Purification and identification of an angiotensin I converting enzyme (ACE) inhibitory peptide from the gastrointestinal hydrolysate of the cotton leafworm, Spodoptera littoralis

Uncovering the Potential Somatic Angiotensin-Converting Enzyme (sACE) Inhibitory Capacity of Peptides from Acheta domesticus: Insights from In Vitro Gastrointestinal Digestion

Entomophagy is being proposed as a sustainable and nutritious alternative protein source. Additionally, insect consumption is also associated with some health benefits mediated by bioactive compounds produced during gastrointestinal (GI) digestion. The antihypertensive property resulting from the inhibition of the somatic angiotensin-converting enzyme (sACE) by small peptides is one of the most common bioactivities related to insect consumption. This study aimed to investigate the potential sACE-inhibitory capacity of six peptides (AVQPCF, CAIAW, IIIGW, QIVW, PIVCF, and DVW), previously identified by the in silico GI digestion of Acheta domesticus proteins, validate their formation after in vitro GI digestion of A. domesticus by LC-MS/MS, and assess the bioactivity of the bioaccessible digesta. The results showed that the IC50 values of AVQPCF, PIVCF, and CAIAW on sACE were 3.69 ± 0.25, 4.63 ± 0.16, and 6.55 ± 0.52 μM, respectively. The obtained digesta demonstrated a sACE-inhibitory capacity of 77.1 ± 11.8 µg protein/mL extract (IC50). This is the first report of the sACE-inhibitory capacity attributed to whole A. domesticus subjected to GI digestion without any pre-treatment or protein concentration. This evidence highlights the potential antihypertensive effect of both the digesta and the identified peptides.

Insects as Valuable Sources of Protein and Peptides: Production, Functional Properties, and Challenges

As the global population approaches 10 billion by 2050, the critical need to ensure food security becomes increasingly pronounced. In response to the urgent problems posed by global population growth, our study adds to the growing body of knowledge in the field of alternative proteins, entomophagy, insect-based bioactive proteolysates, and peptides. It also provides novel insights with essential outcomes for guaranteeing a safe and sustainable food supply in the face of rising global population demands. These results offer insightful information to researchers and policymakers tackling the intricate relationship between population expansion and food supplies. Unfortunately, conventional agricultural practices are proving insufficient in meeting these demands. Pursuing alternative proteins and eco-friendly food production methods has gained urgency, embracing plant-based proteins, cultivated meat, fermentation, and precision agriculture. In this context, insect farming emerges as a promising strategy to upcycle agri-food waste into nutritious protein and fat, meeting diverse nutritional needs sustainably. A thorough analysis was conducted to evaluate the viability of insect farming, investigate insect nutrition, and review the techniques and functional properties of protein isolation. A review of peptide generation from insects was conducted, covering issues related to hydrolysate production, protein extraction, and peptide identification. The study addresses the nutritional value and global entomophagy habits to elucidate the potential of insects as sources of peptides and protein. This inquiry covers protein and hydrolysate production, highlighting techniques and bioactive peptides. Functional properties of insect proteins' solubility, emulsification, foaming, gelation, water-holding, and oil absorption are investigated. Furthermore, sensory aspects of insect-fortified foods as well as challenges, including Halal and Kosher considerations, are explored across applications. Our review underscores insects' promise as sustainable protein and peptide contributors, offering recommendations for further research to unlock their full potential.

Bioactive Peptides Derived from Edible Insects: Effects on Human Health and Possible Applications in Dentistry

Novel foods, including edible insects, are emerging because of their nutritional characteristics and low environmental impacts and could represent a valid alternative source of food in a more sustainable way. Edible insects have been shown to have beneficial effects on human health. Insect-derived bioactive peptides exert antihypertensive, antioxidant, anti-inflammatory, and antimicrobial properties and have protective effects against common metabolic conditions. In this review, the roles of edible insects in human health are reported, and the possible applications of these peptides in clinical practice are discussed. A special mention is given to the role of antimicrobial peptides and their potential applications in controlling infections in orthodontic procedures. In this context, insects' antimicrobial peptides might represent a potential tool to face the onset of infective endocarditis, with a low chance to develop resistances, and could be manipulated and optimized to replace common antibiotics used in clinical practice so far. Although some safety concerns must be taken into consideration, and the isolation and production of insect-derived proteins are far from easy, edible insects represent an interesting source of peptides, with beneficial effects that may be, in the future, integrated into clinical and orthodontic practice.

