Browsing by Author "Nyandoro, Stephen S."
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Item Aflatoxin Levels in Sunflower Seeds and Unrefined Sunflower Oils from Singida, Tanzania(Taylor & Francis, 2018-03-16) Mohammed, Salum; Munissi, Joan J.E; Nyandoro, Stephen S.A total of 61 samples comprising sunflower seeds (40) and unrefined sunflower oils (21) samples collected randomly from Singida, Tanzania were analysed by Reverse Phase-high performance liquid chromatography (RP-HPLC). 15% (6/40) of the seed samples were contaminated with aflatoxin B1 ranging from limit of detection (LOD) to 218 ng g−1 with three of them exceeding the European Commission/European Union (EC/EU) and Tanzania Bureau of Standards (TBS)/Tanzania Food and Drug Authority (TFDA) maximum limits of 2 ng g−1 for AFB1 in oilseeds. The levels of total aflatoxins (AFT) in seeds ranged from LOD to 243 ng g−1. Other aflatoxins, except AFG2, were also detected. For the unrefined sunflower oils, the levels of AFB1 ranged from LOD to 2.56 ng mL−1. About 80.9% (17/21) of the analysed oil samples contained AFB1 of which 17.65% (3/17) exceeded the EC/EU and TBS/TFDA maximum limits of 2 ng mL−1. Other aflatoxins were also detected in the oils. The measured levels indicate there is a need for food quality education among food processors.Item Aflatoxin M1 in raw milk and aflatoxin B1 in feed from household cows in Singida, Tanzania(Taylor & Francis, 2016-02) Mohammed, Salum; Munissi, Joan J. E.; Nyandoro, Stephen S.Aflatoxin M1 (AFM1) contamination in raw milk from household cows fed with sunflower seedcakes or sunflower-based seedcake feeds was determined in 37 milk samples collected randomly from different locations in Singida region, Tanzania. Aflatoxin B1 (AFB1) contamination in sunflower-based seedcake feed was determined in 20 feed samples collected from the same household dairy farmers. The samples were analysed by RP-HPLC using fluorescent detection after immunoaffinity column clean-up. Recoveries were 88.0% and 94.5%, while the limits of detection (LOD) were 0.026 ng mL(-1) and 0.364 ng g(-1) for AFM1 and AFB1, respectively. Of the analysed cow's milk samples, 83.8% (31/37) contained AFM1, with levels ranging from LOD to 2.007 ng mL(-1), exceeding both the European Commission (EC) and Tanzania Food and Drug Authority (TFDA) limit of 0.05 ng mL(-1). Of the contaminated samples, 16.1% exceeded the Codex Alimentarius limit of 0.5 ng mL(-1). AFB1 was present in 65% (13/20) of the feed samples with levels ranging from LOD to 20.47 ng g(-1), 61.53% exceeding the TFDA and EC maximum limits of 5 ng g(-1) for complete dairy animal feed. The observed AFM1 and AFB1 contamination necessitates the need to raise awareness to dairy farmers in Tanzania to safeguard the health of the end-users.Item Antimycobacterial and Cytotoxic Activities of Extracts from Fungal Isolates of Lake Magadi(International Formulae Group, 2017) Kowanga, Keno D; Munissi, Joan J.E; Masalu, Rose; Nyandoro, Stephen S.; Masimba, Pax; Gatebe, E.Antimycobacterial and cytotoxic activities of extracts from fungal isolates of Lake Magadi Keno David Kowanga, Joan John Eliona Munissi, Rose Masalu, Stephen Samwel Nyandoro, Pax Masimba, Erastus Gatebe Abstract In this study, antimycobacterial and cytotoxic activities of ethyl acetate extracts of fungal isolates from Lake Magadi were evaluated. The extracts were tested against Mycobacterium madagascariense (MM) and M. indicus pranii (MIP), and cytotoxicity against brine shrimp (Artemia salina) larvae. Fungal strains were identified using sequence comparison of the Internal Transcribed Spacer (ITS) region. Potent antimycobacterial activities against MM were exhibited by extracts from Volutella colletotrichoides, Helicoon richonis, Penicillium limosum, P. sacculum, Aspergillus parasiticus and A. nomius strains that exhibited minimum inhibition concentration (MIC) in the range of 0.19 – 12.5 mg/mL. On the other hand, significant antimycobacterial effects against MIP was shown by extracts from V. colletotrichoides, H. richonis, A. parasiticus, Fusarium merismoides, A. silvaticus