Biotechnology

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Adhension of Candida albicans to host cells in culutre.
(1989) Maiter, Aziza Ismail.; Alexander, D. M.; Oellermann, Rolf Alfred.
No abstract available.
Aerobic utilization of selected pharmaceutical and personal care product by estuarine heterotrophic bacteria.
(2014) Bulannga, Rendani Bridghette.; Schmidt, Stefan.
Pharmaceutical and personal care products (PPCPs) constitute a broad class of organic compounds, some of which belong to the list of the OECD high production volume (HPV) chemicals. These compounds have emerged as environmental contaminants with potentially detrimental effects. They have been detected in various environmental compartments typically in a nano- to microgram range and sewage treatment plants represent the major point source for the aquatic environment. Salicylic acid, a monohydroxybenzoic acid, is widely used in cosmetic and therapeutic products and is listed as HPV chemical. Benzyl salicylate and phenyl salicylate are diaryl ester compounds commonly used in pharmaceutical formulations, fragrances and household detergents. Benzyl salicylate is listed as HPV chemical. The fate of salicylic acid in the environment has been reported previously while those of benzyl salicylate and phenyl salicylate are unknown. Although studies are available on the microbial degradation of aromatic compounds, studies exclusive to the catabolism of PPCPs by marine heterotrophic bacterial isolates are rather limited. Therefore, the aim of this thesis was to characterize PPCPs (salicylic acid, benzyl salicylate and phenyl salicylate) utilizing bacteria from an estuarine environment (Durban Harbour, KwaZulu-Natal, South Africa). Selective enrichments were employed using artificial seawater medium typically supplemented with 2 mM of the target compounds (salicylic, benzyl salicylate or phenyl salicylate). After successive subculturing, bacteria capable of utilizing target compounds as sole carbon and energy source were characterized by morphological and physiological features, 16S rRNA gene sequence and MALDI-TOF MS analysis. Growth kinetics were assessed by monitoring the optical density, cell count and protein formation over time. The utilization of salicylic acid and phenyl salicylate was verified using UV spectroscopy and HPLC and the key reactions involved were verified by determining the specific oxygen uptake rates using resting cells and specific activities of representative enzymes. A Gram-negative coccus shaped bacterium belonging to the genus Acinetobacter degrading salicylic acid and phenyl salicylate, a Gram-negative rod shaped marine bacterium belonging to the genus Oceanimonas degrading salicylic acid and phenyl salicylate and a Gram-negative rod shaped bacterium belonging to the genus Pseudomonas utilizing benzyl salicylate in the presence and absence of synthetic surfactants (Tween 80) were isolated. The growth of Acinetobacter and Oceanimonas species was dependent on salicylic acid and phenyl salicylate as carbon source as growth was only observed when the carbon source was present and the compound was degraded almost to completion. Growth of Pseudomonas with benzyl salicylate was enhanced in the presence of surfactant. All three strains did not have an obligate requirement for NaCl. Acinetobacter and Oceanimonas strains were tolerant to high concentrations of salicylic acid and were inhibited at a concentration above 20 mM while phenyl salicylate did not show toxic effects on the strains; instead growth increased with the increase in concentration. Salicylic acid was utilized via catechol by both strains as they showed high specific oxygen uptake rates and catechol-1, 2-dioxygenase activity for this chemical. Phenyl salicylate was hydrolyzed at the ester bond to phenol and salicylic acid, as these were the metabolites that accumulated during growth with phenyl salicylate. The mono-aromatic metabolites resulting from the hydrolysis of diaryl substrate were further metabolized via catechol. Microbial catabolic activities were solely responsible for the loss of contaminant in the medium as confirmed by abiotic controls. Heterotrophic bacteria can therefore play an important role in the removal of contaminants from marine environments.
Alkalic salt-based pretreatment strategies for enhancing sugar recovery from corn cobs and process development for simultaneous saccharification and bioethanol production.
(2018) Sewsynker-Sukai, Yeshona.; Gueguim Kana, Evariste Bosco .
