Chemical composition and antioxidant activity of tronchuda cabbage internal leaves

Tronchuda cabbage (Brassica oleracea L. var. costata DC): scavenger of reactive nitrogen species

The ability of tronchuda cabbage ( Brassica oleracea L. var. costata DC) to act as a scavenger of the reactive nitrogen species nitric oxide and peroxynitrite was investigated. The aqueous extracts obtained from tronchuda cabbage seeds and from its external and internal leaves exhibited a concentration dependent scavenging capacity. The antioxidant potential observed against the two reactive species was as follows: seeds > external leaves > internal leaves. In order to establish a possible correlation with the chemical composition of the extracts, the activity of ascorbic and sinapic acids and kaempferol 3- O-rutinoside was also studied. Among the compounds tested, sinapic acid showed the strongest antioxidant activity against both species.

Multivariate analysis of tronchuda cabbage (Brassica oleracea L. var. costata DC) phenolics: influence of fertilizers

A field experiment was carried out to investigate the effect of fertilization level on the phenolic composition of tronchuda cabbage ( Brassica oleracea L. var. costata DC) external and internal leaves. Eight different plots were constituted: a control without fertilization, one with organic matter, and six experiments with conventional fertilizers (nitrogen, boron, and sulfur, two levels each). The phenolic compounds were analyzed by reversed-phase HPLC-DAD. External and internal leaves revealed distinct qualitative composition. In the internal leaves were found 15 phenolics (5 kaempferol and 10 cinnamic acid derivatives), whereas the external leaves presented 3- p-coumaroylquinic acid and 13 kaempferol derivatives. Principal component analysis (PCA) was applied to assess the relationships between phenolic compounds, agronomical practices, and harvesting time. Samples obtained with conventional practices were quite effectively separated from organic samples, for both types of leaves. In general, samples developed without any fertilization presented the highest phenolics amounts: external and internal leaves contained 1.4- and 4.6-fold more phenolic compounds than the ones that received conventional fertilizer, respectively, and the internal leaves presented 2.4 times more phenolics than the ones grown with organic amendment. Additionally, samples from organic production exhibited higher total phenolics content than those from conventional practices, collected at the same time. Samples harvested first were revealed to be distinct from the ones collected later. The results show that it is possible to grow tronchuda cabbage without excess fertilizers, with highest amounts of phenolics and reduced environment contamination.

Identification of flavonoids and hydroxycinnamic acids in pak choi varieties (Brassica campestris L. ssp. chinensis var. communis) by HPLC-ESI-MSn and NMR and their quantification by HPLC-DAD

Twenty-eight polyphenols (11 flavonoid derivatives and 17 hydroxycinnamic acid derivatives) were detected in different cultivars of the Chinese cabbage pak choi ( Brassica campestris L. ssp. chinensis var. communis) by HPLC-DAD-ESI-MS(n). Kaempferol was found to be the major flavonoid in pak choi, glycosylated and acylated with different compounds. Smaller amounts of isorhamnetin were also detected. A structural determination was carried out by (1)H and (13)C NMR spectroscopy for the main compound, kaempferol-3-O-hydroxyferuloylsophoroside-7-O-glucoside, for the first time. Hydroxycinnamic acid derivatives were identified as different esters of quinic acid, glycosides, and malic acid. The latter ones are described for the first time in cabbages. The content of polyphenols was determined in 11 cultivars of pak choi, with higher concentrations present in the leaf blade than in the leaf stem. Hydroxycinnamic acid esters, particularly malic acid derivatives, are present in both the leaf blade and leaf stem, whereas flavonoid levels were determined only in the leaf blade.

Phenolic compounds, organic acids profiles and antioxidative properties of beefsteak fungus (Fistulina hepatica)

The phenolic compounds and the organic acids composition of the edible beefsteak fungus Fistulina hepatica was determined by HPLC/DAD and HPLC/UV, respectively. The results showed a profile composed by five phenolic compounds (caffeic, p-coumaric and ellagic acids, hyperoside and quercetin) and six organic acids (oxalic, aconitic, citric, malic, ascorbic and fumaric acids). The quantification of the identified compounds revealed that ellagic acid (ca. 49.7%) and malic acid (ca. 57.9%) are the main compounds in this species. In a general way the phenolic profile revealed to be more constant than the organic acids one and could be more useful for the quality control of the species. Beefsteak fungus was also investigated for its capacity to act as a scavenger of DPPH() radical and reactive oxygen species (superoxide radical, hydroxyl radical and hypochlorous acid). Good results were obtained against DPPH in a concentration-dependent manner. Beefsteak fungus also displayed good activity against superoxide radical, achieved by its capacity to act as both scavenger and xanthine oxidase inhibitor. A prooxidant effect was noticed for hydroxyl radical, which may be due to its capacity for iron ions reduction. Little ability for iron chelation was also observed. Beefsteak fungus showed a weak protective effect against hypochlorous acid.

Tronchuda cabbage flavonoids uptake by Pieris brassicae

The flavonoid pattern of larvae of cabbage white butterfly (Pieris brassicae L.; Lepidoptera: Pieridae) reared on the leaves of tronchuda cabbage was analysed by HPLC-DAD-MS/MS-ESI. Twenty flavonoids were identified or characterised, namely 16 kaempferol and four quercetin derivatives. Kaempferol 3-O-sophoroside, a minor component of tronchuda cabbage, was found to be the main component in P. brassicae (15.8%). Apart from this, only two other flavonoids present in significant amounts in tronchuda cabbage (kaempferol 3-O-sophoroside-7-O-glucoside and kaempferol 3-O-sophoroside-7-O-sophoroside) were found in the larvae. The larvae have high amounts of quercetin derivatives (18.5%), which were present only in trace amounts in tronchuda cabbage extracts, suggesting that P. brassicae is able to selectively sequester these flavonoids. The occurrence of a high content of flavonoids not detectable in tronchuda cabbage extracts indicates that P. brassicae larvae are able to metabolize dietary flavonoids.

Rumex induratus leaves: interesting dietary source of potential bioactive compounds

The phenolic compounds of Rumex induratus leaves were determined by HPLC-DAD-MS/MS-ESI. The results revealed a profile composed of 19 compounds: caffeoyl-hexoside, two p-coumaroyl-hexoside isomers, feruloyl-hexoside, sinapoyl-hexoside, 6-C-hexosyl-quercetin, 8-C-hexosyl-luteolin, 6-C-hexosyl-luteolin, 6-C-hexosyl-apigenin, 3-O-hexosyl-quercetin, 3-O-rutinosyl-quercetin, 7-O-hexosyl-diosmetin, 3-O-rutinosyl-isorhamnetin, 7-O-(acetyl)-pento-hexosyl-diosmetin, 6-C-hexosyl-genkwanin, and four unidentified O-glycosyl-C-glycosylflavones. The quantification of the identified phenolics by HPLC-DAD showed 6-C-hexosyl-luteolin as the main compound. Organic acid composition was determined by HPLC-UV, revealing a high content of oxalic acid. R. induratus was also investigated for its capacity to act as a scavenger of DPPH and superoxide radicals. Good antioxidative results were obtained against both radicals. Unlike other species of the genus Rumex, R. induratus did not present any anthraquinone derivative.