In vitro and in vivo study of effects of fermented soybean product (chungkookjang) on NGF secretion ability and NGF receptor signaling pathway

Potential neuroprotective benefits of plant-based fermented foods in Alzheimer's disease: an update on preclinical evidence

Alzheimer's disease (AD) currently lacks effective treatments, making its prevention a critical focus. While accumulating evidence supports that plant-based fermented foods may contribute to AD prevention, the neuroprotective effect of plant-based fermented foods on AD has not been comprehensively reviewed. In this study, we conducted a systematic review of preclinical studies on the efficacy of plant-based fermented foods in AD. The literature search was based on databases including PubMed, Embase, Web of Science, and Scopus. The PICO approach was employed for report inclusion, and each report was assessed for risk of bias using the SYRCLE's RoB tool. From the analysis of 25 retrieved reports, we extracted essential details, including bibliographic information, animal models and characteristics, sources of plant-based fermented foods, dosages, administration routes, durations, and outcome measures. Our findings indicate that plant-based fermented foods may positively impact acute and long-term cognitive function, as well as beta-amyloid-mediated neurodegeneration. This review sheds light on the potential neuroprotective benefits of plant-based fermented foods for various AD-related aspects, including oxidative stress, synaptotoxicity, neuroinflammation, tau hyperphosphorylation, dysfunctional amyloidogenic pathways, and cognitive deficits, as observed in rodent models of AD. However, the small number of studies obtained from our literature search and the finding that many of them were of moderate methodological quality suggest the need for further investigation to substantiate the beneficial potential of this class of functional food for the management of AD.

Does a pickle a day keep Alzheimer's away? Fermented food in Alzheimer's disease: A review

Fermented food is commonly viewed as healthy, mostly due to its probiotic and digestion-enhancing properties and recently it has been examined with regard to the development of new therapeutic and preventive measures for Alzheimer's disease. Fermented food has been shown to have anti-inflammatory and antioxidant properties and to alter the gut microbiota. However, the exact pathogenesis of Alzheimer's disease is still unknown and its connections to systemic inflammation and gut dysbiosis, as potential targets of fermented food, require further investigation. Therefore, to sum up the current knowledge, this article reviews recent research on the pathogenesis of Alzheimer's disease with emphasis on the role of the gut-brain axis and studies examining the use of fermented foods. The analysis of the fermented food research includes clinical and preclinical in vivo and in vitro studies. The fermented food studies have shown promising effects on amyloid-β metabolism, inflammation, and cognitive impairment in animals and humans. Fermented food has great potential in developing new approaches to Alzheimer's disease treatment.

Effects of Phytochemicals from Fermented Food Sources in Alzheimer's Disease In Vivo Experimental Models: A Systematic Review

The socioeconomic burden of Alzheimer's Disease (AD) stems from its characteristic multifactorial etiology and, implicitly, the difficulties associated with its treatment. With the increase in life expectancy and health awareness, nutraceuticals and functional foods are filling in the gaps left by the limitation of classical medical treatment in chronic conditions associated with lifestyle factors, such as neurological disorders. Processes, such as fermentation that enhance food phytochemical content are garnering increased attention due to their functional and health-related properties. This systematic review aims to provide an overview of the evidence of phytochemicals from fermented food sources inducing therapeutic outcomes and cognitive benefits from in vivo experimental models of Alzheimer's Disease. The present systematic review was conducted in accordance with PRISMA guidelines. Searches were performed in the following databases: MEDLINE, Embase, Cochrane, Scopus, Google Scholar, and Science Citation Index Expanded (Web of Science) by two independent reviewers. Titles and abstracts yielded by the search were screened for eligibility against the inclusion criteria. The search strategy yielded 1899 titles, encompassing studies from 1948 to 2022. After the removal of duplicates, and screening of titles, abstracts, and full texts, thirty three studies obtained from the original search strategy and seven studies from references satisfied the inclusion criteria and were included in the present systematic review. Several studies have emphasized the potential of fermentation to yield small-molecule phytochemicals that are not present in raw products. When these phytochemicals are combined, their collective strength has demonstrated the ability to exceed the antioxidant, anti-inflammatory, and neuroprotective benefits of individual phytochemicals when given in their pure form. Among the various fermented foods that have been studied, soy isoflavones obtained through fermentation have shown the most substantial evidence of altering phytochemical content and improving outcomes in animal models of AD. While promising in initial results, other fermented foods and traditional medicines require more detailed research in order to establish their effectiveness and proper utilization. As is, many of the experimental designs lacked phytochemical analysis of the used fermented product or comparison with the non-fermented counterpart. This, coupled with proper reporting in animal studies, will significantly raise the quality of performed studies as well as the weight of obtained results.

