Medicinal plants used by Tanzanian traditional healers in the management of Candida infections.

An ethnomedical survey in Coast, Dar es Salaam, Morogoro and Tanga regions of Tanzania has resulted in the identification of 36 plant species belonging to 21 plant families that are used traditionally for the treatment of Candida infections. Twenty-one plants constituting 58.3% of all collected plants are used to treat of oral candidiasis (Utando) one of the important signs of HIV/AIDS. The knowledge of traditional healers for the treatment of Candida infections has been highly supported by the literature in that 13 (36.1%) out of the 36 plants identified have been proven to be active against Candida albicans and/or other species of Candida. Also, some of the plants were reported to be active against other species of fungi including Cryptococcus neoformans, one of the important pathogenic fungi in HIV/AIDS. It can be seen that ethnomedical information from traditional healers provides a solid lead towards development of new drugs than random screening. The task that remains is to screen extracts prepared from these plants and perform a bioassay-guided fractionation of the active extracts so as to isolate the active compounds from these plants.

Some pharmacological properties of extracts of Terminalia sericea roots.

Terminalia sericea Burch. Ex. DC (Combretaceae) extracts are used to treat bacterial infections, diarrhea, and diabetes. Intermediate and polar extracts of the roots exhibited antibacterial activity against Staphylococcus aureus, Escherichia coli, Bacillus anthracis, and Pseudomonas aeruginosa, while the petroleum ether extract was inactive. The extracts were mildly active against Bacillus anthracis and Pseudomonas aeruginosa but exhibited the highest activity against Staphylococcus aureus. They also exhibited antifungal activity against Candida albicans and Aspergillus niger. An 80% aqueous ethanol extract of the roots did not have any effect on blood glucose levels during an oral glucose tolerance test (OGTT), in mice (P>0.05). With the exception of the dichloromethane and petroleum ether extracts, all the intermediate and polar extracts were toxic to brine shrimps giving LC(50) (95% confidence intervals) values ranging from 5.4 (3.5-8.4) to 17.4 (11.4-26.5) microg/ml, while that of cyclophosphamide, a standard anticancer drug, was 16.3 (10.6-25.2) microg/ml. Further work is in progress to isolate and identify active compounds in the extracts.

Current and future prospects of integrating traditional and alternative medicine in the management of diseases in Tanzania.

Traditional medicine and medicinal plants, in general, continue to be a powerful source of new drugs, now contributing about 90% of the newly discovered pharmaceuticals. Traditional medicine continues to provide health coverage for over 80% of the world population, especially in the developing world. The past and the present are all full of living examples of discoveries of drugs, ranging from anticancer, antiasthma, antidiabetic, antihypertensives and many others which owe their origin to traditional medicine. The current era of HIV/AIDS is not short of contributions from traditional medicine. The recent discovery of the non-nucleoside reverse transcriptase inhibitor (NNRTI), calanolide A, is a new addition from traditional medicine. Many more such discoveries are yet to come. While this potential is much acknowledged, little has been done in African countries, to utilize the plants that are already known and proven to be safe for use by patients. A number of plants could be widely cultivated for local industrial production of medicines and herbal nutritional supplements. There is need to ensure that what is known is made use of, for financial gain, and for improvement of the health of our people. We need to establish the necessary expertise for development of traditional medicines and deliberate efforts should be made to encourage local industrial production of traditional/herbal medicines so that cultivation may become possible and hence contribute to poverty reduction.

Acid optimum kininogenases in canine myocardium and aorta.

OBJECTIVE: Canine coronary artery was recently reported to contain a cathepsin like acid optimum enzyme and a kallikrein like alkaline optimum enzyme which cleaved from a crude kininogen preparation a vasodilator uterus contracting substance. The aim of this study was to seek the presence of similar acid optimum enzymes in canine ventricular myocardium and in a large systemic artery, the aorta. METHODS: Aqueous canine tissue extracts were tested for the ability at different pHs to release uterus contracting substance (using rat isolated oestrous uterus) from a kininogen preparation. After gel filtration, the extracts were tested for the presence of arginine-amidase activity (substrate: D-Val.Leu.Arg.pNA) and enzymic activity forming bradykinin like immunoreactivity. Tissues were obtained from anaesthetised greyhounds which had been used in control studies and had received no other drug treatment. RESULTS: Ventricular extracts released uterus contracting substance optimally at pH 5.2-5.4, but not at alkaline pH, neither was bradykinin like immunoreactivity formed at alkaline pH. Inhibitor studies and gel filtration showed this activity to be due to a cathepsin-D-like enzyme, molecular weight (MW) 42.6 (SD 0.9) kd, which was an arginine amidase and released bradykinin like immunoreactivity from a plasma kininogen. Aortic extracts showed two pH related peaks of uterus contracting substance formation, at pH 5.2 and (unlike myocardium) at pH 8. Also unlike myocardium, aortic extracts gave two acid optimum kininogenase peaks on gel filtration, with MW 42(4.6) kd and 252(39) kd, respectively. Both peaks released bradykinin like immunoreactivity. CONCLUSIONS: Canine aorta contained an alkaline optimum and two acid optimum enzymes, while ventricle contained only a cathepsin-D-like acid optimum enzyme, all of which could form bradykinin like immunoreactivity. The ability of the ventricular enzyme to form a kinin in the slightly acid conditions of myocardial ischaemia may have a protective role.