Abstract available in PDF file
Analyses of lipidic bodies from green microalgae.
(2014) Pather, Verushka.; Gupthar, Abindra Supersad.; Bux, Faizal.
This study presents the analyses of oil body components in microalgae which may be involved in oil droplet assembly including certain triacylglycerol precursors which can be processed to biodiesel, an alternative fuel source. Stress induction of microalgae, Chlorella vulgaris CCAP 211/11B and Dunaliella primolecta CCAP 11/34 was achieved by exclusion of nitrates in growth media. Contrary to other forms of nitrogen depletion, this condition did not greatly enhance lipid biosynthesis in the microalgae. Confocal microscopy and fluorescent dyes nile red and bodipy were employed for the visualization of lipidic body components. The fluorescence hues emitted by neutral lipids and phospholipids were differentiated from those due to autofluorescence and chlorophyll using ZEN software to analyse images from a Zeiss LSM 710 confocal microscope. Oil from both algae, which were subjected to transesterification and gas chromatography, revealed a predominant fatty acid, namely palmitic acid (C16:0). D. primolecta produced linolelaidic acid (C18:2n6t) under growth conditions involving both nitrate supplementation and exclusion; whilst the longest fatty acid, docosanoic acid (C22:0 chain) was produced by the alga C. vulgaris only under conditions of nitrate supplementation. Nitrate limitation had minimal effect on the oil hydrocarbon yield which increased only 0.02% and 0.01% for C. vulgaris and D. primolecta, respectively. The highest biodiesel yield of 26.11 % was recorded from D. primolecta when grown under conditions of nitrate exclusion. The protein concentrations extracted from oil of the former alga ranged from 1.87 - 1.95 Gg/ml when grown under nitrate supplemented conditions and 1.74 - 1.90 Gg/ml when nitrate was excluded from the media. The protein concentrations extracted from oil of D. primolecta ranged from 1.91 - 2.23 Gg/ml and 1.88 - 1.98 Gg/ml, respectively, when the algae were grown in the presence and exclusion of nitrates. In the adaptation of protocols for protein extraction from oil, sunflower and salmon oils were initially used. Sunflower oil extracts produced by 10% (w/v) SDS treatment, yielded protein bands of 198, 96, 70 and 58 KDa on 10% (w/v) polyacrylamide gels while 6M urea treatment yielded a band of 200 KDa. Salmon oil treated with 10% (w/v) SDS and 6 M urea yielded bands of 195 and 27 KDa, and 198 KDa, respectively, as well as common bands of 68 and 64 KDa. In comparison, the extraction of discrete proteins from algal oil proved to be difficult as the extractants SDS and urea could have denatured protein components into subunit structure.
Analysis of indigenous herbivore faecal matter as a potential source of hydrolytically active microorganisms.
(2014) Ndlela, Luyanda Lindelwa.; Schmidt, Stefan.
Abstract available in PDF file.
Analysis of microbial populations associated with a sorghum-based fermented product used as an infant weaning cereal.
(1999) Kunene, Nokuthula F.; Hastings, John W.; Von Holy, Alexander.