and A. fumigatus strains in the same MIC range. Notable cytotoxic activities of the extracts were from A. versicolor, A. nomius, P. janthinellum and H. richonis strains with LC50 values ranging from 46.60 – 98.12 μg/mL. These results indicate that fungi inhabiting Lake Magadi have the ability to produce bioactive metabolites that could be further explored for potential medicinal agentsItem Antimycobacterial and cytotoxicity evaluation of the constituents of Monodora carolinae(2013) Magoria, Nyangi; Nyandoro, Stephen S.; Munissi, Joan J. E.; Heydenreichb, MatthiasPhytochemical investigation of the stem bark of the recently described species Monodora carolinae (Annonaceae) afforded prenylindole derivatives (E)-4-(1H-indol-6-yl)-but-3-en-2-one (1), 5-formylindole (2), fatty acid (Z)-hexade-7-enoic acid (3) and the lignanamide cannabisin B (4). The structures of the isolated compounds were established using NMR and MS analyses. The antimycobacterial activities of the extracts and isolated compounds were evaluated against Mycobacterium madagascariense (MM) and M. indicus pranii (MIP) using the two-fold microtitre dilution method. While the extracts exhibited minimum inhibitory concentration (MIC) ranging from 500 – 1000 ìg/mL, the isolated compounds were 125 – 250 ìg/mL, indicating very low activity. Cytotoxic effects were evaluated using brine shrimp larvae whereby the ethanolic extract of the root bark exhibited the lowest LC50 (< 3ìg/mL). Isolation of prenylindole derivatives is of chemotaxonomic significance that affirms taxonomic placement of this plant species into the genus Monodora. This is the first time cannabisin B is reported from the genus Monodora.Item Bioactivities of extracts, debromolaurenterol and fucosterol from macroalgae species(Dar es Salaam University Press, 2018-06) Begum, Sartaz; Nyandoro, Stephen S.; Buriyo, Amelia S.; Makangara, John J; Munissi, Joan J.E; Duffy, Sandra; Avery, Vicky M.; Erdelyi, MateParasitic diseases including malaria, and other numerous microbial infections and physiological diseases are threatening the global population. Tanzanian coast shores are endowed with a variety of macroalgae (seaweeds), hitherto unsystematically explored to establish their biomedical potentials. Thus, antiplasmodial activity using malarial imaging assay, antimicrobial activity using microplate dilution technique, antioxidant activity using DPPH radical scavenging method and cytotoxicity using brine shrimp test were carried out on crude extracts from the selected species of algae (Acanthophora spicifera, Cystoseira myrica, Cystoseira trinodis, Laurencia filiformis, Padina boryana, Sargassum oligocystum, Turbinaria crateriformis, Ulva fasciata and Ulva reticulata) occurring along the coast of Tanzania. The extracts showed antimicrobial activities with MIC ranging from 0.3- 5.0 μg/mL against Staphylococcus aureus, Streptococcus pyogenes, Pseudomonas aeruginosa, Escherichia coli, Candida albicans and Cryptococcus neoformans; DPPH radical scavenging activity at EC50 1.0- 100 μg/mL and cytotoxicity on brine shrimp larvae with LC50 value ranging from20 - 1000 μg/mL. The extracts from C. myrica and P. boryana inhibited growth of Plasmodium falciparum (3D7 strain) by 80 and 71%, respectively at 40 μg/mL while a sesquiterpene debromolaurinterol (1) which was chromatographically isolated from C. myrica exhibited antiplasmodial activity with IC50 20 μM whereas a sterol fucosterol (2) from P. boryana showed weak activity at 40 μM. Bioactivities portrayed by the investigated extracts indicate their ingredients as potential sources of bioactive agents that warrant further explorations.Item Chemical compositions and mosquito repellency of essential oils from Artabotrys hexapetalus and Artabotrys rupestris(AJOL, 2015-05) Suleiman, R. A.; Mgani, Quintino A.; Nyandoro, Stephen S.The two Tanzanian Artabotrys species were investigated to establish the chemical composition and mosquito repellent properties of their essential oils. Hydrodistillation of leaves and stem bark of Artabotrys hexapetalus (L.f.) (Annonaceae) and