Effect of digestive enzymes on antimicrobial, radical scavenging and angiotensin I-converting enzyme inhibitory activities of camel colostrum and milk proteins

Nutritional significance and promising therapeutic/medicinal application of camel milk as a functional food in human and animals: a comprehensive review

Camel milk (CM) is the key component of human diet specially for the population belongs to the arid and semi-arid regions of the world. CM possess unique composition as compare to the cow milk with abundant amount of medium chain fatty acids in fat low lactose and higher concentration of whey protein and vitamin C. Besides the nutritional significance of CM, it also contains higher concentration of bioactive compounds including bioactive peptides, lactic acid bacteria (LAB), lactoferrin (LF), lactoperoxidase, lysozyme casein and immunoglobulin. Recently, CM and their bioactive compounds gaining more attention toward scientific community owing to their multiple health benefits, especially in the current era of emerging drug resistance and untold side effects of synthetic medicines. Consumption of fresh or fermented CM and its products presumed exceptional nutraceutical and medicinal properties, including antimicrobial, anti-inflammatory, antioxidant, anti-diabetic, hepatoprotective, nephroprotective, anticancer and immunomodulatory activities. Moreover, CM isolated LAB exhibit antioxidant and probiotic effects leading to enhance the innate and adaptive immune response against both gram-negative and gram-positive pathogenic bacteria. The main objective of this review is to highlight the nutritional significance, pharmaceutical potential, medicinal value and salient beneficial health aspect of CM for human and animals.

Relation between Color and Chemical Composition of Dromedary Camel Colostrum

Camel milk industrialization faces technological problems related to the presence of colostrum in milk. The determination of color parameters may serve to differentiate between colostrum and milk. This work aimed to study the relationship between the chemical composition of camel colostrum and milk and their colors. Samples of colostrum were collected at 2, 12, 24, 48, 72, 96, 120, 144, 168, and 360 h postpartum (n = 16), and their physicochemical properties (pH, acidity, viscosity, color, dry matter, ash, protein, and fat) were analyzed. The results show that all the components decreased during the first 3 days except fat. The content of this later increased from zero in the three sampling on the first day (2, 12, and 24 h) to 1.92 ± 0.61% at 48 h postpartum. The amount of total dry matter and protein decreased from 20.95 ± 3.63% and 17.43 ± 4.28% to 13.05 ± 0.81% and 3.71 ± 0.46%, respectively, during the first 7 days postpartum. There was a weak correlation between the brightness (L*) of the camel milk and its contents of dry matter, protein, and fat; however, these parameters were strongly correlated with redness (a*) and yellowness (b*). Ash content was poorly correlated with the color parameters. Hence, the measurement of the color parameters of camel colostrum and milk can be a new tool to evaluate their quality.

Significance of Lactobacillus fermentum on Antioxidative and Anti-Inflammatory Activities and Ultrafiltration Peptide Fractions as Potential Sources of Antioxidative Peptides from Fermented Camel Milk (Indian Breed)

OBJECTIVE

The present study aimed to assess the bio-functional analysis of camel milk viz. anti-oxidative, anti-inflammatory activities using potent Lactobacillus fermentum (KGL4) strain through fermentation and also to release the bioactive peptides during fermentation.

METHOD

The antioxidant and proteolytic activities of the fermented camel milk were studied followed by SDS-PAGE analysis and 2 D PAGE. The separations of the bioactive peptides of water-soluble extract (WSE) of 3 and 10 kDa (Permeates & Retentates) were achieved by RP-HPLC. The purified bioactive peptides were identified and characterized using RPLC/MS and the effect of WSE of camel milk fermented with KGL4 on lipopolysaccharide (LPS)/endotoxin-induced inflammation in RAW 264.7 macrophages were also studied.

RESULTS

The maximal activity was observed in ABTS assay (64.03%), then in hydroxyl free radical scavenging assay, and minimal activity was observed in superoxide free radical assay (57.75%). ABTS assay was significantly (P < 0.05) higher than other assays. MTT assay was performed on WSE of camel milk fermented with KGL4 using treated macrophage cells with different concentrations and found the decreasing range of cell viability at 0.25 mg/mL treatment which was non-significant. 7.80 mg/ml peptide production was found after 48 h of fermentation using the OPA method. Further, WSE of fermented camel milk was separated and analyzed their protein profiles using SDS-PAGE and 2 D-PAGE techniques. Here, many new peptides were found in camel milk when fermented with KGL4 strain. Each protein sequence was characterized through bioinformatic tools, including SWISS-PROT & PIR protein databases. Novel bioactive anti-oxidative peptides were found by searching in the BIOPEP database.

