Bioactivities of Garcinia kola enzymatic hydrolysates at different enzyme-substrate ratios

Natural products, such as enzymatic hydrolysates and bioactive peptides from dietary sources, are safe alternatives to synthetic compounds linked to various deleterious effects. The purpose of this study is to determine the in vitro bioactivities (antioxidant and anti-inflammatory activities) of Garcinia kola seeds enzymatic hydrolysates (GKPHs) at different enzyme (pepsin)-substrate ratios. G. kola protein, isolated by alkaline solubilization and acid precipitation, was hydrolyzed with pepsin at varying enzyme-substrate (E:S) ratios. The antioxidant parameters investigated include 1,1-diphenyl-2-picrylhydrazyl (DPPH)-radical scavenging, hydrogen peroxide scavenging and ferrous ion (Fe²⁺) chelating activities. For anti-inflammatory properties, membrane stabilization and protein denaturation activities tests were used. GKPH produced at 1:32 had the highest degree of hydrolysis (66.27 ± 4.21%). All GKPHs had excellent in vitro anti-inflammatory properties. However, only enzymatic hydrolysates produced at 1:16 (E:S) ratio chelated iron (II) and as well had the highest percentage hemolysis inhibition of 84.45 ± 0.007%, percentage protein denaturation inhibition of 53.36 ± 0.01% at maximum concentration and exhibited highest DPPH scavenging activity (87.24 ± 0.10%). The enzymatic hydrolysates had excellent solubility, emulsifying and foaming properties. It could be deduced from this study that pepsin at a ratio of 1:16 of G. kola protein produced the most effective enzymatic hydrolysates in terms of their antioxidant and anti-inflammatory activities. G. kola pepsin enzymatic hydrolysates, thus, have potential in development as functional foods and as therapeutics pharmaceutical industries in the management of diseases associated with oxidative stress and inflammation owing to their excellent functional, antioxidant and anti-inflammatory properties.

Functional Bioactivities of Soluble Seed Proteins from Two Leguminous Seeds

Storage proteins from Sphenostylis stenocarpa and Phaseolus lunatus were fractionated, and their in vitro bioactivities were investigated. Albumin, globulin, prolamin, and glutelin constituents of the respective seeds were successively fractionated using the modified Osborne method. Phenylmethylsulfonyl fluoride (1 mM) was used as a protease inhibitor. The antioxidant, anti-inflammatory, and acetylcholinesterase-inhibitory activities of the protein fractions were evaluated using different appropriate techniques. Globulin was the predominant fraction, with a yield of 43.21±0.01% and 48.19±0.03% for S. stenocarpa and P. lunatus, respectively, whereas prolamin was not detected in both seeds. The protein fraction markedly scavenges hydroxyl radicals, nitric oxide radicals, and 2,2-diphenyl-1-picryldydrazyl radicals with concomitant high free radical-reducing power. Albumin and globulin fractions elicited the highest acetylcholinesterase-inhibitory potential of 48.75% and 49.75%, respectively, indicating their great application potential in managing neurodegenerative diseases. In this study, the albumin, globulin, and glutelin fractions of these underutilized legumes showed great analeptic bioactivities, which could be utilized as health-promoting dietary supplements/products.

Antimicrobial Activities and Phylogenetic Study of Erythrina senegalensis DC (Fabaceae) Seed lectin

Erythrina senegalensis (Fabaceae) have been traditionally used in the treatment of microbial ailments, and the specific agent mediating its efficacy has been investigated in several studies. In this study, the antimicrobial activity of purified E. senegalensis lectin (ESL) was analyzed. The phylogenetic relationship of the gene encoding lectin with other legume lectins was also established to investigate their evolutionary relationship via comparative genomics. Antimicrobial activity of ESL against selected pathogenic bacteria and fungi isolates was evaluated by the agar well diffusion method, using fluconazole (1 mg/ml) and streptomycin (1 mg/ml) as positive controls for fungi and bacteria sensitivity, respectively. Potent antimicrobial activity of ESL against Erwinia carotovora, Pseudomonas aeruginosa, Klebsiella pneumonia, Staphylococcus aureus, Aspergillus niger, Penicillium camemberti, and Scopulariopsis brevicaulis was observed, with inhibition zones ranging from 18 to 24 mm. Minimum inhibitory concentrations of ESL ranged between 50 and 400 μg/ml. Primer-directed polymerase chain reaction of E. senegalensis genomic DNA detected a 465-bp lectin gene with an open reading frame encoding a 134-amino acid polypeptide. The obtained nucleotide sequence of the ESL gene shared high sequence homology: 100, 100, and 98.18% with Erythrina crista-galli, Erythrina corallodendron, and Erythrina variegata lectin genes, respectively, suggesting that the divergence of Erythrina lectins might follow species evolution. This study concluded that ESL could be used to develop lectin-based antimicrobials, which could find applications in the agricultural and health sectors.