stem bark of Artabotrys rupestris Diels (Annonaceae) gave essential oils which were analyzed by Gas Chromatography – Mass Spectrometry (GC-MS). While the oil from the stem bark of A. hexapetalus contained high amount of β-caryophyllene oxide, the oil from the leaves had both β- caryophyllene oxide and 11-hexadcyn-1-ol as the main components. The oil from the root barks of A. rupestris contained large amount of 6-(p-tolyl)-2-methyl-2-heptanol and (-)-spathulenol. β-Caryophyllene oxide, cadinol, cubenol, (-)-spathulenol and 7-methyl-4-methylene-1-(1-methylethyl)-naphthalene were identified as common constituents of the essential oils from the two plant species investigated. On evaluation for mosquito repellency, the essential oil from the leaves of A. hexapetalus was found to exhibit strong activity with RC50 = 1.81×10-5 mg/cm2 and 2.79×10-5 mg/cm2 for the first and the second fractions, respectively against female Anopheles gambiae s.s. mosquitoes. The repellency activity of essential oil from leaves were significantly higher than from stem bark, but less than that of the standard citronella oil used (RC50 = 4.1×10-6 mg/cm2). The observed high mosquito repellent activity for the essential oil fractions from A. hexapetalus could be attributed to the presence of β-caryophyllene oxide.Item Chemical Compositions and Mosquito Repellency of Essential Oils From Artabotrys Hexapetalus and Artabotrys Rupestris(2015-05) Suleiman, R. A .; Mgani, Quitino A.; Nyandoro, Stephen S.The two Tanzanian Artabotrys species were investigated to establish the chemical composition and mosquito repellent properties of their essential oils. Hydrodistillation of leaves and stem bark of Artabotrys hexapetalus (L.f.) (Annonaceae) and stem bark of Artabotrys rupestris Diels (Annonaceae) gave essential oils which were analyzed by Gas Chromatography – Mass Spectrometry (GC-MS). While the oil from the stem bark of A. hexapetalus contained high amount of β-caryophyllene oxide, the oil from the leaves had both β- caryophyllene oxide and 11-hexadcyn-1-ol as the main components. The oil from the root barks of A. rupestris contained large amount of 6-(p-tolyl)-2-methyl-2-heptanol and (-)-spathulenol. β-Caryophyllene oxide, cadinol, cubenol, (-)-spathulenol and 7-methyl-4-methylene-1-(1-methylethyl)-naphthalene were identified as common constituents of the essential oils from the two plant species investigated. On evaluation for mosquito repellency, the essential oil from the leaves of A. hexapetalus was found to exhibit strong activity with RC50 = 1.81×10-5 mg/cm2 and 2.79×10-5 mg/cm2 for the first and the second fractions, respectively against female Anopheles gambiae s.s. mosquitoes. The repellency activity of essential oil from leaves were significantly higher than from stem bark, but less than that of the standard citronella oil used (RC50 = 4.1×10-6 mg/cm2). The observed high mosquito repellent activity for the essential oil fractions from A. hexapetalus could be attributed to the presence of β-caryophyllene oxiItem Cleistenolide and cleistodienol: Novel bioactive constituents of Cleistochlamys kirkii(2007-01) Nyandoro, Stephen S.; Mdachi, Stephen; Nkunya, Mayunga H. H.; Irungu, Beatrice N.; Moshi, Mainen; Moulton, Brian; Luisi, Brian S.(-)-5-Acetoxy-6-(1-benzoyloxy-2-acetoxyethyl)-pyr-3-en-2-one (cleistenolide) and (-)-2, 6-diacetoxy-5-hydroxy-cyclohex-3-enylidenemethyl benzoate (cleistodienol) were isolated as novel antimicrobial and cytotoxic constituents of Cleistochlamys kirkii (Annonaceae), together with (Z)-(+)-5-(2, 3-dihydroxy-propylidene)-5H-furan-2-one and its acetyl and benzoyl derivatives, (-)-1, 6-desoxy-β-senepoxide, pinocembrin and polycarpol. Structural determination was achieved based on spectroscopic and other physical data. The structure of cleistenolide was confirmed by single crystal X-ray crystallographic analysis.Item Flavonoids from Erythrina Schliebenii(American Chemical Society, 2017-01-23) Nyandoro, Stephen S.; Munissi, Joan J.E; Kombo, Msim; Mgina, Clarence A; Pan, FangFang; Gruhonjic, Amra; Fitzpatrick, Paul