Repellency property of long chain aliphatic methyl ketones against Anopheles gambiae s.s.

Long chain aliphatic methyl ketone series of C7-C15 were tested for repellency activity against the malaria transmitting mosquito Anopheles gambiae s.s. All methyl ketones produced a dose dependent (P < 0.001) repellency response with 2-tridecanone giving comparable protection efficacy to DEET at 10% and 1% concentrations. Aliphatic methyl ketones of C7-C10 had lower activity than those of C11-C15. However, within this range compounds with odd carbon atoms (2-undecanone, 2-tridecanone and 2-pentadecanone) were more effective than compounds with even carbon atoms (2-decanone and 2- dodecanone). Comparable repellency activity of 2-tridecanone to DEET show that, it may save as Anopheles gambiae s.s. mosquito repellent.

Repellency Property of Long Chain Aliphatic Methyl Ketones against Anopheles gambiae s.s

Long chain aliphatic methyl ketone series of C7-C15 were tested for repellency activity against the malaria transmitting mosquito Anopheles gambiae s.s. All methyl ketones produced a dose dependent (P0.001) repellency response with 2-tridecanone giving comparable protection efficacy to DEET at 10 and 1concentrations. Aliphatic methyl ketones of C7-C10 had lower activity than those of C11-C15. However; within this range compounds with odd carbon atoms (2-undecanone; 2-tridecanone and 2-pentadecanone) were more effective than compounds with even carbon atoms (2-decanone and 2- dodecanone). Comparable repellency activity of 2-tridecanone to DEET show that; it may save as Anopheles gambiae s.s. mosquito repellent

Isolation of a stilbene glycoside and other constituents of Terminalia sericeae.

The ethanol extract of the root bark of Terminalia sericea yielded an unreported stilbene glycoside, 3'5'-dihydroxy-4-(2-hydroxy-ethoxy) resveratrol-3-O-beta-rutinoside (1) together with known compounds resveratrol-3-beta-rutinoside glycoside (2), 3',4,5'-Trihydroxystilbene (resveratrol) (3), triterpenoic acid arjungenin and a mixture of beta-sitosterol and stigmasterol. Structure determination of the isolated compounds was achieved on the basis of spectroscopic measurements.

Larvicidal and mosquitocidal extracts, a coumarin, isoflavonoids and pterocarpans from Neorautanenia mitis.

The present study aimed to evaluate extracts and compounds from tubers of Neorautanenia mitis against the malaria- and filariasis-transmitting mosquitoes, Anopheles gambiae and Culex quinquefaciatus, respectively. The extracts exhibited activity against larvae of A. gambiae and C. quinquefaciatus mosquitoes, and were also active against adult A. gambiae mosquitoes. The active extracts yielded the coumarin derivative pachyrrhizine, the isoflavonoids neotenone and neorautanone, and the pterocarpans neoduline, nepseudin and 4-methoxyneoduline as the active constituents. The activity of the crude extracts was at about the same magnitude as that of the constituent natural products, the latter's efficacy being almost at the same level for all the isolated compounds. The mosquitocidal activities of the pure compounds were comparable to those of the standard mosquitocides deltamethrin and alphacypermethrin. These findings corroborate traditional insecticidal application of N. mitis and the results can be extended for the control of mosquitoes especially at breeding sites.

Aporphinoid alkaloids and other constituents from Lettowianthus stellatus.

Two new aporphinoid alkaloids, f1ttowianthine and 11-methoxylettowianthine were isolated from the root bark of Lettowianthus stellatus, together with the new sesquiterpene 11-hydroxyguaia-4,6-diene and the known compounds liriodenine, (Z)-7-octadecen-9-ynoic acid, methyl (2E,6E,10R)-10,11-epoxy-3,7,11-trimethyl-2,6-dodecadienoate, methyl (2E,6E,10R)-10,11-dihydroxy-3,7,11-trimethyl-2,6-dodecadienoate , and 3,4,5-trimethoxyphenol. The structure elucidation was achieved by spectroscopic methods.

In vitro trypanocidal activity of some rare Tanzanian medicinal plants.

Extracts prepared from 15 rare Tanzanian medicinal plants were tested for their in vitro antitrypanosomal activity against human pathogenic trypanosomes (Trypanosoma brucei rhodesiense). Of 37 extracts investigated, two were found to have strong activity with IC50 values below 1 microgram/ml and ten extracts revealed promising activities with IC50 values between 1 and 5 micrograms/ml.

In vitro trypanocidal activity of some rare Tanzanian medicinal plants.

Extracts prepared from 15 rare Tanzanian medicinal plants were tested for their in vitro antitrypanosomal activity against human pathogenic trypanosomes (Trypanosoma brucei rhodesiense). Of 37 extracts investigated, two were found to have strong activity with IC50 values below 1 microgram/ml and ten extracts revealed promising activities with IC50 values between 1-5 micrograms/ml.

In vitro antitrypanosomal activity of African plants used in traditional medicine in Uganda to treat sleeping sickness.

