Styphnolobium japonicum Fruit and Germinated Soybean Embryo Complex Extract for Postmenopausal-Symptom Relief

Abstract

Background/objectives: Hormonal alterations during menopause result in substantial physiological changes. Although hormone replacement therapy (HRT) is widely used as a treatment strategy for these changes, its use remains controversial due to its associated risks. Plant isoflavones are phytoestrogens that are considered a potential alternative therapy for postmenopausal syndrome. We aimed to investigate the efficacy of ethanolic extracts from Styphnolobium japonicum fruit (SJF) and germinated soybean embryo (GSE) in alleviating prominent menopausal symptoms.

Methods: A cell model (MCF7 human breast cancer cells) was used to investigate estrogen-like activity. A rat ovariectomy model was used to simulate estrogen depletion after menopause and to evaluate the efficacy of the SJF-GSE complex extract at ratios of 1:1, 1:2, and 2:1.

Results: Treatment with the SJF-GSE extract elicited estrogen-like effects, raising pS2 and estrogen receptor α expression in MCF7 cells. The extract was found to contain 48-72 mg/g sophoricoside and 8-12 mg/g soyasaponin 1, identified as active compounds. In ovariectomized rats, the extract effectively reduced body weight and fat content, alleviated vasomotor symptoms, improved vaginal mucosal health, and exerted osteoprotective effects by enhancing bone density and structure, reducing bone-resorption markers and positively altering estradiol levels and lipid profiles.

Conclusions: The SJF-GSE extract, working synergistically, provides a safe and effective alternative to HRT for managing postmenopausal symptoms and enhancing bone health, without adverse effects. These findings support the inclusion of SJF and GSE in health-functional foods and underscore the importance of further research into plant-based therapies for menopause.

Keywords: Styphnolobium japonicum fruit; germinated soybean embryo; medicinal plant; menopause; ovariectomized rat model; phytoestrogen.

Figure 1

In vivo study design and group allocation. The flowchart illustrates the design of our in vivo study involving adult female Sprague-Dawley (SD) rats. The rats were divided into six groups (n = 7 per group): (1) non-ovariectomized control (Sham); (2) ovariectomized control (OVX); (3) positive control group receiving 0.1 mg/kg of 17β-estradiol (E2); groups 4–6 were OVX groups treated with the blended SJF–GSE complex extract at 25 mg/kg (Low), 50 mg/kg (Medium), and 100 mg/kg (High), respectively. After the 3-week recovery period, the rats were provided with custom-manufactured diets containing the specific treatment compounds. The SJF-GSE complex extract was prepared as detailed in the Section 2, with a 1.5:1 ratio of SJF to GSE. SJF, Styphnolobium japonicum fruit; GSE, germinated soybean embryo.

Figure 2

Evaluation of the estrogen-like activity of Styphnolobium japonicum fruit extract (SJFE) and germinated soybean embryo extract (GSEE) combinations in MCF7 cells. (A) Expression of pS2 mRNA, quantified using qPCR. (B–D) Representative immunoblots of ERα, phosphorylated Akt (p-Akt), total Akt, and β-actin. (E) Immunocytochemical analysis of ERα expression (left panel). The relative ERα/PI ratio is presented as fold-change relative to the control (right panel). 17β-estradiol (E2) was used as a positive control, and ICI 182,780 was used as an estrogen antagonist. Scale bar, 100 µm. Results from three independent experiments are shown as means ± standard deviation. * p < 0.05, ** p < 0.01, vs. the control group; ## p < 0.01, vs. the indicated group. ER, estrogen receptor; PI, propidium iodide.

Figure 3

Analysis of active compounds in the Styphnolobium japonicum fruit (SJF) and germinated soybean embryo (GSE) complex extract, prepared by blending the SJF and GSE. HPLC was used to analyze sophoricoside (A) and soyasaponin 1 (B) levels. The compounds were identified and measured by comparing their retention times (RTs) against those of the standards.

Figure 4

Body weight and vasomotor symptoms in ovariectomized (OVX) rats treated with the Styphnolobium japonicum fruit (SJF) and germinated soybean embryo (GSE) complex extract. (A) Body weight over 12 weeks. (B) Rectal temperature changes during the 120 min post-exercise. The complex extract was prepared by blending SJF and GSE. 17β-estradiol (E2) was used as a positive control. The results are presented as the means ± standard deviation (n = 7). * p < 0.05, ** p < 0.01, *** p < 0.001 vs. the sham group; # p < 0.05, ## p < 0.01, ### p < 0.001, vs. the OVX group.

Figure 5

Vaginal cornification in ovariectomized (OVX) rats treated with the Styphnolobium japonicum fruit (SJF) and germinated soybean embryo (GSE) complex extract. Representative images of stained vaginal epithelial cells, illustrating the proportion of nucleated and cornified cells (left panel). Counting and comparison of the number of cornified cells (right panel). Scale bar, 100 µm. The complex extract was prepared by blending the SJF and GSE. 17β-estradiol (E2) was used as a positive control. The results are presented as means ± standard deviation (n = 7). ** p < 0.01, vs. the sham group; ## p < 0.01, ### p < 0.001, vs. the OVX group.

Figure 6

Uterine changes in ovariectomized (OVX) rats treated with the Styphnolobium japonicum fruit (SJF) and germinated soybean embryo (GSE) complex extract. (A) Representative images of dissected uterine tissue from the rats (left panel). Uterine weight (right panel). Scale bar, 1 cm. (B) Representative images of hematoxylin and eosin-stained uterine walls (left panel). Uterine thickness (right panel). Scale bar, 500 µm. The complex extract was prepared by blending the SJF and GSE. 17β-estradiol (E2) was used as a positive control. The results are presented as means ± standard deviation (n = 3). *** p < 0.001, vs. the sham group; # p < 0.05, ## p < 0.01, ### p < 0.001, vs. the OVX group.

Figure 7

Adipose tissue analysis in ovariectomized (OVX) rats treated with the Styphnolobium japonicum fruit (SJF) and germinated soybean embryo (GSE) complex extract. (A) Representative images of the perirenal adipose tissue (left panel). Fat weight (right panel). Scale bar, 1 cm. (B) Representative images of lipid droplets (left panel). Lipid droplet size (right panel). Scale bar, 100 µm. The complex extract was prepared by blending the SJF and GSE. 17β-estradiol (E2) was used as a positive control. The results are presented as means ± standard deviation (n = 3). *** p < 0.001, vs. the sham group; ## p < 0.01, ### p < 0.001, vs. the OVX group.

Figure 8

Bone features and gene expression profiles in ovariectomized (OVX) rats treated with the Styphnolobium japonicum fruit (SJF) and germinated soybean embryo (GSE) complex extract. (A–C) Expression of bone resorption-related genes, evaluated using qPCR, in femoral bone-derived bone marrow cells. (D) Hematoxylin and eosin-stained transverse sections of femur (left panel). Trabecular bone loss area (right panel). (E) Representative X-ray images of femoral bone (left panel). Bone mineral density (BMD) and bone mineral content (BMC) (right panel). Scale bar, 500 µm. The complex extract was prepared by blending the SJF and GSE. 17β-estradiol (E2) was used as a positive control. The results are presented as means ± standard deviation (n = 3). * p < 0.05, ** p < 0.01, *** p < 0.001, vs. the sham group; # p < 0.05, ## p < 0.01, ### p < 0.001, vs. the OVX group. IL-1β, interleukin 1β; RANK, receptor activator of nuclear factor κB; TRAP, tartrate-resistant acid phosphatase.