Apollinaire Tsopmo | Carleton University (original) (raw)

Papers by Apollinaire Tsopmo

Scientific Reports, Oct 25, 2019

Bioprocessing of common pulses changed seed microstructures, and improved dipeptidyl peptidase-iV... more Bioprocessing of common pulses changed seed microstructures, and improved dipeptidyl peptidase-iV and α-glucosidase inhibitory activities elisa Di Stefano 1,2 , Apollinaire tsopmo 3 , teresa oliviero 2 , Vincenzo fogliano 2 & chibuike c. Udenigwe 1,4* Type 2 diabetes mellitus (T2DM) is a leading cause of death globally. T2DM patients experience glucose intolerance, and inhibitors of dipeptidyl peptidase IV (DPP-IV) and α-glucosidase are used as drugs for T2DM management. DPP-IV and α-glucosidase inhibitors are also naturally contained in foods, but their potency can be affected by the food matrix and processing methods. In this study, germination and solid-state fermentation (SSF) were used to alter pulse seed microstructures, to convert compounds into more bioactive forms, and to improve their bioaccessibility. Germination substantially modified the seed microstructure, protein digestibility, contents and profiles of phenolic compounds in all the pulses. it also increased Dpp-iV and α-glucosidase inhibitory activities in chickpeas, faba beans and yellow peas. compared to germination, SSf with Lactobacillus plantarum changed the content and the profile of phenolic compounds mainly in yellow peas and green lentils because of greater disruption of the seed cell wall. In the same pulses, heat treatment and SSF of flour increased DPP-IV and α-glucosidase inhibitory activities. the results of this study suggest that germination and SSf with L. plantarum are effective and simple methods for modulating phenolic and protein profiles of common pulses and improve the action on Dpp-iV and α-glucosidase.

Heterocyclic Communications, 2023

The present work describes the synthesis, characterization, and evaluation of the antibacterial a... more The present work describes the synthesis, characterization, and evaluation of the antibacterial activity of a new poly azo compound resulting from the coupling of a previously reported N-arylsuccinimid precursor 5 with the diazonium ion of aniline. This azo compound was characterized using its physical, elemental, and 1D and 2D spectroscopic data. The novel azo compound 7 (minimum inhibitory concentration [MIC] = 16-32 μg/mL) showed higher antibacterial activity than its precursor 5 (MIC = 32-64 μg/mL), although it was low compared to the reference drug ciprofloxacin (MIC = 0.5-4 μg/mL).

Proceedings of the Virtual 2021 AOCS Annual Meeting & Expo, May 3, 2021

Food Chemistry, Feb 1, 2023

Phytoprotection, Jun 28, 2010

Tous droits réservés © La société de protection des plantes du Québec, 2009 Ce document est proté... more Tous droits réservés © La société de protection des plantes du Québec, 2009 Ce document est protégé par la loi sur le droit d'auteur. L'utilisation des services d'Érudit (y compris la reproduction) est assujettie à sa politique d'utilisation que vous pouvez consulter en ligne.

Journal of Chemistry, 2016

The aim of this study was to determine pepsin hydrolysis conditions to produce digested oat bran ... more The aim of this study was to determine pepsin hydrolysis conditions to produce digested oat bran proteins with higher radical scavenging activities and separate and identify peptides. Isolated proteins were then digested with different concentrations of pepsin and incubation times. Hydrolysates produced with 1 : 30 enzyme substrate (E/S) ratio and 2 h possessed the highest peroxyl radical scavenging activity, 608 ± 17 M TE/g (compared to 456-474 M TE/g for other digests), and was therefore subsequently fractionated into eight fractions (F1-F8) by high performance liquid chromatography (HPLC). F1 and F2 had little activity because of their low protein contents. Activities of F3-F8 were 447-874 M TE/g, 20-36%, and 10-14% in the peroxyl, superoxide anion, and hydroxyl radical tests, respectively. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to identify a total of fifty peptides that may have contributed to the activity of F3, a fraction that better scavenged radicals.