A.; Lu, Yu; Wang, Bin; Rissanen, Kari; Erdelyi, MatePrenylated and O-methylflavonoids including one new pterocarpan (1), three new isoflavones (2–4), and nineteen known natural products (5–23) were isolated and identified from the root, stem bark, and leaf extracts of Erythrina schliebenii. The crude extracts and their constituents were evaluated for antitubercular activity against Mycobacterium tuberculosis (H37Rv strain), showing MICs of 32–64 μg mL–1 and 36.9–101.8 μM, respectively. Evaluation of their toxicity against the aggressive human breast cancer cell line MDA-MB-231 indicated EC50 values of 13.0–290.6 μM (pure compounds) and 38.3 to >100 μg mL–1 (crude extracts).Item Hydrophobic π-π stacking interactions and hydrogen bonds drive self-aggregation of luteolin in water(Elsevier, 2022-06-23) Deogratias, Geradius; Shadrack, Daniel M; Munissi, Joan J.E.; Kinunda, Grace A.; Jacob, Fortunatus R.; Mtei, Regina P.; Masalu, Rose J.; Mwakyula, Issakwisa; Kiruri, Lucy W.; Nyandoro, Stephen S.Luteolin is a flavonoid obtained from different plant species. It is known for its versatile biological activities. However, the beneficial effects of luteolin have been limited to small concentrations as a result of poor water solubility. This study aimed at investigating the hydrophobic interaction and hydration of luteolin towards the improvement of its solubility when used as a drug. We report the aggregation properties of luteolin in water by varying the number of monomers using atomistic molecular dynamics simulation. Results show that the equilibrium structure of luteolin occurs in an aggregated state with different structural arrangements. As the monomers size increase, the antiparallel flipped conformation dominates over T-shaped antiparallel, T-shaped parallel, and antiparallel conformations. The formation of intramolecular hydrogen bonding of 0.19 nm between the keto-enol groups results in hydrophobic characteristics. A larger cluster exhibits slow hydrogen bond dynamics for luteolin-luteolin than luteolin-water interaction. Water structure at large cluster size exhibited slow dynamics and low self-diffusion of luteolin. The existence of hydrophobic π-π and hydrogen bonds between luteolin molecules drives strong self-aggregation resulting in poor water solubility. Breakage of these established interactions would result in increased solubility of luteolin in water.Item Hydrophobic π-π stacking interactions and hydrogen bonds drive self-aggregation of luteolin in water(Elsevier, 2022-06-28) Deogratias, Geradius; Shadrack, Daniel M.; Munissi, Joan J.E.; Kinunda, Grace A.; Jacob, Fortunatus R.; Mtei, Regina P.; Masalu, Rose J.; Mwakyula, Issakwisa; Kiruri, Lucy W.; Nyandoro, Stephen S.Luteolin is a flavonoid obtained from different plant species. It is known for its versatile biological activities. However, the beneficial effects of luteolin have been limited to small concentrations as a result of poor water solubility. This study aimed at investigating the hydrophobic interaction and hydration of luteolin towards the improvement of its solubility when used as a drug. We report the aggregation properties of luteolin in water by varying the number of monomers using atomistic molecular dynamics simulation. Results show that the equilibrium structure of luteolin occurs in an aggregated state with different structural arrangements. As the monomers size increase, the antiparallel flipped conformation dominates over T-shaped antiparallel, T-shaped parallel, and antiparallel conformations. The formation of intramolecular hydrogen bonding of 0.19 nm between the keto-enol groups results in hydrophobic characteristics. A larger cluster exhibits slow hydrogen bond dynamics for luteolin-luteolin than luteolin-water interaction. Water structure at large cluster size exhibited slow dynamics and low self-diffusion of luteolin. The existence of hydrophobic π-π and hydrogen bonds between luteolin molecules drives strong self-aggregation resulting in poor water solubility. Breakage of these established interactions would result in increased solubility of luteolin in water.Item