CONCLUSIONS

The present study suggests that the L. fermentum KGL4 strain could be explored to produce novel antioxidative peptides from fermented camel milk (Indian breed).

Bioactive natural products in donkey and camel milk: a perspective review

Mammalian milk has numerous components that exhibit chemical and functional activities. They support human homeostasis. Immunoglobulins, peptides with antibacterial and antimicrobial activities, carbohydrates, lipids, and minor molecules have positive effects on health. Beyond the nutritional values of milk, milk-borne biologically active compounds such as proteins and other minor constituents exhibit essential physiological and biochemical functions. Human milk guarantees a healthy development and improves immunity. It is hypoallergenic. Sometimes, it is necessary to substitute this food with other milk for different reasons. Cow, sheep, goat, camel and donkey milk are natural alternatives. We evaluated the different compounds within donkey and camel milk analysing their biomolecular characteristics and potential benefits for human health. Camel and donkey milk bioactive products could be good candidates for controlling several diseases and excellent substitutes in the case of milk protein allergies in infants. However, more research should be conducted to further evaluate their nutraceutical potential.

Prospective Role of Bioactive Molecules and Exosomes in the Therapeutic Potential of Camel Milk against Human Diseases: An Updated Perspective

Camel milk (CM) constitutes an important dietary source in the hot and arid regions of the world. CM is a colloidal mixture of nutritional components (proteins, carbohydrates, lipids, vitamins, and minerals) and non-nutritional components (hormones, growth factors, cytokines, immunoglobulins, and exosomes). Although the majority of previous research has been focused on the nutritional components of CM; there has been immense interest in the non-nutritional components in the recent past. Reckoning with these, in this review, we have provided a glimpse of the recent trends in CM research endeavors and attempted to provide our perspective on the therapeutic efficacy of the nutritional and non-nutritional components of CM. Interestingly, with concerted efforts from the research fraternities, convincing evidence for the better understanding of the claimed traditional health benefits of CM can be foreseen with great enthusiasm and is indeed eagerly anticipated.

The Antioxidant, Anti-Inflammatory and Immunomodulatory Effects of Camel Milk

Camel milk (CM) has been found to have several health benefits, including antiviral, antibacterial, anti-tumor, anti-fungal, antioxidant, hypoglycaemic and anti-cancer activities. In addition, CM can counter signs of aging and may be a useful naturopathic treatment for autoimmune diseases. The composition of CM varies with geographic origin, feeding conditions, seasonal and physiological changes, genetics and camel health status. In the present review, we collate the diverse scientific literature studying antioxidant, anti-inflammatory and immunomodulatory effects of CM and its bioactive compounds. The databases Scopus, PubMed, and Web of Science were searched until the end of September 2021 using the keywords: camel milk, antioxidant, anti-inflammatory, immunomodulatory. The anti-inflammatory mechanism of CM in various inflammatory disorders was consistently reported to be through modulating inflammatory cells and mediators. The common anti-inflammatory bioactive components of CM seem to be lactoferrin. The antioxidant effects of α-lactalbumin, β-caseins and vitamin C of CM work by reducing or inhibiting the production of reactive oxygen species (ROS), hydroxyl radicals, nitric oxide (NO), superoxide anions and peroxyl radicals, likely alleviating oxidative stress. Higher levels of protective proteins such as lysozyme, IgG and secretory IgA compared to cow's milk, and insulin-like protein activity of CM on ß cells appear to be responsible for the immunomodulatory properties of CM. The evidence indicates that CM and its bioactive components has the potential to be a therapeutic value for diseases that are caused by inflammation, oxidative stress and/or immune-dysregulation.

Digestibility of proteins in camel milk in comparison to bovine and human milk using an in vitro infant gastrointestinal digestion system

The absence of β-lactoglobulin, high β-/α_s-casein ratio and protective proteins make camel milk a promising alternative protein base for making human infant formulae. In this study, protein digestibility of camel milk was compared with that of bovine and human milk using an in vitro infant gastrointestinal digestion system. A low degree of gastric proteolysis was observed in all three kinds of milk, and a single clot was formed in camel milk. The soluble milk proteins remaining in the gastric digesta were digested rapidly and extensively in the intestinal phase, while the proteins in the camel milk clot were hydrolysed gradually. Despite several similarities, bioactive peptides unique to individual milk were identified in the three intestinal milk digesta. The results suggest that camel milk proteins are equally digestible as bovine and human milk proteins under infant gastrointestinal digestion conditions, and it may be a prospective substitute for infant formula base.

