Secoisolariciresinol Diglucoside

J Physiol Biochem. 2014 Dec;70(4):961-9.

Secoisolariciresinol diglucoside in high-fat diet and streptozotocin-induced diabetic nephropathy in rats: a possible renoprotective effect.[Pubmed: 25316298]

Due to substantial morbidity and high complication rate of diabetes mellitus, which is considered as the third killer in the world, a search for the effective blockade of the progression of diabetic nephropathy (DN) remains a therapeutic challenge. Alternative antidiabetic drugs from natural plants are highly demanded nowadays. The aim of this study was to investigate the renoprotective effect of Secoisolariciresinol Diglucoside (SDG) on DN induced in rats.
METHODS AND RESULTS:
Diabetes was induced in male Sprague-Dawley rats by a high-fat diet (HFD) and an intraperitoneal 35 mg/kg streptozotocin (STZ) injection. Rats were divided into four groups: normal control rats, diabetic control rats, diabetic rats treated with SDG at 10 mg/kg/day for 4 weeks, and diabetic rats treated with SDG at 20 mg/kg/day for 4 weeks. At the end of the treatment, blood and renal tissue samples were collected for biochemical examination. The results revealed that SDG treatment significantly increased insulin level and decreased blood glucose, fructosamine, creatinine, and blood urea nitrogen levels in diabetic rats. Also, SDG significantly increased renal reduced glutathione, superoxide dismutase and decreased malondialdehyde and nitric oxide levels. In addition, SDG downregulated the renal nuclear factor kappa-B (NF-κB), tumor necrosis factor (TNF)-α, and inducible nitric oxide synthase (iNOS) and upregulated renal survivin and B-cell lymphoma-2 (Bcl-2) expressions when compared with untreated diabetic control rats.
CONCLUSIONS:
This study demonstrated, for the first time, the renoprotective effects of SDG in HFD/STZ-induced DN in rats through correction of hyperglycemia; attenuation of oxidative/nitrosative stress markers; downregulation of renal expressions of inflammatory markers NF-κB, TNF-α, and iNOS; along with upregulation of renal expressions of antiapoptotic markers survivin and Bcl-2.

Int J Angiol. 2013 Dec;22(4):235-8.

Secoisolariciresinol Diglucoside (SDG) Isolated from Flaxseed, an Alternative to ACE Inhibitors in the Treatment of Hypertension.[Pubmed: 24436618]

Secoisolariciresinol Diglucoside(SDG) is a plant lignan isolated from flaxseed and is phytoestrogen. SDG is a potent and long-acting hypotensive agent. Plant phytoestrogens have inhibitory effects on angiotensin-converting enzyme (ACE). The hypotensive effects of SDG, a phytoestrogen, may be mediated through inhibition of ACE. The objective of this study was to investigate if SDG-induced hypotension is mediated through inhibition of ACE.
METHODS AND RESULTS:
The Sprague Dawley male rats were anesthetized and trachea was cannulated. The right jugular vein was cannulated to administer the drug and the carotid artery was cannulated to record arterial pressures using PIOEZ-1 miniature model transducer (Becton, Dickinson and Company, Franklin Lakes, NJ) and Beckman dynograph (Beckman Instruments, Inc., Schiller Park, IL).
CONCLUSIONS:
The data suggest that SDG reduced the angiotensin I-induced rise in the arterial pressures and hence SDG is a potent ACE inhibitor.

PLoS One. 2015 Mar 30;10(3):e0122852.

Secoisolariciresinol diglucoside abrogates oxidative stress-induced damage in cardiac iron overload condition.[Pubmed: 25822525]

Cardiac iron overload is directly associated with cardiac dysfunction and can ultimately lead to heart failure.
METHODS AND RESULTS:
This study examined the effect of Secoisolariciresinol Diglucoside (SDG), a component of flaxseed, on iron overload induced cardiac damage by evaluating oxidative stress, inflammation and apoptosis in H9c2 cardiomyocytes. Cells were incubated with 50 μ5M iron for 24 hours and/or a 24 hour pre-treatment of 500 μ M SDG. Cardiac iron overload resulted in increased oxidative stress and gene expression of the inflammatory mediators tumor necrosis factor-α, interleukin-10 and interferon γ, as well as matrix metalloproteinases-2 and -9. Increased apoptosis was evident by increased active caspase 3/7 activity and increased protein expression of Forkhead box O3a, caspase 3 and Bax. Cardiac iron overload also resulted in increased protein expression of p70S6 Kinase 1 and decreased expression of AMP-activated protein kinase. Pre-treatment with SDG abrogated the iron-induced increases in oxidative stress, inflammation and apoptosis, as well as the increased p70S6 Kinase 1 and decreased AMP-activated protein kinase expression. The decrease in superoxide dismutase activity by iron treatment was prevented by pre-treatment with SDG in the presence of iron.
CONCLUSIONS:
Based on these findings we conclude that SDG was cytoprotective in an in vitro model of iron overload induced redox-inflammatory damage, suggesting a novel potential role for SDG in cardiac iron overload.

