Bioavailability of Isoflavone Metabolites After Korean Fermented Soybean Paste (Doenjang) Ingestion in Estrogen‐Deficient Rats

Abstract

Doenjang (DJ), a fermented soybean product used in soups, stews, and sauces, contains high quality proteins, fats, vitamins, minerals, and other functional ingredients, including isoflavones and saponins. This study investigated whether DJ improves the bioavailability of isoflavones compared to boiled soybean (BS) in sham-operated or ovariectomized (OVX) rats. We also examined the effects of ovariectomy on the differences in bioavailability of isoflavones. BS and DJ were administered in sham-operated and OVX rats, and blood samples were collected. Twenty-six isoflavone-derived metabolites were identified. Pharmacokinetic analysis revealed that T values of the individual isoflavone metabolites were most different in sham and OVX rats, even after the same sample treatment; however, T values were significant different in a few metabolites such as daidzein 4'-glucuronide, daidzein 4'-sulfate, 2-(4-hydroxyphenyl)propionic acid, and benzoic acid. For most of the individual metabolites, C was higher in both sham and OVX rats administered BS than those administered DJ. The AUC was generally lower in OVX rats than in sham rats. The AUC of daidzein and genistein in BS-fed sham rats was approximately 1.7-fold higher than those administered DJ, whereas glycitein was detected only in the DJ group. No significant differences in AUC of daidzein and genistein were observed between BS and DJ administration in OVX rats, although the total isoflavone content of DJ was lower; thus, DJ-mediated isoflavone bioavailability was more effective in OVX rats. Similar tendencies were observed for phase II and gut-mediated metabolites. These results suggested that DJ enhanced isoflavone bioavailability under estrogen deficiency, even when the total isoflavone content was decreased by fermentation.

Alleviation of Metabolic Disturbance by Substituting Kanjang High in Bacillus for Salt through Modulation of Gut Microbiota in Estrogen-Deficient Rats

“…Fermented soybean products alleviate metabolic disturbance with estrogen deficiency, and their effects are associated with isoflavonoids and the changes in gut microbiota [10,43]. The present study also showed that TMK intake, particularly HBHB and HBLB, modulated fecal microbiota from the cecum and alleviated menopausal symptoms.…”

Fermentation Improves the Preventive Effect of Soybean Against Bone Loss in Senescence‐Accelerated Mouse Prone 6

“…In general, DJ is made by soaking Meju, a main ingredient and a starter culture, made of cooked and crushed soybeans, in brine for a long period of time (Jeong, ). It was recently reported that compared to boiled soybean, although the total isoflavone content is lower, DJ exerts increased bioavailability of isoflavone (Lee et al., ). Despite clear evidence that the fermentation process alters soybean isoflavones, it is not clear how these alterations affect bone loss prevention (Choi Yang et al., ; Zhang, Chen, Lai, & Wong, ).…”

Recent Advances in Heterologous Synthesis Paving Way for Future Green-Modular Bioindustries: A Review With Special Reference to Isoflavonoids

“…Due to this affinity, isoflavonoids interfere with cellular signaling mechanisms and play an important role in cellular growth and protection (Figure 3). Isoflavonoid aglycones (without glucose) are sometimes biologically more active and available than glycones, as glucose moiety has a strong effect on their function and absorbance in the human gastrointestinal tract (Lee et al, 2018). For example, in its un-glycosylated form, the affinity of genistein is comparable with that of 17β-estradiol, but in its glycosylated forms, its affinity is up to 100-500 times less (Kuiper et al, 1997;Breinholt and Larsen, 1998).…”