Antibacterial, anti-HIV-1 protease and cytotoxic activities of aqueous ethanolic extracts from Combretum adenogonium Steud. Ex A. Rich (Combretaceae).

BACKGROUND: Records have shown that Combretum adenogonium Steud. Ex A. Rich (Combretaceae) is used in traditional medicine systems of several tribes in Tanzania. This study focused on the investigation of antibacterial activity, anti-HIV-1 protease activity, toxicity properties and classes of phytochemicals in extracts from C. adenogonium Steud. Ex A. Rich (Combretaceae) to evaluate potential of these extracts for development as herbal remedies. METHODS: Dried plant material were ground to fine powder and extracted using 80% aqueous ethanol to afford root, leaf and stem bark extracts. The extracts were assayed for anti-HIV-1 protease activities, antibacterial activities using microdilution methods and cytotoxicity using brine shrimps lethality assay. Screening for major phytochemical classes was carried out using standard chemical tests. RESULTS: All extracts exhibited antibacterial activity to at least one of the test bacteria with MIC-values ranging from 0.31-5.0 mg/ml. Two extracts, namely, root and stem bark exhibited anti-HIV-1 PR activity with IC50 values of 24.7 and 26.5 µg/ml, respectively. Stem bark and leaf extracts showed mild toxicity with LC50 values of 65.768 µg/ml and 76.965 µg/ml, respectively, whereas roots were relatively non-toxic (LC50 = 110.042 µg/ml). Phytochemical screening of the extracts indicated presence of flavonoids, terpenoids, alkaloids, tannins, glycosides and saponins. CONCLUSION: These results provide promising baseline information for the potential development of C. adenogonium extracts in treatment of bacterial and HIV/AIDS-related opportunistic infections.

Larvicidal, antimicrobial and brine shrimp activities of extracts from Cissampelos mucronata and Tephrosia villosa from coast region, Tanzania.

BACKGROUND: The leaves and roots of Cissampelos mucronata A. Rich (Menispermaceae) are widely used in the tropics and subtropics to manage various ailments such as gastro-intestinal complaints, menstrual problems, venereal diseases and malaria. In the Coast region, Tanzania, roots are used to treat wounds due to extraction of jigger. Leaves of Tephrosia villosa (L) Pers (Leguminosae) are reported to be used in the treatment of diabetes mellitus in India. In this study, extracts from the roots and aerial parts of C. mucronata and extracts from leaves, fruits, twigs and roots of T. villosa were evaluated for larvicidal activity, brine shrimps toxicity and antimicrobial activity. METHODS: Powdered materials from C. mucronata were extracted sequentially by dichloromethane followed by ethanol while materials from T.villosa were extracted by ethanol only. The extracts obtained were evaluated for larvicidal activity using Culex quinquefasciatus Say larvae, cytotoxicity using brine shrimp larvae and antimicrobial activity using bacteria and fungi. RESULTS: Extracts from aerial parts of C. Mucronata exhibited antibacterial activity against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi, Vibrio cholera, Bacillus anthracis, Streptococcus faecalis and antifungal activity against Candida albicans and Cryptococcus neoformans. They exhibited very low toxicity to brine shrimps and had no larvicidal activity. The root extracts exhibited good larvicidal activity but weak antimicrobial activity. The root dichloromethane extracts from C. mucronata was found to be more toxic with an LC50 value of 59.608 µg/mL while ethanolic extracts from root were not toxic with LC50>100 µg/mL). Ethanol extracts from fruits and roots of T. villosa were found to be very toxic with LC50 values of 9.690 µg/mL and 4.511 µg/mL, respectively, while, ethanol extracts from leaves and twigs of T. villosa were found to be non toxic (LC50>100 µg/mL). CONCLUSION: These results support the use of C. mucronata in traditional medicine for treatment of wounds. Extracts of C. mucronata have potential to yield active antimicrobial and larvicidal compounds. The high brine shrimp toxicity of T. villosa corroborates with literature reports that the plant is toxic to both livestock and fish. The results further suggest that T. villosa extracts have potential to yield larvicidal and possibly cytotoxic compounds. Further studies to investigate the bioactive compounds responsible for the observed biological effects are suggested.