In ovo antiviral potency of the leaf constituents of Tanzanian Toussaintia species against Infectious Bursal Disease Virus and Newcastle Disease Virus(AJOL, 2014-10) Nyandoro, Stephen S.; Nkunya, M. H. H.; Cosam, J. C.; Msoffe, Peter L. M.The chemical constituents of Toussantia orientalis and T. patriciae (Annonaceae) leaf extracts were evaluated for their antiviral activities in ovo against Infectious Bursal Disease Virus (IBDV) and Newcastle Disease Virus (NDV). The nine-day-old embryonated eggs in a set of five were used for testing through the allantoic route inoculation assay for each tested compound and controls. For NDV assay, the allantoic fluids from the specimens were further harvested to determine viral contagion. The tested compounds exhibited potency with varying levels of significance at a screening concentration of 360 µg/ml against the two viral strains. Embryos infected with IBDV survived, grew to normal size with complete organ formation and had mean weights comparable to those of the uninfected ones when treated with the aminocinnamoyl tetraketides 1, 2, and 4, glucosylflavonoid 7 from T. orientalis and ursolic acid derivatives 9 and 10 from T. patriciae demonstrating high efficacy against IBDV. The compounds also exhibited antiviral activity against NDV, showing viral titre reduction ranging from 1:16 - 1:256 in the haemagglutination test, with compound 11 having the lowest titre value (1:16) followed by compound 7 (1:32). The compounds that exhibited significant antiviral efficacy could be considered potential leads for the development of antiviral agents.Item In Silico Evaluation of Anti-Malarial Agents from Hoslundia opposita as Inhibitors of Plasmodium falciparum Lactate Dehydrogenase (P f LDH) Enzyme(Scientific Research, 2016-06-17) Shadrack, Daniel M.; Nyandoro, Stephen S.; Munissi, Joan J. E.; Mubofu, Egid B.Malaria has continued to be a health and economic problem in Africa and the world at large. Many anti-malarial drugs have been rendered ineffective due to the emergence of resistant strains of Plamodium falciparum. A key malaria parasite enzyme in glycolytic pathway, P. falciparum lactate dehydrogenase (PfLDH) is specially targeted for anti-malarial drugs development. Thus, the aim of this investigation was to determine the in silico inhibition effects of antimalarial compounds from Hoslundia opposita Vahl. namely hoslundin, hoslundal and hoslunddiol on PfLDH enzyme. The compounds were docked to the three-dimensional structure of PfLDH as enzyme using AutoDock Vina in PyRx virtual screening software. Binding affinity and position of the inhibitors were evaluated using PyMol software. The PfLDH enzyme showed two binding sites: the cofactors binding site (Site A) and secondary binding site (Site B). In the absence of the cofactor all ligands showed higher affinity than NADH, and were bound to the cofactors binding site (Site A). When docked in the presence of the cofactor, site B was the preferred binding site. Binding to cofactor site with higher binding energy than NADH suggests that these ligands could act as preferential competitive inhibitors of PfLDH. However, the binding to site B also suggests that they may be non-competitive allosteric inhibitors. Amino acid residues Gly99, Asn140, Phe100 and Thr97 were indicated to form hydrogen bonds with Hoslundin. Hoslunddiol showed hydrogen bonding with Thr97 and Met30, while Hoslundal formed hydrogen bond with Thr101 and Asn140.Item In silico pharmacokinetic, molecular docking and molecular dynamics simulation studies of n-cinnamoyltetraketide derivatives as inhibitors of cyclooxygenase-2 enzyme(Dar es Salaam University Press, 2018-06) Nyandoro, Stephen S.; Shadrack, Daniel M; Munissi, Joan J.E; Mubofu, Egid B.Recent phytochemical analysis of Toussaintia orientalis leaves yielded series of novel bioactive N-cinnamoyltetraketide derivatives namely toussaintines A-G (t_1 - t_8) some portraying cytotoxicity against the triple negative aggressive human breast cancer cell line (MDA-MB-231) among other potencies. Despite having broad bioactivity spectrum, their