Current state of insect proteins: extraction technologies, bioactive peptides and allergenicity of edible insect proteins

This review aims to provide an updated overview of edible insect proteins and the bioactivity of insect-derived peptides. The essential amino acid content of edible insects is compared with well-known protein sources to demonstrate that edible insects have the potential to cover the protein quality requirements for different groups of the population. Then the current methodologies for insect protein extraction are summarized including a comparison of the protein extraction yield and the final protein content of the resulting products for each method. Furthermore, in order to improve our understanding of insect proteins, their functional properties (such as solubility, foaming capacity, emulsifying, gelation, water holding capacity and oil holding capacity) are discussed. Bioactive peptides can be released according to various enzymatic hydrolysis protocols. In this context, the bioactive properties of insect peptides (antihypertensive, antidiabetic, antioxidant and anti-inflammatory properties) have been discussed. However, the allergens present in insect proteins are still a major concern and an unsolved issue for insect-based product consumption; thus, an analysis of cross reactivity and the different methods available to reduce allergenicity are proposed. Diverse studies of insect protein hydrolysates/peptides have been ultimately promoting the utilization of insect proteins for future perspectives and the emerging processing technologies to enhance the wider utilization of insect proteins for different purposes.

An in silico approach to unveil peptides from Acheta domesticus with potential bioactivity against hypertension, diabetes, cardiac and pulmonary fibrosis

Entomophagy is a sustainable alternative source of proteins for human nutrition. Acheta domesticus is one of the three insect species that complies with the European Union Regulation on novel foods, but to date, there are no reports on their potential bioactive peptides. In this study, an in silico approach was applied to simulate the gastrointestinal (GI) digestion of six A. domesticus proteins and identify new peptides with potential anti-hypertensive and/or anti-diabetic properties, resulting from their capability to inhibit the somatic Angiotensin-I converting enzyme (sACE) and/or dipeptidyl peptidase 4 (DPP-4), respectively. A molecular docking protocol was applied to evaluate the binding interactions between the 43 peptides ranked with high probability of being bioactive and three drug targets: DPP-4 and two catalytic domains (N- and C-) of sACE. Five peptides (AVQPCF, CAIAW, IIIGW, DATW and QIVW) showed high docking scores for both enzymes, suggesting their potential to inhibit the DPP-4 and both catalytic domains of sACE, thus possessing multifunctional bioactive properties. Two peptides (PIVCF and DVW) showed higher docking scores for the N-domain of sACE, indicating a potential action as selective inhibitors and consequently with anti-cardiac and pulmonary fibrosis bioactivities. This is the first study identifying peptides originated from the simulated GI digestion of A. domesticus with potential activities against hypertension, diabetes, cardiac and pulmonary fibrosis.

Edible Insects as a Novel Source of Bioactive Peptides: A Systematic Review

The production of food and feed to meet the needs of the growing world's population will soon become a serious challenge. In search for sustainable solutions, entomophagy is being proposed as an alternative source of proteins, with economic and environmental advantages when compared to meat. Edible insects are not only a valuable source of important nutrients, but their gastrointestinal digestion also originates small peptides with important bioactive properties. The present work intends to provide an exhaustive systematic review on research articles reporting bioactive peptides identified from edible insects, as demonstrated by in silico, in vitro, and/or in vivo assays. A total of 36 studies were identified following the PRISMA methodology, gathering 211 potentially bioactive peptides with antioxidant, antihypertensive, antidiabetic, antiobesity, anti-inflammatory, hypocholesterolemia, antimicrobial, anti-severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), antithrombotic, and immunomodulatory properties, originated from the hydrolysates of 12 different insect species. From these candidates, the bioactive properties of 62 peptides were characterized in vitro and 3 peptides were validated in vivo. Data establishing the scientific basis of the health benefits associated with the consumption of edible insects can be a valuable contribution to overcoming the cultural issues that hinder the introduction of insects in the Western diet.

