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Anguelov R, Manjunath G, Phiri AE, Nyakudya TT, Bipath P, C Serem J, N Hlophe Y. Quantifying assays: inhibition of signalling pathways of cancer. Math Med Biol 2023; 40:266-290. [PMID: 37669569 DOI: 10.1093/imammb/dqad005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 02/24/2023] [Accepted: 08/25/2023] [Indexed: 09/07/2023]
Abstract
Inhibiting a signalling pathway concerns controlling the cellular processes of a cancer cell's viability, cell division and death. Assay protocols created to see if the molecular structures of the drugs being tested have the desired inhibition qualities often show great variability across experiments, and it is imperative to diminish the effects of such variability while inferences are drawn. In this paper, we propose the study of experimental data through the lenses of a mathematical model depicting the inhibition mechanism and the activation-inhibition dynamics. The method is exemplified through assay data obtained from an experimental study of the inhibition of the chemokine receptor 4 (CXCR4) and chemokine ligand 12 (CXCL12) signalling pathway of melanoma cells. The quantitative analysis is conducted as a two step process: (i) deriving theoretically from the model the cell viability as a function of time depending on several parameters; (ii) estimating the values of the parameters by using the experimental data. The cell viability is obtained as a function of concentration of the inhibitor and time, thus providing a comprehensive characterization of the potential therapeutic effect of the considered inhibitor, e.g. $IC_{50}$ can be computed for any time point.
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Affiliation(s)
- Roumen Anguelov
- Department of Mathematics and Applied Mathematics, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
- Institute of Mathematics and Informatics, Bulgarian Academy of Sciences, Acad. Georgi Bonchev St., Block 8, Sofia 1113, Bulgaria
| | - G Manjunath
- Department of Mathematics and Applied Mathematics, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Avulundiah E Phiri
- Department of Mathematics and Applied Mathematics, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Trevor T Nyakudya
- Department of Physiology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Priyesh Bipath
- Department of Physiology, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - June C Serem
- Department of Anatomy, University of Pretoria, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Yvette N Hlophe
- Department of Physiology, University of Pretoria, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
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Ndlovu M, Serem JC, Selepe MA, Opoku AR, Bester MJ, Apostolides Z, Mosa RA. Triterpenoids from Protorhus longifolia Exhibit Hypocholesterolemic Potential via Regulation of Cholesterol Biosynthesis and Stimulation of Low-Density Lipoprotein Uptake in HepG2 Cells. ACS Omega 2023; 8:30906-30916. [PMID: 37663489 PMCID: PMC10468762 DOI: 10.1021/acsomega.3c01995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 06/16/2023] [Indexed: 09/05/2023]
Abstract
The increasing incidence of hypercholesterolemia-related diseases even in the presence of the currently available cholesterol-lowering drugs indicates a need to discover new therapeutic drugs. This study aimed to investigate the hypocholesterolemic potential of two triterpenoids isolated from Protorhus longifolia stem bark. In silico techniques and in vitro enzyme assays were used to evaluate the potential inhibition of cholesterol esterase and HMG-CoA reductase by the triterpenoids (ARM-2 and RA-5). The toxicity, modulation of low-density lipoprotein (LDL) uptake, and associated gene expression were determined in HepG2 hepatocytes. In silico molecular docking revealed that ARM-2 compared with RA-5 has a relatively stronger binding affinity for both enzymes. Both triterpenoids further demonstrated promising in silico drug-likeness properties and favorable ADMET profiles characterized by high intestinal absorption and lack of CYP450 enzyme inhibition. The compounds further showed, to varying degrees of efficacy, inhibition of cholesterol micellization as well as both cholesterol esterase and HMG-CoA reductase activities with IC50 values ranging from 16.4 to 41.1 μM. Moreover, enhanced hepatic cellular LDL uptake and the associated upregulation of the LDL-R and SREBP-2 gene expression were observed in the triterpenoid-treated HepG2 cells. It is evident that the triterpenoids, especially ARM-2, possess hypocholesterolemic properties, and these molecules can serve as leads or structural templates for the development of new hypocholesterolemic drugs.
