Stress-Induced Biosynthesis of Dicaffeoylquinic Acids in Globe Artichoke

Abstract

Leaf extracts from globe artichoke ( Cynara cardunculus L. var. scolymus) have been widely used in medicine as hepatoprotectant and choleretic agents. Globe artichoke leaves represent a natural source of phenolic acids with dicaffeoylquinic acids, such as cynarin (1,3-dicaffeoylquinic acid), along with its biosynthetic precursor chlorogenic acid (5-caffeoylquinic acid) as the most abundant molecules. This paper reports the development of an experimental system to induce caffeoylquinic acids. This system may serve to study the regulation of the biosynthesis of (poly)phenolic compounds in globe artichoke and the genetic basis of this metabolic regulation. By means of HPLC-PDA and accurate mass LC-QTOF MS and MS/MS analyses, the major phenolic compounds in globe artichoke leaves were identified: four isomers of dicaffeoylquinic acid, three isomers of caffeoylquinic acid, and the flavone luteolin 7-glucoside. Next, plant material was identified in which the concentration of phenolic compounds was comparable in the absence of particular treatments, with the aim to use this material to test the effect of stress application on the regulation of biosynthesis of caffeoylquinic acids. Using this material, the effect of UV-C, methyl jasmonate, and salicylic acid treatments on (poly)phenolic compounds was tested in different globe artichoke genotypes. UV-C exposure consistently increased the levels of dicaffeoylquinic acids in all genotypes, whereas the effect on compounds from the same biosynthetic pathway, for example, chlorogenic acid and luteolin-7-glucoside, was much less pronounced and was not statistically significant. No effect of methyl jasmonate or salicylic acid was found. Time-response experiments indicated that the level of dicaffeoylquinic acids reached a maximum at 24 h after UV radiation. On the basis of these results a role of dicaffeoylquinic acids in UV protection in globe artichoke is hypothesized.

Isolation and mapping of a C3′H gene (CYP98A49) from globe artichoke, and its expression upon UV-C stress

“…In order to evaluate the changes of CYP98A49 expression levels in response to UV-C induction, we performed RT-PCR experiments. We have shown in a previous work (Moglia et al 2008) that in globe artichoke the production of dicaffeoylquinic acids, which are powerful antioxidants, can be induced upon exposure to UV-C, which suggests a role for these compounds in the protection of young leaf tissue from reactive oxygen species generated by excess light. The expression level of CYP98A49 gene was strongly increased (greater than fourfold higher) in UV-C treated leaves, as compared to non-treated control leaves, thus indicating not only activation in response to UV light, but likely also a putative role of this enzyme in dicaffeoylquinic acid accumulation.…”

“…Enzymatic assays were analyzed by reverse-phase HPLC with PDA detection, as described recently (Moglia et al 2008). In short, the HPLC system comprised a Waters 600 gradient controller, a Waters 996 PDA detector and a column incubator held at 40°C.…”

“…Three globe artichoke foliar discs were exposed to UV-C treatment (16 W germicidal lamp during 20 min) as described by Moglia et al (2008). They were then ground separately to a fine powder in liquid nitrogen, and RNA extraction was performed from 100 mg of each powdered leaf, as described above.…”

“…The involvement in the stress response of chlorogenic acid has been reported, with its concentration increasing in lettuce upon wounding, and in tobacco upon both UV-B irradiation and insect feeding (Cantos et al 2001;Izaguirre et al 2007). In globe artichoke, we have recently shown that exposure to UV-C consistently increases the level of the major dicaffeoylquinic acid isomer, while the exogenous application of either methyl jasmonate or salicylic acid has no such effect (Moglia et al 2008). Furthermore we previously generated the first genetic map of globe artichoke, based on a two-way pseudo-testcross strategy (Lanteri et al 2006).…”

Satiety and amino-acid profile in overweight women after a new treatment using a natural plant extract sublingual spray formulation

“…The formulation contains extract of Griffonia simplicifolia, which is rich in 5-HTP; 36 Guaranà, known for its stimulatory effect on fat metabolism; 37 Centella asiatica, which is useful for its beneficial effects on blood and lymph circulation; 38 Taraxacum, which has an antioxidative and diuretic effect; 39 artichoke, with its detoxifying action 40 and klamath algae, which has a high content of nutritive substances including phenylethylamine, which improves mood. 41 …”