Current Perspectives on the Physiological Activities of Fermented Soybean-Derived Cheonggukjang

Abstract

Cheonggukjang (CGJ, fermented soybean paste), a traditional Korean fermented dish, has recently emerged as a functional food that improves blood circulation and intestinal regulation. Considering that excessive consumption of refined salt is associated with increased incidence of gastric cancer, high blood pressure, and stroke in Koreans, consuming CGJ may be desirable, as it can be made without salt, unlike other pastes. Soybeans in CGJ are fermented by Bacillus strains (B. subtilis or B. licheniformis), Lactobacillus spp., Leuconostoc spp., and Enterococcus faecium, which weaken the activity of putrefactive bacteria in the intestines, act as antibacterial agents against pathogens, and facilitate the excretion of harmful substances. Studies on CGJ have either focused on improving product quality or evaluating the bioactive substances contained in CGJ. The fermentation process of CGJ results in the production of enzymes and various physiologically active substances that are not found in raw soybeans, including dietary fiber, phospholipids, isoflavones (e.g., genistein and daidzein), phenolic acids, saponins, trypsin inhibitors, and phytic acids. These components prevent atherosclerosis, oxidative stress-mediated heart disease and inflammation, obesity, diabetes, senile dementia, cancer (e.g., breast and lung), and osteoporosis. They have also been shown to have thrombolytic, blood pressure-lowering, lipid-lowering, antimutagenic, immunostimulatory, anti-allergic, antibacterial, anti-atopic dermatitis, anti-androgenetic alopecia, and anti-asthmatic activities, as well as skin improvement properties. In this review, we examined the physiological activities of CGJ and confirmed its potential as a functional food.

Keywords: bioactive molecule; biological activity; cheonggukjang; fermented soybean paste; human health benefit.

Figure 1

General procedure for preparation of CGJ (A) [2] and the broad type of traditional fermented soybean products in Asia (B) [5].

Figure 2

Chemical structure of the major classes of isoflavone and metabolites and γ-glutamic acid produced by CGJ fermentation. Structures were drawn using the ChemSpider (Royal Society of Chemistry, Cambridge, UK; http://www.chemspider.com, accessed on 24 May 2021) tool.

Figure 3

Proximate composition (A), concentration of amino acids (B) and mineral and vitamin content (C) of CGJ [1,2].

Figure 4

Potential mechanism of CGJ in memory function. The boxed panel contains a schematic diagram representing the metabolism of isoflavones in the intestine. Soybean-fermented CGJ components actively influence cellular metabolism in the liver and brain, exerting positive effects through the gut–intestine–microbiome–liver–brain axis. Improved cellular metabolism in the hippocampus decreases β-amyloid accumulation, insulin resistance, neuroinflammation, and memory impairment in the brain. This result suggests that a diet containing CGJ, in part, protects against type 2 diabetes, Alzheimer’s disease, and post-stroke symptoms [3,63]. ISO, isoflavone; ISO-A, isoflavone aglycone; ISO-G, isoflavone glycoside; ISO-g, isoflavone glucuronide; ISO-s, isoflavone sulfate; sHPA-axis, short hypothalamic–pituitary–adrenal axis; LPH, membrane-bound lactase phlorizin hydrolase; MRP; (multi-drug resistance-related protein); γ-PGA, poly-γ-glutamic acid; SCFA, short-chain fatty acids. Figure adapted from Jeong, D.Y. et al. [3] and Larkin, T. et al. [63].

Figure 5

Soybean-protein-mediated blood pressure regulation via angiotensin-converting enzyme (ACE). Bradykinin, a peptide, a component of the kallikrein–kinin system associated with a blood pressure-lowering effect, is degraded by ACE.ACE inhibition has been postulated as a strategy for treating hypertension, which is an important factor associated with numerous diseases conditions, such as ischemic heart-diseases and cerebrovascular events [33]. ↑, increase; ↓, decrease. Figure adapted from Chattet, L. et al. [33].

Figure 6

The mechanism of daidzein (DZ) and genistein (GS) regulation at transcriptional and translational levels in HT29 colon cancer cells. GS represses expression of phosphorylated p38 (p-p38), and matrix metalloproteinases (MMP2 and MMP9) to inhibit HT29 cell proliferation, upregulates Bax/Bcl-2, caspase-8, and caspase-3 activity to enhance HT29 cell apoptosis, reverses epithelial–mesenchymal transition (EMT) through regulation of EMT markers and regulates Wnt signaling pathways by increasing Wnt inhibitory factor 1(WIF1) to block HT29 cell migration and invasion. Additionally, DZ and GS inhibit expression of phosphatidylinositol 3-kinase (PI3K) and forkhead box O3 (FOXO3) to suppress HT29 cell proliferation and decrease lipid droplet accumulation to provoke HT29 cells apoptosis [9]. ADRP, adipose differentiation-related protein; Bax2, apoptosis regulator belonging to Bcl2 family; Bcl2, anti- or pro-apoptosis regulator; c-Myc, multifunctional transcriptional factor; FARP1, RhoGEF and pleckstrin domain-containing protein 1; Fas, fatty acid synthetase; FOXC1, forkhead box C1; MMP2; matrix metalloproteinase 2; MTTP, microsomal triglyceride transfer protein; Notch-1, member of type 1 transmembrane protein family; p65 (RELA), transcription factor 65; p-NF-κB, phosphorylated nuclear factor kappa B; PPARγ, peroxisome proliferator-activated receptor-gamma; Snail/Slug, master regulatory transcription factor; Tip-47, lipid droplets-associated protein; TWIST, time without symptoms of diseases and subjective toxic effects of treatment; UCP2, uncoupling protein 2; ZEB, zinc-finger E-box-binding homeobox protein as a transcription factor; ↑, induction; ↓, repression; →, activation; ˧, inhibition. Figure adapted from Hsiaoa, L.H. et al. [9].

