growth inhibitory effect on the bacterium.

Figure 4

Showing 2D and 3D representations of best-screened compounds and their interaction against penicillin-binding protein 4 (dacB) from Escherichia coli (PDB:2EXB). (A,B) represents 2exb-chlorogenic Acid, (C,D) represents 2exb-quercetin, and (E,F) represents 2exb-vindolinine complexes. The receptor molecules (PDB:2EXB) are shown by a rainbow line ribbon pattern, and compounds are in the center, shown by a grey ball and stick shape. In the 3D representation, a cyan stick pattern indicates the most interacting amino acids. In 2D representation, the multicolor spheres show amino acid residues forming different types of interactions.

Figure 5

Simple presentation of sample collection, preparation, and metabolite extraction from Catharanthus roseus from different parts like flower, leaf, and stem.