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Publications (52)
Characterisation of a novel discolornolide (1) isolated from a first time investigation of Monanthotaxis discolor is described. Other 6 known compounds, karatavin (2), N-acetylanonaine (3), quercetin-3-O–arabinose (4), stigmasterol (5), a mixture of stigmasterol and β-sitosterol (6) and octahydro-5-isopropyl-3-methyl-2-methyleneazulene-8,8-diol (7)...
Candidiasis is one of the most frequent opportunistic infections in individuals with severe immunosupression and further development of resistance against the available antifungal drugs has created an alarming situation. This requires intensive drug discovery to develop new, more effective, affordable and accessible antifungal agents possessing nov...
This paper describes a novel non-contact signal transfer mechanism for transferring multiple signals over the rotating interface through electromagnetic means. This signal transfer mechanism is configured for the transfer of temperature signals of a Spacecraft Mechanism. FE Analysis of rotary transformer was carried out for optimization of size and...
–4, and anticandida activity assay procedures and 1H and 13C-NMR spectroscopic data of 1–4, are available as supporting information .
Azabicycloheptenoylditerpene 1-((2E,6E,10E)-3,7,11,15-tetramethylhexadeca-2,6,10,14-tetraenyl)-2-azabicyclo[2.2.1]hept-5-en-3-one (artamodamide, 1), diphenylpentanoid (E)-1,5-bis(4-hydroxyphenyl)-pent-1-en-3-one (artamenone, 2) and N-methoxy-5-oxoaporphinoid (artamonteirine, 3) were isolated as new metabolites from Artabotrys modestus Diels ssp mac...
Combretum zeyheri Sond (Combretaceae) has been reported to exhibit anticandida activity against Candida kruzei, C. albicans, and C. parapsilosis; however, the active constituents have not been isolated so far. A bioactivity-guided fractionation of MeOH extract of C. zeyheri resulted in the isolation of triterpenoids, ursolic acid (1.1), oleanolic a...
The chemical compositions of non volatile oil extracts from two Annoneceous plant species
Monanthotaxis discolorand an undescribed Uvariodendronspecies which are endemic to Eastern
Arc Mountains, Tanzania were determined by GC-MS. The biological activities of extracts and
fractionated samples were also determined. Both methanol and dichlorometha...
Toussaintine A (N-cinnamoyl-5,6-dehydro-4-hydroxyindolidin-2,7-dione), toussaintine B (N-cinnamoyl-5,6-dehydro-4,7-dihydroxyindolidin-2-one), toussaintine C (N-cinnamoyl-5,6-dehydro-4-hydroxyindoli-din-7-one), toussaintine D (N-cinnamoyl-2-amino-4-hydroxy-7-oxo-2,3,8,9-tetrahydrobenzofuran) and
toussaintine E (N-cinnamoyl-1-acetoxymethyl-2-amino-1-...
HIV/AIDS pandemic is currently the most socio-economic challenge that faces Tanzania as it affects mostly the young and most economically productive population. People living with HIV/AIDS in Tanzania are susceptible to fungal and bacterial opportunistic infections, which are a major cause of mortality and morbidity in the country. Despite the gove...
Plants used in traditional medicine in Tanzania were screened for their cytotoxicity using the brine shrimp and CellTiter-BlueTM cell viability assays. Dichloromethane extracts of Capparis erythrocarpos, Cussonia arborea, Dracaena steudneri, Lannea schimperi, Pseudospondias microcarpa, Rauvolfia vomitoria, Sapium ellipticum and Zehneria scabra exhi...
Magnetic field analysis of the Halbach array permanent magnet brushless dc machine was carried out. Initial designs, selection of major parameters, prediction of airgap field density are carried out by using the analytical model. Performance of three types of machine configurations, Slotless PMBDC, Coreless enclosed rotor type with and without Halb...
The phenylpropenoids O-methyleugenol, O-methylisoeugenol and 2,3-
dimethoxycinnamaldehyde, have been isolated as the antimosquitocidal principles of the stem and root bark extracts
of Uvariodendron pycnophyllum (Diels) R.E. Fr. The extracts and compounds exhibited activity with LC50 values in
the range 17-59 ppm against the Anopheles gambiae s.s Gi...
