Alleviation of Cardiac Damage by Dietary Fenugreek (Trigonella foenum‑graecum) Seeds is Potentiated by Onion (Allium cepa) in Experimental Diabetic Rats via Blocking Renin–Angiotensin System.

Hyperglycemia is one of the metabolic and
homeostatic abnormalities that increase the cardiovascular
mortality in diabetic patients by increased oxidative stress.
We have recently reported amelioration of oxidative stress
in cardiac tissue by dietary fenugreek (Trigonella foenumgraecum)
seeds and onion (Allium cepa) in streptozotocininduced
diabetic rats. The mechanistic aspects of the cardioprotective
influence of dietary fenugreek seeds (10%) and
onion (3% powder) both individually and in combination
on hyperglycemia-mediated cardiac damage was further
investigated in this study on streptozotocin-induced diabetic
rats. Cardio-protective influence of these dietary spices was
evidenced by their blocking potential on renin–angiotensin
system. This might be the consequence of reduced activation
of angiotensin-converting enzyme (ACE) and angiotensin
type 1 receptor (
AT1) in cardiac tissue. The combination
produced an additive effect on ACE and AT1
protein
and mRNA expressions. Increased expression of type IV
collagen, fibronectin, Bax, 4-hydroxynonenal, iNOS and
metabolites of nitric oxide (nitrate/nitrite) along with disturbed
PUFA-to-SFA ratio and activities of cardiac marker
enzymes in blood confirmed the myocardial damage. Dietary
fenugreek seed, onion and fenugreek + onion were found
to ameliorate these pathological changes in the cardiovascular
system. The beneficial effect being higher with the
combination sometime amounting to additive (iNOS expression)
or even a synergistic (cardiac Bax and type IV collagen
expression and circulatory marker enzymes) in diabetic
rats. Thus, the results of present investigation suggested that the combination of fenugreek seeds and onion offers higher
beneficial influence in ameliorating cardiac damage accompanying
diabetes.