In Uganda, as in many other African countries, herbal treatment of various diseases is still common. In the present study, 9 plant species collected from Tanzania and Uganda and used by traditional healers in southern-eastern Uganda for the treatment of human African trypanosomiasis (sleeping sickness) were extracted and screened for their in vitro activity against Trypanosoma brucei rhodesiense, one of the two causative agents of sleeping sickness. Eight lipophilic extracts of 5 plants revealed very promising antitrypanosomal activity with IC50 values below 1 microgram/ml; among them were extracts prepared from Albizia gummifera (2), Ehretia amoena (1), Entada abyssinica (2), Securinega virosa (1) and Vernonia subuligera (2). Activity with IC50 values between 1 and 10 micrograms/ml was determined for 15 further extracts. Cytotoxicity of active extracts, tested on a human fibroblast cell line (WI-38), was found to be high, and therefore selectivity indices resulted in less favourable ranges than those for the few commercially available drugs. Nevertheless, the results confirm the potential of ethnobotanically selected plants as remedies against sleeping sickness and call for phytochemical studies.

Evaluation of African medicinal plants for their in vitro trypanocidal activity.

Petroleum ether, dichloromethane, methanol and water extracts from 24 plants, belonging to 19 families, which are reported in the literature as traditional remedies for sleeping sickness (human African trypanosomiasis) were screened for in vitro activity against Trypanosoma brucei rhodesiense, as well as fro cytotoxicity for a human fibroblast cell-line (WI-38). The trypanocidal activity of the natural compounds berberine and harmane, both documented as being trypanocidal, was also evaluated. Promising trypanocidal activity with IC50 values below 10 micrograms/ml was found in 32 extracts of 13 plant species. The most active extracts with IC50 below 1 microgram/ml were derived from Annona senegalensis, Bussea occidentalis and Physalis angulata. The plant extracts showed a modest selectivity index, in contrast to commercially available trypanocides which have a more distinct selective toxicity against trypanosomes.

Traditional healers in Tanzania: the perception of malaria and its causes.

The coordination of traditional and western medicine is still in its infancy in most African countries. Although there is much discussion about the contribution of traditional medicine and its practitioners, especially on the primary health care level, it has rarely be done in practice. This is probably due to the lack of knowledge of how to do it, because a serious attempt to include traditional medicine in health planning would presuppose that it is known what traditional medicine has specifically to offer for certain diseases/illnesses and how traditional healers manage such conditions. The aim of this study was to investigate the management of malaria by traditional healers in different areas in Tanzania. This included looking at the perception, the causation concepts and the knowledge about prevention of the disease/illness of malaria. For this purpose traditional healers were interviewed in different rural and urban places in Tanzania: in the Kilombero valley (Kilombero/Ulanga District), on the main island of Ukerewe (Ukerewe District), in the region near Bukoba town (Bukoba District) and in the settlement of Dar es Salaam (largest town of Tanzania). The results of the study show that most of the interviewed traditional healers were very familiar with the signs and symptoms relating to malaria, as it is defined by western medicine. Many healers were aware of different manifestations of malaria and attributed to them different local names, which match the scientific terms which describe the different types of Plasmodium falciparum malaria, such as cerebral malaria, clinical malaria or febrile type, and gastrointestinal type, respectively. Differences compared to western medical knowledge were found for concepts of causation, and in the fact that severe malaria in children may not be perceived as being associated with malaria.

Traditional healers in Tanzania: the treatment of malaria with plant remedies.

In order to collect ethnobotanical information about antimalarial plants which is essential for the further evaluation of the efficacy of plants an antimalarial remedies, we investigated the management of malaria with traditional herbal remedies, including the use, preparation and administration, by traditional healers in Tanzania. Interviews with traditional healers were conducted in different rural and urban places in Tanzania: in the Kilombero valley (Kilombero/Ulanga District), on the main island of Ukerewe (Ukerewe District), in the region near Bukoba town (Bukoba district), and in the settlement of Dar es Salaam (largest city in Tanzania). The results of the study show that all traditional healers treat malaria with herbal remedies consisting of one to five different plants. The list of plants which they use for antimalarial treatment contains a large number of species from different families. Multiple citations of plants by different healers were rare. Most of the respondents attributed to the plants mentioned, or to the remedies made from them, specific effects and sometimes side effects, explaining and illustrating their use or non-use for different patients or manifestations of the disease/illness.

Traditional healers in Tanzania: sociocultural profile and three short portraits.