Figure 7

Protective mechanism against apoptosis, inflammation, and oxidative stress, and the membrane potential (ψ) of genistein induced by soybean-fermented CGJ to reduce cell death. Nuclear signaling through estrogen receptors (ERs) α and β, peroxisome proliferator-activated receptor gamma (PPARγ), and aryl hydrocarbon receptor (AhR) upregulates the expression of antiapoptotic genes, including growth factors and their receptors and antiapoptotic members of the B-cell lymphoma 2 (Bcl2) family. Conversely, the proapoptotic Bcl2 members, including Bad and Bax, are downregulated. Nuclear action mode also inhibits inflammation by suppressing nuclear factor kappa B (NF-κB) and activating NF-κB inhibitor (IκB). This, in turn, decreases the expression of genes associated with several inflammation mediators. Additionally, nuclear signaling also stimulates mitochondrial transcription factor A (TFAM) to produce mitochondrial energy and maintain membrane potential. Extranuclear signaling through membrane association (ERs and G protein-coupled ER (GPER)) and interaction with GFr stimulates multiple intracellular signaling pathways to prevent inflammation, apoptosis, and oxidative stress through NF-κB, c-Jun N-terminal kinase (JNK), and NF-κB repressing factor (Nrf), respectively. In addition, genistein acts as an electron acceptor to reduce levels of reactive oxygen and neutralize reactive oxygen species in the cell. [20]. Aβ, beta-amyloid; AhR, aryl hydrocarbon receptor; AIF, apoptosis-inducing factor; Akt, protein kinase B; ATP, adenosine triphosphate; Bad, bipolar affective disorder; Bax, Bcl2-associated X; Bcl2 and BclXL, anti-apoptotic multi-domain protein; BDNF, brain-derived neurotrophic factor; c-Jun, transcription factor involved in extensive pathophysiological process; Cox2, cyclooxygenase 2; eNOS, endothelial nitric oxide synthase; ERK1/2, extracellular regulated kinases 1 and 2; ERs, estrogen receptors; GDNF, glial cell line-derived neurotrophic factor; GFr, growth factor receptor; GPX, glutathione peroxidase; GPER, G protein-coupled ER; ERK, extracellular signal-regulated kinase; GSH, glutathione (reduced form); HO1, heme oxygenase 1; IκB, inhibitory-κB; IL-1β, interleukin 1 beta; iNOS, inducible NOS; JNK, c-Jun N-terminal kinase; Keap1, Kelch-like ECH-associated protein 1; LPS, lipopolysaccharide; MAPK, mitogen-activated protein kinase; MEK, MAPK-kinase; MMP, matrix metalloproteinase; NF-κB, nuclear factor-κB; NGF, nerve growth factor; nNOS, neuronal NOS; NOX, nitric oxide; Nrf2, nuclear factor E2-related factor 2; PI3K, phosphoinositide 3-kinase; PKA, protein kinase A; PPARγ, peroxisomeproliferator-activated receptor gamma; SOD, superoxide dismutase; TFAM, mitochondrial transcription factor A; TNF-α, tumor necrosis factor alpha; Trk, tropomyosin receptor kinase; VEGF, vascular endothelial growth factor; ↑, upregulation; ↓, downregulation; →, activation; ˧, inhibition. Figure adapted from Schreihofer, D.A. and Oppong-Gyebi, A. [20].

