Dominic Agyei

Industrial-scale manufacturing of pharmaceutical-grade bioactive peptides

Recent studies have shown that most peptide sequences encrypted in food proteins confer bioactive properties after release by enzymatic hydrolysis. Such bioactivities, which include antithrombotic, antihypertensive, immunomodulatory and antioxidant properties, are among the traits that are of biological significance in therapeutic products. Bioactive peptides could therefore serve as potential therapeutic agents. Moreover, research has shown that peptide therapeutics are toxicologically safe, and present less side effects when compared to small molecule drugs. However, the major conventional methods i.e. the synthetic and biotechnological methods used in the production of peptide therapeutics are relatively expensive. The lack of commercially-viable processes for large-scale production of peptide therapeutics has therefore been a major hindrance to the application of peptides as therapeutic aids. This paper therefore discusses the plausibility of manufacturing pharmaceutical-grade bioactive peptides from food proteins; the challenges and some implementable strategies for overcoming those challenges.

A Simple Microfluidic Chip Design for Fundamental Bioseparation

A microchip pressure-driven liquid chromatographic system with a packed column has been designed and fabricated by using poly(dimethylsiloxane) (PDMS). The liquid chromatographic column was packed with mesoporous silica beads of Ia3d space group. Separation of dyes and biopolymers was carried out to verify the performance of the chip. A mixture of dyes (fluorescein and rhodamine B) and a biopolymer mixture (10 kDa Dextran and 66 kDa BSA) were separated and the fluorescence technique was employed to detect the movement of the molecules. Fluorescein molecule was a nonretained species and rhodamine B was attached onto silica surface when dye mixture in deionized water was injected into the microchannel. The retention times for dextran molecule and BSA molecule in biopolymer separation experiment were 45 s and 120 s, respectively. Retention factor was estimated to be 3.3 for dextran and 10.4 for BSA. The selectivity was 3.2 and resolution was 10.7. Good separation of dyes and biopolymers was achieved and the chip design was verified.

Pharmaceutical applications of bioactive peptides

There is a mounting interest in the therapeutic potential of bioactive peptides which collectively present a cornucopia of bioactivities for exploitation in vivo. Bioactive peptides trigger certain functionalities such as antioxidative, antimicrobial, antihypertensive, cytomodulatory and immunomodulatory activities in the living body system. With research and development, there exists an opportunity to effectively harness these functionalities for the treatment, prevention and mitigation of different medical conditions. This critical review discusses some potential therapeutic applications of bioactive peptides in the light of advances in general biopharmaceutical production based on proteomics and genomics.

Hygienic Practices among Food Vendors in Educational Institutions in Ghana: The Case of Konongo

With the booming street food industry in the developing world there is an urgent need to ensure food vendors adhere to hygienic practices to protect public health. This study assessed the adherence to food hygiene practices by food vendors in educational institutions in Konongo, Ghana. Structured questionnaires, extensive observation and interviews were used for the study involving 60 food vendors from 20 basic schools. Attributable to the influence of school authorities and the level of in-training of food vendors, the study points out that food vendors in educational institutions generally adhered to good food hygiene practices, namely, regular medical examination (93%), protection of food from flies and dust (55%); proper serving of food (100%); good hand hygiene (63%); and the use of personal protective clothing (52%). The training of food vendors on food hygiene, instead of the level of education had a significant association (p < 0.05) with crucial food hygiene practices such as medical examination, hand hygiene and protection of food from flies and dust. Further, regulatory bodies legally mandated to efficiently monitor the activities of food vendors lacked the adequate capacity to do so. The study proposes that efforts should be geared towards developing training programmes for food vendors as well as capacity building of the stakeholders.

Carbohydrate utilization affects Lactobacillus delbrueckii subsp. lactis 313 cell-enveloped-associated proteinase production

The effect of different sugars (glucose, glycerol, maltose, galactose and lactose) on cell-membrane-associated proteinase production by Lactobacillus delbrueckii subsp. lactis 313 (LDL 313) was investigated. The experimental results showed that aside glycerol and galactose, all the other sugars supported high growth levels of LDL 313, with glucose displaying the maximum biomass concentration of 0.85 mg/mL dry cell weight for cells harvested at the mid-exponential phase of ∼12 h after inoculation. The specific proteinase yield, a measure of the rate of proteinase production relative to cell wall biosynthesis, was used to evaluate the preferential degree of proteinase metabolism as induced by the consumption of different sugar substrates by LDL 313. It was found that maltose displayed the highest specific proteinase yield of 12.59 U/mg sugar consumed. Further, molecular differences were observed in the SDS electrophoretic profile of cell surface proteins generated for the different carbon substrates. This is a preliminary study which supports the inference that different sugars stimulate the production of different cell-surface proteins with a significant effect on cell proteinase activity.

Quick and low cost immobilization of proteinases on polyesters: Comparison of lactobacilli cell-envelope proteinase and trypsin for protein degradation

Cell-envelope proteinases (CEPs) are a class of proteolytic enzymes produced by lactic acid bacteria and have several industrially relevant applications. However, soluble CEPs are economically unfavorable for such applications due to their poor stability and lack of reusability. In a quest to prepare stable biocatalysts with improved performance, CEP from Lactobacillus delbrueckii subsp. lactis 313 and trypsin (as a model enzyme) were immobilized onto nonwoven polyester fabrics in a three-step protocol including ethylenediamine activation and glutaraldehyde crosslinking. Immobilization gave protein loading yields of 21.9% (CEP) and 67.7% (trypsin) while residual activity yields were 85.6% (CEP) and 4.1% (trypsin). The activity of the immobilized enzymes was dependent on pH, but was retained at elevated temperatures (40-70 °C). An increase in Km values was observed for both enzymes after immobilization. After 70 days of storage, the immobilized CEP retained ca. 62% and 96% of initial activity when the samples were stored in a lyophilized form at -20 °C or in a buffer at 4 °C, respectively. Both immobilized CEP and trypsin were able to hydrolyze proteins such as casein, skimmed milk proteins and bovine serum albumin. This immobilization protocol can be used to prepare immobilized biocatalyst for various protein degradation processes.

