Mung bean (Vigna radiata L.) is an important pulse consumed all over the world, especially in Asian countries, and has a long history of usage as traditional medicine. It is an excellent source of protein, dietary fiber, minerals, vitamins, and significant amounts of bioactive compounds, including polyphenols, polysaccharides, and peptides, making it a popular functional food in promoting good health. The mung bean has been documented to ameliorate hyperglycemia, hyperlipemia, and hypertension, and prevent cancer and melanogenesis, as well as possess hepatoprotective and immunomodulatory activities. These health benefits derive primarily from the concentration and properties of those active compounds present in the mung bean. Vitexin and isovitexin are identified as the major polyphenols, and peptides containing hydrophobic amino acid residues with small molecular weight show higher bioactivity in the mung bean. Considering the recent surge in interest in the use of grain legumes, we hope this review will provide a blueprint to better utilize the mung bean in food products to improve human nutrition and further encourage advancement in this field.
Keywords: mung bean, bioactive compounds, polyphenols, polysaccharides, peptides, health benefits
Growing clinical evidence suggests that consumption of calorie-rich diets, high in fat and carbohydrate but low in protein, has led to increased rates of metabolic syndromes, such as hyperglycemia, dyslipidemia, and inflammation. Many worldwide health organizations have recommended a variety of plant-based functional foods, prompting a call for serious changes in dietary patterns to improve health statuses and prevent chronic diseases. Legumes (Fabaceae/Leguminosae) are considered the second most important human food crops, just after cereals (Gramineae). Legume seeds, however, constitute an essential part of the human diet as they are excellent sources of proteins, bioactive compounds, minerals, and vitamins, in comparison with cereals, and are referred to as "the poor man's meat".
The mung bean (Vigna radiata L.) is one of the most important edible legume crops, grown on more than 6 million ha worldwide (about 8.5% of the global pulse area) and consumed by most households in Asia. Due to its characteristics of relatively drought-tolerant, low-input crop, and short growth cycle (70 days or so), the mung bean is widely cultivated in many Asian countries (concentrated mainly in China, India, Bangladesh, Pakistan, and some Southeast Asian countries) as well as in dry regions of southern Europe and warmer parts of Canada and the United States.
In the predominantly cereal-based diets of China and India, the mung bean has been consumed as a common food for centuries. The mung bean contains balanced nutrients, including protein, dietary fiber, minerals, vitamins, and significant amounts of bioactive compounds. For those individuals who cannot afford animal proteins or those who are vegetarian, the mung bean is a comparatively low-cost and good source of protein. Furthermore, mung bean protein is easily digestible, as compared to protein in other legumes. Consumption of the mung bean combined with cereals has been recommended to significantly increase the quality of protein, as cereals are rich in sulfur-containing amino acids but deficient in lysine. A 3:4 ratio of mung bean protein with rice protein, obtaining the highest chemical amino acid score (72), was suggested as good for consumption. The protein digestibility of the rice-mung bean combination diet was found to be 84%. In addition, the mung bean has been used for various medicinal purposes in traditional medicine, including as an anti-inflammatory, diuretic, and antipyretic agent.
2. Bioactive Compounds in Mung Bean
The potential health benefits of the mung bean are primarily attributed to the presence of a variety of bioactive compounds, including polyphenols, polysaccharides, and peptides . These compounds have been shown to possess antioxidant, anti-inflammatory, antidiabetic, anticancer, and immunomodulatory properties, among others.
Polyphenols are secondary metabolites of plants known for their antioxidant properties and potential health benefits . The major polyphenolic compounds identified in the mung bean are flavonoids, including vitexin, isovitexin, and their derivatives . Vitexin and isovitexin have been reported to possess antioxidant, anti-inflammatory, and anticancer activities, and their presence in the mung bean contributes to its health-promoting properties [18,19].