γ-PGA-Rich Chungkookjang, Short-Term Fermented Soybeans: Prevents Memory Impairment by Modulating Brain Insulin Sensitivity, Neuro-Inflammation, and the Gut-Microbiome-Brain Axis

Fermented soybean paste is an indigenous food for use in cooking in East and Southeast Asia. Korea developed and used its traditional fermented foods two thousand years ago. Chungkookjang has unique characteristics such as short-term fermentation (24–72 h) without salt, and fermentation mostly with Bacilli. Traditionally fermented chungkookjang (TFC) is whole cooked soybeans that are fermented predominantly by Bacillus species. However, Bacillus species are different in the environment according to the regions and seasons due to the specific bacteria. Bacillus species differently contribute to the bioactive components of chungkookjang, resulting in different functionalities. In this review, we evaluated the production process of poly-γ-glutamic acid (γ-PGA)-rich chungkookjang fermented with specific Bacillus species and their effects on memory function through the modulation of brain insulin resistance, neuroinflammation, and the gut–microbiome–brain axis. Bacillus species were isolated from the TFC made in Sunchang, Korea, and they included Bacillus (B.) subtilis, B. licheniformis, and B. amyloliquefaciens. Chungkookjang contains isoflavone aglycans, peptides, dietary fiber, γ-PGA, and Bacillus species. Chungkookjangs made with B. licheniformis and B. amyloliquefaciens have higher contents of γ-PGA, and they are more effective for improving glucose metabolism and memory function. Chungkookjang has better efficacy for reducing inflammation and oxidative stress than other fermented soy foods. Insulin sensitivity is improved, not only in systemic organs such as the liver and adipose tissues, but also in the brain. Chungkookjang intake prevents and alleviates memory impairment induced by Alzheimer’s disease and cerebral ischemia. This review suggests that the intake of chungkookjang (20–30 g/day) rich in γ-PGA acts as a synbiotic in humans and promotes memory function by suppressing brain insulin resistance and neuroinflammation and by modulating the gut–microbiome–brain axis.

Doenjang, A Korean Traditional Fermented Soybean Paste, Ameliorates Neuroinflammation and Neurodegeneration in Mice Fed a High-Fat Diet

Obesity is considered a risk factor for neurodegeneration. Because fermentation of soybean increases contents of various bioactive compounds with anti-obesity and anti-diabetic activities, we investigated the protective effect of doenjang, a Korean traditional fermented soybean paste, against neuroinflammation and neurodegeneration in the cortex and hippocampus of mice fed a high-fat (HF) diet. C57BL/6J mice were fed a low-fat diet, an HF diet, an HF-containing steamed soybean diet, or an HF-containing doenjang (DJ) diet for 11 weeks. Doenjang consumption alleviated hippocampal neuronal loss, which was increased by the HF diet. Accordingly, we observed higher cell proliferation and neurotrophic factor mRNA levels in the DJ group. Contents of oxidative metabolites and mRNA levels of oxidative stress- and neuroinflammation-related genes were lower in the DJ group compared to the HF group. Dietary doenjang reduced β-amyloid peptide (Aβ) levels by regulating gene expressions involved in Aβ production and degradation. Furthermore, doenjang consumption reduced tau hyperphosphorylation induced by HF feeding. Overall, doenjang was more effective than steamed soybean in suppressing neuroinflammation and neurodegeneration in mice fed an HF diet. These results suggest that bioactive compounds produced during the fermentation and aging of soybean may be involved in the enhanced neuroprotective effects of doenjang.

Asparagus cochinchinensis stimulates release of nerve growth factor and abrogates oxidative stress in the Tg2576 model for Alzheimer's disease

Backgroud

Use of multifunctional drugs with neurotrophic supporting and oxidative stress suppressing activity may be considered a therapeutic strategy to protect or repair cellular damage caused during the progression of Alzheimer’s disease (AD). In this study, we investigated the therapeutic effects of aqueous extract of A. cochinchinesis root (AEAC), particularly its role as a nerve growth factor (NGF) stimulator and anti-oxidant in Tg2576 mice showing AD phenotypes of human.

Methods

Tg2576 mice were received 100 mg/kg/day AEAC via oral administration, while mice in the Vehicle treated group received dH₂O for 4 weeks. Non-Tg littermates were used as a control group. Following AEAC treatment for 4 weeks, NGF function, anti-oxidantive status, Aβ-42 peptide level, γ-secretase expression and neuronal cell functions were analyzed in the brain of Tg2576 mice.