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Affiliation(s)
- Musawenkosi Ndlovu
- Department
of Biochemistry, Genetics and Microbiology, University of Pretoria, Hatfield 0028, South Africa
| | - June C. Serem
- Department
of Anatomy, University of Pretoria, Pretoria 0007, South Africa
| | - Mamoalosi A. Selepe
- Department
of Chemistry, University of Pretoria, Hatfield 0028, South Africa
| | - Andrew R. Opoku
- Department
of Biochemistry and Microbiology, University
of Zululand, KwaDlangezwa 3886, South Africa
| | - Megan J. Bester
- Department
of Anatomy, University of Pretoria, Pretoria 0007, South Africa
| | - Zeno Apostolides
- Department
of Biochemistry, Genetics and Microbiology, University of Pretoria, Hatfield 0028, South Africa
| | - Rebamang A. Mosa
- Department
of Biochemistry, Genetics and Microbiology, University of Pretoria, Hatfield 0028, South Africa
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Tolmie M, Bester MJ, Serem JC, Nell M, Apostolides Z. The potential antidiabetic properties of green and purple tea [Camellia sinensis (L.) O Kuntze], purple tea ellagitannins, and urolithins. J Ethnopharmacol 2023; 309:116377. [PMID: 36907477 DOI: 10.1016/j.jep.2023.116377] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 03/07/2023] [Indexed: 06/18/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Tea (Camellia sinensis) has been consumed for centuries as traditional medicine for various diseases, including diabetes. The mechanism of action of many traditional medicines, including tea, often requires elucidation. Purple tea is a natural mutant of Camellia sinensis, grown in China and Kenya, and is rich in anthocyanins and ellagitannins. AIM OF THE STUDY Here we aimed to determine whether commercial green and purple teas are a source of ellagitannins and whether green and purple teas, purple tea ellagitannins and their metabolites urolithins have antidiabetic activity. MATERIALS AND METHODS Targeted UPLC-MS/MS was employed to quantify the ellagitannins corilagin, strictinin and tellimagrandin I, in commercial teas. The inhibitory effect of commercial green and purple teas and purple tea ellagitannins was evaluated on α-glucosidase and α-amylase. The bioavailable urolithins were then investigated for additional antidiabetic effects, by evaluating their effect on cellular glucose uptake and lipid accumulation. RESULTS Corilagin, strictinin and tellimagrandin I (ellagitannins) were identified as potent inhibitors of α-amylase and α-glucosidase, with Ki values significantly lower (p < 0.05) than acarbose. Commercial green-purple teas were identified as ellagitannin sources, with especially high concentrations of corilagin. These commercial purple teas, containing ellagitannins, were identified as potent α-glucosidase inhibitors with IC50 values significantly lower (p < 0.05) than green teas and acarbose. Urolithin A and urolithin B were as effective (p> 0.05) as metformin in increasing glucose uptake in adipocytes, muscle cells and hepatocytes. In addition, similar (p > 0.05) to metformin, both urolithin A and urolithin B reduced lipid accumulation in adipocytes and hepatocytes. CONCLUSIONS This study identified green-purple teas as an affordable widely available natural source with antidiabetic properties. Furthermore, additional antidiabetic effects of purple tea ellagitannins (corilagin, strictinin and tellimagrandin I) and urolithins were identified.
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Affiliation(s)
- M Tolmie
- Department of Biochemistry, Genetics and Microbiology at the University of Pretoria, Pretoria, South Africa.
| | - M J Bester
- Department of Anatomy at the University of Pretoria, Pretoria, South Africa.
| | - J C Serem
- Department of Anatomy at the University of Pretoria, Pretoria, South Africa.
| | - M Nell
- Department of Pharmacology at the University of Pretoria, Pretoria, South Africa.
| | - Z Apostolides
- Department of Biochemistry, Genetics and Microbiology at the University of Pretoria, Pretoria, South Africa.
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Tshiyoyo KS, Bester MJ, Serem JC, Apostolides Z. In-silico reverse docking and in-vitro studies identified curcumin, 18α-glycyrrhetinic acid, rosmarinic acid, and quercetin as inhibitors of α-glucosidase and pancreatic α-amylase and lipid accumulation in HepG2 cells, important type 2 diabetes targets. J Mol Struct 2022. [DOI: 10.1016/j.molstruc.2022.133492] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Ntuli S, Leuschner M, Bester MJ, Serem JC. Stability, Morphology, and Effects of In Vitro Digestion on the Antioxidant Properties of Polyphenol Inclusion Complexes with β-Cyclodextrin. Molecules 2022; 27:molecules27123808. [PMID: 35744933 PMCID: PMC9228204 DOI: 10.3390/molecules27123808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 06/03/2022] [Accepted: 06/07/2022] [Indexed: 11/17/2022]
Abstract
Polyphenols are inversely associated with the incidence of chronic diseases, but therapeutic use is limited by poor stability and bioaccessibility. Encapsulation has been shown to overcome some of these limitations. A selection of polyphenols (catechin, gallic acid, and epigallocatechin gallate) and their combinations were encapsulated in beta-cyclodextrin (βCD). Encapsulation was characterized and the thermal and storage stability was evaluated using the 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay. The samples were then subjected to in vitro digestion using a simple digestion (SD) model (gastric and duodenal phases) and a more complex digestion (CD) model (oral, gastric, and duodenal phases). Thereafter, the chemical (oxygen radical absorbance capacity assay) and cellular (dichlorofluorescein diacetate assay in Caco-2 cells) antioxidant and antiglycation (advanced glycation end-products assay) activities were determined. Inclusion complexes formed at a 1:1 molar ratio with a high encapsulation yield and efficiency. Encapsulation altered the morphology of the samples, increased the thermal stability of some and the storage stability of all samples. Encapsulation maintained the antioxidant activity of all samples and significantly improved the antiglycation and cellular antioxidant activities of some polyphenols following SD. In conclusion, the formed inclusion complexes of βCD with polyphenols had greater storage stability, without altering the beneficial cellular effects of the polyphenols.