Antibacterial and cytotoxic activities of Terminalia stenostachya and Terminalia spinosa.

Plants that belong to the Combretaceae family have long history of use in the traditional medicine systems of Africa and Asia for treatment of diseases and conditions associated with HIV/AIDS-opportunistic infections. The objective of this study was to investigate the biological activities of extracts of Terminalia stenostachya Engl. & Diels and Terminalia spinosa Engl. (Combretaceae), to verify the rationale for their use by traditional health practitioners in the treatment of HIV/AIDS patients in Tanzania. Extracts of the leaves, stem barks and roots of T. stenostachya and extracts of stem barks and roots of T. spinosa have all shown strong activity against a number of standard microbial strains including Mycobacterium madagascariense and Mycobacterium indicus pranii, Streptococcus faecalis, Staphylococcus aureus, Vibrio cholera, Bacillus anthracis, Bacillus subtilis, Klebsiella pneumoniae, Salmonella typhi, Pseuodomonas aeruginosa and Escherichia coli. All extracts from the two plant species showed strong antimycobacterial activity against test organisms. The stem and root bark extracts were more active than leaves against both gram positive and negative bacteria. With the exception of two extracts from stem barks of T. spinosa, all other extracts from T. stenostachya and T. spinosa that were tested exhibited less activity against brine shrimp larvae with LC50 values ≥ 100 µg/mL compared to cyclophosphamide, a standard anticancer drug. These results provide an indication that these plants may possess therapeutically potent antimicrobial compounds worth further development.

Screening of traditionally used plants for in vivo antimalarial activity in mice.

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.

New furanoditerpenoids from Croton jatrophoides.

Four furanoditerpenoids were isolated from roots of Croton jatrophoides (Euphorbiaceae) collected in Tanzania. In addition to the known compounds penduliflaworosin and teucvin (mallotucin A), a new teucvin isomer, which was named isoteucvin, and a furanoditerpenoid with a new skeleton, for which the name jatrophoidin was adopted, were isolated. Their structures were elucidated by spectroscopic methods such as ESI-MS and NMR, including (1)H-, (13)C-, and two-dimensional NMR. The crystal structures of isoteucvin and jatrophoidin were solved using single-crystal X-ray diffraction, by which we also established the absolute configuration of jatrophoidin. The refined crystal structure of isoteucvin has the same (absolute) configuration as jatrophoidin, although the X-ray diffraction data of isoteucvin were not conclusive with respect to the absolute configuration.

Antimicrobial activity and brine shrimp toxicity of extracts of Terminalia brownii roots and stem.

BACKGROUND: Ternimalia 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. METHODS: Extraction 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. RESULTS: Extracts 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 microg/ml, respectively. The stem wood extracts exhibited the highest toxicity against the shrimps (LC50 values 2.58-14.88 microg/ml), while that of cyclophosphamide, a standard anticancer drug, was 16.33 (10.60-25.15) microg/ml. CONCLUSION: These 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.

Experience of initiating collaboration of traditional healers in managing HIV and AIDS in Tanzania.

Collaboration between traditional healers and biomedical practitioners is now being accepted by many African countries south of the Sahara because of the increasing problem of HIV/AIDS. The key problem, however, is how to initiate collaboration between two health systems which differ in theory of disease causation and management. This paper presents findings on experience learned by initiation of collaboration between traditional healers and the Institute of Traditional Medicine in Arusha and Dar-es-Salaam Municipalities, Tanzania where 132 and 60 traditional healers respectively were interviewed. Of these 110 traditional healers claimed to be treating HIV/AIDS. The objective of the study was to initiate sustainable collaboration with traditional healers in managing HIV/AIDS. Consultative meetings with leaders of traditional healers' associations and government officials were held, followed by surveys at respective traditional healers' "vilinge" (traditional clinics). The findings were analysed using both qualitative and quantitative methods. The findings showed that influential people and leaders of traditional healers' association appeared to be gatekeepers to access potential good healers in the two study areas. After consultative meetings these leaders showed to be willing to collaborate; and opened doors to other traditional healers, who too were willing to collaborate with the Institute of Traditional Medicine in managing HIV/AIDS patients. Seventy five percent of traditional healers who claimed to be treating HIV/AIDS knew some HIV/AIDS symptoms; and some traditional healers attempted to manage these symptoms. Even though, they were willing to collaborate with the Institute of Traditional Medicine there were nevertheless some reservations based on questions surrounding sharing from collaboration. The reality of past experiences of mistreatment of traditional healers in the colonial period informed these reservations. General findings suggest that initiating collaboration is not as easy as it appears to be from the literature, if it is to be meaningful; and thus we are calling for appropriate strategies to access potential healers targeted for any study designed with sustainability in mind.

