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Kanaze FI Termentzi A Gabrieli C Niopas I Georgarakis M Kokkalou E 《Biomedical chromatography : BMC》2009,23(3):239-249
The flavonoid content of several methanolic extract fractions of Navel orange peel (flavedo and albedo of Citrus sinensis) cultivated in Crete (Greece) was first analysed phytochemically and then assessed for its antioxidant activity in vitro. The chemical structures of the constituents fractionated were originally determined by comparing their retention times and the obtained UV spectral data with the available bibliographic data and further verified by detailed LC-DAD-MS (ESI+) analysis. The main flavonoid groups found within the fractions examined were polymethoxylated flavones, O-glycosylated flavones, C-glycosylated flavones, O-glycosylated flavonols, O-glycosylated flavanones and phenolic acids along with their ester derivatives. In addition, the quantitative HPLC analysis confirmed that hesperidin is the major flavonoid glycoside found in the orange peel. Interestingly enough, its quantity at 48 mg/g of dry peel permits the commercial use of orange peel as a source for the production of hesperidin. The antioxidant activity of the orange peel methanolic extract fractions was evaluated by applying two complementary methodologies, DPPH(*) assay and the Co(II)/EDTA-induced luminol chemiluminescence approach. Overall, the results have shown that orange peel methanolic extracts possess moderate antioxidant activity as compared with the activity seen in tests where the corresponding aglycones, diosmetin and hesperetin were assessed in different ratios. 相似文献
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Diosmetin, 3',5,7-trihydroxy-4'-methoxy flavone, is the aglycone of the flavonoid glycoside diosmin that occurs naturally in foods of plant origin. Diosmin exhibits antioxidant and anti-inflammatory activities, improves venous tone and it is used for the treatment of chronic venous insufficiency. Diosmin is hydrolyzed by enzymes of intestinal micro flora before absorption of its aglycone diosmetin. A specific, sensitive, precise, accurate and robust HPLC assay for the determination of diosmetin in human plasma was developed and validated. Diosmetin and the internal standard 7-ethoxycoumarin were isolated from plasma by liquid-liquid extraction and separated on a C8 reversed-phase column with methanol-water-acetic acid (55:43:2, v/v/v) as the mobile phase at 43 degrees C. Peaks were monitored at 344 nm. The method was linear in the 10-300 ng/mL concentration range (r > 0.999). Recovery for diosmetin and internal standard was greater than 89.7 and 86.8%, respectively. Intra-day and inter-day precision for diosmetin ranged from 1.6 to 4.6 and from 2.2 to 5.3%, respectively, and accuracy was better than 97.9%. 相似文献
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A formalism for studying the interference between the direct reaction and the compound resonance processes is presented by the S-matrix theory; The mechanism of 12C(d, d) 12C, 12C(d, p1) 13C* and 12C(d, p2) 13C* reactions in the energy range Ed=1.63 MeV to 2.05 MeV is analysed.Te results show that: the interference between these two processes exists; and the quantitative relation between them is given. While the parameters of direct reactions and compound resonance processes, particularly for four resonance states with Ed=1.726, 1.767, 1.792 and 1.86 MeV are determined. 相似文献
4.
The relationship between interaction energies of the most stable structures of the (CO)2, (N2)2 and CO-N2 complexes is investigated using the supermolecule CCSD(T) and MP4 methods and aug-cc-pVXZ (X = D,T,Q) basis sets extended by a set of midbond functions centred in the middle of the intermolecular bond. A simple combining rule for interaction energies of this triad of clusters is proposed. 相似文献
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WANG Chunhong XU Mingcheng SHI Zuoqing FAN Yunge FI Chengiie 《Chinese Journal of Reactive Polymers》2000,(1)
1 INTRODUCTIONAt present time, most of the studies for the adsorption dynamics of macroporous adsorbent,.especially for the film diffusion mass-transfer process, were based on the conclusions for theBoyd ion-exchange dynamics equationl'l. The structure of gel-type ion-exchange resin andmacroporous polystyrene resin is different. Because of having the hydrophilic group, both of theirmer and outer of the ion-exchange resin can swell to the reticulation struCture in the aqueous.Based on the… 相似文献
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F I Kanaze E Kokkalou I Niopas M Georgarakis A Stergiou D Bikiaris 《Journal of Thermal Analysis and Calorimetry》2006,83(2):283-290
Purposes of this paper were to prepare and study
new drug delivery systems for both flavanone glycosides and their aglycones
based on solid-dispersion systems. These compounds are poor water soluble
drugs, so an enhancement of their dissolution is a high priority. Solid-dispersion
systems were prepared using PVP, PEG and mannitol as drug carrier matrices.
Characterizations of these dispersions were done by differential scanning
calorimeter (DSC) and X-ray diffraction (XRD). The glass transition (Tg) temperature of PVP was
only recorded in the DSC thermograms of PVP solid-dispersions of both flavanone
glycosides and their aglycones, while in case of PEG and mannitol solid-dispersions
endotherms of both glycosides and aglycones were noticed with low peak intensity,
indicating that high percent of drug is in amorphous state. The XRD patterns
of all PVP solid-dispersions of aglycones show typical amorphous materials,
but XRD patterns of their glycosides reveal the presence of crystalline material.
However, in all solid dispersions shifts in Tg
of PVP as well as Tm
of PEG were observed, indicating the existence of some interactions between
drugs and matrices. SEM and TEM microscopy revealed that PVP/aglycone flavanone
compounds are nanodispersed systems while all the other solid dispersions
are microcrystalline dispersions. The solubility of both flavanone glycosides
and their aglycones was directly affected by the new physical state of solid
dispersions. Due to the amorphous drug state or nano-dispersions in PVP matrices,
the solubility was enhanced and found to be 100% at pH 6.8 in the nano-dispersion
containing 20 mass% of aglycones. Also solubility enhancement was occurred
in solid dispersions of PEG and mannitol, but it was lower than that of PVP
nano-dispersions due to the presence of the drug compounds in crystalline
state in both matrices. 相似文献
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