122121-92-0

Upstream product

• 10597-60-1 hydroxytyrosol 
• 67-56-1 methanol 
• 501-94-0 p-hydroxyphenethyl alcohol 
• 75-91-2 tert.-butylhydroperoxide 

Downstream Products

• 1417424-32-8 C₃₂H₄₆O₁₀S₄ 
• 1417424-33-9 C₃₂H₄₆O₁₀S₅ 
• 29477-54-1 2-hydroxy-3′,4′-dihydroxyacetophenone 
• 28822-73-3 3,4-dihydroxyphenylethyleneglycol 

Relevant academic research and scientific papers

The metabolic fate of ortho-quinones derived from catecholamine metabolites

ortho-Quinones are produced in vivo through the oxidation of catecholic substrates by enzymes such as tyrosinase or by transition metalions. Neuromelanin, a dark pigment present in the substantia nigra and locus coeruleus of the brain, is produced from dopamine (DA) and norepinephrine (NE) via an interaction with cysteine, but it also incorporates their alcoholic and acidic metabolites. In this study we examined the metabolic fate of ortho-quinones derived from the catecholamine metabolites, 3,4-dihydroxyphenylethanol (DOPE), 3,4-dihydroxyphenylethylene glycol (DOPEG), 3,4-dihydroxyphenylacetic acid (DOPAC) and 3,4-dihydroxyphenylmandelic acid (DOMA). The oxidation of catecholic substrates by mushroom tyrosinase was followed by UV-visible spectrophotometry. HPLC analysis after reduction with NaBH4 or ascorbic acid enabled measurement of the half-lives of ortho-quinones and the identification of their reaction products. Spectrophotometric examination showed that the ortho-quinones initially formed underwent extensive degradation at pH 6.8. HPLC analysis showed that DOPE-quinone and DOPEG-quinone degraded with half-lives of 15 and 30 min at pH 6.8, respectively, and >100 min at pH 5.3. The major product from DOPE-quinone was DOPEG which was produced through the addition of a water molecule to the quinone methide intermediate. DOPEG-quinone yielded a ketone, 2-oxo-DOPE, through the quinone methide intermediate. DOPAC-quinone and DOMA-quinone degraded immediately with decarboxylation of the ortho-quinone intermediates to form 3,4-dihydroxybenzylalcohol (DHBAlc) and 3,4-dihydroxybenzaldehyde (DHBAld), respectively. DHBAlc-quinone was converted to DHBAld with a half-life of 9 min, while DHBAld-quinone degraded rapidly with a half-life of 3 min. This study confirmed the fact that ortho-quinones from DOPE, DOPEG, DOPAC and DOMA are converted to quinone methide tautomers as common intermediates, through proton rearrangement or decarboxylation. The unstable quinone methides afford stable alcoholic or carbonyl products.

Conjugation of Hydroxytyrosol with Other Natural Phenolic Fragments: From Waste to Antioxidants and Antitumour Compounds

Hydroxytyrosol, a natural polyphenol that can be extracted from olive mill waste waters, was converted into a series of more complex and lipophilic analogues by conjugation with other naturally derived (poly)phenolic fragments. Ether and triazole linkers were employed. A small library of compounds was prepared, stressing step economy and operational simplicity. Some of these substances were proven to have activity equal or superior to that of the parent hydroxytyrosol in radical scavenging assays as well as in cytotoxicity tests against tumour cells.

Synthesis and bioactivity profile of 5-S-lipoylhydroxytyrosol-based multidefense antioxidants with a sizeable (poly)sulfide chain

Novel polyfunctionalized antioxidants, 5-S-lipoylhydroxytyrosol (1) and its disulfide 2, trisulfide 3, and tetrasulfide 4, were prepared from tyrosol and dihydrolipoic acid in the presence, when appropriate, of sulfur. Compound 1 exhibited significant activity in the ferric reducing/antioxidant power (FRAP) assay (1.60 Trolox equiv), whereas polysulfides 2-4 were more efficient in the DPPH reduction assay (88-93% reduction vs 68% by Trolox). At 10 μM concentration, all compounds 1-4 proved to be efficient hydroxyl radical scavengers (56-69% inhibition) in a Fenton reaction assay. When administered to human HepG2 cells, 1-4 proved to be nontoxic and exhibited marked protective effects against reactive oxygen species (ROS) generation (60-84% inhibition at 1 μM concentration) and cell damage induced by 400 μM tert- butylhydroperoxide. All compounds 1-4 exhibited overall greater antioxidant activity than hydroxytyrosol.

Tandem sequence of phenol oxidation and intramolecular addition as a method in building heterocycles

A tandem phenol oxidation-Michael addition furnishing oxo- and -aza-heterocycles has been developed. Dirhodium caprolactamate [Rh 2(cap)4] catalyzed oxidation by T-HYDRO of phenols with alcohols, ketones, amides, carboxylic acids, and N-Boc protected amines tethered to their 4-position afforded 4-(tert-butylperoxy)cyclohexa-2,5-dienones that undergo Bronsted acid catalyzed intramolecular Michael addition in one-pot to produce oxo- and -aza-heterocycles in moderate to good yields. The scope of the developed methodology includes dipeptides Boc-Tyr-Gly-OEt and Boc-Tyr-Phe-Me and provides a pathway for understanding the possible transformations arising from oxidative stress of tyrosine residues. A novel method of selective cleavage of O-O bond in hindered internal peroxide using TiCl4 has been discovered in efforts directed to the construction of cleroindicin F, whose synthesis was completed in 50% yield over just 3 steps from tyrosol using the developed methodology.

DDQ oxidation of hydroxyisochromans and homologues

Some hydroxyisochromans and hydroxyphthalans are tested under oxidative conditions obtaining hydroxybenzophenone derivatives. All reactions were followed by 1H NMR spectroscopy. Some final main oxidation products were also isolated and characterised.