Comparative antimicrobial activity and brine shrimp cytotoxicity of two Cissus species: Cissus arguta Hook.f. and Cissus quadrangularis L. (Vitaceae)

Abstract

Antimicrobial resistance is one of the biggest challenges facing global public health. Most microorganisms have developed resistance to available conventional antimicrobial agents, hence, there is a need to develop new antimicrobials to combat this threat to public health. This study was conducted to investigate and compare the antimicrobial activity and brine shrimp cytotoxicity of Cissus arguta and Cissus quadrangularis leaves and the stems methanol extracts. The plants (leaf and stem) were collected, air-dried, pulverized, and extracted with methanol (100%) concentrated in vacuo, and evaporated to dryness at a room temperature of 25 ℃. The antimicrobial activity of the plant extracts against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae, Candida albicans, and Trichophyton rubrum was investigated using the in vitro broth micro-dilution method with ciprofloxacin and ketoconazole as the reference antibacterial and antifungal drugs respectively.
The preliminary phytochemical screening showed the presence of saponin, flavonoid, tannins, alkaloids, anthraquinones, and steroids. The methanol extracts of Cissus arguta and Cissus quadrangularis demonstrated a higher antimicrobial activity against the gram-positive (Staphylococcus aureus and Bacillus subtilis) and gram-negative (Klebsiella pneumoniae and Escherichia coli) bacteria than to the pathogenic fungi (Candida albicans and Trichophyton rubrum). Of all the extracts, Cissus quadrangularisstem extract exhibited the highest antimicrobial activity against both Klebsiella pneumoniae and Escherichia coli with MIC and MBC values of 12.5 µg/mLand 0.78 µg/mLrespectively. It was also found to be the most potent against brine shrimps with LC value of 50 10.62 µg/mL. This study suggests that Cissus arguta and Cissus quadrangularis possess antimicrobial and cytotoxic activities. In addition, the enhanced antimicrobial activity and higher brine shrimp cytotoxicity observed in the stem extract of Cissus quadrangularis suggest that it could serve as a potential source of more effective antimicrobial and cytotoxic agents.