Striga hermonthica (Del.) Benth is a common hemi-parasitic plant growing in a variety of food crops like maize, millet, rice and sorghum roots. It has many medicinal uses include abortifacient, dermatosis, leprosy, ulcer, pneumonia, jaundice and antibacterial activities. The plant material was extracted and concentrated under reduced pressure. Bioassay guided isolation was done by chromatographic methods. Compound coded “003” was isolated as white amorphous substance from combined hexane and ethyl acetate extracts. Spectral analysis was carried out to characterize the isolated compound. The proton Nuclear Magnetic Resonance (1H-NMR) spectrum of isolated compound 003 displayed seven chemical shifts; δ H 4.31ppm, δ H 3.38 ppm, δ H 3.61 ppm, δ H 4.39 ppm, δ H 3.46 ppm, δ H 4.12 ppm and δ H 3.55 ppm. This also showed that there are seven different types of protons in the compound. Interpretation of the spectrum also revealed that signal of alcoholic protons of OH were observed downfield compared with the signal of protons directly attached to carbons. The Carbon-13 Nuclear Magnetic Resonance (13C-NMR) spectrum gave three peak signals at δ C 64.3, 71.9 and 70.3 ppm corresponding to C1/C6, C2/C5 and C3/C4 respectively. Based on the comparison of the spectra of the isolated compound with reported spectral data in the literature, the chemical structure of the isolated compound 003 was deduced and identified as Mannitol. The chemical structure was also confirmed by 1H-1H Correlation Spectroscopy (COSY), Hetero-nuclear single quantum correlation (HSQC) and Hetero-nuclear Multiple Bond Correlation (HMBC) spectra.
Keywords: Characterization, Extraction, Isolation, mannitol, striga hermonthica