The incidences of diarrhoeal episodes in infants and children have mostly been associated with the consumption of contaminated weaning foods. This is especially true in developing countries where factors such as the lack of sanitation systems and electricity have been found to contribute to an increase in the incidence of microbiologically contaminated weaning foods. The process of fermentation has been found to reduce the amount of microbiological contamination in such foods as a result of the production of antimicrobial compounds such as organic acids, peroxides, carbon dioxide and bacteriocins. In this study, microbiological surveys were conducted on sorghum powder samples and their corresponding fermented and cooked fermented porridge samples collected from an informal settlement of the Gauteng Province of South Africa. The process of fermentation was found to result in significant decreases (P>0.05) in Gram-negative counts and spore counts, while aerobic plate counts decreased slightly. Lactic acid bacteria counts, however, increased significantly (P>0.05). The cooking process was found to result in further significant decreases (P>0.05) in all counts. Sorghum powder samples and fermented porridge samples were found to be contaminated with potential foodborne pathogens, including Bacillus cereus, Clostridium perfringens and Escherichia coli, however, none of the pathogens tested for were detected in any of the cooked fermented porridge samples. SDS-PAGE and phenotypic analysis of 180 lactic acid bacteria isolated from sorghum powder samples and their corresponding fermented and cooked fermented porridge samples showed that a majority of the isolates were lactobacilli and leuconostocs, however, some isolates were identified as pediococci and lactococci. These results demonstrated the heterogeneity of the lactic acid bacteria isolates that were associated with fermentation processes in this study. Of the lactic acid bacteria identified, Lactobacillus plantarum and Leuconostoc mesenteroides strains were found to have the highest distribution frequencies, being distributed in 87% and 73% of the households, respectively. Analysis of Lactobacillus plantarum (58) and Leuconostoc mesenteroides (46) strains isolated from sorghum powder samples and corresponding fermented and cooked fermented porridge samples by AFLP fingerprinting showed that they originated from a common source, which was sorghum powder. There was, however, evidence of strains that may have been introduced at household level. Antimicrobial activity of selected lactic acid bacteria was found to be mainly due to a decrease in pH in fermented and cooked fermented porridge samples. None of the lactic acid bacteria tested seemed to produce bacteriocins.
Analysis of the Mycoplasma hominis hsp70 gene and development of a PCR ELISA assay.
(1998) Shearer, Nicollette.; Hastings, John W.
Mycoplasmas conform most closely with the theoretical concept of 'minimum cells', existing as the smallest, free-living organisms capable of self-replication. They survive as parasites of plants, insects, animals or humans, with the most common human colonising species being Mycoplasma hominis. M. hominis has been characterised as a human pathogen responsible for a variety of infections, which pose a significant threat particularly to immunocompromised patients and neonates. However little has been elucidated about the cell physiology and molecular structure of this organism. Of interest to this study were the investigation of the heat shock response of M. hominis and the diagnostic assays used for its detection. The heat shock response is a ubiquitous physiological feature of all organisms and displays unprecedented conservation. This phenomenon is particularly evident in the 70 kDa family of heat shock proteins (hsp70) which exhibits a high degree of homology between different species. The hsp70 gene from M. hominis was cloned and preliminary partial sequencing indicated the similarity with other hsp70 homologs. The regulation of hsp70 expression at the transcriptional and translational levels was investigated. The level of hsp70 mRNA was found to increase correspondingly in response to heat shock, more visibly than the level of hsp70 protein. However imrnunochemical studies of the M. hominis hsp70 translation product demonstrated further the homology with other species. To facilitate rapid diagnosis of M. hominis infections, a PCR ELISA diagnostic assay was developed and optimised. The amplification of a conserved region of the M. hominis 16S rRNA gene was linked to subsequent hybridisation to an appropriate capture probe in a microtiter plate format. The sensitivity of the assay was comparable to other molecular assays although the PCR ELISA produces more rapid results and is less labour intensive.
Anti-c-myc cholesterol-based lipoplexes: development, characterisation and evaluation as Onconanotherapeutic agents in vitro.
(2018) Habib, Saffiya.; Singh, Moganavelli.
