Rosa M. Seabra

Phenolic fingerprint of peppermint leaves

A reversed-phase high-performance liquid chromatography procedure is proposed for the determination of 10 phenolic compounds (eriodictyol 7-O-rutinoside, eriodictyol 7-O-glucoside, luteolin 7-O-rutinoside, luteolin 7-O-glucoside, hesperetin 7-O-rutinoside, apigenin 7-O-rutinoside, rosmarinic acid, 5,6-dihydroxy-7,8,3′,4′-tetramethoxyflavone, pebrellin and gardenin B) in peppermint. The chromatographic separation was achieved using a reversed-phase Spherisorb ODS 2 (5 μm particle size; 25.0×0.46 cm) column. Of the several extractive solvents tried, ethanol was the best for qualitative and quantitative analysis. Best resolution was obtained using a gradient of water-phosphoric acid (999:1) and acetonitrile. Fourteen samples were subjected to quantification and showed a common composition pattern.

Phenolic antioxidant compounds produced by in vitro shoots of sage (Salvia officinalis L.)

In vitro shoots of sage (Salvia officinalis L.) were established under four different cytokinin supplementations by culturing nodal segments excised from aseptically germinated seedlings. The highest rates of shoot proliferation and linear shoot growth occurred with the supplementation of 1.5 mg/l benzyladenine and 0.05 mg/l dichlorophenoxyacetic acid. However, under these conditions, the specific production of total antioxidant phenolics was the lowest. Variation in kinetin (KIN) concentration (1.5; 2.0; 4.0 mg/l), in the presence of 0.05 mg/l 2,4-D, did not influence significantly the rates of shoot proliferation and linear shoot growth but influenced the production of antioxidant phenolics and biomass. Seventeen compounds were identified in the antioxidant phenolic extracts from shoots: gallic acid, 3-O-caffeoylquinic acid, 5-O-caffeoylquinic acid, caffeic acid, and rosmarinic acid, as phenolic acids; hesperetin, apigenin, hispidulin, cirsimaritin, and genkwanin, as flavonoids; epirosmanol, epirosmanol methyl ether, carnosol, epiisorosmanol ethyl ether, rosmadial, carnosic acid, and methyl carnosate, as phenolic diterpenes. With exception of carnosic acid and methyl carnosate, all the other phenolic compounds (15) were also identified in a commercial sample of this species. Rosmarinic acid and carnosol were the main compounds in all the antioxidant phenolic extracts. The increase in concentration of KIN decreased the accumulation of the most of phenolic diterpenes, particularly that of carnosol.

Comparative study of phytochemicals and antioxidant potential of wild edible mushroom caps and stipes

A comparative study of the organic acids and phenolics composition and of the total alkaloids content of entire wild edible mushrooms (Russula cyanoxantha, Amanita rubescens, Suillus granulatus and Boletus edulis) and correspondent caps and stipes was performed. All species presented oxalic, citric, malic and fumaric acids, with A. rubescens exhibiting the highest total organic acids content. Organic acids were preferably fixed in the cap. Among phenolics, only p-hydroxybenzoic acid was found in A. rubescens and S. granulatus, in very low amounts. B. edulis was the species that presented the highest total alkaloid amounts. Except for this species, alkaloids mainly accumulated in the cap. All of the species exhibited a concentration-dependent scavenging ability against DPPH(·). B. edulis revealed the highest antioxidant capacity. The cap seemed to be the part with highest antioxidant potential. Some relationships between chemical composition and antioxidant capacity were considered.

Analysis and quantification of flavonoidic compounds from Portuguese olive (Olea Europaea L.) leaf cultivars

Twenty three samples of 18 Portuguese olive leaf cultivars were analysed by a reversed-phase HPLC/DAD procedure and eight flavonoidic compounds were identified and quantified (luteolin 7,4′-O-diglucoside, luteolin 7-O-glucoside, rutin, apigenin 7-O-rutinoside, luteolin 4′-O-glucoside, luteolin, apigenin and diosmetin). Luteolin 7,4′-O-diglucoside and luteolin 4′-O-glucoside were identified by HPLC/DAD/MS/MS – ESI. The studied olive leaf samples showed a common phenolic pattern, in which luteolin 4′-O-glucoside was almost always the major compound.

