The Antimicrobial Activity of Nigerian Medicinal Plants Potentially Usable as Hop Substitutes
MBAA TQ vol. 41, no. 4, 2004, pp. 398-402 |
VIEW ARTICLE
A. A. Oshodi (1), Isiaka A. Amoo (1), and Afolabi F. Eleyinmi (2). 1. Chemistry Department, Federal University of Technology, Akure, Ondo State, Nigeria. 2. Food Science & Technology Department, Federal University of Technology, Akure, Ondo State, Nigeria.
Abstract
The antimicrobial activities of aqueous extracts of three Nigerian medicinal plants, Vernonia amygdalina (bitter leaf, BL), Garcinia kola (bitter cola, BC), and Gongronema latifolium (utazi, UT), and their blends, BL:BC, UT:BL, UT:BC, and UT:BL:BC in ratios of 24:1, 1:7.42, 3.24:1, and 2.89:2.59:1, respectively, were evaluated against several test organisms, Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Streptococcus salivarus. Proportions of the vegetables in the blends were obtained by using Corel Quattro Pro 8 (a computer software). The effects of aqueous extracts of each plant and blend were tested at concentrations of 100, 200, 300, 400, and 500 mg/mL against the test organisms by determining the zone of growth inhibition (ZGI) and minimum inhibitory concentration (MIC). Results obtained showed that BL and UT:BL:BC were the most active against E. coli, Streptococcus salivarus, and S. aureus, while BC and UT:BC had the highest level of activity against B. subtilis, with the ZGI increasing with increasing extract concentrations. The MIC of the extracts against all the test organisms was 200 mg/mL for BL, 300 mg/mL for UT:BL:BC, 500 mg/mL for UT:BL, 300 mg/mL for BL:BC, and 400 mg/mL for UT:BC. Media containing a crude extract of UT showed no ZGI against E. coli and Streptococcus salivarus, while BC had no effect on E. coli. UT:BL:BC and BL:BC blends were the most active blends, while BL was the most active single-plant extract. A strong positive relationship was observed between extract concentration and ZGI, with UT:BL:BC being the most active. The blends have potential for use in the control of beer-spoilage organisms.
Keywords: antimicrobial activity, beer spoilage, blending, hop substitutes, medicinal plants
S�ntesis
Las actividades microbicidas de extractos acuosos de tres plantas medicinales de Nigeria, Vernonia amygdalina (hoja amarga, HA), Gongronema latifolium (utazi, UT), y Garcinia kola (cola amarga, CA), y las combinaciones HA:CA, UT:HA, UT:CA, y UT:HA:CA en una relaci�n de 24:1, 1:7.42, 3.24:1, y 2.89:2.59:1 (proporciones determinados por el programa Corel Quattro Pro 8), respectivamente, fueron evaluadas contra los siguientes organismos de prueba: Staphylococcus aureus, Bacillus subtilis, Escherichia coli, y Streptococcus salivarus. Los extractos se probaron a concentraciones de 100, 200, 300, 400 y 500 mg/mL, determinando las zonas de inhibici�n de crecimiento (ZIC) y la concentraci�n m�nima de inhibici�n (CMI) contra cada organismo. Los resultados demostraron que HA y UT:HA:CA fueron las m�s activas contra E. coli, Streptococcus salivarus, y S. aureus, mientras que CA y UT:CA fueron las m�s activas contra subtilis, con el ZIC aumentando al aumentar la concentraci�n del extracto. El CMI de los extractos (para todos los organismos) fue 200 mg/mL para HA, 300 mg/mL para UT:HA:CA, 500 mg/mL para UT:HA, 300 mg/mL para HA:CA y 400 mg/mL para UT:CA. Un medio con un extracto crudo de UT no mostr� ning�n ZIC contra E. coli y Streptococcus salivarus, mientras que CA no tuvo ning�n efecto sobre E. coli. UT:HA:CA y HA:CA fueron las mezclas m�s activas, mientras que HA fue el extracto no mezclado m�s activo. Se observ� una fuerte correlaci�n positiva entre la concentraci�n del extracto y la ZIC, siendo la combinaci�n UT:HA:CA la m�s activa. Estas combinaciones ser�an potencialmente �tiles en el control de organismos da�inos a la cerveza.
Palabras claves: actividad microbicida, deterioro de cerveza, mezclas, sustitutos de l�pulo, plantas medicinales
