https://chemistry.mdma.ch/hiveboard/rhodium/pdf/archive/merbst/quinoline1999.pdf

Quinoline, quinazoline and acridone alkaloids

Acyl lipids in Arabidopsis and all other plants have a myriad of diverse functions. These include providing the core diffusion barrier of the membranes that separates cells and subcellular organelles. This function alone involves more than 10 membrane lipid classes, including the phospholipids, galactolipids, and sphingolipids, and within each class the variations in acyl chain composition expand the number of structures to several hundred possible molecular species. Acyl lipids in the form of triacylglycerol account for 35% of the weight of Arabidopsis seeds and represent their major form of carbon and energy storage. A layer of cutin and cuticular waxes that restricts the loss of water and provides protection from invasions by pathogens and other stresses covers the entire aerial surface of Arabidopsis. Similar functions are provided by suberin and its associated waxes that are localized in roots, seed coats, and abscission zones and are produced in response to wounding. This chapter focuses on the metabolic pathways that are associated with the biosynthesis and degradation of the acyl lipids mentioned above. These pathways, enzymes, and genes are also presented in detail in an associated website (ARALIP: http://aralip.plantbiology.msu.edu/). Protocols and methods used for analysis of Arabidopsis lipids are provided. Finally, a detailed summary of the composition of Arabidopsis lipids is provided in three figures and 15 tables.

/pdf/acyl-lipid-metabolism-2156uh7qdu.pdf

Acyl-Lipid Metabolism

https://www.cell.com/trends/plant-science/pdf/S1360-1385(04)00250-X.pdf

Function and regulation of plant invertases: sweet sensations.

The chalcone synthase superfamily of type III polyketide synthases.

Phenolic compounds are a large group of phytochemicals widespread in the plant kingdom. Depending on their structure they can be classified into simple phenols, phenolic acids, hydroxycinnamic acid derivatives and flavonoids. Phenolic compounds have received considerable attention for being potentially protective factors against cancer and heart diseases, in part because of their potent antioxidative properties and their ubiquity in a wide range of commonly consumed foods of plant origin. The Brassicaceae family includes a wide range of horticultural crops, some of them with economic significance and extensively used in the diet throughout the world. The phenolic composition of Brassica vegetables has been recently investigated and, nowadays, the profile of different Brassica species is well established. Here, we review the significance of phenolic compounds as a source of beneficial compounds for human health and the influence of environmental conditions and processing mechanisms on the phenolic composition of Brassica vegetables.

/pdf/phenolic-compounds-in-brassica-vegetables-44ltmksu14.pdf

Phenolic compounds in Brassica vegetables.

Acridone alkaloids formed by acridone synthase in Ruta graveolens L. are composed of N-methylanthraniloyl CoA and malonyl CoAs. A 1095 bp cDNA from elicited Ruta cells was expressed in Escherichia coli, and shown to encode S-adenosyl-l-methionine-dependent anthranilate N-methyltransferase. SDS-PAGE of the purified enzyme revealed a mass of 40 +/- 2 kDa, corresponding to 40 059 Da for the translated polypeptide, whereas the catalytic activity was assigned to a homodimer. Alignments revealed closest relationships to catechol or caffeate O-methyltransferases at 56% and 55% identity (73% similarity), respectively, with little similarity ( approximately 20%) to N-methyltransferases for purines, putrescine, glycine, or nicotinic acid substrates. Notably, a single Asn residue replacing Glu that is conserved in caffeate O-methyltransferases determines the catalytic efficiency. The recombinant enzyme showed narrow specificity for anthranilate, and did not methylate catechol, salicylate, caffeate, or 3- and 4-aminobenzoate. Moreover, anthraniloyl CoA was not accepted. As Ruta graveolens acridone synthase also does not accept anthraniloyl CoA as a starter substrate, the anthranilate N-methylation prior to CoA activation is a key step in acridone alkaloid formation, channelling anthranilate from primary into secondary branch pathways, and holds promise for biotechnological applications. RT-PCR amplifications and Western blotting revealed expression of the N-methyltransferase in all organs of Ruta plants, particularly in the flower and root, mainly associated with vascular tissues. This expression correlated with the pattern reported previously for expression of acridone synthase and acridone alkaloid accumulation.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-313X.2007.03360.x

Anthranilate N-methyltransferase, a branch-point enzyme of acridone biosynthesis.

Callus cultures were established from hypocotyl explants of R. bracteosa, R. chalepensis and R. macrophylla. Calli were maintained for more than three years on MS-medium supplemented with 1 mg l-1 of each 2,4-D and kinetin. Acridone and furoquinoline alkaloids and coumarins have been isolated from four week old calli grown on a hormone containing and hormone-free medium. A new chlorinated acridone alkaloid has been detected.

Secondary metabolites produced by callus cultures of various Ruta species

Acridone synthase has been purified from cell suspension cultures of Ruta graveolens using a combination of gel filtration and ion exchange chromatography. The purified enzyme has an apparent molecular weight of 69 kDa on gel filtration and a subunit structure on SDS-PAGE of 40 kDa. The apparent Km-values are 10.64 microM and 32.8 microM for N-methylanthraniloyl-CoA and malonyl-CoA, respectively. Tryptic digestion of the homogeneous acridone synthase was performed. Seven of the peptides were chosen for microsequencing. The homology of the amino acid sequences from this particular polypeptide and corresponding peptides from chalcone synthase 3 from garden pea amounted to 76%.

Alfred Baumert

Papers

Anthranilate N-methyltransferase, a branch-point enzyme of acridone biosynthesis.

Secondary metabolites produced by callus cultures of various Ruta species

Purification and properties of acridone synthase from cell suspension cultures of Ruta graveolens L.

Triterpenoids from Pisolithus tinctorius isolates and ectomycorrhizas

Synthesis of 1,3-dihydroxy-N-methylacridone and its conversion to rutacridone by cell-free extracts of Ruta graveolens cell cultures