Nutritional Composition, Health Benefits, and Application Value of Edible Insects: A Review

For thousands of years, edible insects have been used as food to alleviate hunger and improve malnutrition. Some insects have also been used as medicines because of their therapeutic properties. This is not only due to the high nutritional value of edible insects, but more importantly, the active substances from edible insects have a variety of biofunctional activities. In this paper, we described and summarized the nutritional composition of edible insects and discussed the biological functions of edible insects and their potential benefits for human health. A summary analysis of the findings for each active function confirms that edible insects have the potential to develop functional foods and medicines that are beneficial to humans. In addition, we analyzed the issues that need to be considered in the application of edible insects and the current status of edible insects in food and pharmaceutical applications. We concluded with a discussion of regulations related to edible insects and an outlook on future research and applications of edible insects. By analyzing the current state of research on edible insects, we aim to raise awareness of the use of edible insects to improve human health and thus promote their better use and development.

How to Develop Strategies to Use Insects as Animal Feed: Digestibility, Functionality, Safety, and Regulation

Various insects have emerged as novel feed resources due to their economical, eco-friendly, and nutritive characteristics. Fish, poultry, and pigs are livestock that can feed on insects. The digestibility of insect-containing meals were presented by the species, life stage, nutritional component, and processing methods. Several studies have shown a reduced apparent digestibility coefficient (ADC) when insects were supplied as a replacement for commercial meals related to chitin. Although the expression of chitinase mRNA was present in several livestock, indigestible components in insects, such as chitin or fiber, could be a reason for the reduced ADC. However, various components can positively affect livestock health. Although the bio-functional properties of these components have been verified in vitro, they show positive health-promoting effects owing to their functional expression when directly applied to animal diets. Changes in the intestinal microbiota of animals, enhancement of immunity, and enhancement of antibacterial activity were confirmed as positive effects that can be obtained through insect diets. However, there are some issues with the safety of insects as feed. To increase the utility of insects as feed, microbial hazards, chemical hazards, and allergens should be regulated. The European Union, North America, East Asia, Australia, and Nigeria have established regulations regarding insect feed, which could enhance the utility of insects as novel feed resources for the future.

Biological activity and processing technologies of edible insects: a review

The burgeoning global population growth has raised concerns regarding the expected increase in the demand for food, which could be partially tackled by identifying novel food sources. To this end, edible insects have recently attracted research interest. Several technologies for utilizing edible insect-derived proteins have been introduced; however, research into their functional utilization is insufficient. Herein, we reviewed the relevant literature on the importance of insects as food sources, extraction of edible insects, the nutritional value of insects, biological activities of components, and their applications in food industries. We summarized the studies primarily focused on the functional utilization of edible insects, suggesting that for successful incorporation and growth of edible insects in food and pharmaceutical industries, strategies to improve the extraction methods are required to explore the biological activity of edible insects. Furthermore, the awareness of edible insects with a focus on their allergens warrants consideration.

Insetos comestíveis como potenciais fontes de proteínas para obtenção de peptídeos bioativos

Resumo O consumo de insetos como uma fonte alternativa de proteínas é considerado uma tendência futura e uma estratégia viável, com potencial notório para garantia do fornecimento de alimentos em nível global. Os insetos são uma fonte não convencional de proteínas, seja para consumo humano direto ou indiretamente, como ingredientes em alimentos formulados. Além disso, estudos científicos têm demonstrado que a hidrólise enzimática destas proteínas resulta na produção de peptídeos com atividades biológicas de grande interesse, como atividade antioxidante, antidiabética, anti-hipertensiva e antimicrobiana. O uso desses peptídeos com fim nutracêutico pode substituir ou reduzir o uso de drogas sintéticas, as quais estão associadas a efeitos colaterais indesejáveis. O presente trabalho teve como objetivo abordar o uso de insetos na alimentação humana, destacando sua aplicação como substrato proteico na hidrólise enzimática para produção de peptídeos bioativos. As principais propriedades bioativas dos peptídeos foram relatadas.