Antinociceptive effects of Treculia africana decne (african breadfruit) seed lectin in Wistar rats

The aim: The use of synthetic compounds to treat many diseases must be strictly controlled due to their potential health hazards. Hence, there is a need to search for natural products to serve as safe alternatives to synthetic products. This study investigated the antinociceptive effects and anti-inflammatory activities of Treculia africana seed lectin. Materials and methods: Lectins were purified from Treculia africana seeds using ion exchange and size-exclusion chromatography. The antinociceptive activity of the lectin was assessed in Wistar rats using abdominal writhing and paw-licking tests induced by acetic acid and formalin, respectively. Anti-inflammatory activity was assessed using carrageenan-induced paw oedema. Results: Treculia africana seed lectins at 10 mg/kg (p.o.) produced sedation, reduced ambulation, reduced response to touch, analgesia, and decreased defecation in experimental animals. Administration of Treculia africana seed lectin (1 mg/kg and 10 mg/kg) in experimental animals significantly reduced (P < 0.05) acetic acid-induced muscular writhing in a dose-dependent manner with 23.88 and 36.80 per cent inhibition, respectively. Both early and late phases of formalin-induced nociception were significantly inhibited (P < 0.001) by the lectin at all doses (0.1, 1.0 and 10.0 mg/kg), comparably with the standard drug, diclofenac sodium. At 10 mg/kg, T. africana lectin caused a 69.12 % and 65.55 % reduction in both early and late phases of formalin-induced paw licking. Treculia africana lectin also significantly brought about a reduction (P < 0.05) in inflammation induced by sub-plantar injection of carrageenan as measured by a decrease in paw swollenness. Conclusion: The study showed that Treculia africana lectin possesses antinociceptive and anti-inflammatory properties and can potentially be employed therapeutics to ameliorate pain and inflammation

Efficacy of selected Nigerian tropical plants in the treatment of COVID-19: in silico and in vitro investigations

The whole world is still challenged with COVID-19 pandemic caused by Coronavirus-2 (SARS-CoV-2) which has affected millions of individuals around the globe. Although there are prophylactic vaccines being used, till now, there is ongoing research into discovery of drug candidates for total eradication of all types of coronaviruses. In this context, this study sought to investigate the inhibitory effects of six selected tropical plants against four pathogenic proteins of Coronavirus-2. The medicinal plants used in this study were selected based on their traditional applications in herbal medicine to treat COVID-19 and related symptoms. The biological activities (antioxidant, free radical scavenging, and anti-inflammatory activities) of the extracts of the plants were assessed using different standard procedures. The phytochemicals present in the extracts were identified using GCMS and further screened via in silico molecular docking. The data from this study demonstrated that the phytochemicals of the selected tropical medicinal plants displayed substantial binding affinity to the binding pockets of the four main pathogenic proteins of Coronavirus-2 indicating them as putative inhibitors of Coronavirus-2 and as potential anti-coronavirus drug candidates. The reaction between these phytocompounds and proteins of Coronavirus-2 could alter the pathophysiology of COVID-19, thus mitigating its pathogenic reactions/activities. In conclusion, phytocompounds of these plants exhibited promising binding efficiency with target proteins of SARS-COV-2. Nevertheless, in vitro and in vivo studies are important to potentiate these findings. Other drug techniques or models are vital to elucidate their compatibility and usage as adjuvants in vaccine development against the highly contagious COVID-19 infection.

