Studies on Quinones. II

Studies on Effects of Certain Quinones: II. Photosynthetic Incorporation of CO(2) by Chlorella.

The effects of various quinone herbicides and fungicides on the photosynthetic (14)CO(2) fixation and the incorporation of (14)C among the products of photosynthesis in Chlorella pyrenoidosa was investigated. Addition of 30 mum 2,3-dichloro-1,4-naphthoquinone (dichlone), 2-amino-3-chloro-1,4-naphthoquinone (06K-quinone), or 2,3,5,6-tetrachloro-1,4-benzoquinone (chloranil) inhibited CO(2) fixati...

Studies of reactions between flavins and quinones, mercaptans, and enolates.

A. Equilibrium and second-order rate constants have been measured for the redox reaction between phthaloquinone and dihydroriboflavin (and its reverse) at a number of pH values. The equilibria and kinetic determinations are in agreement. No intermediates could be found in the reaction, and it is proposed that with this and other quinones electron transfer occurs within a complex of the flavin a...

The chemical action of quinones on proteins and amino-acids. Part II.

Comparative Studies on Plastoquinones: V. Changes in Lipophilic Chloroplast Quinones during Development.

Changes of lipophilic chloroplast quinones in corn, oats, peas, and Vicia faba are reported after 0, 4, 8, 12, 16, 20, 24, 48, 72, or 96 hours of exposure to light. There is a pronounced increase in plastoquinone A and chlorophyll levels and slight increase, in plastoquinone C(1-6), vitamin K(1), and alpha-tocopherylquinone content. Coenzyme Q levels, on the other hand, show little change upon ...

Studies on novel polycyclic heterocycles: synthesis of new naphthaquinoxaline and naphthazaquinoxaline derivatives from naturally occurring quinones

A facile synthesis of novel polycyclic heterocycles namely naphthaquinoxaline and naphthazaquinoxaline derivatives is carried out by the reaction of lapachol and β-lapachone, naturally occurring naphthoquinones with o-phenylene diamine and 2,3-diaminopyridine. Regioselectivity in the reaction of β-lapachone with 2,3-diaminopyridine is confirmed by single crystal X-ray diffraction of a represent...