Abstract
The purpose of the present study was to investigate the role of fresh garlic homogenate (FGH) and its bioactive sulphur compound S-allyl cysteine sulphoxide (SACS) in potentiating antihypertensive and cardioprotective activities of captopril in rats. SACS was extracted from the fresh garlic using ion exchange resins with yield of 890
mg/kg garlic. The dose of SACS was calculated based on the amount of SACS extracted from 125 to 250
mg of FGH. Albino rats weighing 150–200
g were fed with 10% fructose in fluid for 3 weeks for induction of hypertension and subsequently administered FGH (125 and 250
mg/kg, p.o.) or SACS (0.111 and 0.222
mg/kg/day, p.o.) for the next 3 weeks in their respective groups. In CAP alone and interactive groups (GH
+
CAP; SACS
+
CAP), captopril 30
mg/kg was given during sixth week of 10% fructose in fluid. At the end of drug treatment, animals were given isoproterenol 175
mg/kg subcutaneously for two consecutive days. Additionally, varying concentrations of SACS (4, 8, 16, 32 and 64
ng), CAP (1, 2, 4, 8 and 16
ng) and their combination (4:1) were checked for fall in blood pressure in hypertensive rats (10% fructose in fluid without pretreatment) as well as angiotensin-converting enzyme (ACE) inhibiting activity using guinea pig ileum. An isobolographic analysis was used to characterise the interaction between SACS and CAP for fall in blood pressure and ACE inhibiting evaluations. Administration of captopril, low and high doses of FGH (125, 250
mg/kg), either alone or together showed fall in fluid intake and body weight. The combined therapy of FGH 250
mg/kg and CAP was more effective in reducing systolic blood pressure, cholesterol, triglycerides and glucose. The SOD and catalase activities in heart tissue were significantly elevated in groups treated with FGH, SACS, CAP, FGH
+
CAP and SACS
+
CAP. Further, combined therapy of FGH 250
mg/kg and CAP caused significant fall in LDH and CK-MB activities in serum and elevation in heart tissue homogenate. SACS in low dose was less effective than low dose of FGH; similarly, high dose of FGH was more efficacious than high dose of SACS. Corroborating with this, combined therapy of garlic (250
mg/kg) with CAP demonstrated higher synergistic action than combination of SACS (0.222
mg/kg) with CAP suggesting the role of additional bioactive constituents apart from SACS, responsible for therapeutic efficacy of garlic. Moreover, combination of SACS and CAP exerted super-additive (synergistic) interaction with respect to fall in blood pressure and ACE inhibition. This study may represent an advertence on concomitant use of garlic or its bioactive constituent, SACS, with captopril.