Purification and erythrocyte-membrane perturbing activity of a ketose-specific lectin from Moringa oleifera seeds

This study purified a hemagglutinating protein (MoL) from Moringa oleifera seed, and investigated its hemolytic activity. Molecular weight and stability of MoL were also determined. Modification of some amino acid residues was carried out and the effect on MoL hemagglutinating activity determined. Other investigated parameters are the effects of temperature, concentration, incubation period, pH, and sugars on the protein's hemagglutinating and hemolytic activities. The native and subunit molecular weights were estimated as 30 and 27.5 kDa respectively. Hemagglutinating activity of MoL was slightly inhibited by fructose and sucrose, stable at temperature up to 90°C and within pH range of 2-4. Modification of tryptophan and arginine residues resulted in partial loss of hemagglutinating activity. The hemolytic activity of MoL was concentration, temperature, pH, and time-dependent. The study concluded that MoL showed hemolytic (membrane-perturbing) activity in moderate acidic conditions. This suggests its potential exploitation in improved intracellular delivery of bioactive compounds.

Physicochemical, enzymatic and molecular characterisation of the storage protein of aerial tuber, Dioscorea bulbifera Linn

BACKGROUND

The storage protein of the aerial tuber of Dioscorea bulbifera was purified and its physicochemical, enzymatic and molecular properties determined with a view to comparing its functionality and genetic relatedness with other storage proteins.

RESULTS

The purified protein had molecular weight of 21 kDa. The protein showed carbonic anhydrase, trypsin inhibitory, dehydroascorbate reductase and monodehydroascorbate reductase activities. Amplifications with polymerase chain reactions resulted in the detection of two genes encoding the storage protein. The deduced amino acid sequence of the shorter and larger genes had homologies with the storage proteins of members of the Dioscorea family.

CONCLUSION

The study concluded that the storage protein of the aerial tuber of D. bulbifera had similar properties with those of other Dioscorea species and may be suitable for development as functional food.

ISOLATION, CHARACTERIZATION AND IMMUNOCHEMICAL STUDIES ON FIBROUS PROTEINS FROM COWRY SHELL (CYPRAEA MONETA, LINNAEUS)

BACKGROUND

Biomaterials are non-drug substances used to treat, enhance or replace functions of body tissues or organs. Natural sources of biomaterials have recently become the focus of several research activities. Cowry shell constitutes one of the most promising natural sources of biomaterials because of its chemical stability, biodegradability and biocompatibility in the body. However, its applications may be limited due to immunogenic and toxic responses that may occur following implantation, hence this study.

MATERIALS AND METHODS

Crude fibrous protein extracted with citrate buffer from pulverised cowry shells (Cypraea moneta (L)), was resolved into two components (CSP1 and CSP2) by gel filtration. Immunological studies were performed with antisera obtained from rabbits by double immunodiffusion and immunoelectrophoresis techniques. Mice treated with the proteins were observed for signs of toxicity and their liver, kidney, lungs and spleen were processed histologically.

RESULTS

The native molecular weight of CSP1 and CSP2 determined by gel filtration were 91kDa and 33kDa respectively. CSP1 and CSP2 displayed single bands on SDS-PAGE with subunit molecular weight values of 19kDa and 19.5kDa respectively. Antisera obtained from rabbits immunised with the crude citrate buffer extracts precipitated the antigen in double immunodiffusion tests. Histopathological examinations revealed a dose-dependent damaging effect of the shell proteins on liver, kidney, lung and spleen tissues of the treated mice.

CONCLUSION

This study showed that cowry shells contain fibrous proteins which are immunogenic and toxic in mice at relatively high concentrations, causing visible organ damage without concurrent physical manifestations.

Physicochemical properties and acute toxicity studies of a lectin from the saline extract of the fruiting bodies of the shiitake mushroom, Lentinula edodes (Berk)

A lectin (LEL) was isolated from the fresh fruiting bodies of the shiitake mushroom Lentinula edodes by a combination of gel filtration chromatography on Sephadex G-150 and affinity chromatography on an N-acetyl-Dgalactosamine-Sepharose 4B column. Its molecular mass, as determined by gel filtration, was estimated to be 71, 000 Daltons and its structure is homotetrameric with subunit molecular weight of approximately 18,000 Daltons. LEL agglutinated non-specifically red blood cells from the human ABO system as well as rabbit erythrocytes and in haemagglutination inhibition assays, exhibited sugar-binding specificity toward N-acetyl-D-galactosamine. EDTA had no inhibitory effect on its haemagglutinating activity, which was stable up to 70°C and was not affected by changes in pH. The lectin had no covalently-linked carbohydrate and amino acid composition analysis revealed that it contained 124 amino acid residues and was rich in tyrosine, proline, phenylalanine, arginine, glutamic acid and cysteine. LEL did not cause mortality neither was it observed to alter the morphology of key organs when administered intraperitoneally at concentrations up to 10,000 mg kg(-1) body weight of mice.