Diterpenoids from the roots of Croton macrostachys.

Three novel diterpenoids have been isolated from the roots of Croton macrostachys. The structure and stereochemistry of the compounds have been unambiguously settled as neoclerodan-5,10-en-19,6beta;20,12-diolide, 3alpha, 19-dihydroxytrachylobane, and 3alpha,18,19-trihydroxytrachylobane from detailed spectroscopic evidence.

Comparative bioavailability of oral sugar-coated and plain formulation of chloroquine phosphate marketed in Tanzania.

The bioavailability of chloroquine from a single oral dose (10 mg/kg body weight) of a sugar-coated (Dawaquin) and a plain formulation (Shellyquine) of chloroquine phosphate were compared in two groups of 10 volunteers each, following an overnight fast. Whole blood chloroquine concentrations were measured using high-performance liquid chromatography (HPLC) and bioavailability was determined by measuring area under the blood chloroquine concentration curve (AUC ng mL(-1) h) and the peak blood chloroquine concentration (Cpmax ng/mL). The AUC and Cpmax for Shellyquine were 4396.3 +/- 833 ng mL(-1) h and 162 +/- 14 ng/mL, respectively. The AUC and Cpmax for Dawaquin were 2060 +/- 339 ng mL(-1) h and 56.6 +/- 5.2 ng/mL, respectively. Shellyquine was significantly more bioavailable than Dawaquin (P<0.001). Although the Cpmax for Dawaquin was higher than the required therapeutic level for sensitive Plasmodium falciparum of 30 ng/mL, its blood levels may not guarantee a rapid clearance of parasites. The differences between the two formulations point to a problem in the quality of pharmaceuticals marketed in this country, whose extent need to be ascertained further. Failure of chloroquine phosphate in this country has already been declared by the Ministry of Health, and the potential contribution of poorly formulated products remains a subject of debate.

Brine shrimp toxicity of some plants used as traditional medicines in Kagera Region, north western Tanzania.

Dichloromethane and/or ethanol extracts of 30 plants used as traditional medicines in Bukoba district, northwestern Tanzania were evaluated for brine shrimp toxicity. Among the 50 extracts tested, 32 extracts (64%) showed very low toxicity with LC50 values above 100 microg/ml. Among these 12 (24%) which had LC50 >500 microg/ml can be categorized as being practically non-toxic. Among the remaining extracts 19 (38%) which showed LC50 > 100 < 500 microg/ml are also considered to be non-toxic. Extracts that showed LC50 results between 30-100 microg/ml have been categorized as mildly toxic; these include ethanol extracts of Lantana trifolia (LC50 32.3 microg/ml), Vernonia bradycalyx (LC50 33.9 microg/ml), Antiaris toxicaria (LC50 38.2 microg/ml) and Rubus rigidus (LC50 41.7 microg/ml) and the dichloromethane extracts of Gynura scandens (LC50 36.5 microg/ml) and Bridelia micrantha (LC50 32.0 microg/ml). The dichloromethane extracts of Picralima nitida (LC50 18.3 microg/ml) and Rubus rigidus (LC50 19.8 microg/ml), were only moderately toxic. Picralima nitida and Rubus rigidus extracts are only 1.1 and 1.2 less toxic than the standard drug, cyclophosphamide (LC50 16.3 microg/ml). In conclusion, the results indicate that among the 30 plants used as traditional medicines, 28 are safe for short term use. Picralima nitida and Rubus rigidus extracts are mildly toxic, but by comparison have a remote possibility to yield active anticancer compounds.

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 15.35-374.0 microg/ml. However, ethanol extracts of Dissotis brazzae and Strombosia scheffleri had LC50 values of >1000 microg/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.

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.

Effect of caesalpina bonducella seeds on blood glucose in rabbits.

The seeds of Caesalpinia bonducella (L.) Flem. (Caesalpiniaceae) are sold in shops in Dar es Salaam, Tanzania, for the treatment of diabetes mellitus. A suspension of the powdered seed kernel in 0.5% carboxymethylcellulose (CMC) was tested for ability to lower blood glucose in fasted and glucose-fed normal albino rabbits. Following administration of 0.2, 0.4 and 0.8 g/kg body weight of the powder there was no difference in areas under the fasting blood glucose and oral glucose tolerance test (OGTT) curves as compared to controls given CMC (P > 0.05). Similarly, 0.2 g/kg body weight of the powder administered for 7 consecutive days had no effect on either fasting blood glucose or the clearance of a glucose load from the blood. However, 0.1 g/kg body weight chlorpropamide significantly decreased the area under the fasting blood glucose and OGTT curves as compared to controls given CMC (P = 0.05). Thus, contrary to a previous report, we could not detect any hypoglycaemic activity in the seeds of Caesalpinia bonducella growing in Dar es Salaam.