Abstract

The following alkaloids were isolated from Catharanthus roseus L. leaves from the yellow crystal as white powder at (38°C). The chemical and physical properties were studied by thin layer chromatography (TLC), IR-spectrum (IR), Ultraviolet - visible spectrum (UV) and melting point (mp). Standard strains of bacteria: Staphylococcus aureus NCTC 6571, Escherichia coli NCTC 5933 and the clinical multidrug resistance (MDR) S. aureus, E. coli and P. aeruginosa were tested with the alkaloids. The Catharanthus ruseus (L.) alkaloids inhibited both type of bacteria strains of gram positive strains S. aureus NCTC 6571,*S. aureus and *E. coli as gram negative strains when concentrations increase (125, 250, 500 mg/ml) with C. ruseus L. alkaloids being the most active in (500 mg/ml) concentrations against gram positive S. aureus bacteria than gram negative bacteria E. coli, while the clinical resistance *P. aeruginosa showed resistance against C. ruseus L. alkaloids in all concentrations (500, 125, 250 mg/ml). The minimum inhibitory concentration (MIC) (µg/ml) of the alkaloidal compound were also determined. Finally, a test was also carried out to examine the cytotoxicity assay methods towards human red blood cells have no cyto-toxicity in all concentration. The good antimicrobial potency of the alkaloidal compound of C. ruseus L. indicates the treatment of (MDR) as an alternative to the costly antibiotics.

Key words: Catharanthus roseus L. leaves, thin layer chromatography (TLC), alkaloid compound, antibacterial activity.