A state-of-art review on camel milk proteins as an emerging source of bioactive peptides with diverse nutraceutical properties

The generation of camel milk derived bioactive peptides (CM-BAPs) have started to grab keen interest of many researchers during the past decade. CM-BAPs have shown more significant bioactive properties in comparison to camel milk intact proteins. CM-BAPs can be obtained using enzyme hydrolysis to form hydrolysates, or by the fermentation process. In this systematic review, 46 research articles exploring the health-related bioactive properties of CM-BAPs through in-vitro and in-vivo studies have been included. CM-BAPs have been reported for their antioxidant, anti-diabetic, anti-obesity, antihypertensive, antibacterial, antibiofilm, anticancer, anti-inflammatory, anti-haemolytic, and anti-hyperpigmentation activities. The effects of factors such as molecular weight of peptides, type of enzyme, enzyme to substrate ratio, hydrolysis temperature and duration have been analysed. The in-vitro studies have provided enough evidence on certain aspects of the pharmacological actives of camel milk bioactive peptides. Nevertheless, the in-vivo studies are very limited, and no clinical studies on CM-BAPs have been reported.

An evaluation of the in vitro antioxidant and antidiabetic potentials of camel and donkey milk peptides released from casein and whey proteins

In this study, some biological activities including antioxidant activity (DPPH radical scavenging activity, ABTS radical scavenging activity, and CUPRAC assay), DPP-IV enzyme inhibitory activity, and α-glucosidase enzyme inhibitory activity of peptides released from in vitro gastrointestinal digested casein and the whey proteins of camel and donkey milk were evaluated. While the highest antioxidant activity was determined to be in the digested camel casein fraction using the ABTS and CUPRAC methods, the digested donkey casein fraction was determined to have the highest radical scavenging activity using the DPPH method. The highest DPP-IV inhibitory activity was detected in digested camel and donkey milk casein fractions. Digested whey fractions of camel and donkey milk had a lower DPP-IV inhibitory activity compared to the digested casein fractions. However, digested whey fractions of camel and donkey milk did not show α-glucosidase inhibitory activity, and digested donkey casein fraction showed the highest α-glucosidase inhibitory activity with a 12.5 µg/mL IC₅₀ value. It was concluded that peptides released from digested casein fraction of camel and donkey milk have potent antioxidant and particularly antidiabetic properties.

A comparative investigation into novel cholesterol esterase and pancreatic lipase inhibitory peptides from cow and camel casein hydrolysates generated upon enzymatic hydrolysis and in-vitro digestion

Cow (CwC) and camel casein (CaC) hydrolysates were generated using Alcalase™ (CwCA and CaCA) and Pronase-E (CwCP and CaCP) each for 3 and 6 h, and investigated for their potential to inhibit key lipid digesting enzymes i.e., pancreatic lipase (PL) and cholesteryl esterase (CE). Results revealed stronger PL and CE inhibition by CaC hydrolysates compared to CwC. Potent hydrolysates (CwCP-3 h and CaCA-6 h) upon simulated gastrointestinal digestion (SGID) showed significant improvement in inhibition of both PL and CE. However, both the SGID hydrolysates showed similar extent of PL and CE inhibition and were further sequenced for peptide identification. Peptides MMML, FDML, HLPGRG from CwC and AAGF, MSNYF, FLWPEYGAL from CaC hydrolysates were predicted to be most active PL inhibitory peptides. Peptide LP found in both CwC and CaC hydrolysates was predicted as active CE inhibitor. Thus, CwC and CaC could be potential source of peptides with promising CE and PL inhibitory properties.

Research Development on Anti-Microbial and Antioxidant Properties of Camel Milk and Its Role as an Anti-Cancer and Anti-Hepatitis Agent

