Chemical Analysis, Antibacterial Activities and Uses of Leaves and Calyces of Hibiscus sabdariffa Grown in Dodoma, Tanzania

Preliminary phytochemical screening of aqueous and ethanolic extracts of Hibiscus sabdariffa grown in Tanzania revealed the presence of secondary metabolites like steroids, tannins, saponins, glycosides, terpenoids, flavonoids along with L-ascorbic acid (vitamin C) and iron(II). Furthermore, both leaves and calyces showed antibacterial activities (agar well diffusion method) against selected bacterial species (Escherichia coli, Staphylococcus aureus, Salmonella typhi and Shigella sonnei), but calyces possessed potent antibacterial activities compared to leaves. The results also supported the claimed traditional uses of this plant. When interrogated during the cross-sectional study in Dodoma region, 54% of the respondents claimed the plant is used to treat anaemia (supposedly as it increases haemoglobin levels), 23% claimed it is used in the preparation of local wine and the remaining respondents stated use in both areas. Furthermore, the intake of H. sabdariffa leaves and calyces on regular basis can boost the immunity system and helps in preventing bacterial and viral infections as the plant is loaded with flavonoids and vitamin C. Thus, the results observed for the plant H. sabdariffa that is grown in Dodoma in small scale for traditional uses, paves a way for consideration of future large scale production of pharmaceutical and neutraceutical products in Tanzania. Keywords: Phytochemical screening, Hibiscus sabdariffa, antibacterial activity, L-ascorbic acid and iron(II

Bioactivities of extracts, debromolaurinterol and fucosterol from macroalgae species

Parasitic diseases including malaria, and other numerous microbial infections and physiological diseases are threatening the global population. Tanzanian coast shores are endowed with a variety of macroalgae (seaweeds), hitherto unsystematically explored to establish their biomedical potentials. Thus, antiplasmodial activity using malarial imaging assay, antimicrobial activity using microplate dilution technique, antioxidant activity using DPPH radical scavenging method and cytotoxicity using brine shrimp test were carried out on crude extracts from the selected species of algae (Acanthophora spicifera, Cystoseira myrica, Cystoseira trinodis, Laurencia filiformis, Padina boryana, Sargassum oligocystum, Turbinaria crateriformis, Ulva fasciata and Ulva reticulata) occurring along the coast of Tanzania. The extracts showed antimicrobial activities with MIC ranging from 0.3- 5.0 µg/mL against Staphylococcus aureus, Streptococcus pyogenes, Pseudomonas aeruginosa, Escherichia coli, Candida albicans and Cryptococcus neoformans; DPPH radical scavenging activity at EC50 1.0- 100 µg/mL and cytotoxicity on brine shrimp larvae with LC50 value ranging from20 - 1000 µg/mL. The extracts from C. myrica and P. boryana inhibited growth of Plasmodium falciparum (3D7 strain) by 80 and 71%, respectively at 40 µg/mL while a sesquiterpene debromolaurinterol (1) which was chromatographically isolated from C. myrica exhibited antiplasmodial activity with IC50 20 µM whereas a sterol fucosterol (2) from P. boryana showed weak activity at 40 µM. Bioactivities portrayed by the investigated extracts indicate their ingredients as potential sources of bioactive agents that warrant further explorations.Keywords:     Macrolgae, antiplasmodial, antimicrobial, antioxidant, cytotoxicity, DPPH radical scavenging, debromolaurinterol and fucosterol

Screening of aflatoxin-producing fungi in maize and groundnuts from three regions in Tanzania

This study screened aflatoxin-producing fungi in maize and groundnuts from Dodoma, Singida and Iringa regions in Tanzania, and assessed the level of peoples’ awareness on aflatoxins health effects. One hundred and twenty samples (20 each crop) were collected and inoculated on Sabouraud dextrose agar and one hundred and eleven samples were observed to have fungal growths that were identified to belong to four genera, namely Aspergillus, Rhizopus, Mucor and Dermatophyte with occurrence frequencies of 75, 2.5, 5 and 10%, respectively. Among the four screened genera of fungi, Aspergillus was observed to be the major aflatoxin-producing fungi. Five species of genus Aspergillus, namely A. flavus, A. parasiticus, A. niger, A. fumigatus, and A. terreus were isolated with frequencies of 39.1, 10, 7.5, 15.8 and 2.5%, respectively. Macromorphology and micromorphology of isolated Aspergillus spp were also observed using a light microscope. Furthermore, it was noted that the prevalence of fungi and aflatoxins contamination is more in groundnuts than in maize. In terms of awareness in individuals concerning aflatoxins, only 34% respondents in Dodoma, 29.9% in Singida and 24% in Iringa were aware of aflatoxins. Therefore, the creation of awareness and sensitization on aflatoxins health effects to the people is an important part of intervention ways to forestall and control aflatoxins in Tanzania. Keywords: Aflatoxins, Maize, Groundnuts, Aspergillus spp, A. flavus, A. parasiticus, A. niger, A. fumigatus and A. terreu

Evaluation of Antibacterial Activities of Tanzanian Moringa oleifera Extracts against Escherichia coli and Klebsiella pneumonia Clinical Isolates

In vitro antibacterial activities of methanolic leaf and seed extracts of Moringa oleifera grown in Dodoma, Tanzania were evaluated using standard microdilution and disc diffusion methods against extended spectrum beta lactamase producing Gram negative bacteria (Escherichia coli and Klebsiella pneumoniae). Microdilution method showed no activity at concentration of 20 mg/mL for all the extracts except leaf extract which exhibited minimum inhibition at concentration of  2.5 µg/mL for E. Coli but when high concentrations of the extracts were used in the disc diffusion method then the results exhibited the highest killing susceptibility at concentration of 0.4 g/mL with zone of inhibition 31 mm for leaf extract and 26 mm for seed extract against E. coli, and 27 mm for leaf extract and 29 mm for seed extract against K. pneumonia. Additionally, when both extracts were screened qualitatively for phytoconstituents using standard methods, leaf extract confirmed the presence of carbohydrates, cardiac glycosides,  tannins and quinones, and seed extract confirmed the presence of proteins, carbohydrates, cardiac glycosides, alkaloids, terpenoids and quinones. These phytoconstituents can be new sources of future antibiotics that potentially combat the existing problem of antimicrobial resistance and thus, creating an awareness in the community regarding the usage of M. oleifera growing widely but neglected in Tanzania in spite of its nutritional values and traditional uses. Keywords: Moringa oleifera; Phytoconstituents; Antibacterial activity; Escherichia coli and Klebsiella pneumonia