Anti-angiogenic effect of quercetin and its 8-methyl pentamethyl ether derivative in human microvascular endothelial cells.

Angiogenesis is involved in many pathological states such as progression of tumours, retinopathy of prematurity and diabetic retinopathy. The latter is a more complex diabetic complication in which neurodegeneration plays a significant role and a leading cause of blindness. The vascular endothelial growth factor (VEGF) is a powerful pro-angiogenic factor that acts through three tyrosine kinase receptors (VEGFR-1, VEGFR-2 and VEGFR-3). In this work we studied the anti-angiogenic effect of quercetin (Q) and some of its derivates in human microvascular endothelial cells, as a blood retinal barrier model, after stimulation with VEGF-A. We found that a permethylated form of Q, namely 8MQPM, more than the simple Q, is a potent inhibitor of angiogenesis both in vitro and ex vivo. Our results showed that these compounds inhibited cell viability and migration and disrupted the formation of microvessels in rabbit aortic ring. The addition of Q and more significantly 8MQPM caused recoveries or completely re-establish the transendothelial electrical resistance (TEER) to the control values and suppressed the activation of VEGFR2 downstream signalling molecules such as AKT, extracellular signal-regulated kinase, and c-Jun N-terminal kinase. Taken together, these data suggest that 8MQPM might have an important role in the contrast of angiogenesis-related diseases.

Kinetics of curcumin oxidation by 2,2-diphenyl-1-picrylhydrazyl (DPPH˙): an interesting case of separated coupled proton-electron transfer.

The decay of dpph˙ in absolute ethanol at 25 °C and in the presence of curcumin (1), 4-methylcurcumin (3), 4,4-dimethylcurcumin (4) or curcumin 4'-methyl ether (5) follows bi-exponential kinetics. These unusual reaction kinetics are compatible with a two-step process in which an intermediate accumulates in a reversible first step followed by an irreversible process. As in other similar cases (Foti et al., Org. Lett., 2011, 13, 4826-4829), we have hypothesised that the intermediate is a π-stacked complex, formed between one curcumin anion (in the case of 1, 3 and 5 the enolate anion) and the picryl moiety of dpph˙, in which an intra-complex electron transfer from the (enolate) anion takes place. By comparing the kinetics of curcumin 4',4''-dimethyl ether (2) (no phenolic OH), (5) (one phenolic OH) and (1) (two phenolic OHs), we have deduced that the electron transfer process must be accompanied by a simultaneous proton transfer from the phenolic OHs to the bulk solvent (separated coupled proton-electron transfer). The rate constants kα for the forward reaction of 2, 5 and 1 with dpph˙ are in fact ∼0, 7.5 × 10(3) and 1.8 × 10(4) M(-1) s(-1), respectively, in a clear dependence on the number of phenolic OHs.

A pinitol-rich Glycyrrhiza glabra L. leaf extract as functional supplement with potential in the prevention of endothelial dysfunction through improving insulin signalling.

Background: Glycyrrhyza glabra L. is one of the most popular medicinal plant in the world, its roots having been used since ancient times in many traditional medicines. On the contrary, scarce attention has been dedicated to liquorice aerial parts. Previous studies showed the presence of a large group of polyphenols and a consistent amount of d-pinitol in the leaf extract.Methods: The methanolic extract from G. glabra leaves was profiled for its content in polyphenols; the amount of d-pinitol was also measured with two independent methods (HPLC-ELSD and NMR). The extract was tested for its in vitro protective effects against insulin resistance-related endothelial dysfunction in human umbilical vein endothelial cells exposed to palmitic acid, which is the most prevalent saturated free fatty acid in circulation.Results: Methanolic extract from liquorice leaves has a protective effect against the lipotoxicity-associated alterations of insulin pathway in human endothelial cells, similarly to what observed with pure d-pinitol.Conclusions: Liquorice leaves are to be considered a waste product which gives a phytocomplex endowed with interesting potential therapeutic properties, moreover the use of a liquorice leaves phytocomplex rather than a pure compound allows avoiding a series of isolation/purification procedures and can be easily scaled up for industrial applications.