Strategies aimed at inhibiting the expression of the c-myc oncogene could provide the basis for alternative cancer treatment. In this regard, silencing c-myc expression using small interfering RNA (siRNA) is an attractive option. However, the development of a clinically viable, siRNAbased, c-myc silencing system is largely dependent upon the design of an appropriate siRNA carrier that can be easily prepared. Nanostructures formed by the electrostatic association of siRNA and cationic lipid vesicles represent uncomplicated, well-recognised siRNA delivery systems. Therefore, this study has focused on traditional cationic liposomes as the foundation for the development of a simple, but effective anti-c-myc onconanotherapeutic agent. Novel liposome formulations contained equimolar quantities of the cytofectin, N,Ndimethylaminopropylamidosuccinylcholesterylformylhydrazide (MS09), and cholesterol (Chol); with or without 2 mol % pegylation. Liposomes which contained dioleoylphosphatidylethanolamine (DOPE) as the co-lipid were included for comparative purposes. Pegylated and non-pegylated MS09/Chol (1:1) suspensions were reproducibly prepared by lipid film hydration to give unilamellar vesicles that were stable for at least 10 months at 4 ˚C. Liposomes successfully bound siRNA to form lipoplexes of less than 200 nm in size, with zeta potentials between -16 and -44 mV. These assumed globular and bilamellar structures in which siRNA was partially protected. Although all formulations were well tolerated at ≤14 nM siRNA, pegylation severely inhibited siRNA delivery in cancer cell lines, MCF-7 and HT-29, which overexpress c-myc. The non-pegylated MS09/Chol (1:1) lipoplex, at the MS09:siRNA (w /w) ratio of 16:1, was most effectively taken up by MCF-7 and HT-29 cells, with negligible effect in non-transformed cells when applied at 12 nM siRNA. Lipoplexes directed against the c-myc transcript (anti-c-myc siRNA), mediated a dramatic reduction in c-myc mRNA and protein levels. This was accompanied by a loss of migratory potential and apoptotic cell death. Moreover, oncogene knockdown and anti-cancer effects were superior to that of a commercially available transfection reagent, Lipofectamine™ 3000. Although the DOPE-containing counterpart performed with iii comparable efficacy under standard in vitro conditions, it was incapable of siRNA delivery at physiological serum concentration. Hence, the anti-c-myc MS09/Chol (1:1) lipoplex reported exemplifies a straightforward anti-cancer agent that warrants further investigation in vivo.
Antibiogram and virulence determinants of Pseudomonas and Legionella spp. recovered from treated wastewater effluents and receiving surface water in Durban.
(2015) Ntshobeni, Noyise Babalwa.; Olaniran, Ademola Olufolahan.
No abstract available.
Antibody-mediated inhibition of proteases of African trypanosomes.
(2006) Huson, Laura.; Coetzer, Theresa Helen Taillefer.
The protozoan parasites Trypanosoma congolense and T. vivax cause trypanosomosis in cattle. The major lysosomal cysteine proteinase of T. congolense, congopain, may contribute to pathogenesis of the disease, and antibody-mediated inhibition of this enzyme may contribute to mechanisms of trypanotolerance. Oligopeptidase B, a trypanosomal serine peptidase, is also a potential virulence factor in African trypanosomes because it is released into the host circulation by dead or dying parasites, where it retains catalytic activity due to the enzyme's insensitivity to serum protease inhibitors. The vaccine potential of the catalytic domain of congopain, C2, and oligopeptidase B complexed with 0'2-macroglobulin (0'2M) was evaluated by producing antibodies in rabbits. Inhibition of congopain and oligopeptidase B activity by these antibodies was assessed. The oligopeptidase B open reading frame from T. congolense and T. vivax was cloned and expressed in Escherichia coli, from which active recombinant enzymes were purified. These recombinant enzymes exhibited trypsin-like specificity for peptide substrates, cleaving on the carboxy side of basic amino acid residues such as arginine and lysine. Enzymes were found to be optimally active between pH 8 and 10, optimally stable at pH 6, and showed activation by reducing agents and sensitivity to ionic strength. The enzymes showed typical oligopeptidase B-like inhibitor profiles, except that they were not inhibited by thiol sensitive inhibitors such as iodoacetamide and Nethylmaleimide. High yields of bovine and rabbit 0'2M were isolated by a three-step procedure of fractionation by PEG 6000, and zinc chelate and Sephacryl S-300 HR chromatography. Congopain, its catalytic domain C2, papain and cathepsin L all cleaved the bait region of bovine 0'2M and became trapped inside the 0'2M molecule, where their activity against