The growth-inhibiting activity of Tabebuia impetiginosa Martius ex DC dried inner bark-derived constituents against Helicobacter pylori ATCC 43504 was examined using paper disc diffusion and minimum inhibitory concentration (MIC) bioassays. The activity of the isolated compounds was compared to that of the commercially available anti-Helicobacter pylori agents, amoxicillin, metronidazole, and t...

BACKGROUND Worldwide, Streptococcus pyogenes is the leading cause of bacterial pharyngitis. To reduce the use of antibiotics, antimicrobial phytochemical-containing remedies, which have long been in use in traditional medicine, may provide new approaches for management of streptococcal pharyngitis. The objective of this study was to assess the inhibitory activities of 25 natural phenolic compou...

The antibacterial activity of a series of 1,4-naphthoquinones was demonstrated. Disk diffusion tests were carried out against several Gram-positive and Gram-negative bacteria. The compound 5-amino-8-hydroxy-1,4-naphthoquinone was the most effective, presenting inhibition zones measuring 20 mm against staphylococci, streptococci and bacilli at 50 microg/ml. Methicillin-resistant Staphylococcus a...

BACKGROUND Naphthoquinone is a class of phenolic compounds derived from naphthalene. 7-Methyljuglone (7-MJ) is a naphthoquinone also known as ramentaceone or 6-Methyl-8-hydroxy-1,4-naphthoquinone or 5-Hydroxy-7-methyl-1,4-naphthoquinone or 7-Methyl-5-hydroxy-1,4-naphthoquinone or 5-Hydroxy-7-methyl-,1,4-naphtoquinone or 7-Methyl-5-hydroxynaphthalene-1,4-dione. This compound is a biologically ac...

Thylakoid membranes contain two types of quinones, benzoquinone (plastoquinone) and naphthoquinone, which are involved in photosynthetic electron transfer. Unlike the benzoquinone, the chemical species of naphthoquinone present (phylloquinone, menaquinone-4 and 5'-monohydroxyphylloquinone) varies depending on the oxygenic photosynthetic organisms. The green alga Chlamydomonas reinhardtii has be...

The modulation of radiation induced lipid peroxidation in synaptosomes by iron (II) and iron (III) complexes of two naturally occurring and therapeutically relevant naphthoquinones viz. 5,hydroxy-1,4 naphthoquinone; juglone and 2,hydroxy-1,4 naphthoquinone; lawsone, have been studied. At lower concentrations the complexes enhance lipid peroxidation predominantly through redox cycling as observe...

In the crystal structure of the title compound, C(16)H(16)O(6), a pair of naphthoquinone rings are linked via O-H⋯O-C hydrogen bonds in a nearly orthogonal arrangement. This dimeric unit is linked to a neighbouring dimer by π-π stacking inter-actions between the naphthoquinone rings, where the distance between the mean plane of the naphtoquinone backbones is 3.468 Å, and O-H⋯O-C hydrogen bonds.

BACKGROUND Natural products are well recognized as sources of drugs in several human ailments. In the present work, we carried out a preliminary screening of six natural compounds, xanthone V(1) (1); 2-acetylfuro-1,4-naphthoquinone (2); physcion (3); bisvismiaquinone (4); vismiaquinone (5); 1,8-dihydroxy-3-geranyloxy-6-methylanthraquinone (6) against MiaPaCa-2 pancreatic and CCRF-CEM leukemia c...

A novel and simple spectrophotometric method for the determination of tiopronin with sodium 1,2-naphthoquinone-4-sulfonate (NQS) is established in this paper. The detailed mechanism is proposed and discussed. It is based on the fact that tiopronin can catalyze the reaction between sodium 1,2-naphthoquinone-4-sulfonate and hydroxyl ion to form 2-hydroxy-1,4-naphthoquinone in a buffer solution of...