The Diagnostic Performance of Multi-Detector Computed Tomography (MDCT) in Depiction of Acute Spondylodiscitis in an Emergency Department.

BACKGROUND: The diagnosis of acute spondylodiscitis can be very difficult because clinical onset symptoms are highly variable. The reference examination is MRI, but very often the first diagnostic investigation performed is CT, given its high availability in the acute setting. CT allows rapid evaluation of other alternative diagnoses (e.g., fractures), but scarce literature is available to evaluate the accuracy of CT, and in particular of multi-detector computed tomography (MDCT), in the diagnosis of suspected spondylodiscitis. The aim of our study was to establish MDCT accuracy and how this diagnostic method could help doctors in the depiction of acute spondylodiscitis in an emergency situation by comparing the diagnostic performance of MDCT with MRI, which is the gold standard. METHODS: We searched our radiological archive for all MRI examinations of patients who had been studied for a suspicion of acute spondylodiscitis in the period between January 2017 and January 2021 (n = 162). We included only patients who had undergone MDCT examination prior to MRI examination (n = 25). The overall diagnostic value of MDCT was estimated, using MRI as the gold standard. In particular, the aim of our study was to clarify the effectiveness of CT in radiological cases that require immediate intervention (stage of complications). Therefore, the radiologist, faced with a negative CT finding, can suggest an elective (not urgent) MRI with relative serenity and without therapeutic delays. RESULTS: MDCT allowed identification of the presence of acute spondylodiscitis in 13 of 25 patients. Specificity and positive predictive value were 100% for MDCT, while sensitivity and negative predictive value were 68% and 50%, respectively, achieving an overall accuracy of 76%. In addition, MDCT allowed the identification of paravertebral abscesses (92%), fairly pathognomonic lesions of spondylodiscitis pathology. CONCLUSIONS: The MDCT allows identification of the presence of acute spondylodiscitis in the Emergency Department (ED) with a satisfactory accuracy. In the case of a positive CT examination, this allows therapy to be started immediately and reduces complications. However, we suggest performing an elective MRI examination in negative cases in which pathological findings are hard to diagnose with CT alone.

"Bulb-like" sign: Small bowel closed loop obstruction in incarcerated Spigelian hernia.

A Spigelian hernia is a rare hernia, making up approximately 0.1% of all abdominal wall hernias. This hernia goes through a defect in the Spigelian fascia which is the part of the transversus abdominis aponeurosis lateral to the rectus muscle, often at the level of the arcuate line, where the fascia is widest and weakest. Clinical diagnosis is difficult in patients without obvious abdominal mass but imaging can be a valuable adjunct in diagnosis. We report the case of a 64-year-old male who presented to our hospital with small bowel obstruction secondary to an incarcerated Spigelian hernia who was pre-operatively diagnosed with ultrasound and computed tomography. At ultrasound and computed tomography a closed loop obstruction in a Spigelian Hernia was detected, resembling on both imaging modalities a "bulb-like" appearance.

Pleural empyema secondary to nephropleural fistula in complicated pyonephrosis.

Pleural empyema of extra pulmonary origin is uncommon and empyema secondary to a fistula between the urinary tract and thorax is extremely rare. We report a case of nephropleural fistula causing massive pleural empyema in a 64-year-old woman with a long history of urological problems, including nephrolitiasis and urinary tract infection. She was admitted with sepsis, fever, chills, tachypnea, productive cough and pyuria. At clinical examination, breath sounds were reduced over the left hemithorax. CT revealed a fistulous connection from the upper left calyceal group and the pleural space. Drainage of thoracic and perinephric collection was carried out, but nephrectomy and pleural decortication were required due to haemopurulent urine and decreased hemoglobin levels during the hospitalization. This case demonstrates the unusual and prolonged evolution of an obstructive hydroureteronephrosis complicated by pyonephrosis, culminating in retroperitoneal abscess that fistulized into the pleural space, leading to empyema.

Singlet oxygen quenching- and chain-breaking antioxidant-properties of a quercetin dimer able to prevent age-related macular degeneration.

