Dry Olive Leaf Extract Counteracts L-Thyroxine-Induced Genotoxicity in Human Peripheral Blood LeukocytesIn Vitro

Abstract

The thyroid hormones change the rate of basal metabolism, modulating the consumption of oxygen and causing production of reactive oxygen species, which leads to the development of oxidative stress and DNA strand breaks. Olive (Olea europaea L.) leaf contains many potentially bioactive compounds, making it one of the most potent natural antioxidants. The objective of this study was to evaluate the genotoxicity of L-thyroxine and to investigate antioxidative and antigenotoxic potential of the standardized oleuropein-rich dry olive leaf extract (DOLE) against hydrogen peroxide and L-thyroxine-induced DNA damage in human peripheral blood leukocytes by using the comet assay. Various concentrations of the extract were tested with both DNA damage inducers, under two different experimental conditions, pretreatment and posttreatment. Results indicate that L-thyroxine exhibited genotoxic effect and that DOLE displayed protective effect against thyroxine-induced genotoxicity. The number of cells with DNA damage, was significantly reduced, in both pretreated and posttreated samples (P < 0.05). Comparing the beneficial effect of all tested concentrations of DOLE, in both experimental protocols, it appears that extract was more effective in reducing DNA damage in the pretreatment, exhibiting protective role against L-thyroxine effect. This feature of DOLE can be explained by its capacity to act as potent free radical scavenger.

Dry Olive Leaf Extract in Combination with Methotrexate Reduces Cell Damage in Early Rheumatoid Arthritis Patients-A Pilot Study

“…Dry olive leaf extract (DOLE) is a polyphenol rich natural product of olive tree ( Olea europaea L.) and it contains large amounts of the bioactive components, mostly phenolics, that are also found in the olive oil but within the leaves at much higher concentration (Silva et al , 2006). DOLE previously exhibited strong antioxidant and DNA‐protective properties in vitro (Čabarkapa et al , ; Žukovec Topalović et al ., ) and was also found to attenuate inflammation and oxidative stress in vivo (Miljković et al , ). Oleuropein, the main olive leaf‐derived active compound, has shown improvement in clinical features in mouse model of collagen induced arthritis (Impellizzeri et al , ).…”

Oleuropein Ameliorates Cisplatin-induced Hematological Damages Via Restraining Oxidative Stress and DNA Injury

“…OLE, one of the most bioactive polyphenols present in the extra virgin olive oil could provide a protective and therapeutic effect against a number of pathologies, including Alzheimer's disease as well as obesity, type 2 diabetes, non-alcoholic hepatitis, and other natural or experimentally induced pathological conditions [20][21][22]. In particular, the recent data suggest that the OLE presents are able to scavenge free radicals and afford an adequate protection against peroxidation [23].…”

Thyroid-Modulating Activities of Olive and Its Polyphenols: A Systematic Review

“…Olive oil, especially EVOO, contains high levels of polyphenols like oleuropein and hydroxytyrosol, which contributes to its potent antioxidant activity [8,44,95]. Olive leaves also contain similar polyphenols and phytochemicals to olive oil but with a much higher oleuropein concentration [41,42]. Olive leaf extracts could reduce oxidative stress in rats [96,97].…”

“…A phytochemical analysis revealed that olive leaf extracts contain similar phenolics and phytochemicals to VOO, mainly oleuropein, hydroxytyrosol, luteolin, and their derivatives [22,[38][39][40]. Olive leaf phytochemicals like oleuropein are present in much higher concentrations than in olive oil [41][42][43]. Additionally, in vitro and in vivo experiments have shown that oleuropein, hydroxytyrosol, and tyrosol are potent antioxidant, anticancer, chemopreventive, and antiatherosclerotic agents [44][45][46][47][48][49][50][51][52][53].…”