Results

AEAC containing flavonoids, phenols, saponins and protodioscin induced enhancement of NGF secretion and decreased intracellular ROS in the neuronal and microglial cell line. These effects as well as enhanced SOD levels were also detected in AEAC treated Tg2576 mice. The expression of p-Akt among downstream effectors of the high affinity NGF receptor was dramatically recovered in AEAC treated Tg2576 mice, while the expression of p75^NTR was slightly recovered in the same group. Significant recovery on the level of Aβ-42 peptides and the expression of γ-secretase members including PS-2, APH-1 and NCT were detected in AEAC treated Tg2576 mice. Furthermore, AEAC treated Tg2576 mice showed decreased numbers of dead cells and suppressed acetyl choline esterase (AChE) activity.

Conclusions

These results suggest that AEAC contribute to improving the deposition of Aβ-42 peptides and neuronal cell injuries during the pathological progression stage of AD in the brain of Tg2576 mice through increased NGF secretion and suppressed oxidative stress.

Korean traditional Chungkookjang improves body composition, lipid profiles and atherogenic indices in overweight/obese subjects: a double-blind, randomized, crossover, placebo-controlled clinical trial

BACKGROUND/OBJECTIVES

Chungkookjang is a Korean representative fermented soybean food. In this study, we investigated the effect of Korean traditional Chungkookjang compared with placebo on body composition, dyslipidemia and risk factors for atherosclerosis in overweight/obese subjects.

SUBJECTS/METHODS

This double-blind, randomized, controlled crossover trial was conducted on 120 overweight/obese subjects, aged 19-29 years. Subjects were randomly divided into a Chungkookjang (n=60) or a placebo (n=60) group. After 12 weeks, the groups were crossed over for an additional 12 weeks. During the intervention period, subjects were asked to maintain their usual diet and activity and not to take any functional foods or dietary supplements. The anthropometric measures, lipid profiles and atherogenic indices were determined at baseline and at the end of each 12-week period.

RESULTS

The anthropometry measurements, percentage body fat, lean body mass, waist circumference and waist-to-hip ratio of women in the Chungkookjang group were significantly improved compared with the placebo group. Lipid profiles and high-sensitivity C-reactive protein of women in Chungkookjang were significantly improved. The atherogenic indices of apolipoprotein B/apolipoprotein A1 decreased in both the placebo and the Chungkookjang group, and it also decreased below 0.55 for all the men and women in the Chungkookjang group.

CONCLUSIONS

In conclusion, these results suggest that supplementation with Chungkookjang may improve body composition and risk factors for cardiovascular disease in overweight and obese adults.

Neuroprotective effects of fermented soybean products (Cheonggukjang) manufactured by mixed culture of Bacillus subtilis MC31 and Lactobacillus sakei 383 on trimethyltin-induced cognitive defects mice

OBJECTIVES

This study aimed to investigate the beneficial effects of Cheonggukjang (CGK) manufactured by mixed culture of Bacillus subtilis MC31 and Lactobacillus sakei 383 on neurotoxic damages.

METHODS

The specific aspects of brain functions were measured in Institute for Cancer Research (ICR) mice that had been pretreated for 4 weeks with three difference doses of CGK before trimethyltin (TMT) treatment.

RESULTS

The short- and long-term memory loss induced by TMT treatment was significantly improved in the CGK-pretreated group in a dose-dependent manner. The number of dead cells in the granule cell layer of the dentate gyrus was decreased in the TMT/CGK-cotreated group relative to the TMT/vehicle-treated group, whereas significant suppression of acetylcholinesterase (AChE) activity was observed in the same group. Additionally, a dose-dependent increase in nerve growth factor (NGF) concentration, activation of the NGF receptor signaling pathway including the TrkA high affinity receptor and p75(NTR) low affinity receptor, and decline in Bax/Bcl-2 level was measured in all TMT/CGK-treated groups, although a decrease in the active form of caspase-3 was observed in the TMT/H-CGK-treated group. Furthermore, superoxide dismutase (SOD) activity was enhanced in the TMT/CGK-treated group, whereas the level of malondialdehyde (MDA), a marker of lipid peroxidation, was 43-58% lower in the TMT/CGK-treated group than the TMT/vehicle-treated group.

DISCUSSION

These results demonstrate that CGK fermented by mixed culture of B. subtilis and L. sakei could exert a wide range of beneficial activities for neurodegenerative diseases, including Alzheimer, Parkinson, and Huntington disease.