Identification and Characterization of Edible Cricket Peptides on Hypertensive and Glycemic In Vitro Inhibition and Their Anti-Inflammatory Activity on RAW 264.7 Macrophage Cells

Recent studies continue to demonstrate the potential of edible insects as a protein base to obtain bioactive peptides applicable for functional food development. This study aimed at identifying antihypertensive, anti-glycemic, and anti-inflammatory peptides derived from the in vitro gastrointestinal digests of cricket protein hydrolysates. After sequential fractionation, the protein digest subfraction containing the lowest molecular weight (<0.5 kDa), hydrophobic (C18) and cationic peptides (IEX) was found responsible for the most bioactivity. The cationic peptide fraction significantly reduced (p < 0.05) α-amylase, α-glucosidase, and angiotensin converting enzyme (ACE) activity in vitro, and also inhibited the expression of NF-κB in RAW 264.7 macrophage cells. A total of 28 peptides were identified with mass spectrometry (LC–MS/MS) and de novo sequencing from the potent fraction. Three novel peptides YKPRP, PHGAP, and VGPPQ were chosen for the molecular docking studies. PHGAP and VGPPQ exhibited a higher degree of non-covalent interactions with the enzyme active site residues and binding energies comparable to captopril. Results from this study demonstrate the bioactive potential of edible cricket peptides, especially as ACE inhibitors.

Identification of tuna protein-derived peptides as potent SARS-CoV-2 inhibitors via molecular docking and molecular dynamic simulation

The present study aimed to identify potential SARS-CoV-2 inhibitory peptides from tuna protein by virtual screening. The molecular docking was performed to elicit the interaction mechanism between targets (M^pro and ACE2) and peptides. As a result, a potential antiviral peptide EEAGGATAAQIEM (E-M) was identified. Molecular docking analysis revealed that E-M could interact with residues Thr190, Thr25, Thr26, Ala191, Leu50, Met165, Gln189, Glu166, His164, His41, Cys145, Gly143, and Asn119 of M^pro via 11 conventional hydrogen bonds, 9 carbon hydrogen bonds, and one alkyl interaction. The formation of hydrogen bonds between peptide E-M and the residues Gly143 and Gln189 of M^pro may play important roles in inhibiting the activity of M^pro. Besides, E-M could bind with the residues His34, Phe28, Thr27, Ala36, Asp355, Glu37, Gln24, Ser19, Tyr83, and Tyr41 of ACE2. Hydrogen bonds and electrostatic interactions may play vital roles in blocking the receptor ACE2 binding with SARS-CoV-2.

Evaluation of ACE, α-glucosidase, and lipase inhibitory activities of peptides obtained by in vitro digestion of selected species of edible insects

The objective of this study was to examine the inhibition of the activity of enzymes associated with development of the metabolic syndrome by peptide fractions received from simulated gastrointestinal digestion and absorption of heat-treated edible insects. The inhibitory activities of insect-derived peptides were determined against key enzymes relevant to the metabolic syndrome such as the angiotensin-converting enzyme (ACE), pancreatic lipase, and α-glucosidase. After the in vitro absorption process, all hydrolysates showed high inhibitory activity; however, the most effective metabolic syndrome-inhibitory peptides were received after separation on Sephadex G10. The best results were found for peptide fractions obtained from Schistocerca gregaria. The highest enzymes inhibitory activities were obtained for peptide fractions from S. gregaria: boiled for ACE (IC50 3.95 µg mL−1), baked for lipase (IC50 9.84 µg mL−1), and raw for α-glucosiadase (IC50 1.89 µg mL−1) S. gregaria, respectively. Twelve sequences of peptides from the edible insects were identified and their chemical synthesis was carried out as well. Among the synthesized peptides, the KVEGDLK, YETGNGIK, AIGVGAIR, IIAPPER, and FDPFPK sequences of peptides exhibited the highest inhibitory activity. Generally, the heat treatment process applied to edible insects has a positive effect on the properties of the peptide fractions studied.