Natural product chemistry is a main research area in Cameroon, as well as for the division of Bio... more Natural product chemistry is a main research area in Cameroon, as well as for the division of Bioorganic Chemistry at Lund Institute of Technology. A review of the results obtained recently with Cameroonian medicinal plants shows that a large number of compounds, many with complex structures, have been isolated and characterised, and the work presented in this thesis is part of this effort. Based on empirical, ethnodietary, and ethnomedicinal information obtained from medicine men who use the plants to treat various diseases, several species were collected for study. Extraction, fractionation and purification using various chromatographic techniques led to the isolation and characterisation of a large number of compounds including several novel derivatives. Structure elucidation was achieved by a combination of spectroscopic techniques (NMR, UV, IR, MS). Biological tests performed on some of the isolated compounds showed some promising results. Sesquiterpenes obtained from Reneilmia cincinnata were tested against two Plasmodium falciparum clones; the Indochina W-2 clone, resistant to chloroquine, pyrimethamine, sulfadoxine, and quinine; and the Sierra Leone D-6 resistant to mefloquine. Plasmodium species are parasites that cause life-threatening diseases, four related species, P. falciparum, P. malariae, P. ovale, and P. vivax, are responsible for human malaria. P. falciparum, the most virulent malaria parasite, is responsible for more than one million deaths per year while hundreds of millions of cases of malaria occur annually. R. cincinnata was identified in a preliminary screening as a potential antimalarial plant. The isolated sesquiterpenes were then tested against the most virulent parasite. Inhibition concentrations (IC50) of the range 1.5-1.6 ug/ml for D-6 and 1.9-31.9 ug/ml for W-2 were determined. Similar activities were noted with diarylheptanoids isolated from Aframomum letestuianum when tested against three major strains of Trypanosoma brucei, a causative agent of African trypanosomiasis or sleeping sickness. The three strains were Lab 110 EATRO, a drug sensitive strain of Trypanosoma brucei brucei; KETRI 243, an uncloned clinical isolate of Trypanosoma brucei rhodesiense; and KETRI 243 As-10-3 a pentamidine and melarsol-resistant clone of Trypanosoma brucei rhodesiense. In addition, chemical studies were performed with aframodial, an alpha,beta-unsaturated dialdehyde and major component of some Aframomum species. It turned out to be very reactive toward amines and amino acids, and several pyrrole and oxazolidine derivatives were prepared. (Less)

Royal Society of Chemistry eBooks, 2021

Research Square (Research Square), Mar 26, 2021

Background : The present study describes for the rst time, the synthesis of two pyrrolidine-2,5-d... more Background : The present study describes for the rst time, the synthesis of two pyrrolidine-2,5-dione derivatives that belong to Narylsuccinimid (compound 5) and of azo (compound 8) class of molecules. The initial step of the reaction involved the preparation of the intermediate compound (9R, 10R, 11S)-9, 10-dihydro-9, 10-[3, 4] furanoanthracene-12, 14-dione (3) through [4 + 2]-cycloaddition between anthracene and maleic anhydride in xylene which was then condensed with para-hydroxyaniline to give compound 5. Subsequent coupling of 5 with the aryldiazonium ion of aniline gave compound 8. Results: These compounds were characterized by their physical, elemental, and spectroscopic data. 2D-NMR (COSY, HSQC, and HMBC) techniques were used to complete the elucidation of their structures. Compounds 5 (MIC = 32-128µg/mL) and 8 (MIC = 16-256µg/mL) along with the precursor (MIC = 64-128µg/mL) displayed moderate antimicrobial activities against selected bacterial and fungal species when compared with those of nystatin (MIC = 0.50-2µg/mL) and cipro oxacin (MIC = 0.50-16µg/mL) used as reference drugs. Conclusion: The results of biological tests showed that compounds 3, 5, 8 possess antimicrobial activities. Although being less active than the compound taken as a reference, the azo compound has better antibacterial activity than the other two compounds especially on Staphylococcus aureus, V. choleraeSG24 and, V. choleraeCO6 strains. These results show that the azo function (N = N) is indeed a pharmacophore and would be responsible for the biological activity in the azo molecules.

Foods, May 11, 2019

The objective of this work was to find out how the method to extract proteins and subsequent enzy... more The objective of this work was to find out how the method to extract proteins and subsequent enzymatic hydrolysis affect the ability of hepatic cells to resist oxidative stress. Proteins were isolated from oat brans in the presence of Cellulase (CPI) or Viscozyme (VPI). Four protein hydrolysates were produced from CPI and four others from VPI when they treated with Alcalase, Flavourzyme, Papain, or Protamex. Apart from CPI-Papain that reduced the viability of cell by 20%, no other hydrolysate was cytotoxic in the hepatic HepG2 cells. In the cytoprotection test, VPI-Papain and VPI-Flavourzyme fully prevented the damage due to peroxyl radical while CPI-Papain and CPI-Alcalase enhanced the cellular damage. Cells treated with VPI-hydrolysates reduced intracellular reactive oxygen species (ROS) by 20-40% and, also increased the intracellular concentration of glutathione, compared to CPI-hydrolysates. In antioxidant enzyme assays, although all hydrolysates enhanced the activity of both superoxide dismutase and catalase by up to 2-and 3.4-fold, respectively relative the control cells, the largest increase was due to VPI-Papain and VPI-Flavourzyme hydrolysates. In caspase-3 assays, hydrolysates with reduced ROS or enhanced antioxidant enzyme activities were able to reduce the activity of the pro-apoptotic enzyme, caspase-3 indicating that they prevented oxidative stress-induced cell death.

