The antioxidant capacity (oxygen radical absorbance capacity, ORAC value) and total phenolic content for Society Garlic, Tulbaghia violacea, was determined as 1.03 μmol of Trolox equivalents (TE)/g of fresh weight, 7.50 mg of gallic acid equivalents (GAE)/g of fresh weight respectively (Zheng and Wang 2001).

Tulbaghia violacea was one of the many active plants with antihypertensive properties as determined by the angiotensin-converting enzyme (ACE) inhibition assay; it contained no tannin (Duncan et al. 1999). T. violacea leaves had inhibition levels which were above 50 % (aqueous extract gave 72 % inhibition, ethanol extract exhibited 61 % inhibition), while T. violacea roots gave 49 and 27 % inhibition for aqueous and ethanol extracts, respectively, with 25 μg plant extract. This was also confirmed in a recent study. A plant was considered to have potential antihypertensive properties if it inhibited the angiotensin-converting enzyme (ACE) and thus the conversion of angiotensin I to angiotensin II by greater than 50 %, and T. violacea was one of eight of 16 plants screened that demonstrated ACE inhibitory activity and satisfied these criteria (Ramesar et al. 2008). T. violacea in particular showed promise with regard to ACE inhibition as in-vivo administration of this extract showed only a 2.2 % increase in maximum mean arterial pressure when compared to the 14.5 % increase observed in the control group after coadministration with exogenous angiotensin I. Hypertension is treated with medication, including drugs such as angiotensin-converting enzyme inhibitors (ACEI) and angiotensin II receptor blockers (ARB). These drugs not only lower blood pressure but also offer additional protection to the brain and heart. ACEI, in particular, provides beneficial properties to patients with type 1 diabetes.

The methanol leaf extract of Tulbaghia violacea significantly and dose-dependently reduced the systolic, diastolic, and mean arterial blood pressure and heart rate in male spontaneously hypertensive Wistar rats (Raji et al. 2012). Angiotensin I human acetate salt hydrate (ang I, 3.1–100 μg/kg), angiotensin II human (ang II, 3.1–50 μg/kg), phenylephrine hydrochloride (phenylephrine, 0.01–0.16 mg/kg) and dobutamine hydrochloride (dobutamine, 0.2–10.0 μg/kg) all increased the blood pressure dose-dependently. The hypertensive effect of ang I and the heart rate-increasing effect of dobutamine were significantly decreased by their co-infusion with T. violacea (60 mg/kg). However, the co-infusion of ang II or phenylephrine with T. violacea (60 mg/kg) did not produce any significant change in blood pressure or heart rate when compared to the infusion of either agent alone in the same animal. The reduction in blood pressure may be due to actions of the T. violacea methanol leaf extract on the angiotensin-I-converting enzyme (ACE) and β(1) adrenoceptors.

Co-treatment of rats with an atherosclerogenic (Ath) diet (4 % cholesterol, 1 % cholic acid and 0.5 % thiouracil) and Tulbaghia violacea methanolic rhizome extracts (250 and 500 mg/kg body weight) for 2 weeks significantly protected against elevated serum triglyceride (TG), total cholesterol (TC), LDL-cholesterol, VLDL-cholesterol and decreased HDL-cholesterol in a dose-dependent manner when compared with the atherogenic control (Olorunnisola et al. 2012). The extracts also lowered elevated thiobarbituric reacting substance (TBARS) and reversed endothelial dysfunction parameters (fibrinogen and total NO levels) and tissue antioxidant enzyme activities to near normal. The protective ability of the extract was confirmed by the significant reduction in the activities of serum markers of liver (LDH, AST, ALT, ALP, bilirubin) and kidney damage (creatinine and bilirubin) in extract-treated groups compared with the atherogenic control group. Also, the extracts protected against the development of fatty streak plaques (aorta) and fatty changes in hepatocytes. The observed activities of the extracts compared favourably with standard drug atorvastatin. The results showed that the methanol extract of Tulbaghia violacea rhizomes could protect against the early onset of atherosclerosis.