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NUCLEAR RECEPTOR AGONISTIC ACTIVITIES OF A SAPONIN‐ENRICHED SOYBEAN EXTRACT
Author(s) -
SUHARA WAKAKO,
OKUZAWA TSUGUMI,
KOIDE HIDEYUKI,
AITA KIYOSHI,
NAKAMURA TETSURO,
NAKANO SATORU,
SATO KENICHI,
HAYASHI DOBUN,
KOJO HITOSHI
Publication year - 2011
Publication title -
journal of food biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 47
eISSN - 1745-4514
pISSN - 0145-8884
DOI - 10.1111/j.1745-4514.2010.00416.x
Subject(s) - nuclear receptor , liver x receptor , peroxisome proliferator activated receptor , receptor , liver x receptor alpha , chemistry , pharmacology , lipid metabolism , estrogen receptor , biology , endocrinology , transcription factor , biochemistry , medicine , gene , cancer , breast cancer
A saponin‐enriched soybean extract was tested for agonistic activities against a series of nuclear receptors including peroxisome proliferator‐activated receptors (PPARs) and cholesterol metabolism‐related, retinoid‐related, hormone‐related and detoxification‐related receptors as well as the detoxification‐related transcription factor Nrf‐2 to elucidate its mechanism of action. Reporter gene assays were used to measure the activities of the receptors and Nrf‐2. The extract was found to increase the activities of PPARα, PPARδ and PPARγ, liver X receptor (LXR)α and LXRβ, estrogen receptor (ER)α and Nrf‐2 dose‐dependently. At 500 µg/mL, it enhanced the activity of PPARα, PPARδ and PPARγ, LXRα and LXRβ, ERα and Nrf‐2 2.7‐, 6.5‐, 9.9‐, 5.2‐, 2.9‐, 20.1‐ and 9.2‐fold, respectively, more than the vehicle control. It also dose‐dependently enhanced the expression of acyl CoA synthetase and promoted the differentiation of 3T3‐L1 cells. Pharmacological effects of soyasaponins and the saponin‐enriched soybean extract including the ability to increase the activities of nuclear receptors and Nrf‐2 were discussed.PRACTICAL APPLICATIONS Soyasaponins are a major functional component of soybean. The reported pharmacological activities of soyasaponins include the amelioration of blood lipid abnormalities, a reduction of obesity, antioxidative effects, the prevention of liver injury, anticancer activity and antiviral activity. However, the primary mode of action of soyasaponins has not yet been fully elucidated. This work shows that a saponin‐enriched soybean extract increases the activities of nuclear receptors, peroxisome proliferator‐activated receptor (PPAR)α, PPARδ, PPARγ, liver X receptor (LXR)α, LXRβ and estrogen receptor (ER)α, as well as the transcription factor Nrf‐2. Although further studies are needed to conclude whether the agonistic activities are exhibited by soyasaponins alone, our findings provide useful information on the proper use of the soybean extract as a functional food. The pharmacological effects expected based on its agonistic activities against nuclear receptors will help us identify potential targets of the soybean extract.