Camel milk is a rich source of vitamin C, lactic acid bacteria (LAB), beta-caseins and milk whey proteins, including lactoferrin, lysozyme, lactoperoxidase, alpha-lactalbumin and immunoglobulin. The lactoferrin plays a key role in several physiological functions, such as conferring antioxidant, anti-microbial and anti-inflammatory functions in cells. Similarly, the camel milk alpha-lactalbumin has shown greater antioxidative activity because of its higher antioxidant amino acid residues. The antioxidant properties of camel milk have also been ascribed to the structural conformation of its beta-caseins. Upon hydrolysis, the beta-caseins lead to some bioactive peptides having antioxidant activities. Consequently, the vitamin C in camel milk has a significant antioxidant effect and can be used as a source of vitamin C when the climate is harsh. Furthermore, the lysozyme and immunoglobulins in camel milk have anti-microbial and immune regulatory properties. The LAB isolated from camel milk have a protective role against both Gram-positive and -negative bacteria. Moreover, the LAB can be used as a probiotic and may restore the oxidative status caused by various pathogenic bacterial infections. Various diseases such as cancer and hepatitis have been associated with oxidative stress. Camel milk could increase antiproliferative effects and regulate antioxidant genes during cancer and hepatitis, hence ameliorating oxidative stress. In the current review, we have illustrated the anti-microbial and antioxidant properties of camel milk in detail. In addition, the anti-cancer and anti-hepatitis properties of camel milk have also been discussed.

Nutritional, antimicrobial and medicinal properties of Camel's milk: A review

Camel's milk is an important part of staple diet in several parts of the world, particularly in the arid and semi-arid zones. Camel's milk is rich in health-beneficial substances, such as bioactive peptides, lactoferrin, zinc, and mono and polyunsaturated fatty acids. These substances could help in the treatment of some important human diseases like tuberculosis, asthma, gastrointestinal diseases, and jaundice. Camel's milk composition is more variable compared to cow's milk. The effects of feed, breed, age, and lactation stage on milk composition are more significant in camel. Region and season significantly change the ratio of compounds in camel's milk. Camel's whey protein is not only composed of numerous soluble proteins, but also has indigenous proteases such as chymotrypsin A and cathepsin D. In addition to their high nutritional value, these whey proteins have unique characteristics, including physical, chemical, physiological, functional, and technological features that are useful in the food application. The hydrolysis of camel's milk proteins leads to the formation of bioactive peptides, which affect major organ systems of the body and impart physiological functions to these systems. The camel's milk has antioxidant, antimicrobial, angiotensin-I-converting enzyme (ACE)-inhibitory peptides, antidiabetic as well as anticholesterol activities.

Angiotensin-I Converting Enzyme Inhibition and Antioxidant Activity of Papain-Hydrolyzed Camel Whey Protein and Its Hepato-Renal Protective Effects in Thioacetamide-Induced Toxicity

Papain hydrolysis of camel whey protein (CWP) produced CWP hydrolysate (CWPH). Fractionation of CWPH by the size exclusion chromatography (SEC) generated fractions (i.e., SEC-F1 and SEC-F2). The angiotensin converting enzyme inhibitory activity (ACE-IA) and free radical scavenging actions were assessed for CWP, CWPH, SEC-F1, and SEC-F2. The SEC-F2 exerted the highest ACE-IA and scavenging activities, followed by CWPH. The protective effects of CWPH on thioacetamide (TAA)-induced toxicity were investigated in rats. The liver enzymes, protein profile, lipid profile, antioxidant enzyme activities, renal functions, and liver histopathological changes were assessed. Animals with TAA toxicity showed impaired hepatorenal functions, hyperlipidemia, and decreased antioxidant capacity. Treatment by CWPH counteracted the TAA-induced oxidative tissue damage as well as preserved the renal and liver functions, the antioxidative enzyme activities, and the lipid profile, compared to the untreated animals. The current findings demonstrate that the ACE-IA and antioxidative effects of CWPH and its SEC-F2 fraction are worth noting. In addition, the CWPH antioxidative properties counteracted the toxic hepatorenal dysfunctions. It is concluded that the hydrolysis of CWP generates a wide range of bioactive peptides with potent antihypertensive, antioxidant, and hepatorenal protective properties. This opens up new prospects for the therapeutic utilization of CWPH and its fractions in the treatment of oxidative stress-associated health problems, e.g., hypertension and hepatorenal failure.

A comprehensive review on bioactive peptides derived from milk and milk products of minor dairy species

Abstract

Milk from different species has been exploited for the isolation of various functional ingredients for decades. Irrespective of the source, milk is considered as a complete food, as it provides essential nutrients required by the human body. Proteins and their fractions are valuable sources of bioactive peptides that might exert a health beneficial role in the human body such as immune-modulation, antioxidant activity, ACE-inhibitory activity, anti-neoplastic, anti-microbial, etc. In milk, bioactive peptides may either be present in their natural form or released from their parental proteins due to enzymatic action. The increasing interest in bioactive peptides among researchers has lately augmented the exploration of minor dairy species such as sheep, goat, camel, mithun, mare, and donkey. Alternative to cow, milk from minor dairy species have also been proven to be healthier from infancy to older age owing to their higher digestibility and other nutritive components. Therefore, realizing the significance of milk from such species and incentivized interest towards the derivatization of bioactive peptides, the present review highlights the significant research achievements on bioactive peptides from milk and milk products of minor dairy species.