general drug-likeness profiles and mode of action (simulated or actual) targeting any enzyme remains uninvestigated. In silico pharmacokinetic, drug-likeness descriptors and molecular docking of the compounds t_1-t_8 targeting inhibition of cyclooxygenase-2 (COX-2) enzyme were evaluated. The Lipinski Rule of Five heralded the pharmacokinetic properties of the studied metabolites. The studied compounds were docked with COX-2 following already established protocol. ADMET descriptors fell within the recommended range, except for compound t_3 that was predicted to potentially have positive blood brain barrier (BBB+) penetration. Docking studies indicated N-cinnamoyltetraketide derivatives as potential inhibitors of COX-2 enzyme. Compounds t_3 and t_5 showed lower binding energy of -13 and -12.3 kcal/mol, respectively, being closely comparable to celecoxib (-12.3 kcal/mol) indicating compatibility with the protein receptor. The findings provide baseline information on drug or lead-likeness and potential mode of action of the studied molecules towards inhibition of COX-2 enzymeItem In vivo antimycobacterial studies of toussaintine A-chitosan nanocomposites(Dar es Salaam University Press, 2018-06) Rwegasila, Edward; Munissi, Joan J.E; Mubofu, Egid B.; Nyandoro, Stephen S.; Erasto, PaulChitosan (CS, molecular weight (MW) 20.2 kDA, stability of 210 °C and degree of deacetylation (DD) 73.31%) was obtained by deacetylation of chitin extracted from shrimp (Litopenaeus vannamei) shell wastes. The encapsulation of the studied bioactive natural product, toussaintine A (TA) isolated from the leaves of Toussaintia orientalis, on a chitosan-tripolyphosphate (CS/TPP) nanoformulation was attained through ionotropic gelation. Characterization of pure CS, CS/TPP and TA-CS/TPP nanocomposites was carried out by FTIR and SEM. The encapsulation efficiency and loading capacity of the TA were 69.33 and 0.46%, respectively. The in vitro release kinetics established an initial release of 27% of TA in the initial six hours followed by a slow and maintained release up to 72 h. The in vivo antimycobacterial acitivities of both TA and TA-CS/TPP nanocomposites against Mycobacterium indicus pranii (MIP) employing Galleria mellonella larvae as an infection model were evaluated. TA-CS/TPP nanocomposite formulations exhibited remarkable effectiveness against MIP than free TAItem Luteolin: a blocker of SARS-CoV-2 cell entry based on relaxed complex scheme, molecular dynamics simulation, and metadynamics(Springer, 2021-07-08) Shadrack, Daniel M.; Deogratias, Geradius; Kiruri, Lucy W.; Onoka, Isaac; Vianney, John-Mary; Swai, Hulda; Nyandoro, Stephen S.Natural products have served human life as medications for centuries. During the outbreak of COVID-19, a number of naturally derived compounds and extracts have been tested or used as potential remedies against COVID-19. Tetradenia riparia extract is one of the plant extracts that have been deployed and claimed to manage and control COVID-19 by some communities in Tanzania and other African countries. The active compounds isolated from T. riparia are known to possess various biological properties including antimalarial and antiviral. However, the underlying mechanism of the active compounds against SARS-CoV-2 remains unknown. Results in the present work have been interpreted from the view point of computational methods including molecular dynamics, free energy methods, and metadynamics to establish the related mechanism of action. Among the constituents of T. riparia studied, luteolin inhibited viral cell entry and was thermodynamically stable. The title compound exhibit residence time and unbinding kinetics of 68.86 ms and 0.014 /ms, respectively. The findings suggest that luteolin could be potent blocker of SARS-CoV-2 cell entry. The study shades lights towards identification of bioactive constituents from T. riparia against COVID-19, and thus bioassay can be carried out to further validate such observations.Item N -Cinnamoyltetraketide Derivatives from the Leaves of Toussaintia orientalis(PubMed, 2015-07) Nyandoro, Stephen