Abstract:
BACKGROUND: Urinary tract infections (UTIs) caused by opportunistic pathogens are among the leading health
challenges globally. Most available treatment options are failing as a result of antibiotic resistance and adverse
effects. Natural sources such as plants may serve as promising alternatives.
METHODS: Compounds were isolated from the South African weed Chromolaena odorata through column
chromatography. Purified compounds were tested for antimicrobial activity using the p-iodonitrotetrazolium
chloride (INT) colorimetric method, against uropathogenic Escherichia coli, Staphylococcus aureus, Klebsiella
pneumoniae, Aspergillus fumigatus and Cryptococcus neoformans. Anti-biofilm, anti-adhesion and metabolic inhibition
activities were investigated against selected strains. Safety of the compounds was determined against Vero monkey
kidney, C3A human liver and colon (Caco2) cells.
RESULTS: Four compounds identified as pectolinaringenin (1), (±)-4′,5,7-trimethoxy flavanone (2), 5-hydroxy-3,7,4′-
trimethoxyflavone (3) and 3,5,7-trihydroxy-4′-methoxyflavone) (4) were isolated. Minimum inhibitory concentration
(MIC) varied between 0.016 and 0.25 mg/mL. Compounds 2 and 3 showed promising antimicrobial activity against
E. coli, S. aureus, K. pneumoniae, A. fumigatus and C. neoformans with MIC between 0.016 and 0.125 mg/mL,
comparable to gentamicin, ciprofloxacin and amphotericin B used as positive controls. Compounds 2 and 3
showed good anti-biofilm and metabolic inhibition activities against E. coli and S. aureus but weak anti-adhesion
activity against the organisms. Low toxicity with selectivity indexes between 1 and 12.625 were recorded with the
compounds, indicating that the compounds were rather toxic to the microbial strains and not to the human and
animal cells.
CONCLUSION: Pharmacological activities displayed by compounds 2 and 3 isolated from C. odorata and low toxicity
recorded credits it as a potential lead for the development of useful prophylactic treatments and anti-infective
drugs against UTIs. Although known compounds, this is the first time these compounds have been isolated from
the South African weed C. odorata and tested for antimicrobial, anti-biofilm, metabolic inhibition and anti-adhesion
activities.
