A STUDY TO INVESTIGATE THE ANTIBACTERIAL EFFECTS, POLYPHENOL CONTENTS AND ANTIOXIDANT ACTIVITIES OF EXTRACTS FROM ANDROGRAPHIS PANICULATA MEDICINAL PLANTS

Abstract

Andrographis paniculata is a traditional medicinal plant which has been known for various beneficial properties, such as the inhibition of bacterial growth and health enhancement properties. This study was carried out to evaluate the antibacterial effects, polyphenol contents and antioxidant activities of extracts from Andrographis paniculata plant materials, so as to partly explain its traditional application. Plant materials were extracted with 6 solvents: hot water, ethanol, methanol, ethyl acetate, acetone and hexane. We applied the agar-well-diffusion method to evaluate the inhibitory effects of extracts on several bacteria strains, including: Bacillus subtilis ATCC 6633; Geobacillus stearothermophilus ATCC 7953; Pseudomonas aeruginosa ATCC 9027; Staphylococcus aureus ATCC 25023; Staphylococcus aureus ATCC 25923; Escherichia coli ATCC 85922; Escherichia coli ATCC 35218; Escherichia coli ATCC 25922 and Salmonella ATCC 13311. Reagents, such as Folin Ciocalteu and 1,1-diphenyl-2-picrylhydrazyl (DPPH), were used to measure the polyphenol contents and antioxidant activities of the extracts, which were then respectedly converted to mg acid chlorogenic equivelent and mg VTME equivelent per 100 mg plant powder. The results showed that extracts from Andrographis paniculata showed antibacterial effects, in which the ethanol extract showed the highest antibacterial effects on bacteria, as it induced inhibitory zones on all testes bacteria, with the largest one was on Escherichia coli ATCC 25922 (18.81±2.22 mm). Extracts with high polyphenol contents and antioxidant activities were methanol, hot water and ethanol, in which the highest polyphenol content belonged to methanol extract (with the value reached to 0.270±0.019 mg acid chlorogenic equivalent per 100 mg plant powder), and the strongest antioxidant activity belong to hot water extract (with the value reached to 0.691±0.115 mg VTME equivalent per 100 mg plant powder).