Abstract
This study evaluated the antimicrobial property of the aqueous extract of Citrullus lanatus (watermelon) seeds and its concentration-effect relationship (time-kill studies) on typed bacterial and fungal strains. Crude powdered seeds of Citrullus lanatus were extracted by maceration with water. Antimicrobial assay of the aqueous extracts was determined against Bacillus subtilis (NCTC 8236), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 10145), Staphylococcus aureus (ATCC 25923), and Candida albicans (ATCC 24433) using standard microbiological methods. A total of 106 CFU/mL of each test strain was used as a baseline to carry out the time-kill studies. Extract concentration at minimum inhibitory concentration (MIC), 2MIC and 4MIC were used over a period of 24 hours. Aqueous extract had an intermediate antibacterial activity with inhibition zone diameters (IZD) of 15 - 18 mm and MIC range of 2.5 - 20 mg/mL. Time-kill studies showed a bacteriostatic, non-concentration dependent mode of antimicrobial activity with characteristic regrowth for all test strains. Citrullus lanatus seeds aqueous extract exhibited antimicrobial activity with a bacteriostatic, non-concentration dependent mode of action against test bacterial strains. Further studies aimed at isolating and purifying the antimicrobial principle in the aqueous extract of C. lanatus seed is warranted as this could serve as a potential new antibiotic for treating microbial infections.
Highlights
The ability of an antimicrobial agent to inhibit or kill a microbe is often evaluated by a time kill study known as pharmacodynamics study
This study examined the pharmacodynamic relationship between varying concentrations of aqueous extract of C. lanatus seeds, microbial growth and death rate of four typed bacteria strain and a fungal strain, namely; Bacillus subtilis (NCTC 8236), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 10145), Staphylococcus aureus (ATCC 25923), and Candida albicans (ATCC 24433) using standard microbiological methods
An intermediate antimicrobial activity was observed for the extract against all test strains; with minimum inhibitory concentration (MIC) range of 2.5 - 20.0 mg
Summary
The ability of an antimicrobial agent to inhibit or kill a microbe is often evaluated by a time kill study known as pharmacodynamics study. Pharmacodynamics is the study of the biochemical and physiological effects of drugs (pharmaceutical or herbal). These effects can include those manifested within animals, humans, microorganisms or combination of organisms. It is often summarized as a doseresponse relationship as seen by the relationships between drug concentration and its effects (Englehardt and Chiu, 2019).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
