Nyambe MM. 2018. Phytochemical and antibacterial analysis of indigenous chewing sticks, Diospyros lyciodes and Euclea divinorum of Namibia. Biofarmasi 16: 29-43. The purpose of this study was to ascertain the phytochemical and antibacterial properties of Diospyros lycioides and Euclea divinorum and correlate the results obtained to their ethnomedicinal uses as chewing sticks. Fractions of powdered leaves, twigs, and roots were obtained from crude extracts using vacuum liquid chromatography with solvents of increasing polarity. Antimicrobial activities of the crude extracts and fractions were assessed using the agar overlay, disc diffusion, and agar dilution methods against the oral pathogens, Streptococcus mutans and Streptococcus sanguinis. In addition, the effect of fractions on the attachment of oral pathogens to tooth surface were also analyzed using saliva-coated hydroxyapatite beads (S-HA) as a model. Phytochemical screen tests revealed the presence of the following secondary metabolites in the twigs and roots of both plants: anthraquinones, cardenolides, saponins, tannins, polyphenols, and terpenoids. Alkaloids were detected only in the roots of both plants. Root fractions from both plants displayed higher antibacterial activity than twig fractions. This supports the preference of roots over twigs by stick users. D. lycioides root fraction displayed minimum inhibitory concentrations (MICs) of 0.625 mg/mL and 1.25 mg/mL against S. sanguinis and S. mutans, respectively. E. divinorum root fraction showed MICs of 1.25 mg/mL and 2.5 mg/mL against the aforementioned organisms. Adherence of the bacteria to S-HA was reduced more by root fractions from D. lycioides while twig fractions from both plants also showed significant anti-adhesive properties. Since fractions from both plants inhibited the growth of bacteria and reduced attachment to S-HA, it is an indication that these plants are potential sources of antibacterial and anti-adhesive agents and their use should be encouraged. The anti-adhesive activity of extracts from these plants has not yet being reported. Further research on isolation and characterization of the active compounds from fractions that showed antibacterial and anti-adhesive activity is recommended.

Nyaitondi OD, Wanjau R, Nyambaka H, Hassanali A. 2018. Anti-bacterial properties and GC-MS analysis of extracts and essential oils of selected plant product. Biofarmasi J Nat Prod Biochem 16: 44-58. Plants are traditionally used for the treatment of bacterial infections though they are not clinically regulated due to lack of awareness and sufficient data to support the reported therapeutic claims. Some plants used as food and vegetables are hardly considered in such studies. This study aimed to investigate the antibacterial properties associated with garlic, ginger, turmeric, lemon, and onion in the form of juices, methanol extracts, and essential oils. These materials were tested against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Salmonella typhi. Identification of suspected antibacterial compounds was made by comparison of retention indices and the mass spectra with those in National Institute of Standards and Technology (NIST) libraries using GC-MS analyses. Garlic juice was bactericidal against all tested strains. Lemon/garlic juice exhibited significantly higher activity against E. coli and S. typhi. Turmeric/lemon/garlic methanol extracts blend was most active against S. aureus. Preliminary screening of the essential oils indicated significant antibacterial activity of lemon/garlic essential oil blend against P. aeruginosa. GC-MS analysis of the active samples confirmed the presence of compounds containing-OOH,-OH,-N,-Cl,-F,-NH2 and-S groups which are associated with bacterial inhibition in conventional antibiotics. The 10 major constituents obtained from samples suspected to contain antibacterial activity, include limonene; 3-vinyl-1,2-dithiacyclohex-4- ene; α-zingiberene; diallyl disulphide; 2-butanone,4-(-hydroxy-3-methoxyphenyl); 3-chlorothiophene; methanehydrazonic acid,N-[3- (methylthio)-1,-2,4-thiadiazol-5-yl]-,ethyl ester; n-hexadecanoic acid; γ-sitosterol and propanamide,2-amino-3-phenyl. Juices of garlic, lemon and lemon/garlic blend were found to be active against one or more of the bacteria tested unlike methanol extracts and essential oils, and they should be used in raw form as heating and drying is likely to render them inactive. Further studies on methanol extract and fresh juice of lemon/garlic blend need to be undertaken to elucidate the active principles in these extracts and may lead to the discovery of novel antimicrobial agents and models for the new generation of synthetic antibiotics.