A bioassay-guided fractionation scheme for characterization of new antibacterial compounds from Prosopis cineraria aerial parts.

OBJECTIVE

Due to the importance of finding of new antibacterial agents, the antibacterial properties of Prosopis cineraria aerial parts were investigated using a bioassay guided fractionation scheme.

METHODS

The organic extract was prepared via maceration in methanol, followed by the fractionation using n-hexane and ethyl acetate. The MICs of fractions were determined against some human pathogenic bacteria using broth micro-dilution assay. The primary characterization and identification of bioactive substance(s) was based on a bio-autographical method using HPTLC and flash chromatography in parallel with agar overlay assays. Finally the exact mass of effective compound(s) was determined by LC-MS.

RESULTS

The best antibacterial activities were related to the ethyl acetate fraction. The effective antibacterial compound of the plant were 2 substances with molecular weight of 348 and 184 Dalton that inhibited the growth of assessed Gram positive bacteria with MIC values lower than 125 to 62.5 μg/ml synergistically.

CONCLUSIONS

Further analysis using nuclear magnetic resonance could reveal the exact structure of these two antibacterial substances. These 2 effective antibacterial compounds could be applied as lead compound for synthesis of new antibacterial agents.