Antiatheromatic and hypolipidemic activity of Chios Mastic Gum in anesthetized rabbits
Chios Mastic gum, the resin of the trunk and branches of Pistacia lentiscus var. chia (Anacardiaceae), has been used since antiquity in traditional greek medicine. The main compounds of mastic are triterpenes, both acidic and neutral. Tirucallol and butyrospermol, the main neutral components, possess phytosterolic structure. This led to the hypothesis that mastic and particularly its neutral phytosterolic fraction could possess antiatheromatic activities. Mastic Total Extract without Polymer (TMEWP) and the phytosterolic fraction (Neutral Mastic Fraction, NMF), were administered to rabbits in the form of sunflower oil solution for 6 weeks. Anesthetized rabbits were subjected to 30min regional ischemia of the heart, followed by 3 hrs of reperfusion and were randomized into 6 groups: Normal fed animals: Control group, Group A, treated with 46.3mg/(kg-d) of TMEWP, Group B, treated with 45.8mg/(kg-d) of NMF. Animals fed with cholesterol-enriched diet: CHOL group, Group C, treated with 46.3mg/(kg-d) of TMEWP, Group D, treated with 45.8mg/(kg-d) of NMF. At the end of the experiment the infarct size was determined and small segments of the ascending and descending aorta and the heart were taken for histologic examination. Blood samples were collected at several time points, for malondialdehyde (MDA) and for total cholesterol determination. NMF reduced the infarct size (18.3±3.4%, P<0.05), while the administration of TMEWP did not reduce the infarct size significantly (30.3±4.7% vs. 47.0±1.9% in the control group) in the normal fed rabbits. In the hypercholesterolemic rabbits no reduction on infarct size was observed by both treatments. There was no detection of atherogenesis in the form of subintimal accumulation of lipids and foamy macrophages in Group A and Group B. TMEWP and NMF reduced the total cholesterol concentration by 47 and 88% respectively (P<0.01). MDA levels were elevated in all study groups at the 20th min of reperfusion. Long –term treatment of Mastic Total Extract and the phytosterolic fraction possesses significant antiatheromatic and hypolipidemic activities in the hypercholesterolemic rabbits in vivo. The phytosterolic fraction reduces significant the infarct size in the normal fed rabbits.
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