Watermelon (Citrullus lanatus) flesh and
seeds were dried and pulverized, and their extracts were diffused to sterile
discs for the evaluation of anti-microbial activity. The disc-diffusion
technique was used to assess anti-bacterial activity against Bacillus subtilis, Escherichia coli,
Pseudomonas aeruginosa, Pasteurella multocida, Yersinia enterocolitica, Serratia marcescens, Klebsiella pneumoniae, Xanthomonas campestris, Staphylococcus aureus. Anti-fungal activity against the yeasts Candida albicans and Rhodotorula glutinis was also examined.
Standard anti-biotics were also tested as controls.
Watermelon flesh and seed extracts
were found to be effective against gram-positive and
gram-negative bacteria and yeasts. The extracts were also screened for
anti-oxidant activity using the 2,2-diphenyl-1-picryl-hydrazyl (DPPH)
free-radical-scavenging assay, total reducing ability using the Fe3+–Fe2+
transformation method and ferrous ion (Fe2+)-chelating activity.
Butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT),
ethylenediaminetetraacetic acid and α-tocopherol were used as reference
anti-oxidant radical scavenger compounds.
The most potent anti-bacterial activity was
demonstrated by watermelon–ethanol extract (inhibition zone 30 mm) against K. pneumoniae, and the most potent anti-fungal
activity was demonstrated by watermelon–acetone extract (inhibition zone 26 mm)
against R. glutinis. Watermelon–ethanol
and watermelon seed–ethanol extracts both demonstrated marked anti-oxidant
activity.
These results highlight that watermelon fruit
and seed extracts have potential for the development of efficient, safe and
cost-effective natural anti-oxidant compounds for application in the functional
food industries.
Subjects | Engineering |
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Journal Section | Articles |
Authors | |
Publication Date | March 30, 2017 |
Published in Issue | Year 2017 Volume: 13 Issue: 1 |