Biological Activities of Essential Oils from Plants Growing in Tanzania

Essential oils from eleven plant species belonging to the Asteraceae, Lamiaceae, Lauraceae and Myrothamnaceae families growing in Tanzania were screened for mosquito larvicidal and anti-candida activities, and were subjected to the brine shrimp lethality test. In the larvicidal and brine shrimp tests, the organisms were exposed to varying oil concentrations for 24 h, after which mortality was assessed. The anticandida activity was determined using the bioautography agar overlay method. All oils showed larvicidal activity with two Ocimum suave oil samples being the most active with LC50 values of 169.8 and 151.3 ppm. The same Ocimum suave oils also exhibited the highest brine shrimp mortality (LC50 4.0 and 12.6 ppm). Most of the oils showed anti-candida activity, with oils from Ocimum species being the most active compared to the others. Thus, Ocimum suave oils merit further investigation towards the development of safe and biodegradable larvicides. Furthermore, oils from Ocimum basilicum and Ocimum kilimandscharicum could offer useful alternatives for combating candidiasis, a common opportunistic infection in HIV/AIDS patients.Keywords: Ocimum species, larvicides, brine shrimp, Candida albicansEast and Central African Journal of Pharmaceutical Sciences Vol. 13 (2010) 85-9

Screening of Tanzanian medicinal plants for anti-Candida activity

BACKGROUND: Candida albicans has become resistant to the already limited, toxic and expensive anti-Candida agents available in the market. These factors necessitate the search for new anti-fungal agents. METHODS: Sixty-three plant extracts, from 56 Tanzanian plant species obtained through the literature and interviews with traditional healers, were evaluated for anti-Candida activity. Aqueous methanolic extracts were screened for anti-Candida activity by bioautography agar overlay method, using a standard strain of Candida albicans (ATCC 90028). RESULTS: Twenty- seven (48%) out of the 56 plants were found to be active. Extracts of the root barks of Albizia anthelmintica and Balanites aegyptiaca, and roots of Plectranthus barbatus showed strong activity. CONCLUSION: The extracts that showed strong anti-Candida activity are worth of further investigation in order to isolate and identify the active compounds

Composition and antimicrobial activity of essential oils of two populations of Tanzanian Lippia javanica (Burm. f.) Spreng. (Verbenaceae)

The chemical composition of essential oils obtained from leaves of two samples of Lippia javanica (Burm. f.) Spreng, collected from the same locality in Tanzania, was analysed by GC and GC-MS. Sixty constituents (91.3%) of one sample and 38 constituents (76.0%) of the other sample were identified. The main components of the two oils were geranial, neral, limonene, germacrene-D, camphor, linalool, β-caryophyllene and myrcene. The two oils were significantly different in their chemical composition. This implies that the two L. javanica populations could be two different chemical races. Furthermore, antimicrobial activity of the oils was evaluated against six Gram-positive or Gram-negative bacteria and three pathogenic fungi, using the agar dilution technique. It was found that both oils exhibited moderate to strong activities against the bacteria tested, while both were inactive against the fungi tested. Copyright © 2003 John Wiley & Sons, Ltd

Chemical composition and in vitro antimicrobial activity of the essential oils of two Helichrysum species from Tanzania

The chemical composition of the essential oils obtained from the aerial parts of Helichrysum cymosum and H. fulgidum, from Tanzania, were analyzed by GC and GC/MS. A total of sixty-five compounds, representing 92.4% and 88.2% of the two oils, respectively, were identified, trans-Caryophyllene, caryophyllene oxide, β-pinene, p-cymene, spathulenol and β-bourbonene were found to be the main components. Furthermore, the oils were tested against six gram (±) bacteria and three pathogenic fungi. It was found that the oil of H. fulgidum exhibited significant antimicrobial activity, while the oil of H. cymosum was not active at all

Composition and antimicrobial activity of essential oils of two populations of Tanzanian Lippia javanica (Burm. f.) Spreng. (Verbenaceae)

The chemical composition of essential oils obtained from leaves of two samples of Lippia javanica (Burm. f.) Spreng, collected from the same locality in Tanzania, was analysed by GC and GC-MS. Sixty constituents (91.3%) of one sample and 38 constituents (76.0%) of the other sample were identified. The main components of the two oils were geranial, neral, limonene, germacrene-D, camphor, linalool, β-caryophyllene and myrcene. The two oils were significantly different in their chemical composition. This implies that the two L. javanica populations could be two different chemical races. Furthermore, antimicrobial activity of the oils was evaluated against six Gram-positive or Gram-negative bacteria and three pathogenic fungi, using the agar dilution technique. It was found that both oils exhibited moderate to strong activities against the bacteria tested, while both were inactive against the fungi tested. Copyright © 2003 John Wiley & Sons, Ltd

Chemical analysis of edible aromatic plants growing in Tanzania

The volatiles from the aerial parts of edible plants growing in Tanzania, Leucas glabrata, Plectranthus laxiflorus, Salvia nilotica and Vernonia smithiana, were investigated by GC and GC/MS. Thirty-five compounds were identified from L. glabrata, representing 80.4% of the total oil; forty-three from P. laxiflorus (86.7%); twenty-four from S. nilotica (94.3%); and thirty-nine compounds from V. smithiana (92.9%). Among the identified components, menthone, (p + o)-cymene, trans-caryophyllene and caryophyllene oxide were found as the main ones. Furthermore, the essential oils were investigated for their antimicrobial activity as well as for their antiradical activity, through the DPPH method. Upon antimicrobial assays, the oil of V. smithiana showed very strong antimicrobial activity against Gram-positive bacteria, oral pathogens and pathogenic fungi; the oil of P. laxiflorus also exhibited strong activity, mostly against Gram-positive bacteria and especially oral pathogens, while L. glabrata showed strong activity against all assayed bacteria. The essential oil of S. nilotica appeared to have the most antioxidant activity but was almost inactive against all tested microorganisms. © 2007 Elsevier Ltd. All rights reserved