Graphical abstract

Antibacterial Activity of Trypsin-Hydrolyzed Camel and Cow Whey and Their Fractions

Simple Summary

Camels are an important part of the ecosystem in desert areas. Camels can survive well under difficult conditions, therefore, they play a key role in local herdsmen’s production, life, and economic structure. China’s Inner Mongolia region has unique environmental and geographical advantages, making it suitable for camel breeding. Camel milk has high nutritional value and unique functional characteristics. It not only has low sensitization, but also contains various immune active factors with high medicinal value. Currently, there are various products derived from cow and goat milk, but few related to camel milk, providing an opportunity for development. This study used trypsin to hydrolyze the whey proteins of camel milk, separated and purified peptide fragments with antibacterial activity, and conducted a comparative study with cow milk. The present study provided new ideas for the use and development of camel whey protein hydrolysates and their dextran purification fractions, and indicated the future development of these peptides as nutritional additives or food preservatives.

Abstract

Antibacterial peptides were isolated and purified from whey proteins of camel milk (CaW) and cow milk (CoW) and their antimicrobial activities were studied. The whey proteins were hydrolyzed using trypsin, and the degree of hydrolysis was identified by gel electrophoresis. The whey hydrolysate (WH) was purified using ultrafiltration and Dextran gel chromatography to obtain small peptides with antibacterial activity. The effect of the antimicrobial peptides on the morphology of bacterial strains was investigated using transmission electron microscopy. Their amino acid composition and antimicrobial activities were then determined. Polypeptides CaWH-III (<3 kDa) and CoWH-III (<3 kDa) had the strongest antibacterial activity. Both Fr.A2 (CaWH-Ⅲ’s fraction 2) and Fr.B1 (CoWH-Ⅲ’s fraction 1) had antibacterial effects toward Escherichia coli and Staphylococcus aureus, with minimum antimicrobial mass concentrations of 65 mg/mL and 130 mg/mL for Fr.A2, and 130 mg/mL and 130 mg/mL for Fr.B1, respectively. The highly active antimicrobial peptides had high amounts of alkaline amino acids (28.13% in camel milk Fr.A2 and 25.07% in the cow milk Fr.B1) and hydrophobic amino acids. (51.29% in camel milk Fr.A2 and 57.69% in the cow milk Fr.B1). This results showed that hydrolysis of CaW and CoW using trypsin produced a variety of effective antimicrobial peptides against selected pathogens, and the antibacterial activity of camel milk whey was slightly higher than that of cow milk whey.

Antilisterial activity of dromedary lactoferrin peptic hydrolysates

The aim of this study was to explore the antibacterial peptides derived from dromedary lactoferrin (LFc). The LFc was purified from colostrum using a batch procedure with a cation exchange chromatography support and was hydrolyzed with pepsin to generate peptic digest. This peptic digest was fractionated by cation exchange chromatography, and the antilisterial activity of LFc, peptic digest, and obtained fractions was investigated using the bioscreen method. The growth of Listeria innocua ATCC 33090 and LRGIA 01 strains was not inhibited by LFc and its hydrolysates. Two fractions of dromedary lactoferrin peptic hydrolysate were active against both strains. A tandem mass spectroscopy analysis revealed that the 2 active fractions comprised at least 227 different peptides. Among these peptides, 9 found in the first fraction had at least 50% similarity with 10 known antimicrobial peptides (following sequence alignments with the antimicrobial peptide database from the University of Nebraska Medical Center, Omaha). Whereas 9 of these peptides presented homology with honeybee, frog, or amphibian peptides, the 10th peptide, F₁₅₂SASCVPCVDGKEYPNLCQLCAGTGENKCACSSQEPYFGY₁₉₂ (specifically found in 1 separated fraction), exibited 54% homology with a synthetic antibacterial peptide (AP00481) derived from human lactoferrin named kaliocin-1. Similarly, the second fraction contained 1 peptide similar to lactoferrampin B, an antibacterial peptide derived from bovine milk. This result suggests that peptic hydrolysis of LFc releases more active antimicrobial peptides than their protein source and thus provides an opportunity for their potential use to improve food safety by inhibiting undesirable and spoilage bacteria.

Bioinformatics and peptidomics approaches to the discovery and analysis of food-derived bioactive peptides

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 "hyphenated" (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.