Figure 8

Anti-obesity and anti-diabetes activity of daidzein (DZ), genistein (GS), and its metabolite (6-hydroxydaidzein; 6-HD) through lower lipogenesis, liver oxidative stress, hyperglycemia, urinary glucose secretion, insulin tolerance, and weight; and decreased levels of triacylglycerol (TG), low-density lipoprotein (LDL), free fatty acids (FFAs), fasting blood glucose (FBG), and plasma insulin [9]. ACC, acetyl-CoA carboxylase; ADRP, adipose differentiation-related protein activator protein 1; AMPK, adenosine 5′-monophosphate-activated protein kinase; Akt, protein kinase B (serine/threonine-specific protein kinase); BMI, body mass index; C/EBP-α, CCAAT/enhancer-binding protein-alpha; ERK1/2, extracellular signal-regulated kinase 1 and 2; FAS, fatty acid synthetase; GLUT4, glucose transporter type 4; gp91 (NOX2), NADPH oxidase subunit; ICAM-1, intracellular adhesion molecule 1; IL-1, interleukin 1; ISN1, inosine 5′-monophosphate (IMP)-specific 5′-nucleotidase; MCP1, monocyte chemoattractant protein 1; MDA, malondialdehyde; MGO, methylglyoxal; NFIL3, nuclear factor interleukin-3-regulated protein; NF-κB, nuclear factor-kappa B; p-AMPK, phosphorylated adenosine 5′-monophosphate-activated protein kinase; p-ERK, phosphorylated extracellular signal-regulated kinase; PI3K, phosphatidylinositol 3-kinase; PKA, protein kinase A; PPARα, peroxisome proliferator-activated receptor-alpha; PPARγ, peroxisome proliferator-activated receptor-gamma; SCD1, stearoyl-CoA desaturase 1; TBARs, thiobarbituric acid reactive substances; UCP1, uncoupling protein 1; TNF-α, tumor necrosis factor-alpha; ↑, enhancing; ↓, lowering; →, activation; ˧, inhibition. Figure adapted from Hsiaoa, Y.H. et al. [9].

Figure 9

Mechanism of anti-osteoporosis effect through modulation of gene expression at the transcriptional and translational level in different kinds of bone cells by daidzein (DZ), genistein (GS), glycetin (GC), and their metabolites (6-hydroxydaidzein (6-HD), formononetin (FNT), dihydrodaidzein (DHD), biochain A (BCA), and cladrin). Cell differentiation and proliferation, osteogenic activity, and bone health (such as bone density) are enhanced, whereas cell apoptosis, bone loss, and bone resorption are attenuated in cells (MG-63, MC3T3-E1, Saos-2, and bone marrow) and rats/mice [9]. ALP, alkaline phosphatase; B.Ar, bone area; BMP2, bone morphogenetic protein 2; BV/TV, bone volume/tissue volume; Ca²⁺, calcium ion; C/EBP-α, CCAAT/enhancer-binding protein alpha; Col1a, collagen type 1; c-Fos, cellular oncogene fos; CTSK, cathepsin K; ERAα/β, estrogen receptor A alpha/beta; NFATc1, nuclear factor of activated T-cells cytoplasmic 1; OCN, osteocalcin; OPG, osteoprotegerin; PPARγ, peroxisome proliferator-activated receptor-gamma; RANKL, receptor of activator of nuclear factor kappa B ligand; RUNX2, runt-related transcription factor 2; SMI, structure model index; T3, triiodothyronine; T4, thyroxine; Tb.N, trabecular number; Tb.Pf, trabecular pattern factor; Tb.Sp, trabecular separation; Tb.Th, trabecular thickness; TNF-α, tumor necrosis factor-α; TRAP, tartrate-resistant acid phosphatase; Wnt/β-catenin, canonical Wnt pathway; ↑, enhancing; ↓, lowering; →, activation; ˧, inhibition. Figure adapted from Hsiaoa, Y.H. et al. [9].

Figure 10

Mechanisms of action for skin lightening agents on melanin biosynthesis under ultraviolet (UV) (A) [156] and core molecular pathways associated with regulation of melanin production in melanocytes (B) [157]. Genes encoding specific melanogenic enzymes, including tyrosinase precursor protein (TYR), and tyrosinase-related protein 1 and 2 (TRP1 and TRP2), are regulated by the master regulator-microphthalmia-associated transcription factor (MITF), which is in turn regulated by a number of important signaling pathways, including α-melanocyte-stimulating hormone (α-MSH)/adrenocorticotropic hormone (ACTH)/agonist stimulating protein (ASP), tyrosine kinase receptor (KIT)/stem cell factor (SCF), and wingless-related integration site (Wnt)/Frizzled (Fzd). Signal transduction is mediated by cyclic adenosine monophosphate (cAMP)/cAMP-dependent protein kinase (PKA), renin-angiotensin-system (RAS)/mitogen-activated protein kinase kinase (MEK)/extracellular signal-regulated kinase (ERK), and β-catenin pathways [157]. APC, adenomatous polyposis coli; AXIN, axis inhibitor; CREB, cAMP response element binding protein; GSK-3β, glycogen synthase kinase-3β; LRP5/6, low-density lipoprotein receptor-related protein 5 and 6; MC1R, melanocyte-specific melanocortin-1 receptor; PKA, protein kinase A; RAF, rapidly accelerated fibrosarcoma; →, activation; ˧, inhibition; ⇢, indirect activation. Figure adapted from Hanif, N. et al. [156] and Qian, W. et al. [157].

Figure 11

Biological effects of S(-)-equol and O-desmethylangolensin (O-DMA), daidzein (DZ), and genistein (GS) associated with gut microbiota growth and composition in rats/mice (right panel) and humans (right panel) [9]. ↑, enhancing; ↓, lowering; →, activation. Figure adapted from Hsiaoa, Y.H. et al. [9].

Figure 12

Schematic diagram of the human health benefits of CGJ.