The antioxidant activity of the phenolic fraction of extra virgin olive oil was assessed in samples that had a decreasing content of antioxidants in the presence and absence of copper ions as a catalyst of autoxidation. The oxidation process was evaluated by measuring primary and secondary oxidation products. Changes in phenols and tocopherols were investigated by high-performance liquid chroma...

The Strecker-type degradation of phenylalanine in the presence of 2-pentanal and phenolic compounds was studied to investigate possible interactions that either promote or inhibit the formation of Strecker aldehydes in food products. Phenylacetaldehyde formation was promoted by 2-pentenal and also by o- and p-diphenols, but not by m-diphenols. This is consequence of the ability of phenolic comp...

Molecular complexes of 4-(4-aminophenoxy)aniline with a series of diphenols are structurally homologous and adopt the carborundum III topology, which is an unprecedented network for organic solids.

Grafted and non-grafted tomato plants were grown at 25 and 35 ◦C for 30 days. In tomato leaves we analysed total phenols, o-diphenols, enzymatic activities (PAL, PPO and GPX) and dry weight. Our results indicate that heat stress in both grafted and non-grafted tomato plants occurred at 35 ◦C and resulted in (1) increased PAL activity, (2) increased total phenols and o-diphenols, (3) decreased P...

Tyrosinase shows kinetic cooperativity in its action on o-diphenols, but not when it acts on monophenols, confirming that the slow step is the hydroxylation of monophenols to o-diphenols. This model can be generalised to a wide range of substrates; for example, type S(A) substrates, which give rise to a stable product as the o-quinone evolves by means of a first or pseudo first order reaction (...

Claus T. Fuchs and G erhard Spiteller Institut für Organische Chemie I, Universität Bayreuth, Universitätsstr. 30, 95440 Bayreuth, Germany Z. Naturforsch. 52c, 761-765 (1997); received July 30/August 19, 1997 Polyphenoloxidase, o-Diphenols, 4-Pentadecylpyridine, Competitive Inhibitor, Taphrina pruni 4-Pentadecylpyridine was isolated from plums infected by Taphrina pruni. This fungal me­ tabolit...

tyrosinase (ec: 1.14.18.1) is a copper - containing enzyme which is distributed in all domains of life such as prokaryote, eukaryote, mammals, invertebrates and plants. tyrosinase catalyzes the oxidation of monophenols to diphenols and diphenols to o-quinones . the tyrosinase crystallographic data shows two histidine -rich regions named cua and cub. a loop containing residues m374, s375 and v37...

Petroleum ether and methylene chloride extracts of Peperomia galioides and three prenylated diphenols, grifolic acid, grifolin and piperogalin exhibited in vitro antileishmanial activity. During the course of infection of BALB/c mice with Leishmania amazonensis, the treatments with each of these compounds did not influence the progression of the disease.