J Mol Cell Cardiol. 2008 Jan;44(1):170-9.

Secoisolariciresinol diglucoside induces neovascularization-mediated cardioprotection against ischemia-reperfusion injury in hypercholesterolemic myocardium.[Pubmed: 18001768 ]

Hypercholesterolemia (HC) induced endothelial cell dysfunction and decreased endothelial nitric oxide formation results in impaired angiogenesis and subsequent cardiovascular disorders. Therapeutic angiogenesis is known to be a novel strategy for treatment of patients with ischemic heart disease. We have shown that Secoisolariciresinol Diglucoside (SDG) is angiogenic as well as cardioprotective against myocardial ischemia.
METHODS AND RESULTS:
In the present study, we examined the efficacy of SDG in a hypercholesterolemic myocardial infarction (MI) model. The rats were maintained on a normal and high cholesterol diet (2%) for 8 weeks followed by oral administration of SDG (20 mg/kg) for 2 weeks. The rats were divided into four groups (n=24 in each): Control (C); SDG control (SDG); HC; and HC+SDG (HSDG). Isolated hearts subjected to 30 min of global ischemia followed by 120 min of reperfusion were used to measure the cardiac functions, infarct size and to examine the protein expression profile. After treatment, MI was induced by ligating the left anterior descending artery. Echocardiographic parameters were examined 30 days after MI. Significant reduction in total cholesterol, LDL-cholesterol, triglycerides and an increase in HDL-cholesterol levels were observed in HSDG as compared to the HC. Decreased infarct size was observed in the HSDG group (43%) compared to the HC (54%). Increased phosphorylation of endothelial nitric oxide synthase (p-eNOS) (3.1-fold), vascular endothelial growth factor (1.9-fold) and heme oxygenase-1 (2.3-fold) was observed in the HSDG group as compared to the HC group. Significant improvement in left ventricular functions was also observed in the HSDG group as evidenced by increased ejection fraction (55% vs. 45%), fractional shortening (28% vs. 22%) and decreased left ventricular inner diameter in systole (8 vs. 6 mm) in HSDG compared to HC. Moreover, MI model has shown increased capillary density (2531 vs. 1901) and arteriolar density (2.6 vs. 1.8) in SDG-treated rats as compared to the HC. The increased capillary and arteriolar density along with increased left ventricular functions on SDG treatment might be due to increased HO-1, VEGF and p-eNOS expression.
CONCLUSIONS:
In conclusion, our study demonstrates for the first time that SDG treatment reduces ventricular remodeling by neovascularization of the infarcted HC myocardium.

Circulation. 1999 Mar 16;99(10):1355-62.

Reduction of serum cholesterol and hypercholesterolemic atherosclerosis in rabbits by secoisolariciresinol diglucoside isolated from flaxseed.[Pubmed: 10077521]

Secoisolariciresinol Diglucoside (SDG) is a plant lignan isolated from flaxseed. Lignans are platelet-activating factor-receptor antagonists that would inhibit the production of oxygen radicals by polymorphonuclear leukocytes.
METHODS AND RESULTS:
SDG is an antioxidant. Antioxidants studied thus far are known to reduce hypercholesterolemic atherosclerosis. The objective of this study was to determine the effect of SDG on various blood lipid and aortic tissue oxidative stress parameters and on the development of atherosclerosis in rabbits fed a high-cholesterol diet. CONCLUSIONS:
CONCLUSIONS:
These results suggest that SDG reduced hypercholesterolemic atherosclerosis and that this effect was associated with a decrease in serum cholesterol, LDL-C, and lipid peroxidation product and an increase in HDL-C and antioxidant reserve.