Antioxidative peptides derived from food proteins

The search for natural antioxidants is an ongoing endeavour as an aid to combat the harmful effects of free radicals. Research advances in the past few decades have shown that, by controlled enzymatic hydrolysis, natural antioxidants can be produced from food proteins. In this chapter, the role of certain antioxidative peptides derived from food proteins is discussed in relation to their prospect in the prevention of oxidative stress. The molecular diversity of these food peptides is described together with their pharmacological effects and mechanisms of action in relation to antioxidation. The production of these peptides and the elucidation of their antioxidative peptides are also presented. Owing to their therapeutic potential, antioxidative peptides derived from food proteins can be incorporated as ingredients in functional foods, nutraceuticals and pharmaceuticals, where their biological activities may inhibit product oxidation or assist in the control and prevention of diseases induced by free radicals. However, further insightful research is needed to overcome certain scientific challenges and thereby increase and promote consumer acceptance of these natural antioxidants.

A Parametric Study of a Monolithic Microfluidic System for On-Chip Biomolecular Separation

A microfabricated poly(dimethylsiloxane) (PDMS) chip containing channel filled with polymer monolith has been developed for on-chip biomolecule separation. Methacrylate monolithic polymers were prepared by photo-initiated polymerization within the channel to serve as a continuous stationary phase. The monolithic polymer was functionalized with a weak anion-exchange ligand, and key parameters affecting the binding characteristics of the system were investigated. The total binding capacity was unaffected by the flow rate of the mobile phase but varied significantly with changes in ionic strength and pH of the binding buffer. The binding capacity decreased with increasing buffer ionic strength, and this is due to the limited available binding sites for protein adsorption resulting from cationic shielding effect. Similarly, the binding capacity decreased with decreasing buffer pH towards the isoelectric point of the protein. A protein mixture, BSA and ovalbumin, was used to illustrate the capacity of the methacrylate-based microfluidic chip for rapid biomolecule separation.

Deploying aptameric sensing technology for rapid pandemic monitoring

Abstract The genome of virulent strains may possess the ability to mutate by means of antigenic shift and/or antigenic drift as well as being resistant to antibiotics with time. The outbreak and spread of these virulent diseases including avian influenza (H1N1), severe acute respiratory syndrome (SARS-Corona virus), cholera (Vibrio cholera), tuberculosis (Mycobacterium tuberculosis), Ebola hemorrhagic fever (Ebola Virus) and AIDS (HIV-1) necessitate urgent attention to develop diagnostic protocols and assays for rapid detection and screening. Rapid and accurate detection of first cases with certainty will contribute significantly in preventing disease transmission and escalation to pandemic levels. As a result, there is a need to develop technologies that can meet the heavy demand of an all-embedded, inexpensive, specific and fast biosensing for the detection and screening of pathogens in active or latent forms to offer quick diagnosis and early treatments in order to avoid disease aggravation and unnecessary late treatment costs. Nucleic acid aptamers are short, single-stranded RNA or DNA sequences that can selectively bind to specific cellular and biomolecular targets. Aptamers, as new-age bioaffinity probes, have the necessary biophysical characteristics for improved pathogen detection. This article seeks to review global pandemic situations in relation to advances in pathogen detection systems. It particularly discusses aptameric biosensing and establishes application opportunities for effective pandemic monitoring. Insights into the application of continuous polymeric supports as the synthetic base for aptamer coupling to provide the needed convective mass transport for rapid screening is also presented.

Formulation of water-in-oil-in-water (W/O/W) emulsions containing trans-resveratrol

Resveratrol is a high-value bioactive polyphenolic compound with vast applications in functional foods; as such, effective and scalable delivery strategies for this compound are worthy of study. In this research, W/O/W emulsions were successfully prepared using polyglycerol polyricinoleate (PGPR) as a lipophilic emulsifier and Tween 80 as a hydrophilic emulsifier with the goal of developing biocompatible carriers to improve the bioavailability of resveratrol. The effects of the type of emulsifier, the concentration of emulsifier, the ratio of the oil phase to the internal water phase, and homogeneous pressure on the physical properties of the W/O/W emulsions (such as microstructure, droplet size, distribution, zeta potential, viscosity and encapsulation efficiency) were investigated. The optimum processing conditions for preparing W/O/W emulsions are as follows: the ratio of the oil phase to the internal water phase is 80 : 20, the concentrations of lipophilic and hydrophilic emulsifiers are 10 wt% and 5 wt%, and the homogeneous pressures in the first and second steps are 30 MPa and 10 MPa. The optimal preparation process of the W/O/W emulsions was used to encapsulate resveratrol. The results showed that at up to 0.040 wt% in the internal water phase (ethanol), resveratrol could be successfully encapsulated in W/O/W emulsions with an encapsulation efficiency of 99.97 ± 0.001%. Moreover, resveratrol was successfully encapsulated in the internal water phase and oil phase together; thus, it was not necessary to increase the amount of carrier materials. This study provides a novel encapsulation formulation to increase the delivery efficacy of resveratrol.