Zakaria, Nik Hasanah
(2022)
Antimicrobial activity and prebiotic
effects of senna alata leaf extracts.
Masters thesis, Universiti Sains Malaysia.
Abstract
Senna alata or Cassia alata is a medicinal plant found mostly in the tropics and
subtropics. The leaves of the plant have been employed in the treatment of skin
infection and digestion-related problems. The purpose of this study was to assess the
antimicrobial activity of S. alata leaf extracts against several intestinal pathogens and
their prebiotic effects against a few probiotic strains, as well as to screen the
phytoconstituents in S. alata leaf extracts. MIC and MBC assays of aqueous and
ethanolic leaf extract in a concentration ranging from 0.39 mg/mL to 200 mg/mL were
performed on the intestinal pathogens in a sterile 96-well microtiter plate. The prebiotic
effects of aqueous and ethanolic leaf extracts in concentrations from 1.25 mg/mL to
10.00 mg/mL were evaluated based on the growth rate of the probiotic within 24 hours.
The phytoconstituents of aqueous and ethanolic leaf extracts were screened by standard
qualitative methods. Both leaf extracts showed a bactericidal effect against S. aureus,
while only aqueous leaf extract showed a bacteriostatic effect against S. Typhi.
Probiotics of L. helveticus and B. longum showed a positive mean growth rate after
being treated with both leaf extracts for 24 hours. However, the growth rate of both
bacteria decreases as the concentration of both leaf extracts increases. Both leaf
extracts showed the presence of tannins, saponins, alkaloids, carbohydrates, and
flavonoids. In conclusion, both S. alata leaf extracts showed significant antimicrobial
activity against S. aureus and S. Typhi at the tested extract concentrations. Besides,
both S. alata leaf extracts are weak prebiotics because they only stimulate a minimal
growth of probiotics.
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