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Affiliation(s)
- Sunday Ntuli
- Department of Anatomy, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Arcadia, Pretoria 0007, South Africa; (S.N.); (M.J.B.)
| | - Machel Leuschner
- Department of Pharmacology, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Arcadia, Pretoria 0007, South Africa;
| | - Megan J. Bester
- Department of Anatomy, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Arcadia, Pretoria 0007, South Africa; (S.N.); (M.J.B.)
| | - June C. Serem
- Department of Anatomy, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Arcadia, Pretoria 0007, South Africa; (S.N.); (M.J.B.)
- Correspondence: ; Tel.: +27-12-356-3091
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6
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Apea-Bah FB, Serem JC, Bester MJ, Duodu KG, Beta T. Effect of simulated in vitro upper gut digestion of processed cowpea beans on phenolic composition, antioxidant properties and cellular protection. Food Res Int 2021; 150:110750. [PMID: 34865768 DOI: 10.1016/j.foodres.2021.110750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 09/09/2021] [Accepted: 10/10/2021] [Indexed: 11/17/2022]
Abstract
The effect of simulated in vitro upper gut digestion on the phenolic composition and antioxidant properties of processed cowpea beans was studied. The samples comprised four cowpea cultivars: a cream, brownish-cream and two reddish-brown cultivars. Dry cowpea seeds were soaked in water, blended into paste and deep-fried in vegetable oil. The fried samples were taken through in vitro upper gut digestion followed by freeze-drying of the supernatant. Phenolic composition of extracts from the supernatants were determined using HPLC-MS. Radical scavenging activities were documented using the TEAC, ORAC and nitric oxide (NO) assays. In vitro digestion of the processed cowpeas resulted in phenolic-peptide complexes that were identified for the first time, and decreased extractable phenolic compounds. However, the radical scavenging activities increased. The processed cowpeas and their digests inhibited cellular NO production, and oxidative DNA and cellular damage. In conclusion, deep-fried cowpeas when consumed, could potentially help alleviate oxidative stress-related conditions.
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Affiliation(s)
- Franklin B Apea-Bah
- Department of Food and Human Nutritional Sciences, Faculty of Agricultural and Food Sciences, University of Manitoba, Fort Garry Campus, Winnipeg, Manitoba R3T 2N2, Canada; Richardson Centre for Functional Foods and Nutraceuticals, Smartpak, 196 Innovation Drive, University of Manitoba, Winnipeg, Manitoba R3T 2E1, Canada; Department of Consumer and Food Sciences, University of Pretoria, Private Bag X20, Hatfield 0028, Pretoria, South Africa.
| | - June C Serem
- Department of Anatomy, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Arcadia 0007, Pretoria, South Africa.
| | - Megan J Bester
- Department of Anatomy, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Arcadia 0007, Pretoria, South Africa.
| | - Kwaku G Duodu
- Department of Consumer and Food Sciences, University of Pretoria, Private Bag X20, Hatfield 0028, Pretoria, South Africa.
| | - Trust Beta
- Department of Food and Human Nutritional Sciences, Faculty of Agricultural and Food Sciences, University of Manitoba, Fort Garry Campus, Winnipeg, Manitoba R3T 2N2, Canada; Richardson Centre for Functional Foods and Nutraceuticals, Smartpak, 196 Innovation Drive, University of Manitoba, Winnipeg, Manitoba R3T 2E1, Canada.
