Title:Antimicrobial Activity of Coleus forskohlii Fractions, Isolation and Characterization
of Phenolic Compounds
Volume: 18
Issue: 1
Author(s): Kamel H. Shaker*, M. Abo Yonus, Mohamed A. Ibrahim, Mona Kilany and Frank Wiggers
Affiliation:
- Chemistry of Natural Compounds Department, Pharmaceutical Industrial Division, National Research Center, El-Behoosst.,
Dokki-Cairo12622, Egypt
Keywords:
Phenolic, Colues forskohlii, isolation, spectroscopy, antimicrobial, medicinal plants.
Abstract: Background: It is known that medicinal plants represent promising candidates against
many species of pathogenic bacteria. The south area of Saudi Arabia “Asir region” has a unique
habitat and its medicinal plant's composition is still nearly unexplored. Therefore, the aim of the
present work is to investigate the antimicrobial activities of Coleus forskohlii fractions and to identify
the major active compounds.
Methods: The total plant extract was partitioned by petroleum ether, ethyl acetate and n-butanol.
Agar well diffusion was assessed to evaluate the antimicrobial activities of the plant fractions
against Gram-positive, Gram-negative and Candida albicans. Successive column chromatography
was performed to isolate the major metabolites. Structures of the isolated compounds were determined
by nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry.
Results: All plant fractions showed significant antimicrobial potential activities against the tested
pathogens, where ethyl acetate exhibited the highest antimicrobial activity, followed by petroleum
ether then n-butanol. From the n-butanol fraction, thymoquinol-2-O-β-glucopyranoside (1) was isolated
while syringic acid (2), methyl 3,4,5-trihydroxybenzoate (3), and luteolin (4) were assigned
from the ethyl acetate fraction.
Conclusion: The antimicrobial assays revealed that ethyl acetate was the most potent fraction and
the major abundant metabolites of C. forskohlii, thymoquinol-2-O-β-glucopyranoside (1), syringic
acid (2), methyl 3,4,5-trihydroxybenzoate (3), and luteolin (4) were isolated herein for the first
time.