Mineral composition and heavy metal risk assesment of selected geophagic soils from Tanzania.

Geophagy or Pica is the unintentional traditional behavior of eating soil by indigenous people in different countries. practiced in many countries due to nausea among pregnant women and mineral deficiencies without knowing the associated health risks. In this study the mineral composition of geophagic soil and its associated health risk among consumers was determined. Dry soil sticks consumed by women were obtained from open markets in Morogoro, Njombe and Mwanza regions in Tanzania. The elemental concentration of geophagic soil was analyzed using Flame Atomic Absorption spectrophotometer. Health risk assessment methods were used to obtain health information after chronic exposure to geophagic soils. The tests used were Target Hazard Quotients (THQ), Total Target Hazard Quotients (TTHQ) and Cancer Risks (CR). The concentration range of metals in samples obtained from three different regions were 16,335.7-47,773.7 mg/kg for Fe, 46.2-1073.5 mg/kg for Ca, 155.3-514.9 mg/kg for K, 44.5-112.4 mg/kg for Zn, 40.7-95.1 mg/kg for Na, 2.4-66.7 mg/kg for Cu, 109.5-572.6 mg/kg for Mn, 3.8-6.85 mg/kg for Pb, 3.1-93 mg/kg for Ni, 62.7-638.6 mg/kg for Cr and 0.4 mg/kg for Cd. The Provisional Daily Intake (PDI), THQ, TTHQ and CR ranged between 3.0 × 10-3 -34.12 mg/kg/day bw, 0.043-48.75, 34.52-77.36 and 2.55×10-5- 0.23 respectively. The TTHQ>1 was evident for metals in all sampling sites which is indicative of non-carcinogenic health effects. Prolonged exposure to Pb at low concentrations in samples from all the sites can cause pathological effects. The cancer risk values for Pb, Ni, Cr and Cd were <1 in which the consumer is likely not to develop cancer in a life time. Essential minerals - Fe, Ca, Zn, Na, K and toxic metals Pb, Cr, Ni and Cu were detected in all the samples. Cd occurred only in samples from Mwanza region that was below the tolerable daily intake. According to WHO/FAO expert's joint committee any amount of Pb consumption is not permitted. Given the presence of essential minerals in the geophagic soils which are however accompanied by toxic minerals in some cases which might have carcinogenic effects, prolonged consumption should be discouraged to avoid risks of serious adverse effects to the health of the general population.

Isolation and antimicrobial activities of a novel discolornolide and other compounds from Monanthotaxis discolor.

Characterisation of a novel discolornolide (1) isolated from a first time investigation of Monanthotaxis discolor is described. Other 6 known compounds, karatavin (2), N-acetylanonaine (3), quercetin-3-O-arabinose (4), stigmasterol (5), a mixture of stigmasterol and ß-sitosterol (6) and octahydro-5-isopropyl-3-methyl-2-methyleneazulene-8,8-diol (7) isolated are also reported. The structures were established by spectroscopic methods. Citotoxicities and antimicrobial activities of the compounds and crude extracts are also reported whereby compound 1 showed in vitro antifungal activity against Candida albicans and Aspergilus niger at concentrations of 0.13 and 0.17 mg/ml with zones of inhibitions of 7.0 and 5.5 mm respectively. The compound also showed cyitotoxic activity in the brine shrimp test with LC50 of 5.88 µg/ml. - Compound 4 exhibited antibacterial activity against E. coli and S. aureus. The compound also exhibited cytotoxic activities in the brine shrimp test with LC50 of 24.73 µg/mL. The crude extracts exhibited varying citotoxic and in vitro antimicrobial activities.

Flavonoids from Erythrina schliebenii.

Prenylated and O-methylflavonoids including one new pterocarpan (1), three new isoflavones (2-4), and nineteen known natural products (5-23) were isolated and identified from the root, stem bark, and leaf extracts of Erythrina schliebenii. The crude extracts and their constituents were evaluated for antitubercular activity against Mycobacterium tuberculosis (H37Rv strain), showing MICs of 32-64 µg mL-1 and 36.9-101.8 µM, respectively. Evaluation of their toxicity against the aggressive human breast cancer cell line MDA-MB-231 indicated EC50 values of 13.0-290.6 µM (pure compounds) and 38.3 to >100 µg mL-1 (crude extracts).

Antifungal Enantiomeric Styrylpyrones from Sanrafaelia ruffonammari and Ophrypetalum odoratum.

Phytochemical investigation of Sanrafaelia ruffonammari Verd and Ophrypetalum odoratum Diels that belongs to the rare genera confined to East African coastal forests led to the isolation of enantiomeric styrylpyrone dimer, (±)-5-methoxy-7-phenyl-[4-methoxy-2-pyronyl]-1-(E)-styryl-2-oxabicyclo-[4.2.0]-octa-4-en-3-one (1) alongside (+)-6-styryl-7,8-epoxy-4-methoxypyran-2-one (2) and the enantiomeric (+)- (3) and (-)-6-styryl-7,8-dihydroxy-4-methoxypyran-2-ones (4). Their structures were established by means of spectroscopic methods. In this paper we reveal for the first time the occurrence of styrylpyrones in East African biodiversity. (+)-6-Styryl-7,8-epoxy-4-methoxypyran-2-one (2) and the dihydroxystyrylpyrone enantiomer (3) showed in vitro antifungal activity against Candida albicans at a concentration of 24.4 and 26.2 µM with zones of inhibition of 17 and 9 mm, respectively. Compound 2 exhibited strong activity in the brine shrimp test with LC50 = 1.7 µg/mL. Their high cytotoxic and antifungal activities render them candidates for further scientific attention for drug development programs against cancer and microbial infections.