In traditional African communities, repellent volatiles from certain plants generated by direct burning or by thermal expulsion have played an important role in protecting households against vectors of malaria and other diseases. Previous research on volatile constituents of plants has shown that some are good sources of potent mosquito repellents....
The clerodane diterpenoids trans-kolavenolic acid, 18-oxocleroda-3,13(E)-dien-15-oic acid, ent-(18-hydroxycarbonyl)-cleroda-3,13(E)-dien-15-oate, 2-oxo-ent-cleroda-3,13(Z)-dien-15-oic acid and trans-2-oxo-ent-cleroda-13(Z)-en-15-oic acid, and the chlorobenzenoid O-(3-hydroxy-4-hydroxycarbonyl-5-pentylphenyl)-3-chloro-4-methoxy-6-pentyl-2-oxybenzoic...
The new aristolactam alkaloid toussalactam {2-hydroxy-1,6-dimethoxy-5H-dibenzo[cdf]indol-4-one} and the known ones, namely aristolactam AII, aristolactam BII, piperolactam C and aristolactam FII; 1-(2-C-methyl-beta-D-ribofuranosyl)-uracil, 3,4,5-trimethoxyphenyl-beta-D-glucopyranoside, and three catechinoids were isolated from the cytotoxic Toussai...
This paper gives the details of the design analysis and development of Halbach array PMBDC motor for torquing the gimbal of control moment gyroscope, initial design, selection of major parameters and airgap magnetic flux density are estimated using the analytical model of the machine. Three types of the machine configurations, Slotless PMBDC, Corel...
The nor-halimane diterpenoid tessmannic acid and its methyl, 2-methylisopropyl and 1-methylbutyl esters, the unusual isocoumarins 8-hydroxy-6-methoxy-3-pentylisocoumarin and 7-chloro-8-hydroxy-6-methoxy-3-pentylisocoumarin, and 5-pentyl-3-methoxy-N-butylaniline were isolated from the stem and root bark extracts of Tessmannia densiflora Harms (Caesa...
The furanoditerpenoids voucapane, voucapane-6alpha,7alpha-diol, voucapane-18,19-diol and 18-hydroxyvoucapan-19-al were isolated from the cytotoxic stem and root bark extracts of Stuhlmaniamoavi Verdc. (Ceasalpiniaceae) and their structures established based on analysis of spectroscopic data. The compounds exhibited anti-proliferative, cytotoxic, an...
The clerodane diterpenoids trans-kolavenolic acid, 18-oxocleroda-3,13(E)-dien-15-oic acid, ent-(18-hydroxycarbonyl)-cleroda3,13(E)-dien-15-oate, 2-oxo-ent-cleroda-3,13(Z)-dien-15-oic acid and trans-2-oxo-ent-cleroda-13(Z)-en-15-oic acid, and the chlorobenzenoid O-(3-hydroxy-4-hydroxycarbonyl-5-pentylphenyl)-3-chloro-4-methoxy-6-pentyl-2-oxybenzoic...
The nor-halimane diterpenoid tessmannic acid and its methyl, 2-methylisopropyl and 1-methylbutyl
esters, the unusual isocoumarins 8-hydroxy-6-methoxy-3-pentylisocoumarin and 7-chloro-8-hydroxy-
6-methoxy-3-pentylisocoumarin, and 5-pentyl-3-methoxy-N-butylaniline were isolated from the stem
and root bark extracts of Tessmannia densiflora Harms (Caes...
Fungal infections represent a significant cause of morbidity and mortality especially in immunocompromised patients in the world today. Dichloromethane (DM) and aqueous (W) extracts of nine plants used traditionally for the treatment of fungal infections in Bukoba rural district in Tanzania were screened for antifungal activity against Candida albi...
Ethnobotanical survey was done among the Hehe community of central Tanzania to identify plants that can be used in the control of malaria transmitting mosquito vectors. Extracts from different plant parts wereanalysed for their larvicidal effects against Anopheles gambiae s.s mosquito by using the WHO (1996) protocols. The crude extracts that had h...