A comparative study of the plasma level of arginase and rhodanese in smokers and non-smokers

The purpose of this investigation was to determine and compare the activities of arginase and rhodanese in the blood plasma of cigarette smokers and non-smokers.The activity of arginase in the blood plasma of smokers was higher than arginase activity in the non-smokers (NS), however,in the smokers with diseases (SWD), the increase was significant. The comparison between the activity of rhodanese in the SWD, smokers without diseases (SWOD) and NS blood plasma revealed a decrease in the activity of rhodanese in NS and no significant difference in the three groups with P=0.8677. This paper reported the enhancing effect of cigarette smoking could have on the disease state of smokers due to high arginase activity.

Physicochemical and kinetic characteristics of rhodanese from the liver of African catfish Clarias gariepinus Burchell in Asejire lake

Two forms of rhodanese were purified from the liver of Clarias gariepinus Burchell, designated catfish rhodanese I (cRHD I) and rhodanese II (cRHD II), by ion-exchange chromatography on a CM-Sepharose CL-6B column and gel filtration through a Sephadex G-75 column. The apparent molecular weight obtained for cRHD I and cRHD II was 34,500 +/- 707 and 36,800 +/- 283 Da, respectively. The subunit molecular weight determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis was 33,200 +/- 283 and 35,100 +/- 141 Da for cRHD I and cRHD II, respectively. Atomic absorption spectrophotometric analysis revealed that cRHD II contained a high level of iron (Fe), which presumably was responsible for the brownish colour of the preparation. In contrast, no Fe was identified in cRHD I, and its preparation was colourless. Further characterization of cRHD II gave true Michaelis-Menten constant (K(m)) values of 25.40 +/- 1.70 and 18.60 +/- 1.68 mM for KCN and Na(2)S(2)O(3), respectively, an optimum pH of 6.5 and an optimum temperature of 40 degrees C. The Arrhenius plot of the effects of temperature on the reaction rate consisted of two linear segments with a break occurring at 40 degrees C. The apparent activation energy values from these slopes were 7.3 and 72.9 kcal/mol. Inhibition studies on the cRHD II enzyme showed that the activity of the enzyme was not affected by Mn(2+), Co(2+), Sn(2+), Ni(2+) and NH(4) (+), but Zn(2+) inhibited the enzyme considerably.

Expression of bilitranslocase in the vascular endothelium and its function as a flavonoid transporter

AIMS

Ingestion of flavonoid-rich beverages acutely affects endothelial function, causing vasodilation. This effect might be dependent on flavonoid transport into the endothelium. We investigated flavonoid uptake into vascular endothelial cells and whether this was mediated by bilitranslocase (TC 2.A.65.1.1), a bilirubin-specific membrane carrier that also transports various dietary flavonoids.

METHODS AND RESULTS

Human and rat aortic primary endothelial cells as well as Ea.hy 926 cells were found to express bilitranslocase, as assessed by immunocytochemistry and immunoblotting analysis using anti-sequence bilitranslocase antibodies targeting two distinct extracellular epitopes of the carrier. Bilitranslocase function was tested by measuring the rate of bromosulfophthalein (a standard bilitranslocase transport substrate) uptake into endothelial cells and was inhibited not only by bilitranslocase antibodies but also by quercetin (a flavonol). Similarly, uptake of both quercetin and malvidin 3-glucoside (an anthocyanin) were also found to be antibody-inhibited. Quercetin uptake into cells was inhibited by bilirubin, suggesting flavonoid uptake via a membrane pathway shared with bilirubin.

CONCLUSION

The uptake of some flavonoids into the vascular endothelium occurs via the bilirubin-specific membrane transporter bilitranslocase. This offers new insights into the vascular effects of both flavonoids and bilirubin.