Prenylated flavonoids from the root bark of Berchemia discolor, a Tanzanian medicinal plant.

Five new prenylated flavonoids (1-5) were isolated from the root bark of Berchemia discolor, collected in Tanzania, along with 10 known compounds, by bioactivity-guided fractionation. The structures of compounds 1-5 were elucidated using various spectroscopic techniques. Of these isolates, compound 4, and the known compounds nitidulin (6), amorphigenin (7), and dabinol (8), exhibited cytotoxic activity when evaluated against a small panel of human cancer cells. Nitidulin (6) was further tested in an in vivo hollow fiber assay and found to be active against LNCaP (human hormone-dependent prostate cancer) cells implanted intraperitoneally, at doses of 10, 20, and 40 mg/kg.

A novel isoflavonoid from Millettia puguensis.

From the roots of Millettia puguensis (Leguminosae), a novel isoflavonoid (5), 2'-methoxy-4',5'-methylenedioxy-7,8-[2-(1-methylethenyl)furo]isoflavone, and four known compounds, i. e., lupeol (1), (-)-maackiain (2), 6,7-dimethoxy-3',4'-methylenedioxyisoflavone (3) and 7,2'-dimethoxy-4',5'-methylenedioxyisoflavone (4) were isolated and identified by 1H-, 13C-NMR and mass spectroscopy. All compounds were evaluated for their antiprotozoal and cytotoxic activities, but only a moderate antileishmanial activity was observed for compound 3 (IC50 = 32 microM against Leishmania infantum), and a moderate cytotoxicity for compound 2 (IC50 = 43 microM on MRC-5 cells).

Antifungal activity of some Tanzanian plants used traditionally for the treatment of fungal infections.

Using the ethnobotanical approach, some Tanzanian plants reported to be used by traditional healers for the treatment of oral candidiasis and fungal infections of the skin were collected and screened for their antifungal activity against Candida albicans, Candida glabrata, Candida tropicalis, Candida parapsilosis, Candida krusei and Cryptococcus neoformans. A total of 65 crude methanol extracts belonging to 56 plant species and 38 families were screened using the broth microdilution method, according to the guidelines of the Clinical and Laboratory Standard Institute (CLSI) (formerly, National Committee for Clinical and Laboratory Standards) [National Committee for Clinical Laboratory Standards, 2002. Reference Method for Broth Dilution Antifungal Susceptibility Testing of Yeasts. Approved Standard-2nd Edition M27-A2, National Committee for Clinical Laboratory Standards, Wayne, PA, USA]. Among the tested plant species, 45% (25 species) showed antifungal activity against one or more of the test fungi. The most susceptible yeasts were Cryptococcus neoformans, followed by Candida krusei, Candida tropicalis, and Candida parapsilosis. The least susceptible were Candida albicans and Candida glabrata. Strong antifungal activity was exhibited by extracts of Clausena anisata Oliv., Sclerocariya birrea Sond, Turraea holstii Gurk, Sterculia africana (Lour) Fiori, Acacia robusta subsp. Usambarensis (Taub) Brenan, Cyphosterma hildebrandti (Gilg), Desc, Elaeodendron buchannanii (Lows), Acacia nilotica (L.) Wild ex Del, Jatropha multifida L., and Pteridium aquilinum (L.) Kuhn.

Antiparasitic activity of some xanthones and biflavonoids from the root bark of Garcinia livingstonei.