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Nathu H, Mbuyama KR, Adarkwah-Yiadom M, Serem JC, Ibrahim MA, Duodu KG, Gaspar ARM, Bester MJ. Antioxidant properties and inhibition of lipid formation in 3T3-L1 adipocytes of in vitro digested mageu, a commercial sample. J Food Biochem 2021; 45:e13929. [PMID: 34519069 DOI: 10.1111/jfbc.13929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 08/19/2021] [Accepted: 08/23/2021] [Indexed: 11/29/2022]
Abstract
Mageu is a fermented, non-alcoholic maize-derived product unique to southern Africa. The aim of this study was to identify the health benefits of a polyphenolic extract of commercially produced mageu related to the antioxidant properties and effects on lipid accumulation in differentiated 3T3-L1 adipocytes. A pooled sample of mageu Number 1 brand (original non-flavored) was subjected to in vitro gastroduodenal digestion (GDD). Reverse phase high-performance liquid chromatography of unfractionated undigested (UD) and GDD mageu revealed that with digestion there was an increased extraction of 1.2, 1.83, 1.45, 4.86, and 3.17-fold of caffeic acid, 3,4-dihydroxybenzoic acid, p-coumaric acid, 4 hydroxybenzoic acid and ferulic acid, respectively. An associated increase in the total phenolic acid content and antioxidant activity in the <3 kDa fraction was obtained. In contrast with digestion, inhibition of advanced glycation end products formation and low-density lipoprotein oxidation was found in the <30 kDa fraction indicating the contribution of larger, possibly feruloylated polysaccharides, to activity. Cellular antioxidant activity in Caco-2 cells was >90% for all UD fractions, but with GDD was reduced. All fractions had low scavenging of nitric oxide in the lipopolysaccharide/murine cell model. Exposure of 3T3-L1 adipocytes to all the UD and GDD mageu fractions (at 1% and 10% concentrations) during differentiation resulted in at least a 35% reduction in lipid accumulation, which was not associated with a loss of cellular viability. In conclusion, mageu, UD, and subjected to GDD contains phenolic acids with beneficial bioactive properties that contribute to antioxidant activity and reduces lipid accumulation in adipocytes. PRACTICAL APPLICATIONS: Mageu is a non-alcoholic fermented maize product which when digested has increased bioactivity. Its reported health benefits are due to its caloric content therefore the practical application of this research is to validate the scientific benefits of this food and encourage increased consumption of this functional food. This is especially important in the context of the South African population where this product is widely consumed as increasing obesity is associated with an increased risk of non-communicable disease. Furthermore, as a non-alcoholic drink, consumption can be promoted for all ages' groups and religions, and a commercialized manufacture processes can be optimized to increase phenolic acid release.
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Affiliation(s)
- Haleema Nathu
- Department of Anatomy, University of Pretoria, Pretoria, South Africa
| | - Kabuzi R Mbuyama
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
| | - Martin Adarkwah-Yiadom
- Department of Consumer and Food Sciences, University of Pretoria, Pretoria, South Africa
| | - June C Serem
- Department of Anatomy, University of Pretoria, Pretoria, South Africa
| | | | - Kwaku G Duodu
- Department of Consumer and Food Sciences, University of Pretoria, Pretoria, South Africa
| | - Anabella R M Gaspar
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
| | - Megan J Bester
- Department of Anatomy, University of Pretoria, Pretoria, South Africa
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8
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Moyo SM, Serem JC, Bester MJ, Mavumengwana V, Kayitesi E. Hydrothermal Processing and In Vitro Simulated Human Digestion Affects the Bioaccessibility and Bioactivity of Phenolic Compounds in African Pumpkin ( Momordica balsamina) Leaves. Molecules 2021; 26:molecules26175201. [PMID: 34500636 PMCID: PMC8434164 DOI: 10.3390/molecules26175201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 08/16/2021] [Accepted: 08/21/2021] [Indexed: 11/16/2022] Open
Abstract
The African pumpkin (Momordica balsamina) contains bioactive phenolic compounds that may assist in reducing oxidative stress in the human body. The leaves are mainly consumed after boiling in water for a specific time; this hydrothermal process and conditions of the gastrointestinal tract may affect the presence and bioactivity of phenolics either positively or negatively. In this study, the effects of hydrothermal processing (boiling) and in vitro simulated human digestion on the phenolic composition, bioaccessibility and bioactivity in African pumpkin were investigated in comparison with those of spinach (Spinacia oleracea). A high-resolution ultra-performance liquid chromatography, coupled with diode array detection, quadrupole time-of-flight and mass spectrometer (UPLC-DAD-QTOF-MS) was used to profile phenolic metabolites. Metabolites such as 3-caffeoylquinic acid, 5-caffeoylquinic acid, 3,4-dicaffeoylquinic acid, 3,5-dicaffeoylquinic acid and 4,5-dicaffeoylquinic acid were highly concentrated in the boiled vegetable extracts compared to the raw undigested and all digested samples. The majority of African pumpkin and spinach extracts (non-digested and digested) protected Deoxyribonucleic acid (DNA), (mouse fibroblast) L929 and human epithelial colorectal adenocarcinoma (Caco-2) cells from 2,2'-Azobis(2-methylpropionamidine) dihydrochloride (AAPH)-induced oxidative damage. From these results, the consumption of boiled African pumpkin leaves, as well as spinach, could be encouraged, as bioactive metabolites present may reduce oxidative stress in the body.
