Triterpenoids in olives: reductions in blood sugar and blood lipids, anticarcinogenic activity.

摘要

Olives contain 14 mg of erythrodiol, 377-420 mg of oleanolic acid and 681-1073 mg maslinic acid per kg. Depending on their acidity, native olive oils can contain up to 138 mg/kg of erythrodiol, up to 344 mg/kg of oleanolic acid and up to 251 mg/kg maslinic acid. Native olive oils of the Extra grade contain only traces of erythrodiol and up to 85 mg/kg of oleanolic acid. Triterpenoids are largely eliminated when oils are refined. Oleanolic and mastinic acids can be isolated by solvent extraction of the residues from pressing and centrifugation. Only about 0.7% of orally ingested oleanolic acid is absorbed; 7% of this is eliminated in 24 h urine. Oleanolic acid is metabolised in the liver by hydroxylation. Triterpenoids inhibit the growth of several human cancer cell lines and of malignant tumours in mice and rats. Oral oleanolic acid reduces blood glucose concentration by 40% and insulin concentration by 47%. On the other hand, intraperitoneal oleanolic acid enhances insulin secretion. Orally administered oleanolic acid reduced serum cholesterol in models of hyperlipidaemia in different animals, coupled to decreases in low density lipoprotein and increases in high density lipoprotein levels.