Effect of some volatile oils on the affinity of intact and oxidized low-density lipoproteins for adrenal cell surface receptors

Abstract

Extensive research has shown that a high plasma concentration and oxidation of low-density lipoproteins (LDL) has an important role in atherogenesis. The affinity of LDL to its classic receptor is reduced due to oxidation. Instead, it is taken up by scavenger molecules in macrophages, as a result of which foam cells are formed that have a major role in increasing the subendothelial fat layers of the blood vessels. In the present study the antioxidant effect of eight volatile compounds in plant essences, namely, anethol, eugenol, limonen, linalool, p-cymol, pulegon, thymol, and geraniol, and their effect on the affinities of intact and oxidized (with Cu(+2)) LDL for LDL receptor in sheep adrenal tissue cells in the presence of labeled LDL with fluorescein isothiocynate (FITC) were investigated. The results obtained show that eugenol and thymol have the highest antioxidant effect, on the uptake of LDL (intact and oxidized) by the adrenal cells. The order of the compounds studied with regard to their antioxidant effect on intact and oxidized LDL is as follows: On intact LDL: eugenol > or = thymol > linalool > p-cymol > limonen > geraniol > anethol; on oxidized LDL: thymol > or = eugenol > geraniol > p-cymol > linalool > pulegon. Our findings also show that the compounds, particularly thymol and eugenol, have an antioxidant property and can change the affinity of the LDL particles for the LDL receptor probably due to their lipophylic property. Further research may prove that these compounds can be used clinically, especially in atherosclerotic and hypercholesterolemic cases.

Pharmaceutical and therapeutic Potentials of essential oils and their individual volatile constituents: a review

“…This inhibition is due to a retarded oxidation of intrinsic carotenoids of LDL, and not, as is the case with some flavonoids, to the protection of intrinsic α-tocopherol (Grassmann et al, 2003(Grassmann et al, , 2005. Essential oils rich in phenolic constituents such as eugenol and thymol have the highest antioxidative activity against LDL oxidation (Naderi et al, 2004) and these components can also change the affinity of the LDL particles for the LDL receptor. A relationship was found between the quantity and quality of phenolic components in the oil and its protection against LDL oxidation: for instance, copper-catalysed oxidation of human LDL in vitro is inhibited by 50%-100% when eugenol is the major component of the essential oil (as in clove oil), while inhibition was only 10%-50% for essential oils containing moderate amounts of the phenolics, thymol, carvacrol or cuminol (Teissedre and Waterhouse, 2000).…”

Linalool is a PPARα ligand that reduces plasma TG levels and rewires the hepatic transcriptome and plasma metabolome

“…The antioxidant activity of linalool has been wellestablished in previous studies ( 17,18 ). We reported that linalool could protect against hypercholesterolemia induced by high-fat diet through the downregulation of hepatic SREBP2-mediated cholesterol synthesis.…”

“…Oral exposure to linalool from formulated food products, including beverages, was estimated at up to 140 g/kg/day, including the dietary intake of linalool from natural sources such as vegetables and spices ( 16 ). Linalool has been traditionally used for medicinal purposes because of its potent antioxidative activities ( 17,18 ). Recent studies have suggested that linalool may have a novel biological activity in TG metabolism, as the oral administration of fragrant herbal essential oils containing linalool, including Plantago asiatica and Melissa offi cinalis essential oils, was shown to improve dyslipidemia by reducing plasma TG concentrations ( 13,19 ).…”

“…In C and D, means without common letters differed, P < 0.05. ( 17,18 ) and possess the ability to directly interact with proteins (e.g., binding and interaction with olfactory receptors), thereby playing important biological roles ( 39,40 ). Studies have shown that the oral administration of aromatic compounds has notable biological effects in animals and humans, suggesting their potential as active therapeutic and preventive agents ( 12,19,41 ).…”

“…Studies have shown that the oral administration of aromatic compounds has notable biological effects in animals and humans, suggesting their potential as active therapeutic and preventive agents ( 12,19,41 ). Linalool, a major aromatic terpenoid of teas and herbal essential oils, has been traditionally used for medicinal purposes because of its potent antioxidative activities ( 17,18 ). Recent reports have shown that the oral administration of fragrant herbal essential oils containing linalool, including Plantago asiatica and Melissa offi cinalis essential oils, improved dyslipidemia by reducing plasma TG concentrations ( 13,19 ).…”