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Affiliation(s)
- Siphosanele Mafa Moyo
- Department of Biotechnology and Food Technology, Faculty of Science, Doornfontein Campus, University of Johannesburg, P.O. Box 17011, Doornfontein, Johannesburg 2028, South Africa
- Department of Consumer and Food Sciences, University of Pretoria, Private Bag X20, Hatfield, Pretoria 0028, South Africa
- Correspondence: (S.M.M.); (E.K.)
| | - June C. Serem
- Department of Anatomy, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Arcadia, Pretoria 0007, South Africa; (J.C.S.); (M.J.B.)
| | - Megan J. Bester
- Department of Anatomy, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Arcadia, Pretoria 0007, South Africa; (J.C.S.); (M.J.B.)
| | - Vuyo Mavumengwana
- Department of Biomedical Sciences, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, P.O. Box 19063, Tygerberg, Cape Town 7505, South Africa;
| | - Eugenie Kayitesi
- Department of Biotechnology and Food Technology, Faculty of Science, Doornfontein Campus, University of Johannesburg, P.O. Box 17011, Doornfontein, Johannesburg 2028, South Africa
- Department of Consumer and Food Sciences, University of Pretoria, Private Bag X20, Hatfield, Pretoria 0028, South Africa
- Correspondence: (S.M.M.); (E.K.)
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9
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Maseko PB, van Rooy M, Taute H, Venter C, Serem JC, Oberholzer HM. Whole blood ultrastructural alterations by mercury, nickel and manganese alone and in combination: An ex vivo investigation. Toxicol Ind Health 2020; 37:98-111. [PMID: 33357111 DOI: 10.1177/0748233720983114] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The distribution of metals across the environment is increasingly becoming a major concern as they not only pollute the environment but also pose a danger to humans and animals. Human exposure to heavy metals often occurs as a combination of metals the synergistic effects of which can be more toxic than a single metal. The aim of this study was to investigate the effects that the metals mercury (Hg), nickel (Ni) and manganese (Mn) alone and in combination have on erythrocyte morphology and other components of the coagulation system using the haemolysis assay, scanning electron microscopy (SEM), and confocal laser scanning microscopy. Human blood was exposed to the heavy metals ex vivo, and percentage haemolysis was determined. Ultrastructural analysis of erythrocytes, platelets and fibrin networks was performed using SEM. Analysis of phosphatidylserine (PS) flip-flop was determined using confocal laser scanning microscopy. At the highest concentration of 10,000× the World Health Organization safety limit, all the metals caused haemolysis. The results showed that the exposure of erythrocytes to Hg alone and in combination with other metals displayed more haemolysis compared to Ni and Mn alone and in combination. Components of the coagulation system showed ultrastructural changes, including the formation of echinocytes and the activation of platelets with all single metals as well as the combinations. Confocal laser scanning microscopy analysis showed the presence of PS on the outer surface of the echinocytes that were exposed to metals alone and in combination. It can, therefore, be concluded that these heavy metals have a negative impact on erythrocytes and the coagulation system.
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Affiliation(s)
- P B Maseko
- Department of Anatomy, 72042Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - M van Rooy
- Department of Physiology, 72042Faculty of Health Sciences, University of Pretoria, Pretoria,South Africa
| | - H Taute
- Department of Anatomy, 72042Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - C Venter
- Laboratory for Microscopy and Microanalysis, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, South Africa
| | - J C Serem
- Department of Anatomy, 72042Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - H M Oberholzer
- Department of Anatomy, 72042Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
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Moyo SM, Serem JC, Bester MJ, Mavumengwana V, Kayitesi E. The impact of boiling and in vitro human digestion of Solanum nigrum complex (Black nightshade) on phenolic compounds bioactivity and bioaccessibility. Food Res Int 2020; 137:109720. [PMID: 33233289 DOI: 10.1016/j.foodres.2020.109720] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 08/12/2020] [Accepted: 09/14/2020] [Indexed: 02/06/2023]
Abstract
Solanum nigrum complex (Black nightshade) is a wild leafy vegetable with phenolic antioxidant compounds related to the reduction of oxidative stress. Changes in phenolics and bioactivity due to cooking and gastrointestinal digestion of black nightshade were compared to spinach. Predominant compounds of black nightshade were myricetin, quercetin-3-O-robinoside, 3,4-dicaffeoylquinic acid, 3-caffeoylquinic acid, and rutin, which were improved after boiling but reduced after in vitro digestion. Phenolics were reduced after digestion of black nightshade and spinach; however, bioactivity was still retained, especially in preventing oxidative stress in Caco-2 cells. Hence, indicating their potential to reduce oxidative stress related diseases of the digestive tract.