Food Chemistry, Jul 1, 2018

This study evaluated for the first time hydroxyl radical scavenging and chromium VI (Cr(VI) reduc... more This study evaluated for the first time hydroxyl radical scavenging and chromium VI (Cr(VI) reducing properties of four cysteine containing peptides derived from rye secalin. Density functional theory (DFT) calculations were performed to determine the antioxidation mechanism and the effect of residue order. The peptides tested (CQV, QCA, QVC, QCV) were obtained from in silico digestion of rye secalin with Proteinase-K and selected because they contained thiol, a known redox functional group. It was found that at pH 7.4, CQV had the highest Cr(VI) reducing activity (76 %) followed by QCA and QCV (30.8 and 25.5 %, respectively). QVC and GSH had similar but lower activities (11.3 and 11.7%). At pH 3.0, CQV and QCV were found to be less active than the other two peptides. In the hydroxyl radical scavenging assay, CQV had the highest activity with 28.9 ± 1.3 % inhibition of the formation of HO• radicals compared to 19.0-13.6% for other peptides. The highest reactivity of CQV with Cr(VI) under neutral conditions was due to the proximity of thiol and amine of glutamine that allowed the formation of a transition state that facilitated the reduction. Cysteine at the N-terminal was important for both the reduction of chromium (pH 7.4) and the HO• scavenging activity because the S-H bond at that position was found by the DFT analysis to have the lowest bond dissociation energy.

Trends in Food Science and Technology, Jul 1, 2020

Abstract Background Proteins are essential macronutrients of the human diet. Currently, major die... more Abstract Background Proteins are essential macronutrients of the human diet. Currently, major dietary sources in developed countries are of animal origin. However, the association of red meat consumption to the increased risks of some health conditions and its unsustainable pressure on the environment have increased the interest in plant proteins as healthier and sustainable alternatives. Of these, legumes have a great potential, but part of their proteins are indigestible due to interaction with other components such as phytate and polyphenols. As such, the quest to improve protein accessibility has become of interest to many researchers. Germination is proposed to be a bioprocess method to improve protein digestibility and protein biological properties. Scope and approach This review discusses the importance of plant proteins and the hindrance of protein digestibility. This paper also highlights the role of germination in the deactivation of antinutritional factors, hydrolysis of indigestible proteins, and improvement of properties and content of proteins of different legume seeds. Key findings and conclusions Protein digestibility is dependent on the nature of antinutritional factors (e.g. trypsin inhibitors and phytate) in the food matrix. Germination represses the activity of trypsin inhibitors and removes the phytate-related inhibition through hydrolysis. Protein content increases in germinated seeds when compared to non-germinated ones, suggesting that proteins were either hydrolysed or dissociated from antinutritional factors. Germination seems like an adequate bioprocessing method to improve the content and nutritional quality of legume seed proteins.

ChemInform, May 20, 2010

ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Arkivoc, Feb 11, 2020

The coupling reactions of diazotized thienocoumarin derivatives with p-acetaminophen, salicylic a... more The coupling reactions of diazotized thienocoumarin derivatives with p-acetaminophen, salicylic acid and acetylsalicylic acid gave four products in which the benzene ring of the phenolic reagents were primarily substituted by two 3-diazenyl-4H-thieno[3,4-c]chromen-4-one or 3-diazenyl-4-imino-4H-thieno[3,4c]chromene moieties. The newly prepared azo dyes were fully characterized based on their analytical and spectroscopic data. The electrochemical analysis of the novel azo dyes carried out on a glassy carbon electrode unequivocally further confirmed the assigned structures. The synthesized compounds tested for their antimicrobial activity using broth microdilution method, showed good activities.

Journal of the American Oil Chemists' Society, Jul 23, 2018

The aim of this work was to study the structure and functionalities of proteins from commercial o... more The aim of this work was to study the structure and functionalities of proteins from commercial oat milling fractions. Protein isolates obtained from fine (FB), medium (MB), and low (LB) oat brans, and whole oat groat flour (WF) contained 75.0–97.1% proteins. However, the protein content of the products of 15% (15% high glucan [15HG]) and 20% (20% high glucan [20HG]) HG flours were four fold less because of their high carbohydrate contents (~75%). There was no apparent difference in molecular weights of the polypeptides (20, 35, 60, and 150 kDa) contained in these protein products. Protein profiling using mass spectrometry showed that avenin was not detected in FB and MB because of their relatively high concentrations of 11–12S globulins. Secondary structural features of the molecules and microstructure details of the gelled proteins were similar for proteins from FB, MB, LB, and WF, but different from those of 15HG and 20HG. Similarly, these differences in the structural features of proteins of the milling fractions were reflected in their water‐holding capacity and the solubility properties of the protein products.

