BackgroundTernimalia brownii Fresen (Combretaceae) is widely used in traditional medicine to treat bacterial, fungal and viral infections. There is a need to evaluate extracts of this plant in order to provide scientific proof for it's wide application in traditional medicine system.MethodsExtraction of stem bark, wood and whole roots of T. brownii using solvents of increasing polarity, namely, Pet ether, dichloromethane, dichloromethane: methanol (1:1), methanol and aqua, respectively, afforded dry extracts. The extracts were tested for antifungal and antibacterial activity and for brine shrimp toxicity test.ResultsExtracts of the stem bark, wood and whole roots of T. brownii exhibited antibacterial activity against standard strains of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella typhi, and Bacillus anthracis and the fungi, Candida albicans and Cryptococcus neoformans. Aqueous extracts exhibited the strongest activity against both bacteria and fungi. Extracts of the roots and stem bark exhibited relatively mild cytotoxic activity against brine shrimp larvae with LC50 values ranging from 113.75–4356.76 and 36.12–1458.81 μg/ml, respectively. The stem wood extracts exhibited the highest toxicity against the shrimps (LC50 values 2.58–14.88 μg/ml), while that of cyclophosphamide, a standard anticancer drug, was 16.33 (10.60–25.15) μg/ml.ConclusionThese test results support traditional medicinal use of, especially, aqueous extracts for the treatment of conditions such as diarrhea, and gonorrhea. The brine shrimp results depict the general trend among plants of the genus Terminalia, which are known to contain cytotoxic compounds such as hydrolysable tannins. These results warrant follow-up through bioassay-directed isolation of the active principles.

Plants which are used by traditional healers in Tanzania have been evaluated to obtain preliminary data of their toxicity using the brine shrimps test. The results indicate that 9 out of 44 plant species whose extracts were tested exhibited high toxicity with LC 50 values below 20µg/ml.

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A number of medicinal plants used for treatment of malaria in Tanzania have been documented, but information on their safety and efficacy is still based on traditional knowledge accumulated over years and not on pre-clinical and clinical evaluation. The present study aimed to assess the cytotoxic activity of extracts of selected plant species used for treatment of malaria in Tanzania. Ethanol extracts were evaluated for cytoxicity by using MTT assay on LLC-MK2 cells and by brine shrimp lethality assay. Forty five (93.75%) out of 48 crude extracts assessed using LLC-MK2 cells were non-cytotoxic while three extracts (6.25%) were cytotoxic with CC50 <30 µg/mL (cut-off point). In the brine shrimp assay 30 (65.2%) out of 46 extracts tested were non-toxic while 16 extracts (34.8%) were toxic (LC50 <100 µg/mL). Antiaris toxicaria stem bark extract was the most cytotoxic to mammalian cells. This study demonstrates that, most of the antimalarial plants tested were non-toxic. These observations corroborate with traditional healers' claims that the herbal medicines used in their areas are safe. However, further studies using different toxicity models are suggested to further confirm their claims.

The development of resistance mutations in drug-targeted HIV-1 genes compromises the success of antiretroviral therapy (ART) programs. Genotyping of these mutations enables adjusted therapeutic decisions both at the individual and population level. We investigated over time the prevalence of HIV-1 primary drug resistance mutations in treatment-naive patients and described the HIV-1 subtype distribution in a cohort in rural Tanzania at the beginning of the ART rollout in 2005-2007 and later in 2009. Viral RNA was analyzed in 387 baseline plasma samples from treatment-naive patients over a period of 5 years. The reverse transcriptase (RT) and protease genes were reversely transcribed, polymerase chain reaction (PCR) amplified, and directly sequenced to identify HIV-1 subtypes and single nucleotide polymorphisms associated with drug resistance (DR-SNPs). The prevalence of major DR-SNPs in 2005-2007 in the RT gene was determined: K103N (5.0%), Y181C (2.5%), M184V (2.5%), and G190A (1.7%), and M41L, K65KR, K70KR, and L74LV (0.8%). In samples from 2009 only K103N (3.3%), M184V, and T215FY (0.8%) were detected. Initial frequencies of subtypes C, A, D, and recombinants were 43%, 32%, 18%, and 7%, respectively. Later similar frequencies were found except for the recombinants, which were found twice as often (15%), highlighting the subtype diversity and a relatively stable subtype frequency in the area. DR-SNPs were found at initiation of the cohort despite very low previous ART use in the area. Statistically, frequencies of major mutations did not change significantly over the studied 5-year interval. These mutations could reflect primary resistances and may indicate a possible risk for treatment failure.