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Affiliation(s)
- S M Moyo
- Department of Biotechnology and Food Technology, Faculty of Science, University of Johannesburg, P.O. Box 17011, Doornfontein Campus, Johannesburg, South Africa
| | - J C Serem
- Department of Anatomy, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Arcadia 0007, Pretoria, South Africa
| | - M J Bester
- Department of Anatomy, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Arcadia 0007, Pretoria, South Africa
| | - V Mavumengwana
- DST-NRF Centre of Excellence for Biomedical Tuberculosis Research/South African Medical Research Council Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, South Africa
| | - E Kayitesi
- Department of Biotechnology and Food Technology, Faculty of Science, University of Johannesburg, P.O. Box 17011, Doornfontein Campus, Johannesburg, South Africa; Department of Consumer and Food Sciences, University of Pretoria, Hatfield, Pretoria, South Africa.
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Ibrahim MA, Serem JC, Bester MJ, Neitz AW, Gaspar ARM. New Antidiabetic Targets of α-Glucosidase Inhibitory Peptides, SVPA, SEPA, STYV and STY: Inhibitory Effects on Dipeptidyl Peptidase-IV and Lipid Accumulation in 3T3-L1 Differentiated Adipocytes with Scavenging Activities Against Methylglyoxal and Reactive Oxygen Species. Int J Pept Res Ther 2019. [DOI: 10.1007/s10989-019-09993-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Ismail NO, Odendaal C, Serem JC, Strömstedt AA, Bester MJ, Sayed Y, Neitz AW, Gaspar AR. Antimicrobial function of short amidated peptide fragments from the tick‐derived OsDef2 defensin. J Pept Sci 2019; 25:e3223. [DOI: 10.1002/psc.3223] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 09/20/2019] [Accepted: 09/24/2019] [Indexed: 12/21/2022]
Affiliation(s)
- Naadhira O. Ismail
- Department of Biochemistry, Genetics and MicrobiologyUniversity of Pretoria Private Bag X20, Hatfield 0028 Pretoria South Africa
| | - Clerisa Odendaal
- Department of Biochemistry, Genetics and MicrobiologyUniversity of Pretoria Private Bag X20, Hatfield 0028 Pretoria South Africa
| | - June C. Serem
- Department of AnatomyUniversity of Pretoria Private Bag X323, Arcadia 0007 Pretoria South Africa
| | - Adam A. Strömstedt
- Pharmacognosy, Department of Medicinal ChemistryUppsala University Box 574 Uppsala SE 75123 Sweden
| | - Megan J. Bester
- Department of AnatomyUniversity of Pretoria Private Bag X323, Arcadia 0007 Pretoria South Africa
| | - Yasien Sayed
- Protein Structure‐Function Research Unit, School of Molecular and Cell BiologyUniversity of the Witwatersrand Private Bag 3, WITS 2050 Johannesburg South Africa
| | - Albert W.H. Neitz
- Department of Biochemistry, Genetics and MicrobiologyUniversity of Pretoria Private Bag X20, Hatfield 0028 Pretoria South Africa
| | - Anabella R.M. Gaspar
- Department of Biochemistry, Genetics and MicrobiologyUniversity of Pretoria Private Bag X20, Hatfield 0028 Pretoria South Africa
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Ibrahim MA, Serem JC, Bester MJ, Neitz AW, Gaspar ARM. Structure - Function Analysis of Peptide Analogs of SQSPA with Respect to α-glucosidase and α-amylase Inhibition. Protein Pept Lett 2019; 26:403-413. [PMID: 30919765 DOI: 10.2174/0929866526666190327121731] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 03/01/2019] [Accepted: 03/18/2019] [Indexed: 11/22/2022]
Abstract
BACKGROUND Peptide-based therapeutics offer a unique avenue for the development of novel agents for the treatment of diabetes mellitus including α-glucosidase inhibitors. The peptide, SQSPA, was reported to possess to α -glucosidase inhibitory activity in addition to resistance to Gastrointestinal Tract (GIT) digestion. METHODS In this study, the in silico and in vitro structure-activity analyses of the peptide was conducted using alanine scanning to identify key amino acid residues. RESULTS The alanine scanning led to four analogs viz; AQSPA, SASPA, SQAPA and SQSAA which were GIT stable. Initially, the peptides were subjected to molecular docking on human α- glucosidase and α -amylase where the binding affinities to the enzymes were in the order; AQSPA>SASPA>SQSPA>SQAPA> SQSAA and AQSPA>SQSAA>SASPA>SQSPA> SQAPA, respectively. Hydrogen bond were important for the binding of all peptides but SASPA and AQSPA had the highest hydrogen bonds interactions with the α-glucosidase and α-amylase, respectively. In vitro analysis revealed that the α -glucosidase and α-amylase inhibitory activities of the peptides were in the order AQSPA>SQSPA>SQAPA>SASPA>SQSAA and AQSPA>SASPA> SQAPA>SQSPA>SQSAA, respectively. Using inhibition kinetics, SQSPA was a mixed inhibitor of α-glucosidase while AQSPA, SQAPA and SQSAA showed non-competitive inhibition. For α- amylase inhibition, SQSPA was a non-competitive inhibitor while AQSPA and SQSAA were mixed inhibitors; SASPA and SQAPA showed uncompetitive inhibition. CONCLUSION The results indicated that P4 and Q2 are important requirements for the α-glucosidase and α-amylase inhibitory activities of the parent peptide, SQSPA. Furthermore, alanine scanning has led to the design of a novel α-glucosidase inhibitory peptide, AQSPA, with increased activities.