A new biflavanoid, ent-naringeninyl-(I-3alpha,II-8)-4'-O-methylnaringenin (6), along with five known xanthones and two known biflavonoids, was isolated from the root bark of Garcinia livingstonei collected in Tanzania. The absolute configuration of 6 was established by CD spectroscopy. This compound showed moderate activity against P. falciparum (IC(50) 6.7 microM). Antitrypanosomal activity (IC(50) 0.87 microM) was observed for 1,4,5-trihydroxy-3-(3-methylbut-2-enyl)-9H-xanthen-9-one (3). The dimeric xanthone garcilivin A (4) showed a higher and nonselective antiparasitic activity and cytotoxicity (IC(50) 2.0 microM against MRC-5 cells) than its diastereoisomer garcilivin C (5) (IC(50) 52.3 microM).

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.

Anticonvulsant activity of extracts of Diospyros fischeri stem bark.

Evaluation of extracts of Diospyros fischeri Gurke (Ebenaceae), which is used traditionally for the treatment of epilepsy shows that the aqueous extract of the tem bark has no effect against picrotoxin induced convulsions in mice. However, an 80% ethanol extract of the bark caused dose-dependent suppression of convulsions induced by 10 mg/kg body wt picrotoxin, at doses between 100-3200 mg/kg body wt. Petroleum ether, 1:1 dichloromethane:methanol, and methanol extracts also suppressed picrotoxin-induced convulsions, but had a slightly lower inhibitory effect. The petroleum ether extract was the most active, but all were less active than the ethanol extract. Unlike phenobarbitone, which at 50 mg/kg body wt completely suppressed convulsions induced by 10 mg/kg body wt picrotoxin, none of the plant extracts completely suppressed convulsions in the mice. These results support the traditional uses of D.fischeri for the treatment of epilepsy. Given the seemingly innocuous nature of the extracts more work is suggested to ascertain their clinical application.

Brine shrimp toxicity evaluation of some Tanzanian plants used traditionally for the treatment of fungal infections.

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 20 microg/ml. These include Aloe lateritia Engl. (Aloaceae) [19.1 microg/ml], Cassia abbreviata Oliv. (Caesalpiniaceae) [12.7 microg/ml], Croton scheffleri Pax (Euphorbiaceae) [13.7 microg/ml], Hymenodactyon parvifolium Brig (Rubiaceae) [13.4 microg/ml], Kigelia Africana L. (Bignoniaceae) [7.2 microg/ml], and Ocimum suave Oliv. (Labiatae) [16.7 microg/ml]. Twelve plants gave LC(50) values between 21 and 50 microg/ml, 11 plants gave LC(50) values between 50 and 100 microg/ml, and 18 plants gave LC(50) values greater than 100 microg/ml.

Anticonvulsant activity of Diospyros fischeri root extracts.

Diospyros fischeri Gurke (Ebenaceae) is used in traditional medicine for the treatment of epilepsy. Dichloromethane, ethylacetate, and ethanol extracts of the roots, at doses between 100 and 1600 mg/kg BW, inhibited convulsions induced by the gamma-aminobutyric acid type A (GABAa) receptor antagonist, pentylenetetrazole (PTZ), in a dose dependent manner. The extracts also exhibited low toxicity against brine shrimps giving LC(50) values between 45.4 and 95.4 microg/ml. These results provide evidence for the potential of D. fischeri extracts to treat absence seizures, especially given their seemingly innocuous nature.

Role of traditional healers in psychosocial support in caring for the orphans: a case of Dar-es Salaam City, Tanzania.

Orphans are an increasing problem in developing countries particularly in Africa; due to the HIV/AIDS pandemic; and needs collective effort in intervention processes by including all stakeholders right from the grass roots level. This paper attempts to present the role of traditional healers in psychosocial support for orphan children in Dar-es-Salaam City with special focus on those whose parents have died because of HIV/AIDS. Six traditional healers who were involved in taking care of orphans were visited at their "vilinge" (traditional clinics). In total they had 72 orphans, 31 being boys and 41 being girls with age range from 3 years to 19. It was learned that traditional healers, besides providing remedies for illnesses/diseases of orphans, they also provided other basic needs. Further, they even provided psychosocial support allowing children to cope with orphan hood life with ease. Traditional healers are living within communities at the grass roots level; and appear unnoticed hidden forces, which are involved in taking care of orphans. This role of traditional healers in taking care of orphans needs to be recognised and even scaling it up by empowering them both in financial terms and training in basic skills of psychosocial techniques in how to handle orphans, in order to reduce discrimination and stigmatisation in the communities where they live.

