naphthoquinones and tryptamine

Secologanin, a secoiridoid glucoside, is a pivotal terpenoid intermediate in the biosynthesis of biologically active monoterpenoid indole alkaloids such as reserpine, ajmaline, and vinblastine which are biosynthesized via strictosidine, an alkaloidal glucoside, formed from secologanin and tryptamine. In secologanin biosynthesis, the oxidative cleavage process of loganin to secologanin and the hydroxylation of 7-deoxyloganin to loganin have remained unknown enzymologically and mechanistically. Cornoside is a unique glucoside with 4-hydroxy-2,5-cyclohexadien-1-one (benzoquinol) ring and is widespread in families such as Cornaceae, Oleaceae, and Scrophulariaceae but its biosynthesis, especially the oxidative process, remain to be investigated. Shikonin is a red naphthazarin pigment derived from the roots of Lithospermum erythorhizon and produced biotechnologically by cell cultures. Its biosynthesis including the production regulation mechanism has been investigated in detail. However, the naphthazarin ring formation process, probably starting with the hydroxylation of the side chain of geranylhydroquinone, a key intermediate at the late stage of shikonin biosynthesis, remained unknown. In the present review, cytochrome P450 monooxygenases involved in the biosyntheses of three structurally and biosynthetically interesting compounds, secologanin, cornoside, and shikonin, a described together with the results of previous and recent biosynthetic studies. The biosyntheses of related compounds are also discussed.

Topics: Cyclohexanones; Cytochrome P-450 Enzyme System; Glucosides; Indole Alkaloids; Iridoid Glucosides; Iridoids; Naphthoquinones; Oxidation-Reduction; Plants; Secologanin Tryptamine Alkaloids; Tryptamines; Vinca Alkaloids

A simple, specific and sensitive high-performance liquid chromatographic (HPLC) method has been developed for the assay of fluvoxamine in human plasma and urine. The method was based on reaction of fluvoxamine with 1,2-naphthoquinone-4-sulphonic acid sodium salt (NQS) forming orange colored product. The fluvoxamine-NQ derivative was separated by isocratic reversed-phase HPLC and detected at 450 nm. The chromatographic conditions were as follows: Phenomenex C(18) (250 mm x 4.6 mm i.d., 5 microm) column, mobile phase consisting of acetonitrile/water (80:20 v/v) at a flow rate of 1 ml/min. Tryptamine was selected as an internal standard. The assay was linear over the concentration range of 5-145 and 2-100 ng/ml for plasma and urine, respectively. The limits of detection (LOD) were 1.4 and 1 ng/ml for plasma and urine estimation at a signal-to-noise (S/N) ratio of 3. The limits of quantification (LOQ) were 5 and 2 ng/ml for plasma and urine, respectively. The extraction recoveries were found to be 96.66+/-0.69 and 96.73+/-2.17% for plasma and urine, respectively. The intra-day and inter-day standard deviations (S.D.) were less than 1. The method indicated good performance in terms of specificity, linearity, detection and quantification limits, precision and accuracy. This assay was demonstrated to be applicable for clinical pharmacokinetic studies.

Topics: Chromatography, High Pressure Liquid; Coloring Agents; Fluvoxamine; Humans; Molecular Structure; Naphthoquinones; Sensitivity and Specificity; Spectrophotometry; Tryptamines