Ivano Morelli

Antioxidant activity of flavonoids from Licania licaniaeflora

In our screening program for antioxidants with DPPH radical scavenging activity we tested several flavonoids isolated from the leaves of Licania licaniaeflora (Chrysobalanaceae family) and identified by spectroscopic evidence, particularly with 1H and 13C NMR. All the isolated compounds exhibited DPPH radical scavenging activity: quercetin derivatives showed the strongest action, while the flavanone 8-hydroxy-naringenin and kaempferol 3-O-alpha-rhamnoside had the lowest.

Composition and antimicrobial properties of essential oils of four Mediterranean Lamiaceae

Essential oils from Satureja montana L., Rosmarinus officinalis L., Thymus vulgaris L., and Calamintha nepeta (L.) Savi, were chemically analysed and their antimicrobial and fungicide activities evaluated on the basis of their minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). All four oils have a biotoxic effect, the most active being those from Calamintha and Thymus.

In vitro antimicrobial activity of extracts and isolated constituents of Rubus ulmifolius

The antimicrobial activity on bacteria and fungi of increasing polarity extracts of Rubus ulmifolius and that of some isolated constituents, quercetin-3-O-beta-D-glucuronide; kaempferol-3-O-beta-D-glucuronide, gallic acid, ferulic acid and tiliroside was evaluated. The phenolic and tannins fractions showed an high antimicrobial activity.

Vasorelaxing effects of flavonoids: investigation on the possible involvement of potassium channels

A flavonoid-rich diet has been associated with a lower incidence of cardiovascular diseases, probably because of the antioxidant and vasoactive properties of flavonoids. Indeed, many flavonoids show vasorelaxing properties, due to different and often not yet completely clarified mechanisms of action. Among them, the activation of vascular potassium channels has been indicated as a possible pathway, accounting, at least in part, for the vasodilatory action of some flavonoid derivatives, such as apigenin and dioclein. Therefore, this work aims at evaluating, on in vitro isolated rat aortic rings, the endothelium-independent vasorelaxing effects of a number of flavonoid derivatives, to identify a possible activation of calcium-activated and/or ATP-sensitive potassium channels and to indicate some possible structure–activity relationships. Among the several flavonoids submitted to the pharmacological assay, only baicalein and quercetagetin were almost completely ineffective, while quercetin, hesperidin, quercitrin and rhoifolin exhibited only a partial vasorelaxing effect. On the contrary, acacetin, apigenin, chrysin, hesperetin, luteolin, pinocembrin, 4′-hydroxyflavanone, 5-hydroxyflavone, 5-methoxyflavone, 6-hydroxyflavanone and 7-hydroxyflavone, belonging to the chemical classes of flavones and flavanones, showed full vasorelaxing effects. The vasodilatory activity of hesperetin, luteolin, 5-hydroxyflavone and 7-hydroxyflavone were antagonised by tetraethylammonium chloride, indicating the possible involvement of calcium-activated potassium channels. Moreover, iberiotoxin clearly antagonised the effects of 5-hydroxyflavone, indicating the probable importance of a structural requirement (the hydroxy group in position 5) for a possible interaction with large-conductance, calcium-activated potassium channels. Finally, glibenclamide inhibited the vasorelaxing action of luteolin and 5-hydroxyflavone, suggesting that ATP-sensitive potassium channels may also be involved in their mechanism of action.

Two flavonoids and other compounds from the aerial parts of Centaurea bracteata from Italy

The flowering aerial parts of Centaurea bracteata Scop. (Asteraceae) have been studied for the first time. Nineteen compounds were isolated and identified, namely a sterol glucoside, two phenolic acids, three quinic acid derivatives, and 13 flavonoids, two of which, are new natural products. Structural elucidation was performed mainly by mean of FABMS, 1D and 2D NMR spectroscopy.