Chemical evaluation of the Rhynchophorus ferrugineus larvae fed on different substrates as human food source

We investigated the chemical composition of the weevil Rhynchophorus ferrugineus larvae, traditionally used as human food in Asia and known worldwide as one of the most significant pest for palm trees. Total fat content and fatty acid composition were analyzed using standard methodologies in (1) weevil larvae reared on apple fruit slices and wild specimens collected from attacked (2) Phoenix canariensis and (3) Syagrus romanzoffiana palm trees. Total fat content was extremely high in all the specimens (ranged between 57.62 and 60.03% based on dry weight). Despite sharing the same prevalent fatty acids (myristic acid, palmitic acid, stearic acid, palmitoleic acid, oleic acid, α-linoleic acid, and α-linolenic acid), fatty acid composition of the wild weevil larvae significantly differed from that of the specimens raised on apple fruit, due to the presence of other minor compounds. In general, a good balance between unsaturated fatty acids (∼53.68% of total fatty acids) and saturated fatty acids (∼43.41% of total fatty acids) and a low cholesterol content (74.61-152.32 mg/kg based on dry matter) were detected in all the specimens. Conversely, the weevil larvae did not represent a good source of α-tocopherol (14.17-26.22 mg/kg based on dry matter). The ability of the protein extracts obtained from the weevil larvae to inhibit in vitro the angiotensin-converting enzyme, the main enzyme involved in blood pressure regulation, was also investigated. To simulate gastrointestinal digestion process, protein extracts were hydrolyzed by the gastrointestinal enzymes. A significantly lower IC₅₀ (0.588-0.623 mg/ml) was measured in all the protein extracts after enzymatic hydrolysis versus the corresponding crude protein extracts (3.270-3.752 mg/ml). Given that the weevil larvae are able to provide interesting benefits for human health, this study supports their use as human food not just in the native countries where they are traditionally consumed and farmed but also throughout the world.

Isolation and characterization of anti-inflammatory peptides derived from whey protein

The present study was conducted to isolate and characterize anti-inflammatory peptides from whey protein hydrolysates using alcalase. Nine subfractions were obtained after sequential purification by ultrafiltration, Sephadex G-25 gel (GE Healthcare, Uppsala, Sweden) filtration chromatography, and preparative HPLC. Among them, subfraction F4e showed the strongest inhibitory activity on interleukin-1β (IL-1β), cyclooxygenase-2, and tumor necrosis factor-α (TNF-α) mRNA expression in lipopolysaccharide-induced RAW 264.7 mouse macrophages. Eight peptides, including 2 new peptides-Asp-Tyr-Lys-Lys-Tyr (DYKKY) and Asp-Gln-Trp-Leu (DQWL)-were identified from subfractions F4c and F4e, respectively, using ultra-high performance liquid chromatography-quadrupole-time-of-flight mass spectrometry. Peptide DQWL showed the strongest inhibitory ability on IL-1β, cyclooxygenase-2, and TNF-α mRNA expression and production of IL-1β and TNF-α proteins at concentrations of 10 and 100μg/mL, respectively. Additionally, DQWL treatment significantly inhibited nuclear factor-κB activation by suppressing nuclear translocation of nuclear factor-κB p65 and blocking inhibitor κB kinase phosphorylation and inhibitor κB degradation together with p38 mitogen-activated protein kinase activation. Our study suggests that peptide DQWL has anti-inflammatory potential; further confirmation using an in vivo model is needed.

