naphthoquinones and isoshinanolone

Novel cytochrome P450s, CYP81B140 and CYP81B141 from Plumbago zeylanica were functionally characterized to understand their involvement in polyketide plumbagin biosynthesis. Further, we propose 3-methyl-1-8-naphthalenediol and isoshinanolone as intermediates for plumbagin biosynthesis. Plumbago zeylanica L. (P. zeylanica) is a medicinally important plant belonging to the family Plumbaginaceae. It comprises the most abundant naphthoquinone plumbagin having anti-cancer activity. Only the polyketide synthase (PKS) enzyme has been identified from the biosynthetic pathway which catalyzes iterative condensation of acetyl-CoA and malonyl-CoA molecules. The plumbagin biosynthesis involves hydroxylation, oxidation, hydration and dehydration of intermediate compounds which are expected to be catalyzed by cytochrome P450s (CYPs). To identify the CYPs, co-expression analysis was carried out using PKS as a candidate gene. Out of the eight identified CYPs, CYP81B140 and CYP81B141 have similar expression with PKS and belong to the CYP81 family. Phylogenetic analysis suggested that CYP81B140 and CYP81B141 cluster with CYPs from CYP81B, CYP81D, CYP81E and CYP81AA subfamilies which are known to be involved in the hydroxylation and oxidation reactions. Moreover, artificial microRNA-mediated transient individual silencing and co-silencing of CYP81B140 and CYP81B141 significantly reduced plumbagin and increased the 3-methyl-1-8-naphthalenediol and isoshinanolone content. Based on metabolite analysis, we proposed that 3-methyl-1-8-naphthalenediol and isoshinanolone function as intermediates for plumbagin biosynthesis. Transient silencing, over-expression and docking analysis revealed that CYP81B140 is involved in C-1 oxidation, C-4 hydroxylation and [C2-C3] hydration of 3-methyl-1-8-naphthalenediol to form isoshinanolone, whereas CYP81B141 is catalyzing [C2-C3] dehydration and C-4 oxidation of isoshinanolone to form plumbagin. Our results indicated that both CYP81B140 and CYP81B141 are promiscuous and necessary for plumbagin biosynthesis. This is the first report of identification and functional characterization of P. zeylanica-specific CYPs involved in plumbagin biosynthetic pathway and in general hexaketide synthesis in plants.

Topics: Acetyl Coenzyme A; Cytochromes; Dehydration; Genomics; MicroRNAs; Naphthoquinones; Phylogeny; Plant Roots; Plumbaginaceae; Polyketide Synthases; Polyketides

Chemical investigatation of Drosera peltata var. multisepala led to the isolation of eleven compounds using various chromatographic techniques. The structures of these compounds were elucidated as isoshinanolone-4-O-beta-D-glucoside (1), isoshinanolone (2), epi-isoshinanolone (3), plumbagin (4), droserone (5), droserone-5-O-glucoside (6), quercetin (7), kaempferol (8) , gossypetin-8-O-glucoside (9), 3,3'-dimethoxy ellagic acid (10), and ellagic acid (11) by their physicochemical properties and spectral data analysis. Compound 1 was a new compound. Compounds 3, 8, 10, and 11 were isolated from this plant for the first time.

Topics: Chromatography, Liquid; Drosera; Drugs, Chinese Herbal; Ellagic Acid; Glucosides; Kaempferols; Magnetic Resonance Spectroscopy; Molecular Structure; Naphthoquinones; Plant Extracts; Quercetin; Spectrometry, Mass, Electrospray Ionization; Tetrahydronaphthalenes

Plumbago scandens L. is a Brazilian tropical/subtropical species that occurs along the coast. Chemically it is mainly represented by naphthoquinones, flavonoids, terpenoids and steroids. The aim of the present work is to study quantitative changes in the root metabolic production of Plumbago scandens during different physiologic developmental stages relative to floration. The results indicated the presence of four substances in the extracts: plumbagin, epi-isoshinanolone, palmitic acid and sitosterol, independent on developmental stage. The naphthoquinone plumbagin has always showed to be the major component of all extracts. Naphthoquinones exhibited their highest content during floration, while the content of the two others components decreased during this stage, revealing an inverse profile. The chemical composition changed depending on the plant requirements.

Topics: Chromatography, Gas; Naphthoquinones; Palmitic Acid; Plant Roots; Plumbaginaceae; Sitosterols; Tetrahydronaphthalenes

The roots of Plumbago zeylanica Linn. (Plumbaginaceae) are reputed to have a wide spectrum of therapeutic properties in the Ayurvedic system of medicine. They are useful in curing many ailments such as skin diseases, diarrhea, plague and leprosy.. The study was aimed at isolating, separating and evaluating the antimicrobial properties of compounds such as neoisoshinanolone and 1-epineo-isoshinanolone from the roots of P. zeylanica.. The crude petroleum ether extract of roots of P. zeylanica was subjected to repeated chromatographic techniques to separate compounds 2 and 3 along with plumbagin. Structure elucidation was carried out using nuclear magnetic resonance (NMR), infra red (IR) and mass spectroscopy. The serial dilution method was used to test antimicrobial activities and their minimum inhibitory concentration (MIC) expressed in microg/mL.. 1-Epineo-isoshinanolone is more active with a MIC of 12.5-25 microg/mL whereas neoisoshinanolone has recorded a MIC of 50-100 microg/mL. The activities are compared with plumbagin (0.78-3.13 microg/mL) and standards streptomycin for bacteria and nystatin for fungi.. Earlier researchers have established the presence of plumbagin in the roots of P. zeylanica and its antimicrobial activities. The structure elucidation of two more biologically active biogenetic precursors along with their activities in the root extracts has been established for the first time in the present study.. The root extract of P. zeylanica possesses good antimicrobial activity, which suggests its therapeutic use in the Ayurvedic system of medicine to cure skin diseases.

Topics: Anti-Infective Agents; Drug Discovery; Fungi; Gram-Negative Bacteria; Gram-Positive Bacteria; Isomerism; Magnetic Resonance Spectroscopy; Mass Spectrometry; Medicine, Ayurvedic; Microbial Sensitivity Tests; Molecular Structure; Naphthoquinones; Plant Extracts; Plant Roots; Plumbaginaceae; Spectrophotometry, Infrared; Tetrahydronaphthalenes; Transition Temperature

To investigate the chemical constituents of the aerial parts of Plumbago zeylanica Linn.. The constituents of the EtOAc-soluble portion in the 95% ethanol extract were isolated and purified by means of chromatography. Compounds were identified by their physical characteristics and spectral features.. Nine compounds were isolated as plumbagin (I), isoshinanolone (II), plumbagic acid (III), beta-sitosterol (IV), 4-hydroxybenzaldehyde (V), trans-cinnamic acid (VI), vanillic acid (VII), 2, 5-dimethyl-7-hydroxychromone (VIII), indole-3-carboxaldehyde (IX).. Compounds V, VII, VIII and IX were isolated for the first time from Plumbago Linn.

Topics: Benzaldehydes; Cinnamates; Indoles; Magnetic Resonance Spectroscopy; Molecular Structure; Naphthoquinones; Plant Components, Aerial; Plants, Medicinal; Plumbaginaceae; Sitosterols; Tetrahydronaphthalenes; Vanillic Acid