Cardiovascular effects of Urtica dioica L. (Urticaceae) roots extracts: in vitro and in vivo pharmacological studies

Urtica dioica (Urticaceae) is a plant principally used in the traditional medicine of oriental Marocco as antihypertensive remedy (J. Ethnopharmacol., 58 (1997), 45). The aim of this work was to evaluate a possible direct cardiovascular action of the plant and to investigate its mechanism of action. In aortic preparations with intact and functional endothelial layer, pre-contracted with KCl 20 mM or norepinephrine 3 microM, the crude aqueous and methanolic extracts of the plant roots, as well as purified fractions elicited a vasodilator action. Nevertheless, the vasodilator activity was not present in aortic rings without endothelial layer. In aortic rings with intact endothelial layer, the vasorelaxing effect was abolished by L-NAME, a NO-biosynthesis inhibitor, and ODQ, a guanylate cyclase inhibitor. Furthermore, potassium channel blockers (TEA, 4-aminopyridine, quinine, but not glybenclamide) antagonized the vasodilator action of the purified fraction F1W of U. dioica. The same fraction produced a marked decrease of inotropic activity, in spontaneously beating atria of guinea-pig, and a marked, but transient, hypotensive activity on the blood pressure of anaesthetized rats. It is concluded that U. dioica can produce hypotensive responses, through a vasorelaxing effect mediated by the release of endothelial nitric oxide and the opening of potassium channels, and through a negative inotropic action.

GC–MS analysis of essential oil of some commercial Fennel teas

Abstract Fennel teas were prepared by classical infusion or microwave decoction of unbroken and crushed fruits, three pre-packaged teabags and two instant teas. Their volatile constituents were obtained by extraction with n-hexane and analysed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC–MS), using two columns with stationary phases of different polarity. Of the constituents 85–95% were identified on the basis of their GC retention times and their mass spectra in relation to authentic compounds. No volatile constituents were detected in one sample of instant tea. Conventional teas from crushed fruits and teas prepared from the other instant tea showed the highest levels of volatile constituents. Anethole (30–90%) and/or anisaldehyde (0.7–51%) were the main constituents of all the samples. Methychavicol (0.8–4.1%), eugenol (1.5–11.3%) and fenchone (0.5–47%) were detected in most samples. Carvone (2.1–6.1%) was presenting only some teabags and camphor (2.3–2.6%) in others. The volatile constituents of only one instant tea included limonene (1.4%) and α-terpineol (0.4%).

Use of solid-phase micro-extraction as a sampling technique in the determination of volatiles emitted by flowers, isolated flower parts and pollen☆

The volatiles emitted by fresh whole flowers or isolated flower parts of mandarin, Citrus deliciosa Ten. (Rutaceae), were sampled using solid-phase micro-extraction (SPME). This technique offers several advantages over dynamic headspace sampling techniques used in previous investigations. In particular, SPME requires smaller sample sizes and very short sampling times, which can minimize the formation of artifacts due to damage to the plant, and contaminations or loss of compounds. This was especially applicable to the collection of volatiles from pollen.

Antimicrobial activity of the essential oil of Calamintha nepeta and its constituent pulegone against bacteria and fungi.

The chemical composition of the essential oil of Calamintha nepeta and its antimicrobial activity against Listeria monocytogenes, Bacillus cereus, Salmonella veneziana, S. paratyphi B, S. typhimurium, Fusarium moniliforme, Botrytis cinerea, Aspergillus niger and Pyricularia oryzae have been studied. Moreover the main constituents of the oil (limonene, menthone, pulegone, menthol) have been tested against the same microorganisms. Only pulegone showed antimicrobial activity, particularly against all the Salmonella species. Copyright

Aliphatic and triterpenoid hydrocarbons from ferns

A detailed analysis of the hydrocarbon fractions from the extracts of 21 ferns belonging to 13 families was carried out. n-Alkanes from C24 to C35 and triterpenoid hydrocarbons of the hopane series were identified. The taxonomic value of these results is discussed.