Composition and antimicrobial activity of the essential oils of three Satureja species growing in Tanzania

Hydro-distilled volatile oils from the aerial parts of three Satureja species were investigated, mainly by a combination of GC and GC/MS. One hundred and thirteen compounds were identified, representing 82.9-92.0% of the total oil. Among the identified components, spathulenol, cis-piperitone oxide, α-bisabolol oxide-B, terpinen-4-ol, linalool, bornyl acetate, β-bourbonene, isomenthone, thymol, neoisomenthol and menthone were found as the main components. Furthermore, the essential oils were investigated for their antimicrobial activity, by the agar dilution technique. The antimicrobial test results showed that the oils had a high antimicrobial activity against two Gram-positive and four Gram-negative bacteria, two oral pathogens and three pathogenic fungi. Gram-positive bacteria were more sensitive to the investigated oils than were Gram-negative bacteria. These results could support the suggestion of Satureja species as a source of antimicrobial ingredients for the food industry. © 2006 Elsevier Ltd. All rights reserved

Chemical analysis and antimicrobial activity of essential oils from the aromatic plants artemisia afra jacq. And leonotis ocymifolia (Burm. F.) iwarsson var. Raineriana (vision1) iwarsson growing in Tanzania

Hydrodistilled volatile oils from the aerial parts of Artemisia afra and leaves of Leonotis ocymifolia var. raineriana were investigated, by a combination of GC and GC/MS. From A. afra 37 compounds were identified, representing 95.3% (area percent) of the total oil and from L. ocymifolia var. raineriana, 27 compounds were identified, representing 91.1% of the total oil. Among the identified components camphor (46.2%), α-thujone (15.2%), artemisia ketone (7.4%) and 1,8-cineole (4.2%) were found as the main components of A. afra oil and germacrene D (36.8%), (Z)-β-ocimene (7.9%), β-caryophyllene (7.0%) and (E)-β-ocimene (4.4%) were the major components of L. ocymifolia oil. Furthermore, the oils, as well as nine of their constituents, were evaluated for their antimicrobial activity, against six bacteria, two oral pathogens and three pathogenic fungi. The results showed that the oil of A. afra has a moderate antimicrobial activity, while the oil of L. ocymifolia exhibited a stronger one against Gram-negative bacteria and oral pathogens, and a weaker one against Gram-positive bacteria. This interesting profle can be attributed to the high content of the oil, of germacrene D which is known for its antimicrobial activity. © 2007, Taylor & Francis Group, LLC. All rights reserved

Research Trends in Emerging Contaminants on the Aquatic Environments of Tanzania

The continuity for discovery and production of new chemicals, allied products, and uses has currently resulted into generation of recent form of contaminants known as Emerging Contaminants (ECs). Once in the aquatic environment ECs are carcinogenic and cause other threats to both human’s and animals’ health. Due to their effects this study was aimed at investigating research trends of ECs in Tanzania. Findings revealed that USA and EU countries were leading in ECs researches, little followed by Asia, South Africa, and then Zambia. Only few guidelines from USA-EPA, WHO, Canada, and Australia existed. Neither published guidelines nor regulations for ECs existed in Tanzania; rather only the occurrence of some disinfection by-products and antibiotics was, respectively, reported in Arusha and Dar es Salaam, Tanzania. As these reports had a limited coverage of ECs, henceforth, these findings constitute the first-line reference materials for ECs research in Tanzania which shall be useful for future monitoring and regulation planning

Quality of antiretroviral drugs, stavudine and indinavir capsules available in the Tanzanian market

Background: The number of antiretroviral drugs (ARVs) available to HIV/AIDS patients in Tanzania is increasing due to a number of intervention programs such as PEPFAR and the Clinton Foundation. These ARVs are imported from a number of countries. However, currently there are no reports on the quality of these medicines imported into Tanzania. The sale of substandard and counterfeit drugs has been well documented particularly in developing countries. The marketing of counterfeit and substandard antiretroviral drugs has also been widely reported in Africa. It is therefore important to closely monitor the quality of ARVs marketed in Tanzania to ensure that substandard or fake products are uncovered before great harm is done to public health. Objective: To assess the quality of ARVs marketed in Tanzania. Methodology: A total of five samples of two generic drugs (stavudine and indinavir) from different manufacturers were randomly collected from various retail pharmacies. Assessment of package inserts and labels was carried out using the Tanzania Food and Drugs Authority (TFDA) specifications. The capsules were analyzed for the content of the active components using validated in-house methods Results: All samples of Indinavir and Stavudine investigated conformed to the packaging and labeling specifications. However, all Indinavir samples were found to contain excess amount of active ingredient (112.6% - 118%) compared to the official limit of 95 – 105%. One sample of stavudine capsules failed the dissolution test, releasing only 56% instead of the specified 80% of the active ingredient. Conclusion: The results of this study emphasize the need for careful monitoring of the quality of drugs to ensure their safety and efficacy. Keywords: Antiretroviral drugs, Quality, Substandard drugs. Tanzania Medical Journal Vol. 21 (1) 2006: pp. 8-1