large molecular weight substrates was inhibited. C2 could thus be complexed with 0'2M directly or used to form C2-0'2M-oligopeptidaseB complexes for immunisation purposes. iv The catalytic domain of congopain, C2, was used to immunise rabbits either without adjuvant, as a water-in-oil emulsion with Freund's adjuvant, or in a complex with either bovine or rabbit U2M. Freund's adjuvant elicited the highest anti-C2 antibody response. However, the greatest inhibition, 65%, of C2 activity against Z-Phe-Arg-AMC was obtained with antibodies produced by rabbits receiving C2-U2Mcomplexes. In a second study, C2 and oligopeptidase B were used to immunise rabbits , either in alum, or complexed to bovine U2M. Anti-C2 antibody levels were highest in rabbits immunised with the free proteins in alum, whereas anti-oligopeptidase B antibody levels were comparable for each adjuvant system. Anti-oligopeptidase antibodies produced with alum gave 100% inhibition of oligopeptidase B activity. In contrast, antibodies produced against C2-u2M-oligopeptidase B complexes had little effect on oligopeptidase B activity. However, these antibodies inhibited 55% of C2 activity. Alum was a slightly less efficient adjuvant for C2 and 50% inhibition of C2 activity was observed. It appeared that immunisation of rabbits with C2 complexed to U2M resulted in the production of antibodies that were better able to neutralise the proteolytic activity of C2 and congopain in vitro than that with conventional adjuvants . The immunisation of C2 complexed to bovine u2-macroglobulin therefore has the potential to neutralise parasite congopain in vivo, and may contribute to an anti-disease vaccine against African trypanosomosis. Complexation of oligopeptidase B to u2M offers no benefit, since antibodies produced against this complex are not able to inhibit the activity of oligopeptidase B. Immunisation with oligopeptidase B in alum is sufficient to produce efficient enzyme-inhibiting antibodies in the context of an anti-disease vaccine against African trypanosomosis.
Antidiabetic activity of Warburgia salutaris (Bertol. f.) Chiov. (Canellaceae).
(2017) Msomi, Nontokozo Zimbili.; Simelane, Mthokozisi Blessing Cedric.; Murambiwa, Pretty.
Abstract available in PDF file.
Antidiabetic and toxicological properties of some African medicinal plants used in the treatment of diabetes and its complications.
(2018) Erukainure, Ochuko Lucky.; Islam, Mohammad Shahidul.
This study investigated the antioxidant, antidiabetic and toxicity properties of antidiabetic medicinal plants comprising of Vernonia amygdalina, Cola nitida, Raffia palm (Raphia hookeri) wine, Phaseolus lunatus, Dacryodes edulis, and Clerodendrum volubile using in vitro, ex vivo, in silico and in vivo models. The leaves of V. amygdalina and D. edulis, as well as C. volubile flower were sequentially extracted with solvents of increasing polarity to yield ethyl acetate, ethanol and aqueous extracts. Cola nitida and V. amygdalina were infused in hot water to yield infusion extracts. Phaseolus lunatus was subjected to aqueous extraction to yield aqueous extract, while Raffia palm wine was concentrated to yield the concentrate. The extracts and concentrate were screened for their in vitro and ex vivo antioxidant activities, as well as their inhibitory effect on α-glucosidase, α-amylase and pancreatic lipase activities, and their ability to stimulate muscle glucose uptake and inhibit intestinal glucose absorption in vitro. The ethanol extracts of D. edulis, C. volubile and V. amygdalina were subjected to GC-MS analysis, while the aqueous extract of P. lunatus, palm wine concentrate and the infusions were analyzed with LC-MS to elucidate the active compounds that may be responsible for their bioactivities. The ethanol extracts of C. volubile and D. edulis were further subjected to liquid-liquid fractionation to yield the hexane, dichloromethane, ethyl acetate, butanol and aqueous fractions. These fractions were also assayed for their antioxidant and antidiabetic properties in vitro and ex vivo. The dichloromethane, ethyl acetate and butanol fractions were subjected to GC-MS analysis to elucidate their active compounds. The identified compounds were molecularly docked with the test enzymes in silico to further validate their bioactivities. The antidiabetic properties of palm wine concentrate, C. nitida infusion, and D. edulis butanol fraction were investigated in a type 2 diabetes rat model. The in vivo study revealed a potent hypoglycemic activity, with concomitant amelioration of oxidative stress in the serum, pancreas, testes and brain. This was further substantiated by the downregulation of Nrf2 expressions in the pancreas and brain. These results further validate the use and safety of these plants in diabetes management.