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Affiliation(s)
- Mohammed A Ibrahim
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria 0002, South Africa.,Department of Biochemistry, Ahmadu Bello University, Zaria, Nigeria
| | - June C Serem
- Department of Anatomy, University of Pretoria, Pretoria 0002, South Africa
| | - Megan J Bester
- Department of Anatomy, University of Pretoria, Pretoria 0002, South Africa
| | - Albert W Neitz
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria 0002, South Africa
| | - Anabella R M Gaspar
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria 0002, South Africa
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14
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van Rensburg MJ, van Rooy M, Bester MJ, Serem JC, Venter C, Oberholzer HM. Oxidative and haemostatic effects of copper, manganese and mercury, alone and in combination at physiologically relevant levels: An ex vivo study. Hum Exp Toxicol 2018; 38:419-433. [PMID: 30537864 DOI: 10.1177/0960327118818236] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Water contamination with metals due to anthropogenic activity is increasing and subsequent exposure increases the risk of associated toxicity. Exposure is not limited to a single metal but usually involves mixtures of different metals at different concentrations. Little is known about the contribution of this type of exposure, in humans, to the development of non-communicable diseases such as cardiovascular disease, and an increased risk to thrombosis. The World Health Organization has established limits for metal levels in drinking water and this includes levels for copper (Cu), manganese (Mn) and mercury (Hg). In this study, at 100X these limits, the ability of the metals' oxidative effects as catalysts of the Fenton reaction and/or ability to bind glutathione (GSH) were determined. The haemostatic effects of these metals, alone and in combination, at the World Health Organization limit were then evaluated. The ultrastructural and viscoelastic alterations of exposed ex vivo whole blood were also evaluated using scanning electron microscopy and thromboelastography® (TEG), respectively. Cu, alone and in combination with Mn and/or Hg, induced hydroxyl radical formation and reduced GSH levels. Ex vivo exposure caused deformation of erythrocytes and accelerated platelet activation especially for Cu, alone and in combination, with Mn. Reduction in the lysis potential of the clot was also observed for all combinations, especially Cu in combination with Hg as well as Mn alone. Although the TEG findings were not statistically significant, the trends indicate that the exposure to these metals, alone and in combination, adversely affects thrombus formation in ex vivo blood, thereby potentially increasing the risk in exposed individuals for thrombosis.
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Affiliation(s)
- M J van Rensburg
- 1 Department of Anatomy, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - M van Rooy
- 2 Department of Physiology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - M J Bester
- 1 Department of Anatomy, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - J C Serem
- 1 Department of Anatomy, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - C Venter
- 1 Department of Anatomy, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - H M Oberholzer
- 1 Department of Anatomy, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
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Pardau MD, Pereira ASP, Apostolides Z, Serem JC, Bester MJ. Antioxidant and anti-inflammatory properties of Ilex guayusa tea preparations: a comparison to Camellia sinensis teas. Food Funct 2018; 8:4601-4610. [PMID: 29134218 DOI: 10.1039/c7fo01067b] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Ilex guayusa tea preparations are now commercially available as Runa tea. Little is known regarding the antioxidant and anti-inflammatory bioactivities of this tea. The I. guayusa teas had a total polyphenolic content between 54.39 and 67.23 mg GAE per g dry mass and peroxyl radical scavenging capacities between 1773.41 and 2019 μmol TE per g dry mass, nearly half of that for the Camellia sinensis teas. The I. guayusa teas afforded 60-80% protection from oxidative stress in the Caco-2 cellular antioxidant assay, comparable to the C. sinensis teas. The anti-inflammatory activity in lipopolysaccharide-stimulated RAW 264.7 cells of I. guayusa teas was similarly comparable to the C. sinensis teas with nitric oxide production reduced by 10-30%. Major compounds identified by mass spectrometry were the phenolic mono- and dicaffeoylquinic acid derivatives. I. guayusa teas are a good source of dietary phenolic compounds with cellular antioxidant and anti-inflammatory properties.
