In vitro Antibacterial Activity and Phytochemical Analysis of Ethanolic Leaf Extracts of Cnidoscolus aconitifolius and Commelina diffusa


  • Kareem Daniels University of Belize
  • Thippi Thiagarajan University of Belize
  • Apolonio Aguilar University of Belize


In recent years, the indiscriminate and arbitrary use of commercial antimicrobial drugs has resulted in multiple antibiotic-resistant pathogenic microorganisms. Natural products derived from plants can serve as important sources of bioactive compounds that can be used as alternatives in the treatment of various infectious diseases. Cnidoscolous aconitifolius (colloquially known as Chaya), is used in Belize, Guatemala, and Mexico as a leafy vegetable as well as a medicinal herb in the treatment of diabetes, skin disorders, and venereal diseases. Commelina diffusa (also known Dayflower), is used throughout the Americas for both culinary and medicinal purposes, most often as a diuretic and febrifuge. The present study investigated the in vitro antibacterial activity as well as phytochemical properties of ethanolic leaf extracts of C. aconitifolius and C. diffusa. Fifty (50) grams of dried leaves of C. aconitifolius and C. diffusa respectively, were pulverized in 100 mL of 95% ethanol and the solvent portion was separated and concentrated to 3 mL of each. Antibacterial activity was assessed using disc diffusion assay against Gram-positive Streptococcus pyogenes and Gram-negative Escherichia coli bacterial strains. Leaf extract of C. aconitifolius exhibited highest antibacterial activity (average zone of inhibition 10.16mm +- 4.34) against S. pyogenes, whereas the leaf extract of C. diffusa exhibited least antibacterial activity (average zone of inhibition 7.81mm +-1.27) against E. coli. Thin layer chromatographic studies of C. aconitifolius and C. diffusa leaf extracts revealed several colored and UV-active fractions of phytochemical compounds at discrete Rf values. The results indicate that the active ingredients in these extracts could be plant secondary metabolites such as Terpenoids, Phenylpropanoids, and Alkaloids, which are known for their antioxidant, cytotoxic, and antimicrobial properties. Results obtained from the preliminary in vitro experiment support the ethnopharmacological uses of both plants. Further studies are needed