Toxicity of fermented soybean product (cheonggukjang) manufactured by mixed culture of Bacillus subtilis MC31 and Lactobacillus sakei 383 on liver and kidney of ICR mice

To investigate the toxic effects of cheonggukjang (CKJ) manufactured using mixed cultures of Bacillus subtilis MC31 and Lactobacillus sakei 383 on the liver and kidney of ICR mice, an alteration on the related markers including body weight, organ weight, urine composition, liver pathology and kidney pathology were analyzed after oral administration at dosage of 25, 50 and 100 mg/kg body weight/day of CKJ for 14 days. Any significant toxicity was not observed on the body and organ weight, clinical phenotypes, urine parameters and mortality in the CKJ-treated group compared with the vehicle-treated group. Also, liver toxicity analysis revealed no significant increase in alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST) or lactate dehydrogenase (LDH) in response to CKJ. Additionally, the specific pathological features induced by most toxic compounds were not observed upon liver histological analysis. Furthermore, kidney toxicological analysis revealed that blood urea nitrogen (BUN) and the serum creatinine (Cr) levels and pathological features on histological sections did not differ significantly between the vehicle- and CKJ-treated groups. Overall, these results suggest that CKJ does not induce any specific toxicity in liver and kidney organs of ICR at dose of 100 mg/kg body weight/day as no observed adverse effect level (NOAEL).

Quantitative evaluation of the therapeutic effect of fermented soybean products containing a high concentration of GABA on phthalic anhydride-induced atopic dermatitis in IL-4/Luc/CNS-1 Tg mice

Cheonggukjang (CKJ) is a fermented soybean product that exhibits diverse biological and pharmacological activities, including anti-obesity, anti-diabetic, and anti-inflammatory effects on human chronic diseases. In this study, the effects of the aqueous extract of CKJ containing a high concentration of GABA on atopic dermatitis (AD) were quantified using the luciferase reporter system in IL-4/Luc/CNS-1 transgenic (Tg) mice. Alterations of the luciferase signal and phenotypes of AD were quantified in the IL-4/Luc/CNS-1 Tg mice co-treated with phthalic anhydride (PA) and CKJ for 4 weeks using the IVIS imaging system. A strong luciferase signal was detected in the abdominal region of IL-4/Luc/CNS-1 Tg mice treated with PA alone. However, this signal was significantly reduced in IL-4/Luc/CNS-1 Tg mice co-treated with PA and CKJ. The thymus showed the greatest decrease in luciferase following CKJ treatment, but the level increased after PA treatment. Furthermore, the CKJ-treated group showed improvement of common allergic responses including decreased ear thickness, dermis thickness, auricular lymph node (ALN) weight and infiltrating mast cells. However, IgE concentration and epidermis thickness were maintained a constant level. These results indicated that the luciferase signal may successfully reflect the therapeutic effects of CKJ in IL-4/Luc/CNS-1 Tg mice. The results also suggested that CKJ may be considered an effective substance for the treatment of AD.

Fermented soybean product (Cheonggukjang) improved some attributes of protein and growth hormone measurements in Sprague-Dawley rats

We hypothesized that the administration of Cheonggukjang (CKJ) would exert positive effects on factors implicated with growth in Sprague-Dawley (SD) rats. To test this hypothesis, we measured specific aspects of bone and organ growth in male SD rats that were treated for 6 weeks with 3 concentrations of CKJ. Although the CKJ extract contained high concentrations of flavonoids and phenolic compounds, no significant differences in body length, organ weights, or femur weight were detected between the CKJ- and vehicle-treated groups. However, thicknesses of the epiphyseal growth plate in the proximal femoral epiphysis and the compact bone in the linea aspera were broadest in the femur of the 2 CKJ-treated groups when compared with the vehicle-treated groups. Furthermore, the levels of growth hormone (GH) and calcium ion were higher in the sera of the high-concentration CKJ-treated groups, whereas the expression level of GH receptor was higher in muscle tissue of all CKJ-treated groups and in the liver tissue of the high-concentration CKJ-treated group. In the GH receptor downstream signaling pathway, the phosphorylation levels of Akt and Erk were expressed differently between liver and muscle tissues upon CKJ treatment. However, the phosphorylation level of STAT5 was very similar to the expression level of the GH receptor in all CKJ-treated groups. These results indicate that CKJ extract may increase the thickness of the epiphyseal growth plate and the compact bone of the femur, elevate GH secretion, and stimulate regulation of the GH receptor downstream signaling pathway in the liver and muscle tissues of SD rats.