According to a recently reported metabolic pathway, phenolic A-ring estrogens are metabolized in rat liver microsomes partially to the corresponding quinols by cytochrome P450 isoenzymes. We found that these quinols could, in turn, undergo reduction to regenerate the parent estrogens consumed during the metabolic process. Among the tested endogenous reducing agents, NADH and especially NADPH pr...

Article history: Received on: 27/04/2016 Revised on: 14/06/2016 Accepted on: 29/07/2016 Available online: 29/10/2016 Endophytic mycoflora are ubiquitous organisms residing in the internal tissues of the plants, at least for a portion of their lives without causing apparent symptoms of infection. Endophytes serve as rich sources of novel natural compounds with a wide-spectrum of biologically act...

Significant recent advances have been made in studies of the major dissimilatory nitrate reductase (NarGHI) of Escherichia coli. This enzyme is a complex iron-sulfur ([Fe-S]) molybdoenzyme that oxidizes menaquinol or ubiquinol at a periplasmically oriented Q-site (Qp site), and reduces nitrate at a cytoplasmically-oriented molybdo-(bismolybdopterin guanine dinucleotide) (Mo-bisMGD) cofactor. Th...

Quinols (5a-c) generate the corresponding aryloxenium ions (6a-c) reversibly at pH 1.0 (0.1M HClO4, 30C) although they are stable for a duration of at least 2-3 weeks at pH 4.6 and pH 7.1 at 30C. Kinetics of decomposition of the parent quinols has been monitored by HPLC in the presence and absence of a trapping agent, Br. In the presence of Br, both bromo adduct and dienonephenol rearranged pro...

Rumput laut hijau Ulva sp. dapat dimanfaatkan sebagai bahan baku pembuatan garam rendah natrium tinggi kalium dari rumput laut. Peningkatan kandungan ditambahkan dengan alami salah satunya tanaman genjer ( Limnocharis flava ). Tujuan penelitian ini adalah mendapatkan komposisi kimia tepung dan aktivitas antioksidan ekstrak lactuca L . Penelitian terdiri beberapa tahapan meliputi preparasi U. ge...

A kinetic study of the regeneration reaction of vitamin E (tocopherol) with eight biological hydroquinones (HQs) (ubiquinol-10 (Q10H2 1); ubiquinol-0 (Q0H2 2); vitamin K1 HQ (VK1H2 3); vitamin K3 HQ (VK3H2 4); alpha-, beta-, and gamma-tocopherol-HQs (alpha-, beta-, and gamma-TQH2 5-7); and 2,3,5-trimethyl-1,4-HQ (TMQH2 8)) in solution was performed. The second-order rate constants (k4) for the ...

Long-distance electron transfer in marine environments couples physically separated redox half-reactions, impacting biogeochemical cycles of iron, sulfur and carbon. Bacterial bio-electrochemical systems that facilitate electron transfer via conductive filaments or across man-made electrodes are well-known, but the impact of abiotic currents across naturally occurring conductive and semiconduct...

A kinetic study of the regeneration reaction of vitamin E (tocopherol) with eight biological hydroquinones (HQs) (ubiquinol-10 (QloH2 1); ubiquinol-0 (QoH2 2); vitamin K1 HQ (VKIH2 3); vitamin Kg HQ (VKSHZ 4); a-, 8-, and y-tocopherol-HQs (a-, B-, and r-TQH2 B-z); and 2,3,5-trimethyl-1,4-HQ (TMQH2 S)) in solution was performed. The second-order rate constants (k4) for the reaction of HQs 1-S wi...