Antibacterial activity of watermelon (Citrullus lanatus) seed against selected microorganisms

Abstract

This study was aimed at evaluating the effect of extraction methods on the antibacterial activity of Citrullus lanatus seed extract. C. lanatus (watermelon) is a popular fruit consumed all over the world. Three solvents were used for the extraction process: chloroform, methanol and distilled water while two extraction conditions-cold extraction and Soxhlet extraction (coded as hot in this study) were employed. Antibacterial activity of the seed extracts was determined by agar well diffusion method. The seed extracts were tested against clinical isolates including Staphylococcus sp., Escherichia coli, Proteus sp., Klebsiella sp. and a type Pseudomonas aeruginosa (ATCC 27853). It was observed that the cold methanol extracts had the highest antibacterial effect on Staphylococcus sp. followed by hot methanol extract while cold chloroform extract showed no antibacterial activity. In the presence of P. aeruginosa only the hot methanol and chloroform extracts showed significant antibacterial potentials (p≤0.05). Also, saponins which have been implicated in antimicrobial activity were found to be present in moderate and high concentrations in the hot and cold methanol extracts respectively. Results of this study reveal that the kind of solvent employed as well as the conditions for extraction (cold maceration and Soxhlet extraction) influenced the efficacy of the extract against specific test organisms. Furthermore, the presence of saponins may have influence the relatively high zone of inhibition recorded with cold and hot methanol extracts against some of the test organisms.

Antioxidant and antimicrobial efficacy of watermelon rind extract (WMRE) in aerobically packaged pork patties stored under refrigeration temperature (4±1°C)

“…Thus, in the present study, higher antimicrobial efficacy was noted against E. coli followed by B. cereus and S. aureus. Soetan, Oyekunle, Aiyelaagbe, and Fafunso (2006) and Adunola, Chidimma, Olatunde, and Peter (2015) also reported antibacterial effect of saponin on Gram positive bacteria. Cemaluk (2015) studied the antibacterial and antifungal properties of aqueous and ethanolic extract of watermelon rind against 10 pathogens and noted that ethanolic extract had higher antibacterial and antifungal activites than aqueous extract.…”

Antioxidant, antibacterial properties and the light barrier assessment of raw and purified melanins isolated from Citrullus lanatus (watermelon) seeds

“…No antibacterial activity towards B. cereus, E. coli and S. aureus was observed. In previous works, crude extracts of watermelon seeds using hot and cold water, methanol and ethanol showed the antimicrobial activity using the standard disc diffusion assay method against pathogenic microorganisms including B. cereus, E. coli, Klebsiella pneumoniae, P. aeruginosa and S. aureus [1,13,37]. In another study, crude extracts of C. lanatus, C. colocynthis and C. vulgaris were very effective against bacteria and some fungal strains.…”

Remedial Action of Yoghurt Enriched with Watermelon Seed Milk on Renal Injured Hyperuricemic Rats

“…Replacing cow's milk with WMS milk resulted in a significant (p ≤ 0.05) decrease in titratable acidity in a concentration-dependent manner. This reduction in titratable acidity may be due to antimicrobial activity associated with vegetable seed protein [14,16,49,50], which might inhibit starter activity and acid production [51,52]. In line with these findings, the pH values of all treatments showed a reverse trend to TA, expressing the level of alkalinity.…”