A dimer of quercetin prepared through a Mannich reaction protects pyridinium bisretinoid A2E from photooxidation at 430 nm in aqueous medium at pH 7.4. In the presence of light and O2, A2E is quickly attacked by 1O2 produced in situ (by excited A2E) to give nonaoxirane and other oxygenated compounds which can be involved in diseases of the macula. Peroxyl radicals might have only a marginal role on the photooxidation of A2E. The dimer is actually a potent quencher of 1O2 with a rate constant kQ of 8.5 × 108 M-1 s-1 in methanol at room temperature. On the other hand, its antioxidant abilities against ROO· radicals are quite limited since kROO·â€¯= 7.3 × 105 M-1 s-1 (in buffer solution at pH 7.4), the value being essentially identical to that of quercetin. The quenching of 1O2 by the dimer is therefore the main reason for the A2E protection and prevention of age-related macular degeneration.

Quercetin derivatives as potent inducers of selective cytotoxicity in glioma cells.

Quercetin (Q) is a flavonoid widely distributed in the plant kingdom and well-known for its ability to exert antioxidant, prooxidant and anticarcinogenic activities in several tumor cells. Furthermore, quercetin plays an important role both in the regulation of key elements in cellular signal transduction pathways related to apoptotic cell death, and in cell cycle progression. Several studies have reported of toxic effects of Q against glioma cell lines. In this study, the effects of Q and of some Q-derivatives (acyl esters and bromo-derivatives) on U373-MG and 9L glioma cell lines survival are analyzed. The 24-hour treatment of glioma cells with several concentrations of Q (25, 50 and 100µM) did not cause any cytotoxic effects, while the administration of Q-derivatives, such as acylated and brominated quercetin, caused a sharp increase in cell death. Among all tested derivatives, 3-O-decanoylquercetin 10 manifested the strongest cytotoxic effect at a concentration as low as 25µM both in U373-MG (ca. 40% viability after 24h) and in 9L cells (ca. 20% viability after 24h). The cytotoxic effects of the Q-derivatives 3 and 10-13 were proven to be satisfactorily selective for glioma cells. When Q-derivatives were in fact administered to mouse primary astroglial or human fibroblast cell cultures, a higher cell survival rate (~90-70% and 55-45%, respectively) was observed relative to that detected in glioma cells. These results prove that selective esterification and bromination of Q increase to a great extent the toxicity of this polyphenol against glioma cells, thereby providing a possible new tool for cyto-specific glioma therapy.

Alkylation Products of a Calix[8]arene Trianion. Effect of Charge Redistribution in Intermediates.

The behavior of a well-defined calix[8]arene trianion under alkylation conditions was investigated by reacting the tetraethylammonium salt of p-tert-butylcalix[8]arene trianion with p-methylbenzyl bromide. Chromatography of the reaction mixture afforded the following derivatives in order of decreasing yields: 1,3,5,7-tetrakis-, 1,3-bis-, 1,3,5-tris-, 1,2,4-tris-, and mono(p-methylbenzyl)-p-tert-butylcalix[8]arene, besides trace amounts of 1,4- and 1,5-disubstituted compounds. Comparable results were obtained using p-tert-butylbenzyl bromide. The observed regioselectivity has been explained by assuming that after each alkylation step the left negative charge is redistributed, by exchange equilibria, over the remaining phenolic groups with preferential localization at those positions where contiguous H-bond stabilization is possible and the electrostatic repulsion is minimized. The occurrence of protonation/deprotonation equilibria allows the formation of 1,3,5,7-tetrasubstituted calix[8]arene.

'In vitro' antioxidant and photoprotective properties and interaction with model membranes of three new quercetin esters.