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Affiliation(s)
- Madelein D Pardau
- Department of Anatomy, Faculty of Health Sciences, University of Pretoria, South Africa.
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16
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Apea-Bah FB, Serem JC, Bester MJ, Duodu KG. Phenolic composition and antioxidant properties of koose, a deep-fat fried cowpea cake. Food Chem 2017; 237:247-256. [PMID: 28763993 DOI: 10.1016/j.foodchem.2017.05.109] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Revised: 05/02/2017] [Accepted: 05/21/2017] [Indexed: 11/30/2022]
Affiliation(s)
- Franklin B Apea-Bah
- Department of Food Science, Institute for Food, Nutrition and Well-being, University of Pretoria, Private Bag X20, Hatfield 0028, Pretoria, South Africa; Biotechnology and Nuclear Agriculture Research Institute, Ghana Atomic Energy Commission, P.O. Box LG 80, Legon, Accra, Ghana.
| | - June C Serem
- Department of Anatomy, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Arcadia 0007, Pretoria, South Africa.
| | - Megan J Bester
- Department of Anatomy, Faculty of Health Sciences, University of Pretoria, Private Bag X323, Arcadia 0007, Pretoria, South Africa.
| | - Kwaku G Duodu
- Department of Food Science, Institute for Food, Nutrition and Well-being, University of Pretoria, Private Bag X20, Hatfield 0028, Pretoria, South Africa.
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Malan M, Serem JC, Bester MJ, Neitz AWH, Gaspar ARM. Anti-inflammatory and anti-endotoxin properties of peptides derived from the carboxy-terminal region of a defensin from the tick Ornithodoros savignyi. J Pept Sci 2015; 22:43-51. [PMID: 26662999 DOI: 10.1002/psc.2838] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 10/27/2015] [Accepted: 10/28/2015] [Indexed: 12/18/2022]
Abstract
Antimicrobial peptides are small cationic peptides that possess a large spectrum of bioactivities, including antimicrobial, anti-inflammatory and antioxidant activities. Several antimicrobial peptides are known to inhibit lipopolysaccharide (LPS)-induced inflammation in vitro and to protect animals from sepsis. In this study, the cellular anti-inflammatory and anti-endotoxin activities of Os and Os-C, peptides derived from the carboxy-terminal of a tick defensin, were investigated. Both Os and Os-C were found to bind LPS in vitro, albeit to a lesser extent than polymyxin B and melittin, known endotoxin-binding peptides. Binding to LPS was found to reduce the bactericidal activity of Os and Os-C against Escherichia coli confirming the affinity of both peptides for LPS. At a concentration of 25 µM, the nitric oxide (NO) scavenging activity of Os was higher than glutathione, a known NO scavenger. In contrast, Os-C showed no scavenging activity. Os and Os-C inhibited LPS/IFN-γ induced NO and TNF-α production in RAW 264.7 cells in a concentration-dependent manner, with no cellular toxicity even at a concentration of 100 µM. Although inhibition of NO and TNF-α secretion was more pronounced for melittin and polymyxin B, significant cytotoxicity was observed at concentrations of 1.56 µM and 25 µM for melittin and polymyxin B, respectively. In addition, Os, Os-C and glutathione protected RAW 264.7 cells from oxidative damage at concentrations as low as 25 µM. This study identified that besides previously reported antibacterial activity of Os and Os-C, both peptides have in addition anti-inflammatory and anti-endotoxin properties.
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Affiliation(s)
- Melissa Malan
- Department of Biochemistry, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, 0002, South Africa
| | - June C Serem
- Department of Anatomy, Faculty of Health Sciences, University of Pretoria, Pretoria, 0002, South Africa
| | - Megan J Bester
- Department of Anatomy, Faculty of Health Sciences, University of Pretoria, Pretoria, 0002, South Africa
| | - Albert W H Neitz
- Department of Biochemistry, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, 0002, South Africa
| | - Anabella R M Gaspar
- Department of Biochemistry, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, 0002, South Africa
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