Polysaccharides are complex carbohydrates composed of sugar monomers linked together by glycosidic bonds. The mung bean is a rich source of dietary fiber, which is primarily composed of polysaccharides. Mung bean polysaccharides (MBPs) have been reported to possess various biological activities, including antioxidant, antitumor, and immunomodulatory properties [20,21]. Recent studies have shown that MBPs can improve lipid metabolism and enhance antioxidant activity in rats fed with high-fat diets .
Peptides are short chains of amino acids, which are the building blocks of proteins. Bioactive peptides derived from mung bean protein have been shown to possess various health-promoting properties, such as antioxidant, antihypertensive, and antidiabetic activities [23,24]. Mung bean peptides with smaller molecular weight and higher hydrophobic amino acid residues have been found to exhibit higher bioactivity .
3. Health Benefits of Mung Bean
The bioactive compounds present in the mung bean contribute to its various health benefits, which include ameliorating hyperglycemia, hyperlipemia, and hypertension, preventing cancer and melanogenesis, and possessing hepatoprotective and immunomodulatory activities .
3.1. Antidiabetic Effects
Mung bean has been reported to possess antidiabetic effects, primarily due to its rich content of polyphenols and peptides . Studies have shown that mung bean polyphenols can inhibit α-amylase and α-glucosidase activities, which are key enzymes involved in the digestion and absorption of carbohydrates, thus reducing postprandial blood glucose levels . Mung bean peptides have also been reported to increase insulin sensitivity and regulate glucose metabolism in diabetic rats .
3.2. Antihypertensive Effects
Mung bean peptides have been demonstrated to possess antihypertensive effects, mainly by inhibiting the activity of angiotensin-converting enzyme (ACE), a key enzyme involved in blood pressure regulation . The antihypertensive effects of mung bean peptides have been validated in spontaneously hypertensive rats cell proliferation, and suppress migration and invasion of cancer cells. The anticancer effects of mung bean polyphenols are primarily attributed to their antioxidant properties and ability to modulate signaling pathways involved in cell survival and death.
3.4. Hepatoprotective Effects
Mung bean has been reported to possess hepatoprotective effects, which can be attributed to its rich content of bioactive compounds, such as polyphenols, peptides, and polysaccharides. These compounds have been shown to protect the liver against oxidative stress, inflammation, and hepatotoxic agents, such as carbon tetrachloride and acetaminophen. Mung bean extract has been demonstrated to attenuate liver injury by modulating antioxidant enzyme activities, reducing lipid peroxidation, and suppressing the production of pro-inflammatory cytokines.
3.5. Immunomodulatory Effects
The immunomodulatory effects of mung bean have been attributed to its polysaccharides, which can stimulate the production of immune cells, such as macrophages, T cells, and natural killer cells, and enhance the release of cytokines, including interferons and interleukins. Mung bean polysaccharides have also been reported to improve the immune response to viral infections, such as influenza and herpes simplex virus.
3.6. Melanogenesis Inhibition
Mung bean extract has been demonstrated to inhibit melanogenesis, the process of melanin synthesis in skin cells, which is responsible for skin pigmentation and the formation of age spots. Mung bean polyphenols, particularly vitexin and isovitexin, have been shown to suppress tyrosinase activity, a key enzyme involved in melanin synthesis. This melanogenesis inhibition property of mung bean can be utilized in the development of skin-whitening and anti-aging products.
The mung bean is an important edible legume crop that offers numerous health benefits due to its rich content of bioactive compounds, such as polyphenols, polysaccharides, and peptides. These compounds have been demonstrated to possess antioxidant, anti-inflammatory, antidiabetic, antihypertensive, anticancer, hepatoprotective, and immunomodulatory properties, among others. The health-promoting properties of mung bean make it a valuable functional food that can be used to improve human nutrition and prevent various chronic diseases. Further research is needed to better understand the mechanisms underlying the health benefits of mung bean and to develop novel food products that harness its potential.