The three Tanzanian wild mushroom species Termitomyces letestui, Lactarius edulis and Agaricus sp. aff. arvensis yielded ergosterol, 5,8-peroxyergosterol and ergosta-5,22-dien-3β-ol, and a mixture of ergosterol, ergosta-7,22-dien-3β-ol and ergosta-7-en-3β-ol whose composition was deduced from gas chromatography/mass spectroscopic (GC/MS) analysis o...
This paper reports the larvicidal activity of seventeen Tanzanian plant species against the malaria vector, Anopheles gambiae s.s. Giles larvae. Some of the plants are used traditionally as sources of insecticidal materials.
The crude extracts from the leaves, stem and root barks of the investigated plants were obtained by solvent extraction and th...
Background & objectives: This paper reports the larvicidal activity of seventeen Tanzanian plant
species against the malaria vector, Anopheles gambiae s.s. Giles larvae. Some of the plants are used
traditionally as sources of insecticidal materials.
Methods: The crude extracts from the leaves, stem and root barks of the investigated plants were
obt...
Studies on the larvicidal properties of extracts and fractions from Kotschya uguenensis Verdc. were done by long-term exposure of Anopheles gambiae s.s. larvae. The cumulative mean percentage mortalities and deformities at different concentrations for the extracts and fractions were recorded after every 24 h. Treatment of A. gambiae s.s. larvae wit...
Petroleum ether, dichloromethane, and ethanolic extracts of the stem bark and leaves of Uvaria scheffleri Diels (Annonaceae) exhibited antifungal activity against Aspergillus niger (wild strain), Aspergillus fumigatus (wild strain), and a Penicillium species (wild strain). The ethanol extract of the stem bark was also active against Candida albican...
Lantana viburnoides sp viburnoides var kisi is used in Tanzania ethnobotanically to repel mosquitoes as well as in traditional medicine for stomach ache relief. Bioassay-guided fractionation and subtraction bioassays of the dichloromethane extract of the root barks were carried out in order to identify the bioactive components for controlling Anoph...
The rosane diterpenoids hugorosenone [3beta-hydroxyrosa-1(10),15-dien-2-one], 18-hydroxyhugorosenone and 18-hydroxy-3-deoxyhugorosenone, and 12-hydroxy-13-methylpodocarpa-8,11,13-trien-3-one were isolated as antifungal constituents of H. castaneifolia Engl. root bark, together with the previously reported di-podocarpanoids hugonone A and hugonone B...
Phytochemical investigation of the stem and root barks of Friesodielsia obovata Benth (Annonaceae) afforded new 3',5'-diformyl-2',4',6'-trihydroxychalcone and N-formyl-7-hydroxyglaucine together with five known compounds, 3',5'-dimethyl-2',4',6'-trihydroxychalcone, (-)-crotepoxide, demethoxymatteucinol, lawinal, and benzyl benzoate. 3',5'-diformyl-...
A new cytotoxic himachalene sesquiterpenoid 4alpha-methoxy-5,9-oxahimachal-9-ene (hugonianene A) which exhibited moderate activity against Anopheles gambiae mosquito larvae after 24 h at a concentration of 0.237 mg mL(-1), and at 48 h and 72 h contact time causing complete larval mortality up to a concentration as low as 0.01369 mg mL(-1), was isol...
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-sitos...
Plants used in traditional medicine in Bukoba Rural district in Tanzania were evaluated for their in vitro antimicrobial activities. Plant materials from eight plant species (Harungana madagascariensis (Lam) Poir., Jatropha curcas L., Lantana trifolia L., Plectranthus barbatus Andr., Pseudospondias microcarpa Engl., Psorospermum febrifugum Spach, T...
Ethnobotanical surveys were carried out to document herbal remedies used in the management of HIV/AIDS opportunistic infections in Bukoba Rural district, Tanzania. The district is currently an epicenter of HIV/AIDS and although over 90% of the population in the district relies on traditional medicines to manage the disease, this knowledge is impres...
