Studies of the molecular genetics, mechanisms of activation and functional connections between general phenylpropanoid metabolism and certain branch pathways in parsley, bean, potato plants and cell cultures

Physiology and Molecular Biology of Phenylpropanoid Metabolism

The advent of well-defined catalysts for olefin metathesis which combine high activity, durability, and excellent tolerance towards polar functional groups has revolutionized the field. The past decade has seen the rapid embrace of these reagents as tools for advanced organic and polymer chemistry and the success of this development is witnessed by a plethora of elegant applications to the synthesis of natural and nonnatural products. This review article provides an overview of these developments and intends to familiarize the reader with some very recent advances which hold the promise to expand the scope of the reaction even further. Moreover, the positive impact of metathesis on the fundamental logic of retrosynthetic planning is demonstrated by means of typical examples. Finally, it will be shown that metathesis is by no means restricted to alkenes as substrates, and some comments on metathesis reactions following unconventional mechanistic pathways will also be presented.

Olefin Metathesis and Beyond

Antibiotic phenols have been found in all plants investigated to date. Some occur constitutively and are thought to function as preformed inhibitors associated with nonhost resistance (84, 94, 128, 134). Others, which are the subject of this review, are formed in response to the ingress of pathogens, and their appearance is considered as part of an active defense response. Since the first suggestions that phenolic intermediates have a role in the active expres­ sion of resistance, an underlying problem in ascertaining that such secondary metabolites are of primary (rather than secondary) importance has been the localization and timing of the host response. In this review we address the problem of response localization and localization of phenolics relative to the sequential development of stages of disease that lead ultimately to resistance expression. Initial demonstrations that phenols are significant components of the host

Phenolic Compounds and Their Role in Disease Resistance

Thermal stability and flame retardancy of polyurethanes

This review defines the range of forms in which cinnamates (p-coumarates, caffeates, ferulates and sinapates) occur in foods and beverages subdividing them into (i) the classic chlorogenic acids and close allies, (ii) other esters, amides and glycosides, and (iii) transformation products formed during processing. Cinnamate derivatives which would not release cinnamic acid by hydrolysis are excluded. The quantitative data are reviewed concisely and attention is drawn to certain shortcomings, in particular a complete absence of data for certain commodities (breakfast cereals, baked goods, tomato products and nuts) and minimal data for pulses, legumes and processed or cooked foods. In addition, more data are required for the edible portion of modern varieties. By extrapolating from such data as are available the important source(s) (i) of individual cinnamates (regardless of the conjugate type) and (ii) of each major class of conjugate, have been identified as follows: (i) Cinnamates: caffeic acid: coffee beverage, blueberries, apples, ciders; p-coumaric acid: spinach, sugar beet fibre, cereal brans; ferulic acid: coffee beverage, citrus juices, sugar beet fibre, cereal brans; sinapic acid: broccoli, kale, other leafy brassicas, citrus juices. (ii) Conjugates: caffeoylquinic acids: coffee beverage, blueberries, apples, ciders; p-coumaroylquinic acids: sweet cherries; feruloylquinic acids: coffee beverage; tartaric conjugates: spinach, lettuce, grapes and wines; malic conjugates: lettuce, spinach, possibly legumes; rosmarinic acid: culinary herbs, mixed herbs, possibly stuffings; cell wall conjugates: spinach, sugar beet fibre, cereal brans. It seems likely that the UK population will fall into several categories depending on (i) their consumption of coffee, (ii) their consumption of bran, and (iii) their consumption of citrus. Those who drink several cups of coffee per day augmented by bran and citrus might easily ingest 500-800mg cinnamates (or even 1 g for the greatest coffee ingest consumption) whereas those who eschew all these and take little fresh fruit or vegetables might struggle to consume 25 mg.

Chlorogenic acids and other cinnamates – nature, occurrence and dietary burden

Dark-grown cell suspension cultures of parsley, Petroselinum hortense, produce furanocoumarins after treatment with elicitor preparations of either Phytophthora megasperma f.sp. glycinea (Pmg elicitor) or Alternaria carthami Chowdhury (Ac elicitor). The linear furanocoumarins, psoralen and xanthotoxin, and the benzodipyrandione, graveolone, are the major products synthesized in response to Pmg elicitor, besides small amounts of the furanocomarin bergapten. Treatment with Ac elicitor induces predominantly the formation of bergapten and the furanocoumarin isopimpinellin, as well as small amounts of graveolone. While Pmg elicitor leads to cell death within a few days, cell mass increased for at least 6 days after treatment with Ac elicitor. Brefeldin A, a phytotoxin produced by A. carthami, inhibits growth of parsley cell suspension cultures considerably at a concentration of 0.01 mM and growth of the cells ceased at a concentration of 0.1 mM toxin. Concomitantly, furanocoumarin biosynthesis was suppressed in our system by a concentration of brefeldin A within 0.01–0.1 mM.

https://febs.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1432-1033.1983.tb07277.x

Differential response of cultured parsley cells to elicitors from two non-pathogenic strains of fungi. 1. Identification of induced products as coumarin derivatives.

From the aerial parts of Pluchea symphytifolia, four known and two new caffeoylquinic acids, 1,3,4,5-tetra-O-caffeoylquinic acid and 1,3-di-O-[3,4,-bis-(3,4-dihydroxyphenyl)-cyclobutane-1,2-dicarbonyl]- 4,5-di-O-caffeoylquinic acid, and two flavonols were isolated and their structures elucidated by mass and NMR spectroscopy and by chemical degradation. The aqueous extract had weak antibacterial and weak antisecretory effects; the lipophilic extract showed a modest anthelmintic activity. The higher caffeoylated quinic acids participated in the antibacterial and anthelmintic effect of the extracts.

Dieter Hunkler

Papers

Differential response of cultured parsley cells to elicitors from two non-pathogenic strains of fungi. 1. Identification of induced products as coumarin derivatives.

Caffeoylquinic acids and some biological activities of Pluchea symphytifolia.

Iridoid-related aglycone and its glycosides from Scrophularia ningpoensis

Proanthocyanidins with (+)-epicatechin units from Byrsonima crassifolia bark

Dodecahedranes from [1.1.1.1]Pagodanes