Analytical and Bioanalytical Chemistry, Mar 7, 2018

There are emerging advancements in the strategies used for the discovery and development of food-... more There are emerging advancements in the strategies used for the discovery and development of food-derived bioactive peptides because of their multiple food and health applications. Bioinformatics and peptidomics are two computational and analytical techniques that have the potential to speed up the development of bioactive peptides from bench to market. Structure-activity relationships observed in peptides form the basis for bioinformatics and in silico prediction of bioactive sequences encrypted in food proteins. Peptidomics, on the other hand, relies on Bhyphenated^(liquid chromatography-mass spectrometry-based) techniques for the detection, profiling, and quantitation of peptides. Together, bioinformatics and peptidomics approaches provide a low-cost and effective means of predicting, profiling, and screening bioactive protein hydrolysates and peptides from food. This article discuses the basis, strengths, and limitations of bioinformatics and peptidomics approaches currently used for the discovery and analysis of food-derived bioactive peptides.

Antioxidants, Jun 26, 2020

The aim of this work was to determine the physicochemical and biological activities of hydrolyzed... more The aim of this work was to determine the physicochemical and biological activities of hydrolyzed proteins from sonicated oat brans. In addition to the control bran sample, two types of pre-treatment procedures-namely, ultrasonic bath and probe-type sonication-were performed to extract proteins, followed by hydrolysis with various proteases. Physicochemical analyses showed that Flavourzyme-hydrolysates had greater amounts of aromatic amino acids, Papain-hydrolysates low surface charges (−0.78 to −1.32 mV) compared to the others (−3.67 to −9.17 mV), and Alcalase-hydrolysates a higher surface hydrophobicity. The hydrolysates had good radical scavenging activities but, as the ultrasonic pre-treatment of the brans showed, in certain cases there was a reduction in activities of up to 22% for ROO • and HO • and 15% for O 2 •− radicals. In anti-diabetic tests, the maximum inhibition of α-amylase was 31.8%, while that of dipeptidyl peptidase-4 was 53.6%. In addition, the secretion of glucagon-like peptide-1 in NCI-H716 cells was enhanced by 11.5% in the presence of hydrolysates.

Journal of Food Biochemistry, May 16, 2021

This work aimed to determine the antioxidant properties of identified hydrolyzed oat proteins and... more This work aimed to determine the antioxidant properties of identified hydrolyzed oat proteins and peptides, and their capacity to inhibit lipase and α-amylase. The protein hydrolysates retarded the oxidation of peanut oil by reducing peroxide values (up to 2.5-fold), relative to the control oil. Of the five tested peptides, P1 (YFDEQNEQFR), P3 (SPFWNINAH), and P4 (NINAHSVVY) significantly reduced the oxidation of linoleic acid. In the enzyme assays, P3 was the best lipase inhibitor (IC50 85.4 ± 3 µM) while P1 was the most potent inhibitor of α-amylase (IC50 37.5 ± 1.1 µM). The structure-activity relationship assessed using the CABS-dock computational model predicted that interactions between peptides and pancreatic lipase residues of Ser153 , His264 , and Asp177 were important for the inhibition. In the case of α-amylase, interactions with residues of the active sites (Asp197 , Glu233 , and Asp300 ), but not those of calcium- or chloride-binding domains, were important for the inhibition. PRACTICAL APPLICATIONS: In recent years, there have been many studies focussing on isolating multifunctional peptides from food and food waste with antioxidant and bioactivity potential to promote human health. Some of these antioxidant peptides have been found to be effective to prevent diseases and complications such as hypertension, cardiovascular disease, cancer, diabetes, and obesity. The peptides studied in this work showed a great potential to prevent oxidation in a lipid system and demonstrated a significant ability to reduce the enzymatic activity of lipase and α-amylase. These enzymes contribute to the digestion of fat and carbohydrate, and their inhibition can reduce the absorption of these macronutrients and make them a great target for designing antioxidant and anti-obesity compounds. With the multifunctional activity of oat bran-derived peptides, it is proposed that these peptides can be used in food formulations due to their antioxidant and potential anti-obesity properties.