Chemical composition and antimicrobial activity of the essential oil of Ocimum gratissimum L. growing in Eastern Kenya

Hydro-distilled volatile oils from the leaves of Ocimum gratissimum L. (Lamiaceae) from Meru district in Eastern Kenya were analysed by gas chromatography-mass spectrometry (GC-MS) and also evaluatedfor antimicrobial activity. The oil was dominated by monoterpens which accounted for 92.48%. This monoterpene fraction was characterized by a high percentage of eugenol (68.8%). The other major monoterpenes were methyl eugenol (13.21%), cis-ocimene (7.47%), trans-ocimene (0.94%), -pinene (1.10%) and camphor (0.95%). The sesquiterpenes present in fairly good amounts were germacrene D(4.25%) and trans-caryophyllene (1.69%). The minor  sesquiterpenes were -farnesene (0.85%) and -bisabolene (0.74%). The antimicrobial activities of the essential oils were evaluated against both Gram positive (Staphylococcus aureus, Bacillus spp.) and Gram negative (Escherichia coli, Pseudomonasaeruginosae, Salmonella typhi, Klebisiella pneumoniae, Proteus mirabilis) bacteria and a pathogenic fungus Candida albicans. The oil had pronounced antibacterial and antifungal activities on all themicrobes

Evaluation of nutritional properties of tissue cultured sorghum [Sorghum bicolor (L) Moench]

Tissue culture techniques are commonly used in plants as an efficient way to propagate and store valuable genotypes. Often, some of the regenerants differ from the parental type, a phenomenon called somaclonal variability. Assessment of nutritional value variability in crops that may arise from somaclonal variability during tissue culture propagation may have a strong impact on plant breeding, conservation of genetic resources and nutrition in the areas of use. It is particularly useful in the characterization of individual cultivars, and in determining duplications in germplasm collections and for selecting parents. The Sorghum bicolor (L) Moench tissue culture (TC) regenerants (Seredo, Mtama 1 and El Gardam) were developed at the Jomo Kenyatta University of Agriculture and Technology towards improvement for water stress tolerance for improved food production in the ASALs in Kenya. The study was conducted to evaluate the nutritional value of the parents and TC regenerants of Sorghum bicolor (L) Moench local cultivars (Seredo, Mtama 1 and El Gardam) in Kenya. For proximate composition significant (p≤0.05) differences were observed in parents and regenerants of the El‐Gardam (moisture, proteins and crude fiber), Mtama 1 (proteins) and Seredo (fats and crude fiber). The mineral compositions of the parents and regenerants of the cultivars were not significantly different (p ≤ 0.05) except for Zinc in Mtama 1 cultivar and Iron in both El‐Gardam and Mtama 1 cultivars. B‐vitamins showed significant differences (p ≤ 0.05) for both thiamine and Pyridoxine in El‐Gardam and Seredo. Significant variability (p ≤ 0.05) was shown phytates content in each cultivar. The parents were observed to have significantly higher amounts of Phytates than the regenerants within all the cultivars. The study recommends Mtama 1 regenerants with low anti‐nutrient appropriate for ASALs with respect to nutrient availability since anti‐nutrients in sorghum have been shown to impair the bioavailability of the other nutrients to the body.Key words: Cultivars, TC regenerants, water stress tolerance, nutritional valu

Leaf storage conditions and genomic DNA isolation efficiency in Ocimum gratissimum L. from Kenya

Storage of plant tissues for DNA is important to avoid degradation of DNA. Preliminary studies were conducted on Ocimum gratissimum L. in order to establish the storage conditions for the collected samples before DNA extraction. Secondly, the aim was to determine the best protocol for the extraction of high quality DNA, which would later be used for molecular analysis. DNA was extracted from thesamples one month after field sampling. During the DNA extraction, four protocols were used; the modified hexadecyltrimethyl ammonium bromide (CTAB) mini preparation method described by Doyleand Doyle (1990), with reductants either mercaptoethanol or dithiothreitol; the modified sodium dodecyl sulphate (SDS) mini preparation method of Edwards et al. (1991) with redundant either mercaptoethanol or dithiothreitol. The DNA was purified, treated with RNase, quantified and examined for intactness using gel electrophoresis method. Good quality and high yield DNA  could only be extracted with the buffer containing the detergent SDS and the reducing agent dithiothreiotol