Bioactive peptides identified in thornback ray skin's gelatin hydrolysates by proteases from Bacillus subtilis and Bacillus amyloliquefaciens

Thornback ray skin gelatin has been hydrolyzed with two different proteases in order to obtain peptides with ACE inhibitory and antioxidant activity. Hydrolysates with protease from Bacillus subtilis A26 (TRGH-A26) displayed ACE inhibitory activity with an IC50 value of 0.94 μg/μL whereas Neutrase® hydrolysate from Bacillus amyloliquefaciens (TRGH-Neutrase) showed an IC50 value of 2.07 μg/μL. Regarding antioxidant activity, IC50 values of 1.98 and 21.2 μg/μL in TRGH-A26 and TRGH-Neutrase, respectively, were obtained using the DPPH radical-scavenging assay. The most active fractions identified by size-exclusion chromatography were further purified by RP-HPLC and analysed using nanoESI-LC-MS/MS to identify the sequence of the peptides. APGAP was the most active peptide inTRGH-A26 for ACE inhibitory activity with an IC50 value of 170 μM, whereas GIPGAP showed the best ACE inhibitory activity in TRGH-Neutrase sample with an IC50 value of 27.9 μM. The highest antioxidant activity was identified in peptide AVGAT, showing a 33% of activity at 3mg/mL using the DPPH radical-scavenging assay. The obtained results proved the potential of thornback ray skin gelatin hydrolysates as a source of bioactive peptides.

STATEMENT OF SIGNIFICANCE

This study describes a peptidomic approach for the identification of ACE-inhibitory and antioxidant peptides generated from thornback ray gelatin (Raja clavata) hydrolysates from Bacillus subtilis A26 and Bacillus amyloliquefaciens Neutrase® enzymes and expose the potential of thornback ray gelatin hydrolysate as a source of bioactive peptides. In this sense, the decrease of systolic blood pressure is one of the main measurements considered in public health for the treatment of cardiovascular diseases, stroke and even end-stage renal disease. Traditionally, synthetic drugs such as captopril and enalapril have been used as ACE inhibitors despite their secondary effects, but the finding of new sources for the generation of natural bioactive peptides such as thornback ray muscle results is very important in the knowledge of less hostile but highly effective antihypertensive peptides as well as the development of new uses for waste and by-products generated from marine products, helping to solve the already existing environmental problem affecting this industry.

Isolation, purification and molecular mechanism of a peanut protein-derived ACE-inhibitory peptide

Although a number of bioactive peptides are capable of angiotensin I-converting enzyme (ACE) inhibitory effects, little is known regarding the mechanism of peanut peptides using molecular simulation. The aim of this study was to obtain ACE inhibiting peptide from peanut protein and provide insight on the molecular mechanism of its ACE inhibiting action. Peanut peptides having ACE inhibitory activity were isolated through enzymatic hydrolysis and ultrafiltration. Further chromatographic fractionation was conducted to isolate a more potent peanut peptide and its antihypertensive activity was analyzed through in vitro ACE inhibitory tests and in vivo animal experiments. MALDI-TOF/TOF-MS was used to identify its amino acid sequence. Mechanism of ACE inhibition of P8 was analyzed using molecular docking and molecular dynamics simulation. A peanut peptide (P8) having Lys-Leu-Tyr-Met-Arg-Pro amino acid sequence was obtained which had the highest ACE inhibiting activity of 85.77% (half maximal inhibitory concentration (IC50): 0.0052 mg/ml). This peanut peptide is a competitive inhibitor and show significant short term (12 h) and long term (28 days) antihypertensive activity. Dynamic tests illustrated that P8 can be successfully docked into the active pocket of ACE and can be combined with several amino acid residues. Hydrogen bond, electrostatic bond and Pi-bond were found to be the three main interaction contributing to the structural stability of ACE-peptide complex. In addition, zinc atom could form metal-carboxylic coordination bond with Tyr, Met residues of P8, resulting into its high ACE inhibiting activity. Our finding indicated that the peanut peptide (P8) having a Lys-Leu-Tyr-Met-Arg-Pro amino acid sequence can be a promising candidate for functional foods and prescription drug aimed at control of hypertension.

