Extraction of Bioactive Compounds from Different Vegetable Sprouts and Their Potential Role in the Formulation of Functional Foods against Various Disorders: A Literature-Based Review

In this review, we discuss the advantages of vegetable sprouts in the development of food products as well as their beneficial effects on a variety of disorders. Sprouts are obtained from different types of plants and seeds and various types of leafy, root, and shoot vegetables. Vegetable sprouts are enriched in bioactive compounds, including polyphenols, antioxidants, and vitamins. Currently, different conventional methods and advanced technologies are used to extract bioactive compounds from vegetable sprouts. Due to some issues in traditional methods, increasingly, the trend is to use recent technologies because the results are better. Applications of phytonutrients extracted from sprouts are finding increased utility for food processing and shelf-life enhancement. Vegetable sprouts are being used in the preparation of different functional food products such as juices, bread, and biscuits. Previous research has shown that vegetable sprouts can help to fight a variety of chronic diseases such as cancer and diabetes. Furthermore, in the future, more research is needed that explores the extraordinary ways in which vegetable sprouts can be incorporated into green-food processing and preservation for the purpose of enhancing shelf-life and the formation of functional meat products and substitutes.

Isolation of bioactive peptides and multiple nutraceuticals of antidiabetic and antioxidant functionalities through sprouting: Recent advances

The employment of proteases directly from enzymes or indirectly from microorganisms during fermentation for the purpose of proteolysis of food proteins has been the conventional trend for the derivation of bioactive peptides from food matrices. However, recent studies have shown that inherent protease enzymes can be activated for this activity for vegetable foods using the sprouting process. The benefits of ease of operation, and reduced processing costs are formidable advantages for the optimal consideration of this technique. On another note, the demand for functional foods with therapeutic health effects has increased in recent years. Globally, plant foods are perceived as dietetic choices bearing sufficient quantities of concomitant nutraceuticals. In this manuscript, the sprouting route for the isolation of peptides and glucosinolates, and for the enhancement of total phenolic contents, polyunsaturated fatty acid profiles, and other bioactive constituents was explored. Advances regarding the phytochemical transformations in the course of sprouting, the therapeutic functionalities, and microbiological safety concerns of vegetable sprouts are delineated. In addition, consumption of vegetable sprouts has been shown to be more efficient in supplying nutraceutical components relative to their unsprouted counterparts. Biochemical mechanisms involving the inhibition of digestive enzymes such as α-amylase, β-glucosidase, and dipeptidyl peptidase IV (DPP-IV), single electron transfer, and metal chelation, for impartation of health benefits, have been reported to occur from bioactive components isolated from vegetable sprouts. PRACTICAL APPLICATIONS: Sprouting initiates proteolysis of vegetable proteins for the release of bioactive peptides. Abiotic stresses can be used as elicitors during the sprouting process to achieve enhanced phytochemical profiles of sprouts. Sprouting is a relatively more convenient approach to the improvement of the health benefits of vegetable foods. Vegetable sprouts are potential for the management of metabolic syndrome disorders.

Recent Advances in Bioactive Compounds, Health Functions, and Safety Concerns of Onion (Allium cepa L.)

Onion (Allium cepa L.) is a common vegetable, widely consumed all over the world. Onion contains diverse phytochemicals, including organosulfur compounds, phenolic compounds, polysaccharides, and saponins. The phenolic and sulfur-containing compounds, including onionin A, cysteine sulfoxides, quercetin, and quercetin glucosides, are the major bioactive constituents of onion. Accumulated studies have revealed that onion and its bioactive compounds possess various health functions, such as antioxidant, antimicrobial, anti-inflammatory, anti-obesity, anti-diabetic, anticancer, cardiovascular protective, neuroprotective, hepatorenal protective, respiratory protective, digestive system protective, reproductive protective, and immunomodulatory properties. Herein, the main bioactive compounds in onion are summarized, followed by intensively discussing its major health functions as well as relevant molecular mechanisms. Moreover, the potential safety concerns about onion contamination and the ways to mitigate these issues are also discussed. We hope that this paper can attract broader attention to onion and its bioactive compounds, which are promising ingredients in the development of functional foods and nutraceuticals for preventing and managing certain chronic diseases.

Effect of storage, food processing and novel extraction technologies on onions flavonoid content: A review

Onions play an important part in the daily diet for most populations around the world owing to their nutritional composition and their unique capacity to naturally flavor dishes. Onions contain quercetin and its derivatives - the predominant flavonoid in onions that exert a great contribution to the effective bioactive properties of onion, including its derived products. The present paper comprehensively reviewed flavonoids (with a specific focus on quercetin in onions): their chemical composition, distribution, bioactivities in onion, and impacting factors with a focus on how they can be affected by various post-harvest conditions (storage and food processing). In addition, research on the extraction of flavonoid compounds from onions using a number of novel technologies was also reviewed.

Valorization of onion solid waste and their flavonols for assessment of cytotoxicity, enzyme inhibitory and antioxidant activities

Onion (Allium cepa L.) is rich with flavonols which perceived benefits to human health. Flavonols like quercetin and quercetin glycosides from onion solid waste (OSW) have been extracted and tested against enzymes of clinical importance in Alzheimer's disease and diabetes and be shown to have cytotoxic and antioxidant effects. A simple high-performance liquid chromatography-diode array detector method using a Zorbax Eclipse XDB C18 column was developed to separate quercetin-3, 4'-O-diglucoside, quercetin-4'-O-monoglucoside, and quercetin from OSW. These compounds were identified using infrared, ultra-violet, ¹H, and ¹³C nuclear magnetic resonance spectroscopic techniques. The OSW solvent fractions and flavonols showed significant antioxidant activities using DPPH (1, 1-diphenyl-2-picrylhydrazyl), FRAP (ferric reducing antioxidant power), and ABTS (2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid) radical scavenging assays. The samples exhibited significant in vitro anti-cholinesterase activity with strong antidiabetic effects. OSW extracted with methanol and ethanol showed greater in vitro anti-cholinesterase and hypoglycemic effects than QDG, QMG, and Q possibly due to interactions between multiple compounds and/or complex multivariate interactions with other factors in OSW. In addition, cytotoxicity assays showed that OSW and QDG, QMG, and Q could inhibit the proliferation of selected cancer cell lines. Results indicate that OSW and flavonol glycosides are potential antioxidant, antidiabetic, anticancer, and sedative agents.

Effect of Light- and Dark-Germination on the Phenolic Biosynthesis, Phytochemical Profiles, and Antioxidant Activities in Sweet Corn (Zea mays L.) Sprouts

Sweet corn is one of the most widely planted crops in China. Sprouting of grains is a new processes to increase the nutritional value of grain products. The present study explores the effects of light on the nutritional quality of sweet corn sprouts. Gene expression of phenolic biosynthesis, phytochemical profiles and antioxidant activity were studied. Two treatments (light and dark) were selected and the morphological structure of sweet corn sprouts, as well as their biochemical composition were investigated to determine the effects of light on the regulation of genes responsible for nutritional compounds. Transcription analyses for three key-encoding genes in the biosynthesis of the precursors of phenolic were studied. Results revealed a negative regulation in the expression of _ZmPAL with total phenolic content (TPC) in the light group. TPC and total flavonoid content (TFC) increased during germination and this was correlated with an increase in antioxidant activity (r = 0.95 and 1.0). The findings illustrate that the nutritional value of sweet corn for the consumer can be improved through germination to the euphylla stage.