Antidiabetic properties of centella asiatica in type II diabetic rats.
(2016) Oyenihi, Ayodeji Babatunde.; Masola, Bubuya.; Mukaratirwa, Samson.
Abstract available in PDF file.
Antimicrobial resistance, plasmid profiles and sequence typing of enterotoxigenic escherichia coli isolates causing colibacillosis in neonatal and weaning piglets of South Africa.
(2016) Ranketse, Mary.; Dzomba, Edgar Farai.; Muchadeyi, Farai Catherine.; Madoroba, Evelyn.
Abstract available in PDF file.
Antioxidative and antidiabetic activity and phytochemicals analysis of some selected Sudanese traditional medicinal plants.
(2021) Idris, Almahi Idris Mohamed.; Islam, Shahidul.
This study was conducted to evaluate the antioxidant and anti-diabetic properties of selected traditional Sudanese medicinal plants (Cyperus rotundus, Nauclea latifolia, and Hibiscus sabdariffa) using in vitro, ex vivo, and in silico experimental models. The crude extracts (ethyl acetate, ethanol, and aqueous) were screened in vitro for their antioxidant activities using ferricreducing antioxidant power (FRAP), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and nitric oxide radical (NO) scavenging activities, as well as their carbohydrate digesting enzyme inhibitory activities for antidiabetic evaluation. Subsequently, the extracts were subjected to Gas Chromatography-Mass Spectrometry (GC-MS) analysis to elucidate their possible bioactive compounds. Additionally, ex vivo studies was conducted to investigate their capability to promote muscle glucose uptake and suppress glucose absorption in the intestine as well as to analyze antioxidative effects in iron–induced oxidative stress in hepatic tissue. Molecular docking was carried out to determine the probable enzymes' inhibitory mode of action by ligands identified through GC-MS. This study indicates that these traditional Sudanese medicinal plants have remarkable antioxidant and antidiabetic activities, which may help to ameliorate oxidative stress and diabetes. Therefore, these plants may be considered a natural source of bioactive compounds beneficial for human health, particularly for managing diabetes and oxidative stress-related metabolic disorders.
Antioxidative and antidiabetic activity and phytochemicals, analysis of some selected Sudanese traditional medicinal plants.
(2021) Idris, Almahi Mohamed.; Islam, Shahidul.
This study was conducted to evaluate the antioxidant and anti-diabetic properties of selected traditional Sudanese medicinal plants (Cyperus rotundus, Nauclea latifolia, and Hibiscus sabdariffa) using in vitro, ex vivo, and in silico experimental models. The crude extracts (ethyl acetate, ethanol, and aqueous) were screened in vitro for their antioxidant activities using ferricreducing antioxidant power (FRAP), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and nitric oxide radical (NO) scavenging activities, as well as their carbohydrate digesting enzyme inhibitory activities for antidiabetic evaluation. Subsequently, the extracts were subjected to Gas Chromatography-Mass Spectrometry (GC-MS) analysis to elucidate their possible bioactive compounds. Additionally, ex vivo studies was conducted to investigate their capability to promote muscle glucose uptake and suppress glucose absorption in the intestine as well as to analyze antioxidative effects in iron–induced oxidative stress in hepatic tissue. Molecular docking was carried out to determine the probable enzymes' inhibitory mode of action by ligands identified through GC-MS. This study indicates that these traditional Sudanese medicinal plants have remarkable antioxidant and antidiabetic activities, which may help to ameliorate oxidative stress and diabetes. Therefore, these plants may be considered a natural source of bioactive compounds beneficial for human health, particularly for managing diabetes and oxidative stress-related metabolic disorders.
