3 research outputs found
Mammea-type coumarins from Mammea usambarensis Verdc.
Phytochemical investigations of Mammea usambarensis resulted into the isolation a δ-tocotrienol (1) and five known mammea-type coumarins (2–6). Their structures were determined by NMR, IR, and LC-MS spectroscopic methods and by comparison of their spectral and physical data with those reported previously in the literature. The presence of these compounds is consistent with the compound classes reported from other members of the genus Mammea. Compound 6 is isolated from the Mammea genus for the first time. This is the new source of mammea-type coumarin compounds while the chemotaxonomic significance of this investigation is summarized
Evaluation of the potential of the marine sponges of the Zanzibar Island to yield antimalarial and antimicrobial active compounds
Emergence of new and re-emergence of old infections continue to elude
prospects of reducing morbidity and mortality caused by microbial
infections. Trends of resistance to currently in use antimicrobials and
antimalarials threaten to increase mortality caused by these
infections. This study explores the potential of marine invertebrates
as a source for new antimicrobials and antimalarials. The lactate
dehydrogenase method was used to assay marine sponges for activity
against Plasmodium falciparum, while the disc diffusion method was used
to assay the extracts for antibacterial and antifungal activity.
Extracts of some marine sponges from the Zanzibar Island exhibited both
antiplasmodial and antimicrobial activities. Among the 55 marine sponge
extracts that were tested 23 (41.8%) inhibited Plasmodium falciparum W2
strain by more than 50% at both 250 and 50 μg/ml concentrations.
Moderate polar extracts were more active against Plasmodium falciparum
W2 strain than polar and non-polar extracts. None of the 12 extracts
that were tested on Plasmodium falciparum strain D6 exhibited
inhibitory activity reaching 50%. Among 18 marine sponge extracts that
were tested for antimicrobial activity 12 (66.7%) showed activity
against one or more of the bacteria and fungi used ranging from weak to
strong on an arbitrary criterion. The ethyl acetate extracts of Agelas
mauritania and Oceanopia sp. exhibited high activity against the
fungi Candida albicans and Cryptococcus neoformans . The best
antibacterial profile was exhibited by ethyl acetate extracts of
Aplysinopsis sp., Halichondrida sp. 1 and Oceanopia sp. In
conclusion, these results support the need for intensified efforts to
search for active antimalarial and antimicrobial compounds from the
Zanzibar marine sponges
Antimicrobial and brine shrimp toxicity of some plants used in traditional medicine in Bukoba District, north-western Tanzania
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 Canarium schweinfurthii Engl., Dissotis brazzae Cong.,
Iboza urticifolia (Bak) E.A.Bruce, Isoglosa lacteal Lindau,
Strombosia Scheffleri Engl., and Whitfieldia 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 Whitfieldia
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 Whitfieldia 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 LC50 values ranging from 15.35-374.0μg/ml.
However, ethanol extracts of Dissotis brazzae and Strombosia scheffleri
had LC50 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