Phytochemical analysis, antimicrobial activity of Euclea divinorum (Magic guarri) leaves, tender stems, root bark extracts and Formulation of a Herbal- based Toothpaste for Dental caries Control

Abstract

Dental caries is a significant global health challenge as it affects people throughout their lifetime causing pain, discomfort, disfigurement and even deaths with approximately 3.5 billion people affected. The responsible oral pathogens have become resistant to the available drugs most of which have side effects like tooth discoloration, vomiting and change of oral micro-biota. The purpose of this study was to identify potential active ingredients and make a safe toothpaste from Euclea divinorum Hern locally known as omuswa (Luhya) which has been used in a long time to manage dental caries. The objectives of the study were to compare the phytochemicals, antimicrobial activity of organic extracts of E. divinorum leaves, tender stems and root bark against Streptococcus pyogenes ATCC 19615, Staphylococcus aureus ATCC 25923, Candida albicans and Escherichia coli ATCC 25922 and formulation of a herbal toothpaste from its most active extract. Plant parts of E. divinorum were collected from Elgeiyo Marakwet, Rift Valley located in the North Rift region of Kenya. Shade-dried samples were ground into powder and successively extracted with hexane, dichloromethane and ethanol. The methods used to characterize the extracts were classical phytochemical screening, Ultra Violet-Visible Spectrophotometry, Fourier Transform Infrared Spectroscopy and Gas chromatography/mass spectrometry while the antimicrobial activity was determined by agar disc diffusion method. Results showed the presence of alkaloids, phenols, saponins, flavonoids, steroids, cardiac glycosides, tannins, terpenes, and volatile oils in qualitative phytochemical screening. UV- Visible spectra of extracts of various parts had the absorption maxima in the region of 370 – 700 nm implying the presence of flavonoids and their derivatives plus conjugated systems of multiple bonds. FT-IR results showed O=C- O-C, =C-H, C-O, Ar-C=C, C-H, CN, –OH among others that revealed the presence of alcohols, phenols, alkanes, alkenes, alkynes, aldehydes, carboxylic acids, aromatics, nitro compounds and amines in the extracts. A total of 30 compounds were identified by GC- MS in the hexane and DCM extracts of E. divinorum. The major compounds were 3,4- Methylenedioxybenzylacetone, Eicosane, Tetratriacontane, Hexatriacontane, 9- Hexadecen-1-ol, 2-Hydroxy-2-methyl-8,8-diphenyl-octa-5,7-dien-3-one, 1,4- Naphthoquinone and Octacosanal, some of which have been reported to possess antimicrobial activity. The E. divinorum extracts (leaves, stems and root bark extracts) showed inhibitory activity against Streptococcus pyogenes, Staphylococcus aureus, Escherichia coli and Candida albicans. Ethanolic E. divinorum root bark extract had a MIC of 50 μg/ml for S. aureus and 25 μg/ml for E. coli and C. albicans. It follows that E. divinorum ethanolic root bark extract should be used for the formulation of herbal toothpaste. Different compounds with antimicrobial activity were identified in the extracts of E. divinorum hence the difference activity against the selected microbes observed. The formulated toothpaste may be used for the control of dental caries. However, its physical and chemical parameters should be investigated.