Quercetin is well known to possess the strongest protective effect against UV light-induced lipoperoxidation. However, the absolute water insolubility of quercetin is a key step that may limit its bioavailability and, thus, its 'in vivo' employment as a photoprotective agent. The aim of the present paper was to evaluate 'in vitro' the antioxidant and photoprotective properties and the interaction with model membranes of three new semisynthetic quercetin derivatives, quercetin-3-O-acetate (Q-ac), quercetin-3-O-propionate (Q-pr) and quercetin-3-O-palmitate (Q-pal), obtained by esterification of the C-3 OH function with an aliphatic side-chain of different length. The antioxidant activity of quercetin and of its three esters was assessed in two 'in vitro' experimental models: (a) the bleaching of the stable 1,1-diphenyl-2-picrylhydrazyl radical; (b) UV radiation-induced peroxidation in multilamellar vesicles (MLVs). Differential scanning calorimetry on dimyristoylphosphatidylcholine MLVs and unilamellar vesicles was employed to investigate the interaction of the drugs tested with model membranes. Finally, the stability following UV light exposure and the lipophilicity and water solubility of quercetin and its three esters were examined. The findings obtained demonstrated that the esterification with an opportune aliphatic side chain of the OH function located at the C-3 position allows the production of new quercetin derivatives, which may be good candidates as photoprotective agents. In particular, one could speculate that the esterification with a short side-chain (such as in Q-ac and Q-prop) provides the suitable chemico-physical features not only to maintain the antioxidant and photoprotective effectiveness of the parent drug, but also to be able to migrate through the aqueous environment and to interact with and cross phospholipid membranes.

Agronomic characterization and α- and ß-ODAP determination through the adoption of new analytical strategies (HPLC-ELSD and NMR) of ten sicilian accessions of grass pea.

Ten accessions of grass pea (Lathyrus sativus L.) from different Sicilian sites, cultivated in the same environmental conditions, were analyzed for their morphological and productive parameters and for the content of two non-protein amino acids: α- and ß-ODAP (α- and ß-N-oxalyl-l-α,ß-diaminopropionic acid). The ß-isomer is the neurotoxin responsible for the neuron disease known as lathyrism. This analysis was carried out using two common analytical methodologies never applied in their determination, an HPLC separation with evaporative light scattering (ELS) as detector, and nuclear magnetic resonance (NMR). The content of the two isomers falls in the range reported for these compounds: 0.42-0.74 and 2.69-4.59 g/kg for α- and ß-ODAP, respectively; and the two methods yield comparable results. High productivity and a high protein content were detected in three Sicilian accessions. Low ß-ODAP content was found to be linked to accessions with heavier seeds and those originating at lower altitudes.

Dihydrostilbene derivatives from Glycyrrhiza glabra leaves.

Four new dihydrostilbenes, alpha,alpha'-dihydro-3,5-dihydroxy-4'-acetoxy-5'-isopentenylstilbene (1), alpha,alpha'-dihydro-3,3',4'-trihydroxy-5-O-isopentenyl-6-isopentenylstilbene (2), alpha,alpha'-dihydro-3,5,3'-trihydroxy-4'-methoxystilbene (3), and alpha,alpha'-dihydro-3,3'-dihydroxy-5beta-d-O-glucopyranosyloxy-4'-methoxystilbene (4), together with seven known flavonoids, glabranin isomer, naringenin, lupiwighteone, pinocembrin 7-O-glucoside, astragalin, isoquercitrin, vicenin II, and the inositol, pinitol, were isolated from the leaves of Glycyrrhiza glabra grown in Sicily. The structures of 1-4 were elucidated by spectroscopic methods.

New dihydrostilbene derivatives from the leaves of Glycyrrhiza glabra and evaluation of their antioxidant activity.

Five new prenylated dihydrostilbenes, alpha,alpha'-dihydro-3,5,4'-trihydroxy-4,5'-diisopentenylstilbene (1), alpha,alpha'-dihydro-3,5,3',4'-tetrahydroxy-4,5'-diisopentenylstilbene (2), alpha,alpha'-dihydro-3,5,4'-trihydroxy-5'-isopentenylstilbene (3), alpha,alpha'-dihydro-3,5,3'-trihydroxy-4'-methoxy-5'-isopentenylstilbene (4), and alpha,alpha'-dihydro-3,5,3',4'-tetrahydroxy-5'-isopentenyl stilbene (5), along with four known flavonoids, glabranin (6), pinocembrin, (7), licoflavone (8), and wighteone (9), were isolated from a lipid extract of the leaves of Sicilian Glycyrrhiza glabra. The structures of the compounds were elucidated by spectroscopic methods. The antioxidant activities of the crude extracts and the isolated compounds were tested.