The effects of solvent dielectric response on the isotropic hyperfine coupling constants of the 1,4-benzoquinone, 1,4-naphthoquinone and 9,10-anthraquinone anions and 1,4-naphthalenediol cation radicals were studied by electron spin resonance (ESR) spectroscopy and by the theoretical density functional method within the polarizable continuum model. Experimental results demonstrate that the isot...

It has been known since the isolation of the vitamins K that derivatives of 2-methyl-1,4-naphthoquinone (MN&) are unstable to light (l-5). However, the exact nature of the chemical change is still under discussion (6, 7). An interesting observation by MacCorquodale and coworkers (3) that the vitamin is quite stable as it exists in crude extracts, only becoming labile after a fair degree of puri...

Novel 11-substituted 3,11-dihydro-2H-benzo[6,7]thiochromeno[2,3-d][1,3]-thiazole-2,5,10-triones 4a-i were synthesized in 75-90% yields via the hetero-Diels-Alder reaction of 5-arylidene-4-thioxo-2-thiazolidinones with 1,4-naphthoquinone. The synthesized compounds were evaluated for their antineoplastic and antimycobacterial activities. A moderate selectivity against melanoma cancer cells (GI50 ...

Naphthoquinone pigments 2-methyl-3-(4- or 2-hydroxyphenylthio)-1,4-naphthalenedione show characteristic optical properties in solution and in the solid state. The position of the OH group in the pigment leads to varied optical properties, including a characteristic colour, in the solid state. The pigment with a 2-OH substituent displays solvatochromism in solution, and that with a 4-OH substitu...

In this work, we report the synthesis of three series carbohydrate-based benzo[f]indole-4,9-diones and amino-1,4-naphthoquinone derivatives evaluated their cytotoxic activity against eight human cancer cell lines. Several compounds showed a promising toward tumor lines (half maximal inhibitory concentration (IC50) < 10.0 ?M). The importance substitution pattern quinone on antitumor was also dis...

Two simple visible spectrophotometric methods are developed and validated for the quantification of modafinil using 1,2-naphthoquinone-4-sulphonic acid (NQS method) and 2,4-dinitrophenol (DNP method) as analytical reagents. The NQS method involves the reaction of modafinil with 1,2-naphthoquinone-4-sulphonate in alkaline medium at room conditions to form a yellow colored product exhibiting maxi...

The Cover Feature represents the Antioxidant – “Antiox” like an eccentric figure, because of its quality donating what is yours, and personifies naphthoquinone polyphenols in paper. “Thief” free radical “Female figure” describes atoms with all electrons healthy cells. In action, antioxidant offers electron to frightened thief, preventing him from stealing woman′s bag full electrons, who holds i...

2,3-Dichloro-1,4-naphthoquinone and tetrabromoor tetrachloro-1,4-benzoquinone were converted into pyridinium enolate betaines by reaction with pyridine or 4,4′-bipyridine. The reaction conditions were applied to poly-(4-vinylpyridine) and a modified Merrifield resin to obtain functionalized polymeric materials. These were examined in thermogravimetric analyses. Reversible photocatalytic electro...

We report here a simple entry into naphtho[2,3-d]isoxazole-4,9-dione system containing a EWG in position 3 using the readily available 2,3-dichloro-1,4-naphthoquinone and nitromethyl derivatives in the presence of base. Antifungal activity of synthesised naphthoquinones was evaluated against ATCC and PYCC reference strains of Candida. The results suggest that the naphtho[2,3-d]isoxazole-4,9-dio...