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...

The pomegranate seeds of four Iranian commercial varieties  (Abanmahi (AB), Malas (MS), Pust Sefid (PS) and Shahvar (SH)) were evaluated in terms of some quality properties including protein, oil, dietary fiber, mineral contents and fatty acid composition. Physicochemical properties and antioxidant activity of pomegranate seed oils (PSOs) were also determined. The oil antioxidant activity was m...

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.

Two new p-cymene based diphenols (1-2) were isolated from the heartwood of Calocedrus decurrans. Structures were elucidated by 1D and 2D NMR techniques and HRMS. Libocedroquinone (3) was also isolated as a natural product for the first time. A new system of nomenclature is proposed for description of such oligomeric p-cymene derivatives.

Red clover (Trifolium pratense) leaves accumulate several mumol g(-1) fresh weight of phaselic acid [2-O-(caffeoyl)-l-malate]. Postharvest oxidation of such o-diphenols to o-quinones by endogenous polyphenol oxidases prevents breakdown of forage protein during storage. Forage crops like alfalfa (Medicago sativa) lack both polyphenol oxidase and o-diphenols, and breakdown of their protein upon h...

The reaction of 2-hydroxybenzophenone derivatives with europium ions has afforded a new family of luminescent nonanuclear Eu(III) clusters. Crystal structure analysis of the clusters reveals that the metal core comprises two vertex-sharing square pyramidal units. Most of these complexes show emissions typical of Eu(3+) ion under visible light excitation (400-420 nm) at room temperature. Photoph...