Browsing by Author "Munissi, Joan J.E"

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    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.
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    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 agents
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    Aromatic Bio-Based Solvents
    (John Wiley & Sons, 2017-06-30) Mubofu, Egid B.; Mgaya, James; Munissi, Joan J.E
    This chapter focuses on alkylresorcinols (AR) and cashew nut shell liquid (CNSL) as bio‐based solvents from agricultural produce and waste. It highlights the possible biological sources for bio‐based aromatics, such as cereals and CNS wastes, and the techniques for their extraction. The chapter also introduces the possible potential applications of these extracts as solvents or reagents in the production of functional or platform chemicals. The competitive advantage of utilizing agricultural by‐products or wastes, such as cereal bran and CNSs, as renewable bio‐resources for the production of aromatic bio‐based solvents is manifested in non‐interference with food supply and their contributions towards waste minimization. Thus, this chapter centres its discussion onaromatic bio‐based solvents from agricultural by‐products and waste materials, and emphases on resorcinolic lipids and CNSL. Basically, there are three methods used to extract CNSL from the shells: solvent extraction, thermal extraction and mechanical extraction
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    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, Mate
    Parasitic 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.
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    Evaluation of Antimycobacterial Activity of Higenamine Using Galleria mellonella as an In Vivo Infection Model
    (Springer, 2018-02) Erasto, Paul; Omolo, Justin; Sunguruma, Richard; Munissi, Joan J.E; Wiketye, Victor; Konig, de Charles; Ahmed, Atallah F.
    The Phytochemical investigation on MeOH extract on the bark of Aristolochia brasiliensis Mart. & Zucc (Aristolochiaceae) led to the isolation of major compound (1) as light brown grainy crystals. The compound was identified as 1-(4-hydroxybenzyl)-1,2,3,4-tetrahydroisoquinoline-6,7-diol (higenamine) on the basis of spectroscopic analysis, including 1D and 2D NMR spectroscopy. The compound was evaluated for its antimycobacterial activity against Mycobacterium indicus pranii (MIP), using Galleria mellonella larva as an in vivo infection model. The survival of MIP infected larvae after a single dose treatment of 100 mg/kg body weight of higenamine was 80% after 24 h. Quantitatively the compound exhibited a dose dependent activity, as evidenced by the reduction of colony density from 105 to 103 CFU for test concentrations of 50, 100, 150 and 200 mg/kg body weight respectively. The IC50 value for higenamine was 161.6 mg/kg body weight as calculated from a calibration curve. Further analysis showed that, a complete inhibition of MIP in the G. mellonella could be achieved at 334 mg/kg body weight. Despite the fact that MIP has been found to be highly resistant against isoniazid (INH) in an in vitro assay model, in this study the microbe was highly susceptible to this standard anti-TB drug. The isolation of higenamine from the genus Aristolochia and the method used to evaluate its in vivo antimycobacterial activity in G. mellonella are herein reported for the first time.
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    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, Mate
    Prenylated 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).
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    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 enzyme
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    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, Paul
    Chitosan (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 TA
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    Polyamido(amine) Dendrimers for Enhanced Solubility of Small Molecules and Other Desirable Properties for Site Specific Delivery: Insights from Experimental and Computational Studies
    (MDPI, 2018-06-12) Shadrack, Daniel M; Swai, Hulda S.; Munissi, Joan J.E; Mubofu, Egid B.; Nyandoro, Stephen S.
    Clinical applications of many small molecules are limited due to poor solubility and lack of controlled release besides lack of other desirable properties. Experimental and computational studies have reported on the therapeutic potential of polyamidoamine (PAMAM) dendrimers as solubility enhancers in pre-clinical and clinical settings. Besides formulation strategies, factors such as pH, PAMAM dendrimer generation, PAMAM dendrimer concentration, nature of the PAMAM core, special ligand and surface modifications of PAMAM dendrimer have an influence on drug solubility and other recommendable pharmacological properties. This review, therefore, compiles the recently reported applications of PAMAM dendrimers in pre-clinical and clinical uses as enhancers of solubility and other desirable properties such as sustained and controlled release, bioavailability, bio-distribution, toxicity reduction or enhancement, and targeted delivery of small molecules with emphasis on cancer treatment.
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    Polyoxygenated Cyclohexenes and Other Constituents of Cleistochlamys kirkii Leaves
    (American Chemical Society, 2016-12-21) Nyandoro, Stephen S.; Munissi, Joan J.E; Gruhonjic, Amra; Duffy, Sandra; Pan, FangFang; Puttreddy, Rakesh; Holleran, John P.; Fitzpatrick, Paul A.; Pelletier, Jerry; Avery, Vicky M.; Rissanen, Kari; Erdelyi, Mate
    Thirteen new metabolites, including the polyoxygenated cyclohexene derivatives cleistodiendiol (1), cleistodienol B (3), cleistenechlorohydrins A (4) and B (5), cleistenediols A–F (6–11), cleistenonal (12), and the butenolide cleistanolate (13), 2,5-dihydroxybenzyl benzoate (cleistophenolide, 14), and eight known compounds (2, 15–21) were isolated from a MeOH extract of the leaves of Cleistochlamys kirkii. The purified metabolites were identified by NMR spectroscopic and mass spectrometric analyses, whereas the absolute configurations of compounds 1, 17, and 19 were established by single-crystal X-ray diffraction. The configuration of the exocyclic double bond of compound 2 was revised based on comparison of its NMR spectroscopic features and optical rotation to those of 1, for which the configuration was determined by X-ray diffraction. Observation of the co-occurrence of cyclohexenoids and heptenolides in C. kirkii is of biogenetic and chemotaxonomic significance. Some of the isolated compounds showed activity against Plasmodium falciparum (3D7, Dd2), with IC50 values of 0.2–40 μM, and against HEK293 mammalian cells (IC50 2.7–3.6 μM). While the crude extract was inactive at 100 μg/mL against the MDA-MB-231 triple-negative breast cancer cell line, some of its isolated constituents demonstrated cytotoxic activity with IC50 values ranging from 0.03–8.2 μM. Compound 1 showed the most potent antiplasmodial (IC50 0.2 μM) and cytotoxic (IC50 0.03 μM, MDA-MB-231 cell line) activities. None of the compounds investigated exhibited translational inhibitory activity in vitro at 20 μM.