Browsing by Author "Mayeka, James G."

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Genus Monanthotaxis: a review on distribution,ethnomedicinal uses and phytochemistry
(Taylor & Francis, 2024-01-23) Mayeka, James G.; Nyandoro, Stephen S.; Munissi, Joan J.E.
This article reviews the geographical distribution, ethnomedicinal applications, and phytochemistry of the genus Monanthotaxis Baill, tribe Uvariae of the family Annonaceae. The reviewed works of lit-erature were collected from various electronic databases including Google Scholar, PubMed, Science Direct, The International Plant Names Index (IPNI), and Research Gate. During this review, ninety-eight species of the genus Monanthotaxis were found to be widely distributed in tropical Africa. Some of those species are used in folkloric medicine by various communities to manage dis-eases and disease conditions such as fever, vomiting, headache, stomach-ache, malaria, helminthiasis, and hysteria. In the past 44 years (1979 to 2023), one hundred and nineteen secondary metabolites with different biomedical potentials have been reported from this genus. The reported compounds are catego-rised into flavonoids, alkaloids, terpenoids, polyoxygenated cyclo-hexane, and cyclohexene derivatives, benzyl derivatives, cinnamic acid derivatives, and stilbenoids. Most of the reported compounds showed an array of bioactivities corroborating the use of some members of the genus in folkloric medicine.
The use of stem and root barks extracts from synadenium glaucescens (euphorbiaeceae) as acid base indicators
(Journal of Chemical and Pharmaceutical Research, 2019) Mayeka, James G.; Mabiki, Faith P.
Currently, the conduction of acid-base chemical reactions involves the use of industrial made indictors which are associated with environment pollutions. This situation necessitates the search for more acid-base indicators from the natural sources. The aim of this work was to study the acid-base indicating capacity of the extracts from Synadenium glaucescens. To study the indicating capacity from S. glaucescens, the extracts from leaves, stem and root barks were studied for their colour change, reversibility, pH range and effectiveness during titration by titration using strong and weak acids and bases. The results indicated that, only the indicators from stem and root barks extracts had indicating capacity as they were capable to change colour due to pH change. The pH range of the two indicators was from 2.9 to 12.7 which make them to be better universal indicators. Both indicators could be reversed clearly while in acidity and alkalinity conditions. Titration showed sharp colour change at the end points. The mean titre of the two indicators were ranging from 24.3 ± 0.31 to 25.4 ± 0.75 and 18.9 ± 0.17 to 24.1 ± 0.05, respectively with their colour change from brick red to colourless and orange to colourless, respectively. The end points obtained by stem and root barks indicators correspond to the end points obtained by standard indicators, phenolphthalein and methyl orange. Thus, the stem and root barks extracts are suitable to serve as acid-base indicator. Further studies could be done aiming to develop paper indicators and isolate pure compound which is responsible for indicating capacity of S. glaucescens.