FLAVONOID AND PHENOLIC CONTENTS, ANTIOXIDANT AND ANTIMICROBIAL ACTIVITIES OF ROOT AND AERIAL PARTS OF CENTAUREA PUMILIO L.

Asmaa Gamal*, Amal A. Al-Gendy, Rasha Adel and Samia S. Hafez

ABSTRACT

The ethanolic extract and its soluble fractions (light petroleum, dichloromethane and ethyl acetate) of Centaurea pumilio root and aerial parts were subjected individually to the evaluation of their flavonoid and phenolic contents, antioxidant and antimicrobial activities. Total phenolics and flavonoids contents were quantified by Folin-Ciocalteu and aluminum chloride - potassium acetate colorimetric methods. Tested extracts and fractions were screened for their radical scavenging potential using a 1,1- diphenyl-2-picryl-hydrazyl (DPPH) in-vitro model system for antioxidant activity. Additionally, antimicrobial activity was carried out against two Gram positive bacteria (Staphylococcus aureus and Bacillus subtilis), two Gram negative bacteria (Enterobacter cloacae and Escherichia coli) and antifungal against two fungal strains (Aspergillus fumigatus and Candida albican) using well diffusion method. Root ethanolic extract exhibited higher phenolic and flavonoid contents than aerial parts. DPPH scavenging activity of root extract was higher than aerial parts. Ethyl acetate soluble fraction of root showed the highest antioxidant activity with SC50 = 35.9 ± 0.81 μg/ml followed by methylene chloride fraction with SC50 40.7 ± 0.5 μg/ml compared with ascorbic acid (SC50 14.2 ± 0.5 μg/ml). Additionally, the total ethanolic extract of the aerial parts showed antibacterial activity against Staphylococcus aureus and Escherichia coli with a percentage inhibition of diameter growth reaches 50% and 43.33%, respectively referred to gentamycin standard. Moreover, ethanolic extract of the root exhibited activity against Bacillus subtilis with a percentage inhibition of diameter growth reaches 38.46% compared to the same standard.

Keywords: Centaurea pumilio, Asteraceae, Antioxidant, Antimicrobial, Total flavonoid and phenolic contents.