INHIBITORY ACTIVITY OF PHENOLIC COMPOUNDS FROM EXTRA VIRGIN OLIVE OILS ON THE ENZYMES INVOLVED IN DIABETES, OBESITY AND HYPERTENSION

Mediterranean diet health benefits have been partially attributed to the dietary consumption of extra virgin olive oil (VOO). Most recent interest has focused on the biologically active phenolic compounds naturally present in VOO. Selected VOO from Italy were investigated for their phenolic profile and inhibitory activity against a-glucosidase and a-amylase, as well as angiotensin-converting enzyme (ACE). These enzymes have been linked to hyperglycemia-associated to hypertension. The total phenolic content (Folin-Ciocalteu) ranged from 109 to 250 mg/kg of oil and was well correlated with the high-performance liquid chromatography (HPLC) data (r(2) = 0.8533). The phenolic profile obtained by HPLC revealed the presence of 3,4-dihydroxyphenylethanol (3,4-DHPEA; 2.9 +/- 2 mg/kg) and p-hydroxyphenylethanol (p-HPEA; 2.6 +/- 1.3 mg/kg), as the main phenolic alcohols. Secoiridoids and their derivatives were also detected in high concentration in all samples, particularly 3,4-DHPEA-EDA (55 +/- 38 mg/kg) and p-HPEA-EDA (42 +/- 14 mg/kg). Vanillic acid (1.8 +/- 1.1 mg/kg), vanillin (1.2 +/- 0.5 mg/kg), p-coumaric acid (0.94 +/- 0.7 mg/kg), apigenin (1.0 +/- 0.2 mg/kg) and luteolin (2.4 +/- 0.5) were also identified. All samples demonstrated a stronger activity against a-glucosidase with respect to a-amylase. The sample that was richer in phenolics showed a half maximal