Hydroxytyrosol Acyl Esters: Biosynthesis and Activities

Abstract

We previously reported the production of high yields of hydroxytyrosol through the bioconversion of tyrosol. In the present work, hydroxytyrosol was subjected to the lipase catalyzed acylation aiming for the recovery of more lipophilic esters that might be easily incorporated in cosmetic and food preparations. Hydroxytyrosyl acetate and hydroxytyrosyl oleate were produced with respective molar esterification yields of 98% and 78%. DPPH free radical quenching potency demonstrated that the acylation of hydroxytyrosol did not alter its antioxidant activity. The acylated esters were shown to be more effective than the natural antioxidant: caffeic acid and two synthetic ones as BHA and BHT. Antiproliferative activity on human cervical cells (HeLa) resulted in IC(50) values of 0.46, 0.42 and 0.33 mM for hydroxytyrosol and its acetyl and oleyl esters, respectively. Additionally, when used at a non-cytotoxic concentration (100 μM), these compounds showed significant effectiveness in preventing iron-induced oxidative stress, resulting in a reduction of 30%, 36% and 38% in thiobarbituric acid-reactive substance production, respectively.

Phenolic profile and antioxidant activity from peels and seeds of melon (Cucumis melo L. var. reticulatus) and their antiproliferative effect in cancer cells

“…These molecules, including phenol compounds, are synthesized by the secondary metabolism maintenance and response mechanisms to offensive conditions such as ultraviolet radiation, absorption of heavy metals, temperature, and acidity, among others (21). In addition, evidence suggests that their use in food, especially in fruits and vegetables, provide antioxidant properties (22), and antithrombotic, anti-inflammatory, antiallergic, cardioprotective, antitumor (23), and antimicrobial actions (24). …”

Preventive effects of dietary hydroxytyrosol acetate, an extra virgin olive oil polyphenol in murine collagen-induced arthritis

“…EVOO is rich in a variety of phenolic compounds, mainly constituted by secoiridoid derivatives of 2‐(3,4‐dihydroxyphenyl)ethanol (hydroxytyrosol, HTy) and of 2‐(4‐hydroxyphenyl)ethanol (tyrosol), and hydroxytyrosyl acetate (HTy‐Ac), along with minor amounts of free HTy . To date, HTy‐Ac has shown protection effects against oxidative DNA damage in blood cells , as well as against iron‐induced oxidative stress in human cervical cells (HeLa) . In addition, a study from González‐Correa et al.…”

Hydroxytyrosol Attenuates Peripheral Neuropathy in Streptozotocin-Induced Diabetes in Rats

“…21 Among these compounds, HT showed the strongest antioxidant effects in in vitro studies. 22,23 HT comes from the hydrolysis of oleuropein and is found in great quantities in the remains from oil processing, such as pomace olive oil, olive-mill wastewater, or the rinse waters, from which it can be recovered with ad hoc techniques. 9,24 The absorption of HT has been reported to be rapid, with maximum plasma concentration being reached 5−10 min after ingestion.…”