Tryptophan-containing milk protein-derived dipeptides inhibit xanthine oxidase

Of twelve dipeptides tested, only the Trp containing peptides Val-Trp and its reverse peptide Trp-Val showed a xanthine oxidase (XO) inhibitory activity. Studies with Val and Trp revealed that XO inhibition was mainly attributed to the Trp residue. No significant difference (P ≥ 0.05) was found for the XO inhibitory potency (IC(50)) values for Trp, Val-Trp and Trp-Val, which were about 200 times higher than that for Allopurinol. Lineweaver and Burke analysis demonstrated that Trp, Val-Trp and Trp-Val were non-competitive inhibitors while Allopurinol was a competitive inhibitor. Of the different milk-protein substrates hydrolyzed with gastro-intestinal enzyme activities, only lactoferrin (LF) hydrolyzates displayed XO inhibition. Peptides present in a LF hydrolyzate (GLF-240 min) were adsorbed onto activated carbon followed by subsequent desorption with stepwise elution using acetonitrile (ACN). Separation and detection of Trp containing peptides within the different fractions were achieved using RP-HPLC coupled with fluorescence detection. The desorbed fractions displayed different XO inhibitory properties, with no inhibition in the unbound fraction and highest inhibition in fractions eluted with 30, 40 and 70% ACN. The fraction eluting at 40% ACN was significantly more potent (19.1±2.3% inhibition at 1.25 mg mL(-1)) than the GLF-240 min hydrolyzate (13.4 ± 0.4% inhibition at 1.25 mg mL(-1)), showing the potential for enrichment of the bioactive peptides on fractionation with activated carbon.

Antihypertensive effect of insect cells: in vitro and in vivo evaluation

In this study, we investigated the in vitro ACE inhibitory and in vivo antihypertensive effect of insect cell extracts. The IC(50) of three insect cell lines from different type and insect species origin: S2 (embryo, Drosophila melanogaster), Sf21 (ovary, Spodoptera frugiperda) and Bm5 (ovary, Bombyx mori), were evaluated. Most interesting results were that the IC(50) values ranged between 0.4 and 0.9 mg/ml, and that an extra hydrolysis with gastrointestinal enzymes did not increase the ACE inhibitory activity conspicuously. Finally, a single oral administration with a gavage of 150 mg cell extract/kg BW to spontaneous hypertensive rats (SHR) significantly decreased (p<0.05) their systolic blood pressure (SBP) with 5-6% (9-12 mmHg) compared to the controls at 6 h post-administration. Here the undigested and digested insect S2 cell extracts were equal in activity to lower the SBP. To the best of our knowledge, this is the first report of in vivo antihypertensive activity of insect cell extracts and this without an extra digestion requirement.

Ala-Val-Phe and Val-Phe: ACE inhibitory peptides derived from insect protein with antihypertensive activity in spontaneously hypertensive rats

In this study, we evaluated the stability/bioavailability and in vivo antihypertensive activity of the tripeptide, Ala-Val-Phe, that was recently purified from insect protein (Spodoptera littoralis; Lepidoptera) and that showed in vitro angiotensin converting enzyme (ACE) inhibitory activity. This tripeptide is partly hydrolyzed by mucosal peptidases to Val-Phe, a more potent in vitro ACE inhibitor. In organ bath experiments using rat aorta, Val-Phe showed ACE inhibition, while Ala-Val-Phe did not. Single oral administration (5mg/kg body weight) to spontaneously hypertensive rats led to a significant decrease in blood pressure for both peptides. Docking experiments indicated an active character for Val-Phe and an inactive character for Ala-Val-Phe as potential inhibitors of human ACE. From our results, it can be suggested that after oral administration of Ala-Val-Phe, Val-Phe is released by in vivo peptidases and is responsible for in vivo activity of Ala-Val-Phe. To the best of our knowledge this is the first report of in vivo antihypertensive activity of peptides derived from insect protein.