New Phenolic Compounds and Antioxidant Potential of Catharanthus roseus

Screening of the phenolic compounds from seeds, stems, leaves and petals of Catharanthus roseus (L.) G. Don (cv. Little Bright Eye) was achieved by HPLC-DAD-ESI-MS/MS. This is the first detailed study of noncolored phenolics in C. roseus, which allowed the characterization of three caffeoylquinic acids and fifteen flavonol glycosides (di- and trisaccharides of kaempferol, quercetin and isorhamnetin). Fifteen compounds are reported for the first time in this species. The scavenging ability of the different plant matrices was assessed against DPPH(*) radical and against reactive oxygen (superoxide radical) and a reactive nitrogen (nitric oxide) species. A concentration-dependent protective effect was observed for seeds and tissues, with petals shown to be the most active.

Physicochemical attributes and pollen spectrum of Portuguese heather honeys

Abstract The qualities of selected honey samples of “Serra da Lousa” (Portugal) from three consecutive harvests (20 samples from each harvest) were evaluated by determing the pollen spectrum and physicochemical attributes. The following determinations were carried out: moisture, electrical conductivity, hydroxymethylfurfural, diastase activity, pH, acidity (free, lactone and total), formol number, reducing sugars, apparent sucrose, insoluble material and ash. The samples were found to meet all major national and international honey specifications. Honeys were considered to be monofloral whenever the dominant pollen was found to be over 45% of total pollen. From the 60 studied samples, 70% were monofloral honeys from Erica sp., 17% monofloral honeys from Ericaceae (Erica sp. and Calluna vulgaris (L.) Hull) and 13% multifloral honeys with a high percentage of Erica sp.

HPLC-DAD-MS/MS-ESI screening of phenolic compounds in Pieris brassicae L. Reared on Brassica rapa var. rapa L.

The phenolic profiles of cabbage white butterfly ( Pieris brassicae L.; Lepidoptera: Pieridae) at different development stages (larvae, exuviae, and butterfly), its excrements, and its host plant Brassica rapa var. rapa L. were determined by high performance liquid chromatography- diode-array detector-mass spectrometry/mass spectrometry-electrospray ionization (HPLC-DAD-MS/MS-ESI). Twenty-five acylated and nonacylated flavonoid glycosides and ferulic and sinapic acids were identified in host plant, from which only 12 compounds were found in the excrements. In addition, the excrements showed the presence of sulfate flavonoids and other flavonoid glycosides that were not detected in the leaves. In the larvae kept without food for 12 h, only 3 compounds common to the plant material and 2 others, also present in the excrements, were characterized. The results indicate that deacylation, deglycosylation, and sulfating steps are involved in the metabolic process of P. brassicae and that its excrements may constitute a promising source of bioactive compounds, which could be used to take profit of this common pest of Brassica cultures.

THE DEVELOPMENT AND EVALUATION OF AN HPLC-DAD METHOD FOR THE ANALYSIS OF THE PHENOLIC FRACTIONS FROM IN VIVO AND IN VITRO BIOMASS OF HYPERICUM SPECIES

A new HPLC-DAD method for separation and identification of the main phenolics present in in vivo and in vitro biomass of Hypericum perforatum and Hypericum androsaemum has been developed. This method accomplished the direct identification of 22 compounds including flavonoids, hypericins, phloroglucinols, and phenolic acids. The HPLC profiles obtained in the course of this work clearly evidenced a distinct phenolic production between in vivo and in vitro biomass. For example calli and suspended cells produced mainly xanthones while in in vivo plants of both species these compounds were not detected. Some luteolin flavone type compounds were identified in calli and suspended cells of H. perforatum while quercetin was found in suspended cells of H. androsaemum. Flavonoids, namely those related to quercetin, were the major metabolites in methanolic extracts from in vivo plants. Hypericins were detected in in vivo plants and in in vitro shoots of H. perforatum but not in calli or suspended cells of the same sp...

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.

Composition of Quince (Cydonia oblonga Miller) seeds: phenolics, organic acids and free amino acids

Phenolic compounds, organic acids and free amino acids of quince seeds were determined by HPLC/DAD, HPLC/UV and GC/FID, respectively. Quince seeds presented a phenolic profile composed of 3-O-caffeoylquinic, 4-O-caffeoylquinic, 5-O-caffeoylquinic and 3,5-dicaffeoylquinic acids, lucenin-2, vicenin-2, stellarin-2, isoschaftoside, schaftoside, 6-C-pentosyl-8-C-glucosyl chrysoeriol and 6-C-glucosyl-8-C-pentosyl chrysoeriol. Six identified organic acids constituted the organic acid profile of quince seeds: citric, ascorbic, malic, quinic, shikimic and fumaric acids. The free amino acid profile was composed of 21 identified free amino acids and the three most abundant were glutamic and aspartic acids and asparagine.