ISOLATION AND CHARACTERIZATION OF BIOACTIVE COMPOUNDS FROM THE AERIAL PARTS OF INDIGOFERA PULCHRA (WILLD) AND EVALUATION OF POSSIBLE SYNERGISTIC ANTIMICROBIAL POTENTIAL WHEN COMBINED WITH CIPROFLOXACIN AND FLUCONAZOLE

ISOLATION AND CHARACTERIZATION OF BIOACTIVE COMPOUNDS FROM THE AERIAL PARTS OF INDIGOFERA PULCHRA (WILLD) AND EVALUATION OF POSSIBLE SYNERGISTIC ANTIMICROBIAL POTENTIAL WHEN COMBINED WITH CIPROFLOXACIN AND FLUCONAZOLE

Abstract:

Indigofera pulchra (Willd) is an annual non climbing erect herb or shrub that can grow upto 1m tall. It belongs to the family PAPILIONACEAE. It is widely distributed throughout tropical and subtropical regions of Nigeria, Niger, Togo, Benin, Ghana and Chad. It is also found in Senegal and over eastern and central Africa from Ethiopia to Angola. In ethnomedicine, it is used for the treatment of infected wound, itching skin, as prophylactic against snake bite, and for the treatment of malaria and dysentery. The aerial parts of the plant was subjected to cold maceration to afford the crude ethyl alcohol extract which was further fractionated using hexane, chloroform, ethylactate and butanol fractions. Phytochemical screening was carried out on the crude ethyl alcohol extract and the fractions using standard procedures and the results revealed the presence of flavonoids, tannins, steroids, carbohydrates and saponins. Extensive phytochemical investigations using silica gel column chromatography followed by preparative thin layer chromatography led to the isolation of 2,4-dihydroxy-4‘-prenyloxychalcone (coded L1) and 3,5-dimethoxy-4‘-O-(2‘‘-3‘‘-dihydroxy-3‘‘-methylbutyl)-dihydrostilbene (coded L2). The structures of the compounds were determined using IR and NMR. Antimicrobial activity was studied using agar well diffusion method and the organisms used are hospital isolates of Methiciline resistant Staphylococcus aureus, Staphylococcus aureus, Proteus mirabilis, Eschericia coli, Candida albicans and Candida tropicalis. The isolated compounds and the various fractions of the ethyl alcohol extract of Indigofera pulchra (Willd) aerial parts were investigated for their effects on the antimicrobial activity of ciprofloxacin and fluconazole. The results of the antimicrobial study obtained indicated that the various fractions of the ethyl alcohol extract of Indigofera pulchra (Willd) inhibited the growth of the test microorganisms with zone of inhibition range of 20-30mm in diameter while the isolated compounds inhibited the growth of the test microorganisms with zone of inhibition range of 29-37mm in diameter and was found to be greater than those observed for ciprofloxacin and fluconazole range of 25-33mm in diameter. Further evaluation of the antimicrobial effects of the two isolated compounds combined with the standard drugs (ciprofloxacin and fluconazole) led to increase in zones of inhibition diameter (25-40mm). The result of this study has justified the use of Indigofera pulchra (Willd) in ethno-medicine for the treatment of bacterial and fungal infections and that the isolated compounds might be potential lead compounds with antibacterial and antifungal activities.

ISOLATION AND CHARACTERIZATION OF BIOACTIVE COMPOUNDS FROM THE AERIAL PARTS OF INDIGOFERA PULCHRA (WILLD) AND EVALUATION OF POSSIBLE SYNERGISTIC ANTIMICROBIAL POTENTIAL WHEN COMBINED WITH CIPROFLOXACIN AND FLUCONAZOLE