Zanzibar yam (Dioscorea sansibarensis Pax) isolates exhibit cyclooxygenase enzyme and lipid peroxidation inhibitory activities.

Several phenanthrenes (1-5), phenolics (6-8) and steroidal sapogenins (9-11) were isolated for the first time from the aqueous and methanolic extracts of Dioscorea sansibarensis Pax yam collected from Tanzania. Chemical structures of all the isolates (1-11) were determined by using 1D and 2D nuclear magnetic resonance spectral methods. All pure isolates were evaluated for anti-inflammatory activity using in vitro cyclooxygenase enzyme (COX-1 and -2) inhibitory assays. Among the isolates tested, phenanthrenes 3-5 showed the highest COX-1 and -2 enzyme inhibitory activity whereas phenolics (6-8) and steroidal sapogenins (9-11) exhibited moderate inhibition when compared to non-steroidal anti-inflammatory drugs aspirin, ibuprofen and naproxen. Compounds 6-11 were evaluated for antioxidant activity using lipid peroxidation inhibitory (LPO) assay for the first time and exhibited moderate LPO inhibition.

Antimicrobial activities of Tephrosia vogelii against selected pathogenic fungi and bacteria strains.

Candida albicans and Cryptococcus neoformans are dangerous pathogens causing fungal diseases. C. albicans and C. neoformans developed resistance to fungicides such as fluconazole. Similarly, pathogenic bacteria Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae and Salmonella typhi have become resistant to antibiotcs such as methicillin. Thus, searching for alternative antimicrobial agents is inevitable. Tephrosia vogelii used traditionally for management of fungal and bacterial diseases is potential source of antimicrobial agents. It is in this vein that, antimicrobial activities of leaf and root extracts of T. vogelii were evaluated against C. albicans (ATCC 90028), C. neoformans (clinical isolate), S. aureus (ATCC25923), E. coli (ATCC29953), K. pneumoniae (ATCC 700603) and S. typhi (NCTC 8385). A two-fold serial dilution method using the sterilised 96 wells of polystyrene microlitre plates used to determine the minimum inhibitory concentration (MIC) of extracts. Hexane and dichloromethane extracts exhibited the lowest activity against fungi strains with MICs >10 mg/mL. Root and leaf methanolic extracts exhibited activity at MICs of 5 and 1.25 mg/mL, respectively, against both tested fungi. Dichloromethane and methanolic extracts exhibited antibacterial activity with MICs ranging from 2.5 - 10 mg/mL and 0.625 - 5 mg/mL, respectively. Antimicrobial activities of the extracts of T. vogelii revealed potentiality of bioactives against fungal and bacterial diseases.

Aflatoxin levels in sunflower seeds and cakes collected from micro- and small-scale sunflower oil processors in Tanzania.

Aflatoxin, a mycotoxin found commonly in maize and peanuts worldwide, is associated with liver cancer, acute toxicosis, and growth impairment in humans and animals. In Tanzania, sunflower seeds are a source of snacks, cooking oil, and animal feed. These seeds are a potential source of aflatoxin contamination. However, reports on aflatoxin contamination in sunflower seeds and cakes are scarce. The objective of the current study was to determine total aflatoxin concentrations in sunflower seeds and cakes from small-scale oil processors across Tanzania. Samples of sunflower seeds (n = 90) and cakes (n = 92) were collected across two years, and analyzed for total aflatoxin concentrations using a direct competitive enzyme-linked immunosorbent assay (ELISA). For seed samples collected June-August 2014, the highest aflatoxin concentrations were from Dodoma (1.7-280.6 ng/g), Singida (1.4-261.8 ng/g), and Babati-Manyara (1.8-162.0 ng/g). The highest concentrations for cakes were from Mbeya (2.8-97.7 ng/g), Dodoma (1.9-88.2 ng/g), and Singida (2.0-34.3 ng/g). For seed samples collected August-October 2015, the highest concentrations were from Morogoro (2.8-662.7 ng/g), Singida (1.6-217.6 ng/g) and Mbeya (1.4-174.2 ng/g). The highest concentrations for cakes were from Morogoro (2.7-536.0 ng/g), Dodoma (1.4-598.4 ng/g) and Singida (3.2-52.8 ng/g). In summary, humans and animals are potentially at high risk of exposure to aflatoxins through sunflower seeds and cakes from micro-scale millers in Tanzania; and location influences risk.