Plants used to treat epilepsy by Tanzanian traditional healers.

A cross-sectional study performed in Temeke District (Dar es Salaam, Tanzania) showed that 5.5% of the traditional healers have knowledge for the treatment of epilepsy. Of the 100 healers interviewed, 30 (30%) believed that epilepsy was caused by witchcraft, while 19 (19%) thought epilepsy has a genetic origin which can be inherited. Other healers thought epilepsy can be caused by head injury or malaria (24%), and the remaining 27% did not know the cause. Most of the healers (92%) could present an accurate account on the symptoms of the disease, including dizziness, loss of consciousness, abrupt falling down, frothing from the mouth, loss of memory, biting of the tongue, confusion, and restlessness. They showed competence in the treatment of the disease, whereby 60 plants that are commonly used were mentioned. Abrus precatorius L. (Leguminosae), Clausena anisata (Willd.) Oliv. (Rutaceae) and Hoslundia opposita Vahl (Lamiaceae), which are among the plants mentioned, have proven anticonvulsant activity, while a few other species on their list have been reported to be useful in the treatment of epilepsy. Biological testing of these plants, using different models of convulsions is, suggested.

Anthranoid compounds with antiprotozoal activity from Vismia orientalis.

A phytochemical investigation of the 80% ethanolic extract of stem bark of Vismia orientalis Engl. (Guttiferae or Clusiaceae), a plant used in traditional medicine in Tanzania, resulted in the isolation and spectroscopic characterisation of 3-geranyloxy-6-methyl-1,8-dihydroxyanthraquinone, emodin, vismione D and bianthrone A1. Vismione D exhibited a broad range of antiprotozoal activities against Trypanosoma brucei rhodesiense and T. cruzi (IC50 < 10 micrograms/mL), Leishmania donovani (IC50 0.37 micrograms/mL) and Plasmodium falciparum strain K1 (IC50 1.0 microgram/mL). However, it was also slightly cytotoxic against human L6 cells (IC50 4.1 micrograms/mL). Emodin showed antileishmanial activity (IC50 2.0 micrograms/mL), while its IC50 against L6 cells was 20.3 micrograms/mL. Other antiprotozoal activities observed for emodin against both Trypanosoma species and P. falciparum, for bianthrone A1 against T. b. rhodesiense and P. falciparum, and for 3-geranyloxy-6-methyl-1,8-dihydroxyanthraquinone against T. b. rhodesiense, L. donovani and P. falciparum were in the range of 10 to 50 micrograms/mL. None of the compounds showed antibacterial or antiviral (including also HIV) activity.

New chemical constituents of Euphorbia quinquecostata and absolute configuration assignment by a convenient Mosher ester procedure carried out in NMR tubes.

Two new compounds, an ent-isopimarane-type diterpene, 3alpha,12alpha-dihydroxy-ent-8(14),15-isopimaradien-18-al (1), and a dihydrobenzo[b]furan neolignan, (-)-trans-9-acetyl-4,9'-di-O-methyl-3'-de-O-methyldehydrodiconiferyl alcohol (2), along with five known compounds, 7,7'-dihydroxy-6,8'-bicoumarin (bicoumol) (3), 3,4-dimethoxycinnamaldehyde (4), 6-hydroxy-7-methoxycoumarin (isoscopoletin), N-butylaniline, and vanillin, have been isolated from an ethyl acetate-soluble extract of the stem wood of Euphorbiaquinquecostata. The structures of compounds 1 and 2 were elucidated on the basis of spectroscopic data interpretation, and single-crystal X-ray diffraction analysis was used to confirm the structure and relative stereochemistry of 1. The absolute configuration of 1 was established by a convenient Mosher ester procedure in which the sample was treated with MTPA chlorides in deuterated pyridine directly in NMR tubes. All isolates were evaluated for the induction of quinone reductase in Hepa1c1c7 hepatoma cells and for the inhibition of the transformation of murine epidermal JB6 cells.