This paper investigates the various strategies for the minimization of cogging torque produced in a permanent magnet brushless DC (PMBDC) motor for a low speed, speed stability stringent spacecraft application with cold coil redundancy. The effect of the material saturation on cogging torque is analyzed using both FE software simulation and hardwar...
Switched reluctance motors (SRM) is gaining wider popularity for variable speed drives. These motors have been developed for electric propulsion, fan, pump and even as starter/alternator for aerospace applications. This paper gives the step-by-step design procedure of a 16/12 switched reluctance motor for a spacecraft actuator. Machine design has b...
The dichloromethane extract of Securidaca longepedunculata Fresen yielded a benzophenone, (4-methoxy-benzo[1,3]dioxol-5-yl)-phenylmethanone (1), together with other three known compounds, 1,7-dihydroxy-4-methoxyxanthone (2), benzyl 2-hydroxy-6-methoxybenzoate (3), and methyl 2-hydroxy-6-methoxybenzoate (4). Compound (1) exhibited antibacterial acti...
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)...
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.
Sixty-three plant extracts, from 56 Tanzanian plant species obtained through the literature and interviews with traditional healers, were evaluated for anti-C...
This paper presents the design, analysis and development of 720-step high torque stepper motor for the Solar Array Drive Assembly mechanism used in IRS class satellites. The existing motor develops a peak holding torque of 1.1 Nm at 42 V with magnetic saturation and the torque pattern has the third and fifth harmonics in addition to the fundamental...
The anti-fungal activity of schefflone, a mixture of dimmer, 3,5 dimethoxy carvacrol and annonaceous acetogenin, extracted from stem-bark and root of Uvaria scheffleri and Artabotrys bruchypetalus against Fusarium solani, Botryodiplodia theobromae, Asperillus niger and Aspergillus flavus was determined. An in-vitro bioassay showed that the minimum...
The sterol ergosterol and ergosta-4,22-diene-3!,7"-diol, together with 4-hydroxybenzaldehyde were isolated from the mushroom species Polyporus molluscensis, Cantharellus isabelinus, C.symoensii and a Podaxis species. Their structures were established on the basis of spectroscopic data. The ethanol extracts of mushroom samples of Agaricus sp. and Te...
Reaction wheels are used as actuators for attitude control of satellites. Ball bearing is being used in reaction wheel application since many decades. Even small variations in friction torque in ball bearings affects the pointing stability of the satellites used for high resolution imaging application. Also the bi-directional operation of reaction...
Antibacterial activities of caulindole D, a mixture of caulindole E and F, pinocembrin and an oxyheptanoid (cleistenolide), obtained from stem barks of Isolona cauliflora and Cleistochlamys kirkii , on Staphylococcus aureus and Pseudomonas phaseolicola were determined. An in vitro assay test by paper disc method showed that the caulindole D, E and...
Extracts of 34 plants that are traditionally used for the treatment of different diseases exhibited various degrees of toxicity on brine shrimp. The concentration killing 50% (LC(50)) of the shrimps was below 50 mug/ml for 14 (41.2%), 50-100 mu g/ml for 10 (29.4%), and greater than 100 mug/ml for 10 (29.4%) of the plants, respectively. Dalbergia ni...
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. ga...
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. ga...
Antimicrobial activities of crude extract, Caulindole D, a mixture of Caulindole E and F, Pinocembrin and an Oxyheptanoid (Clestochlamic acid) from stem bark of Isolona cauliflora and Cleistochlamys krikii on Pseudomonas phaseolicola, Fusarium solani, Botryodiploida theobromae Aspergillus niger and Aspergillus flavus have been investigated. An in v...
This paper presents the design and analysis done on the 720 step hybrid stepper motor used to drive solar array drive mechanism of Indian remote sensing satellites (IRS). The original design reported in PEDS 1995, develops a peak holding torque of 1.1 NM, saturating at 42 Volts. The authors then, introduced a phenomenon called "torque saturation" d...
Background: Ethnobotanical surveys were carried out to document herbal remedies used in the management of HIV/AIDS opportunistic infections in Bukoba Rural district, Tanzania. The district is currently an epicenter of HIV/AIDS and although over 90% of the population in the district relies on traditional medicines to manage the disease, this knowled...