Extra Virgin Olive Oil Contains a Phenolic Inhibitor of the Histone Demethylase LSD1/KDM1A

The lysine-specific histone demethylase 1A (LSD1) also known as lysine (K)-specific demethylase 1A (KDM1A) is a central epigenetic regulator of metabolic reprogramming in obesity-associated diseases, neurological disorders, and cancer. Here, we evaluated the ability of oleacein, a biophenol secoiridoid naturally present in extra virgin olive oil (EVOO), to target LSD1. Molecular docking and dynamic simulation approaches revealed that oleacein could target the binding site of the LSD1 cofactor flavin adenosine dinucleotide with high affinity and at low concentrations. At higher concentrations, oleacein was predicted to target the interaction of LSD1 with histone H3 and the LSD1 co-repressor (RCOR1/CoREST), likely disturbing the anchorage of LSD1 to chromatin. AlphaScreen-based in vitro assays confirmed the ability of oleacein to act as a direct inhibitor of recombinant LSD1, with an IC50 as low as 2.5 μmol/L. Further, oleacein fully suppressed the expression of the transcription factor SOX2 (SEX determining Region Y-box 2) in cancer stem-like and induced pluripotent stem (iPS) cells, which specifically occurs under the control of an LSD1-targeted distal enhancer. Conversely, oleacein failed to modify ectopic SOX2 overexpression driven by a constitutive promoter. Overall, our findings provide the first evidence that EVOO contains a naturally occurring phenolic inhibitor of LSD1, and support the use of oleacein as a template to design new secoiridoid-based LSD1 inhibitors.

CHEMICAL CONSTITUENTS IN WILD OAT (Avenu fatua) HULLS AND THEIR EFFECTS ON SEED GERMINATION

Aqueous extracts of dormant wild oat (Avena fatua L.) hulls had a weak inhibitory effect on lettuce seed germination. Both paper and thin layer chromatographic analyses of the ether-soluble acidic fraction showed the presence of phenolics and short-chain fatty acids. No abscisic acid was detected. Vanillin, protochatechualdehyde, p-coumaric acid, ferulic acid and caffeic acid were isolated from hull extracts. Vanillin was shown to be the main water-soluble phenolic inhibitor of lettuce seed germination. At a concentration higher than 6.6 × 10−3M, vanillin was found to be more inhibitory than nonanoic acid to both lettuce and wild oat germination. The concentration of phenolics in the hulls does not account for suppression of wild oat seed germination.

THE INHIBITED AUTOXIDATION OF STYRENE: PART I.THE DEUTERIUM ISOTOPE EFFECT FOR INHIBITION BY 2,6-DI-tert-BUTYL-4-METHYLPHENOL

Most previous work on the inhibition of autoxidation by phenols has indicated that the reaction involves abstraction of the phenolic hydrogen. However, the apparent absence of any appreciable deuterium isotope effect made it difficult to believe that abstraction could be rate controlling. The present work using styrene as the substrate, 2,6-di-tert-butyl-4-methyl-phenol as the inhibitor, and azo-bis-isobutyronitrile as the initiator has shown that this reaction has an unexpectedly large isotope effect, e.g. ~10.6 at 65 °C. Previous failures to detect an isotope effect are attributed to the rapid exchange of deuterium which takes place between deuterated phenols and traces of moisture or other hydroxyl-containing compounds present in the substrate. Rate constants and activation energies for some of the elementary reactions in the inhibited and uninhibited oxidation of styrene have been measured. It is suggested that a compound which functions in the same way as a weak phenolic inhibitor is formed in the apparently uninhibited oxidation.