Aqueous ethanol (80%) extracts of six plants used traditionally for treatment of malaria, Vepris glomerata (F.Hoffm.) Engl (Rutaceae), Maranthus floribunda (Bak.) F.White (Chrysobalanaceae), Strophanthus eminii Asch. & Pax ex Pax (Apocynaceae), Cassia abbreviata Oliv. (Leguminosae) and Caesalpinia bonducella L. Fleming (Fabaceae) were screened for antimalarial activity to establish validity of their claims. The extracts exhibited antimalarial activity in the 4-day Peter's suppressive antimalarial assay in mice inoculated with red blood cells parasitized with Plasmodium berghei. The extracts gave ID 50 values of 42.8, 111.0, 639.3 and 1560 mg/kg body wt for C. bonducella, C. abbreviata, T. furialis and S. eminii, respectively. The ID 50 values for V. glomerata and M. floribunda were above 2400 mg/kg body wt, above which point solubility was a problem. All the tested extracts were innocuous to the mice, up to 2400 mg/kg body wt, suggesting they may be safe for short-term use.

BackgroundMalaria is an old life-threatening parasitic disease that is still affecting many people, mainly children living in sub-Saharan Africa. Availability of effective antimalarial drugs played a significant role in the treatment and control of malaria. However, recent information on the emergence of P. falciparum parasites resistant to one of the artemisinin-based combination therapies suggests the need for discovery of new drug molecules. Therefore, this study aimed to evaluate the antiplasmodial activity of extracts, fractions and isolated compound from medicinal plants traditionally used in the treatment of malaria in Tanzania.MethodsDry powdered plant materials were extracted by cold macerations using different solvents. Norcaesalpin D was isolated by column chromatography from dichloromethane root extract of Caesalpinia bonducella and its structure was assigned based on the spectral data. Crude extracts, fractions and isolated compound were evaluated for antiplasmodial activity against chloroquine-sensitive P. falciparum (3D7), chloroquine-resistant P. falciparum (Dd2, K1) and artemisinin-resistant P. falciparum (IPC 5202 Battambang, IPC 4912 Mondolkiri) strains using the parasite lactate dehydrogenase assay.ResultsThe results indicated that extracts of Erythrina schliebenii, Holarrhena pubescens, Dissotis melleri and C. bonducella exhibited antiplasmodial activity against Dd2 parasites. Ethanolic root extract of E. schliebenii had an IC50 of 1.87 μg/mL while methanolic and ethanolic root extracts of H. pubescens exhibited an IC50 = 2.05 μg/mL and IC50 = 2.43 μg/mL, respectively. Fractions from H. pubescens and C. bonducella roots were found to be highly active against K1, Dd2 and artemisinin-resistant parasites. Norcaesalpin D from C. bonducella root extract was active with IC50 of 0.98, 1.85 and 2.13 μg/mL against 3D7, Dd2 and IPC 4912-Mondolkiri parasites, respectively.ConclusionsAntiplasmodial activity of norcaesalpin D and extracts of E. schliebenii, H. pubescens, D. melleri and C. bonducella reported in this study requires further attention for the discovery of antimalarial lead compounds for future drug development.

Herbal medicines constitute a potentially important resource for new and safe drugs for the management of microbial infections and other diseases. In this study, dichloromethane, ethylacetate and ethanol extracts of Canarum schwenfurth Engl., Dssots brazzae Cong., Iboza urtcfola (Bak) E.A.Bruce, Isoglosa lacteal Lindau, Strombosa Scheffler Engl., and Whtfielda elongate T. Anders were tested for antimicrobial activity and brine shrimp toxicity. The objective was to validate claims that they are used to treat bacterial infections, diarrhoea and heal wounds among the Haya tribe of north-western Tanzania. At least one extract of each plant showed antibacterial activity. Dichloromethane extracts were the most active while ethanol extracts were the least active. Extracts of Whtfielda elongate and Isoglossa lacteal were the most and least active with MICs in the range 0.08-0.62 mg/ml and 15.6-62.5 mg/ml, respectively. The dichloromethane extract of Whtfielda elongate exhibited strong antifungal activity against Cryptococcus neoformans. Against brine shrimp larvae, the extracts from the six plants exhibited a low to very low toxicity with LC 50 values ranging from 15.35-374.0μg/ml. However, ethanol extracts of Dssots brazzae and Strombosa scheffler had LC 50 values of >1000μg/ml. The seemingly innocuous nature and relatively good antibacterial activity against skin infections and gastrointestinal pathogenic bacteria support the traditional uses of the plants and deserve more detailed studies.