In-vitro anti-typhoid efficacy of an isoquinolone derivative from Bligha sapida Koenig seeds

Abstract

Qualitative and quantitative screening of the 70% ethanol extract of Bligha sapida seeds (labeled B) revealed a strong presence of alkaloids. Separation and extraction of the crude alkaloidal portion (labeled Ba) of extract B using chromatographic techniques led to the isolation and purification of a compound (labeled Ba3i). Structural elucidation of compound Ba3i using physical, chemical and spectral revealed it as 3, 4-dihydro-6,7-dimethoxy-2H-isoquinolin-1-one in comparison with literature data. In-vitro anti-typhoid assay of B, Ba and Ba3i against typhoid and paratyphoid strains using the agar dilution method revealed that all test compounds showed no activity against S. typhi in comparison with Ciprofloxacin. The extract B, at 1000 μg/cm3 was active against Salmonella paratyphi A, B and C, while, the alkaloidal portion, Ba and isolated compound, Ba3i, at 500 μg/cm3 and 100 μg/cm3 respectively were active against S. paratyphi B and C only. The findings from this study have provided some evidence for the ethnomedicinal use of the seeds of B. sapida as an antibacterial agent and in treatment of fevers, especially those caused by paratyphoid bacilli.  Keywords: Alkaloids, anti-typhoid, Bligha sapida, isolation, isoquinolone, seeds