S.; Ndanu, Joseph; Munissi, Joan J. E.; Gruhonjic, Amra; Fitzpatrick, Paul A.; Landberg, Göran; Lu, Yu; Wang, Bin; Pan, Fangfang; Rissanen, Kari; Erdélyi, MátéSeven N-cinnamoyltetraketides (1-7), including the new Z-toussaintine E (2), toussaintine F (6), and toussaintine G (7), were isolated from the methanol extract of the leaves of Toussaintia orientalis using column chromatography and HPLC. The configurations of E-toussaintine E (1) and toussaintines A (3) and D (5) are revised based on single-crystal X-ray diffraction data from racemic crystals. Both the crude methanol extract and the isolated constituents exhibit antimycobacterial activities (MIC 83.3-107.7 μM) against the H37Rv strain of Mycobacterium tuberculosis. Compounds 1, 3, 4, and 5 are cytotoxic (ED50 15.3-105.7 μM) against the MDA-MB-231 triple negative aggressive breast cancer cell line.Item New Antimicrobial, Mosquito Larvicidal and Other Metabolites from Two Artabotrys Species(Taylor & Francis, 2013) Nyandoro, Stephen S.; Joseph, Cosam C.; Nkunya, Mayunga H. H.; Hosea, Ken M.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 macranthus Verdc. and Artabotrys monteiroae Oliv. (Annonaceae), together with several known compounds. Structures of the isolated compounds were established based on analysis of their spectroscopic data. Some of the compounds exhibited antimicrobial activity (minimum inhibitory concentration values between 2.5 and 20 µg mL−1) and varying levels of mosquito larvicidal potency. These results further indicate the versatility of the family Annonaceae in accumulating bioactive natural products with diverse chemical structures and wide spectra of biological activities, and hence suggesting the need to conserve Annonaceae species that are potentially vulnerable to extinction.Item New antimicrobial, mosquito larvicidal and other metabolites from two Artabotrys species(Taylor & Francis, 2012-09) Nyandoro, Stephen S.; Joseph, Cosam C.; Nkunya, Mayunga H. H.; Hosea, Ken M.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 macranthus Verdc. and Artabotrys monteiroae Oliv. (Annonaceae), together with several known compounds. Structures of the isolated compounds were established based on analysis of their spectroscopic data. Some of the compounds exhibited antimicrobial activity (minimum inhibitory concentration values between 2.5 and 20 µg mL−1) and varying levels of mosquito larvicidal potency. These results further indicate the versatility of the family Annonaceae in accumulating bioactive natural products with diverse chemical structures and wide spectra of biological activities, and hence suggesting the need to conserve Annonaceae species that are potentially vulnerable to extinction.Item A new cinnamoylglycoflavonoid, antimycobacterial and antioxidant constituents from Heritiera littoralis leaf extracts(Taylor & Francis, 2014-01-21) Christopher, R.; Nyandoro, Stephen S.; Chacha, Musa; de Koning, C. B.A new cinnamolyglycoflavonoid 3-cinnamoyltribuloside (1), its precursor tribuloside and two known flavonoid glycosides afzelin and astilbin were isolated from Heritiera littoralis Dryand (Sterculiaceae) ethanolic leaf extract. The dichloromethane leaf extract afforded two known pentacyclic triterpenoids, 3β-taraxerol and friedelin. Extracts and compounds isolated therefrom, with the exception of 3β-taraxerol, exhibited antimycobacterial activity against the non-pathogenic Mycobacterium species Mycobacterium madagascariense and Mycobacterium indicus pranii, with a minimum inhibitory concentration (MIC) 5.0 mg/mL for the crude extracts and MICs in the range of 1.6-0.8 mg/mL for the pure compounds. The extracts together with 3-cinnamoyltribuloside (1), tribuloside and astilbin exhibited 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity. The compounds that showed dual activities could be further evaluated under clinical settings for co-administration with standard anti-tuberculosis drugs. Data on the essential oil composition of Fissistigma villosissimum, Fissistigma latifolium and Fissistigma glaucescens are reported for the first time.