Antioxidative and antidiabetic effects of some African medicinal plants.
(2016) Mohammed, Aminu.; Islam, Mohammad Shahidul.
Three (3) medicinal plants [Aframomum melegueta K. Schum., Xylopia aethiopica (Dunal.) A. Rich. and Capsicum annuum L.] were selected based on their traditional uses in the treatment of diabetes in Africa. Various crude extracts and fractions from different parts of the plants were screened using several anti-oxidative and anti-diabetic tests in vitro. Most active fractions from each plant were used to examine in vivo anti-diabetic activity in type 2 diabetes (T2D) rat model. Additionally, possible bioactive compounds from most active extracts and fractions were analyzed by using GC-MS, TLC and NMR spectroscopy. The results showed that ethanolic extracts derived from the fruits of the plants demonstrated excellent anti-oxidative and anti-diabetic activities in vitro compared to other extracts from the same or different parts of these plants. After fractionation, ethyl acetate fraction from A. melegueta and acetone fractions from X. aethiopica and C. annuum exhibited strong radical scavenging (IC₅₀: 1-120 μg/mL) activity, inhibition of hemoglobin glycation (IC₅₀: 100-150 μg/mL), α-amylase (IC₅₀: 50-170 μg/mL) and α-glucosidase (IC₅₀: 40-87 μg/mL) activities hence were used for the in vivo study. The GC-MS analysis of the three (3) most active fractions revealed the presence of mostly phenolic compounds of 4-hydroxy-3-methoxyphenyl derivatives. Furthermore, the data of the in vivo study showed that oral intervention of the fractions (150 and 300 mg/kg bw) for 4 weeks demonstrated potent anti-diabetic actions via improving body weight gain, reducing feed and fluid intake and hyperglycemia, improving glucose tolerance ability, insulin sensitivity, amelioration of pancreatic β-cell histology and β-cell functions, improving dyslipidemia in a T2D rat model. Additionally, the pancreatic histopathological damages and other oxidative damages caused by the induction of diabetes were attenuated to near normal in the liver, kidney, heart and pancreas of the treated animals. The bioassay-guided fractionations lead to the isolation of 3 arylalkanes (6-paradol (1), 6-shagaol (2), and 6- gingerol (3)) and oleanolic acid (4) from A. melegueta fruits, when oleanolic acid (4) was the first to be isolated from A. melegueta. Moreover, 6-gingerol (3) and oleanolic acid (4) were similarly isolated for the first time from X. aethiopica fruits as well. These compounds have exhibited significant inhibitions against the α-amylase and α-glucosidase actions and thus are possible anti-diabetic agents and the anti-diabetic action of A. melegueta and X. aethiopica fruits is attributed to the presence of these compounds. This study also confirmed the use of these plants in African anti-diabetic traditional medicines by traditional healers. However, further clinical study is required to confirm these effects in human subjects.
Antiplasmodial activity of Warburgia salutaris (Bertol. F.) Chiov. (Cannelaceae).
(2017) Nyaba, Zoxolo Nokulunga.; Simelane, Mthokozisi Blessing Cedric.; Murambiwa, Pretty.
Abstract available in PDF file.
Apoptosis in peripheral blood mononuclear cells of human immunodeficiency virus (HIV) infected patients undergoing highly active antiretroviral therapy.
(2008) Karamchand, Leshern.; Chuturgoon, Anil Amichund.; Dawood, Halima.