Traditional healers are an important part of African societies, but unfortunately the knowledge of the extent and character of traditional healing and the people involved in the practice is limited and impressionistic. They are frequently ignored in studies of user/provider patterns, although they cover the health needs of a substantial proportion of the population. For future health planning it is necessary to know what the reasons are that even in big cities, where western health care services are available, traditional healers flourish, and even compete with each other for certain aspects. The aim of this study was to investigate certain aspects of the profession of traditional healing in general in different areas in Tanzania in order to get an idea about the kind of traditional medical services which are available, and about the people who provide such services. For this reason traditional healers were interviewed with a semi-structured questionnaire in different rural and urban places: in the Kilombero valley (Kilombero/Ulanga district), on the main island of Ukerewe (Ukerewe District), and in the region near Bukoba town (Bukoba District), and in the settlement of Dar es Salaam (largest city of Tanzania). The results of the study show that traditional healers are a very heterogeneous group of persons not having much in common relating to their religion, sex and level of education. The traditional practice is very often taken over from a family member, but also other reasons for becoming a healer, like initiation through ancestor spirits, are very frequently given. More than 50% of the respondents practice full time. These full time practitioners are mainly found among men and in the younger age group. Treatment of in-patients, who can stay in special patient-houses, is offered by half of the traditional healers. Divination used as a diagnostic tool was found mainly among men. Referral of patients to the hospital was mentioned by almost all respondents in cases where they failed with their own treatment or when they knew that the patient would be better treated in the hospital or dispensary.

PIP: While traditional healers are an important part of African societies, not enough is known about the extent and character of traditional healing and the people involved in the practice. The authors interviewed 23 male and 8 female traditional healers in the Kilombero Valley, on the main island of Ukerewe, in the region near Bukoba town, and in the settlement of Dar es Salaam to gain insight into what kind of traditional medical services are available and the people who provide such services. The healers are a very heterogenous group of persons without much in common with regard to their religion, sex, and educational level. The traditional practice is often taken over from a family member. Other reasons for becoming a healer, such as initiation by ancestral spirits, were also frequently given. More than 50% of the respondents practice full time; these healers are mainly male and younger. Inpatient treatment is offered by half of the healers, and divination was used in diagnosis mainly by male practitioners. Almost all healers reported referring patients to hospitals when traditional treatment failed to work or when they knew that the patient would be better treated at a hospital or dispensary.

Screening Tanzanian medicinal plants for antimalarial activity.

Forty-three different plant species commonly used in traditional medicine for the treatment of malaria were selected and screened for their antimalarial activity against Plasmodium falciparum in vitro. Thirteen of the 43 species were obtained directly from traditional healers who use these plants for the treatment of malaria. The other plant species were collected on the basis of ethnomedicinal information in the literature. The plant material was collected from Morogoro, Dar es Salaam and Kagera regions in Tanzania. Fifty-eight plant samples from these 43 plant species, including leaves, roots and stem bark, were investigated. Apart from the crude EtOH extracts, petroleum ether (PE), ethyl acetate (EtAc) and H2O fractions of these extracts were also tested. The in vitro testing revealed that 37% of the investigated plants showed strong antimalarial activity with IC50 values below 10 micrograms/ml. The four most active plants included Cissampelos mucronata, Maytenus senegalensis, Salacia madagascariensis and Zanthoxylum chalybeum.

Antimalarial activity of Tanzanian plants and their active constituents: the genus Uvaria.

Petroleum ether, dichloromethane, and methanol extracts of leaves, stem, and root bark of nine Uvaria species: U. dependens, U. faulknerae, U. kirkii, U. leptocladon, U. lucida ssp. lucida, Uvaria sp. (Pande)k U scheffleri, and U. tanzaniae were tested for their in vitro activity against the multidrug resistant K1 strain of Plasmodium falciparum. The IC50 values of the extracts varied between 5 and 500 micrograms/ml. The most active extracts were obtained from the stem and root bark of U. lucida ssp. lucida and Uvaria sp. (Pande) and the root bark of U. scheffleri, all of which had IC50 values between 5 and 9 micrograms/ml. Among the compounds isolated, uvaretin, diuvaretin, and (8',9'-dihydroxy)-3-farnesylindole were the most active (IC50 = 3.49, 4.20, and 2.86 micrograms/ml, respectively).

Antimalarial activity of Tanzanian medicinal plants.

Tanzanian medicinal plants were extracted and tested for in vitro antimalarial activity, using the multidrug resistant K1 strain of Plasmodium falciparum. Of 49 plants investigated, extracts of three plants were found to have an IC50 between 5-10 micrograms/ml, extracts of 18 other plants showed an IC50 between 10 and 50 micrograms/ml, all others were less active. The three most active extracts were obtained from the tubers of Cyperus rotundus L. (Cyperaceae), the rootbark of Hoslundia opposita Vahl. (Labiatae), and the rootbark of Lantana camara L. (Verbenaceae).

Antimalarial compounds containing an alpha,beta-unsaturated carbonyl moiety from Tanzanian medicinal plants.

Pure compounds were isolated from plant extracts with antimalarial activity. The extracts were obtained from the tubers of Cyperus rotundus L. (Cyperaceae), the rootbark of Zanthoxylum gilletii (De Wild) Waterm. (Rutaceae), and the rootbark of Margaritaria discoidea (Baill.) Webster (Euphorbiaceae). The most active compounds included (IC50 within brackets): alpha-cyperone (1) (5.5 micrograms/ml), N-isobutyldeca-2,4-dienamide (2) (5.4 micrograms/ml), and securinine (3) (5.4 micrograms/ml). A mixture of autoxidation products of beta-selinene was found to be the most active antimalarial substances obtained from C. rotundus (5.6 micrograms/ml.