Structure elucidation of compounds isolated from the stem bark of Euclea latidens used in treatment of dental caries

Abstract

Dental caries has remained a global threat despite the numerous antibacterial agents. The high global prevalence of 2.4 billion people reported is due to resistance against the antibiotics by the dental caries bacteria. Plants have been used for ages to treat dental caries and isolation of compounds from those plants could yield lead compounds for new and better antibacterial agents against dental caries bacteria. Euclea latidens is being used traditionally to treat dental caries, and yet no information is known about the active phytochemicals against dental caries bacteria. The study was aimed at determining the antibacterial activity of different solvent extracts and characterizing phytochemicals from the extracts that were active against dental caries bacteria. Extraction of compounds was done by maceration using hexane, ethyl acetate, methanol and water. The aqueous extract was obtained by maceration with water. Agar well diffusion and broth dilution method were employed to determine the antibacterial activity. Chromatographic techniques and recrystallization were employed in the isolation and purification of compounds from the ethyl acetate stem bark extract of E. latidens. Structure elucidation of compounds was done using spectroscopic techniques, such as, IR, NMR, Mass and UV- VIS spectrophotometry. Aqueous, methanol and ethyl acetate extracts exhibited inhibition against the growth of both Streptococcus mutans and Lactobacillus acidophilus. Hexane extract did not inhibit the growth of both test organism. Ethyl acetate exhibited higher inhibition as seen from the MIC of 62.5 mg/ml compared with that of aqueous and methanol extracts with both having an MIC of 125.0 mg/ml. Isolation and structure determination of compounds from ethyl acetate extract yielded betulin and lupeol. The antibacterial activities reported in the literature for lupeol and betulin indicate that the compounds could be responsible for the therapeutic properties of this plant, hence the antibacterial activity of lupeol and betulin on S. mutans and L. acidophilus should be investigated