Highly active antiretroviral therapy (HAART) is currently the only treatment that effectively reduces the morbidity and mortality of individuals infected with Human Immunodeficiency Virus-1 (HIV-1). Standard HAART regimens typically comprise 2 nucleoside reverse transcriptase inhibitors and either one non-nucleoside reverse transcriptase inhibitor or a protease inhibitor. These drugs bind to and inhibit the HIV-1 Reverse Transcriptase and Protease enzymes respectively, thereby suppressing viral replication. The nucleoside reverse transcriptase inhibitors promote mitochondrial (mt) dysfunction by strongly inhibiting mt polymerase gamma (Pol-y) and subsequently, mtDNA replication. In contrast, the non-nucleoside reverse transcriptase inhibitors, efavirenz (EFV) and nevirapine (NVP) do not inhibit Pol-y although EFV has been shown to induce mt depolarisation ( mlow) in vitro at supra-therapeutic concentrations. However, the capacity of non-nucleoside reverse transcriptase inhibitor drugs to induce mt toxicity in vivo previously remained undetermined. The objective of this study was to determine the influence of EFV and NVP on peripheral lymphocyte mt transmembrane potential (Avj/m) and apoptosis in HIV-1-infected patients treated with these non-nucleoside reverse transcriptase inhibitors. Thirty-two HIV-1-infected patients on HAART between 4 and 24 months (12 on EFV, 20 on NVP) and 16 HAART-naive HIV-1-infected patients were enrolled into this study. All participants were black South African patients. Spontaneous peripheral lymphocyte apoptosis and mlow were measured ex vivo by flow cytometry for all patients. CD4 T-helper apoptosis for the EFV and NVP cohorts was 19.38% ± 2.62% and 23.35% ± 1.51% (mean ± SEM), respectively, whereas total lymphocyte mlow was 27.25% ± 5.05% and 17.04% ± 2.98%, respectively. Both parameters for each cohort were significantly lower (P < 0.05) than that of the HAART-naive patients. The NVP cohort exhibited both a significant time dependent increase in peripheral lymphocyte ö¿mlow (P = 0.038) and correlation between Thelper apoptosis and low (P = 0.0005). These trends were not observed in the EFV cohort. This study provides evidence that both EFV and NVP induce peripheral lymphocyte ö¿ m low in HIV-1-infected patients on non-nucleoside reverse transcriptase inhibitor-based HAART, which in the case of NVP is sufficient to induce the apoptosis cascade.
Apoptosis, redox stress and cancer.
(2000) Moodley, Thunicia.; Elliott, Edith.
Apoptosis is a regulated "programme" by which cells are induced to die in a manner which does not result in pathological inflammatory reactions, and involves dismantling of the cell into membrane-bound fragments that are removed by phagocytosis. This process is induced in order to remodel tissues and maintain homeostasis in cell numbers. Apoptosis may be induced via many pathways, many of which are redox-regulated, and is dysregulated in cancer cells, mainly due to mutational inactivation of certain pathways. Cancer cells also have a non-linear response to redox imbalance, a potentially exploitable characteristic for the therapeutic selective induction of apoptosis in cancer cells in mixed cell populations. Model cell culture systems are required for the selective toxicity testing of anti-cancer drugs, many of which work by inducing redox stress. In the current study, hydrogen peroxide was selected as the redox stress-inducing agent, and the test cells were an immortal, non-invasive breast epithelial cell line (MCFlOA) and its rastransfected, pre-malignant derivative (MCF10AneoT). A reliable, sensitive, cost effective and least time-consuming system for detection of apoptosis in such a system was sort and two novel methods, cytochrome c release and caspase-3 activity assays, were finally selected and compared with results seen by conventional DNA laddering and morphological examination at the light and electron microscopic level. No single procedure was found to be reliable individually. For the model system used, a combination of electron microscopy and DNA laddering was sufficient for simply detecting apoptotic cell death and necrosis. The caspase activity assay distinguished between apoptosis and necrosis, and cytochrome c release proved the most sensitive indicator of cell response. However, since cytochrome c release may be reversible and may not necessarily proceed to the downstream events of apoptosis in the time frame used in the current assays, it is not certain that cytochrome c release ultimately leads to apoptosis. However, three forms of cytochrome c were observed on western blots, the nature and significance of which remains to be determined. A comparison of the results of different methods allowed a model for the sequence of specific apoptotic events to be proposed.

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