Recent advances in using of chitosan-based adsorbents for removal of pharmaceutical contaminants: A review

Dengue is a major mosquito-borne disease currently with no effective antiviral or vaccine available. Effort to find antivirals for it has focused on bioflavonoids, a plant-derived polyphenolic compounds with many potential health benefits. In the present study, antiviral activity of four types of bioflavonoid against dengue virus type -2 (DENV-2) in Vero cell was evaluated. Anti-dengue activity of these compounds was determined at different stages of DENV-2 infection and replication cycle. DENV replication was measured by Foci Forming Unit Reduction Assay (FFURA) and quantitative RT-PCR. Selectivity Index value (SI) was determined as the ratio of cytotoxic concentration 50 (CC50) to inhibitory concentration 50 (IC50) for each compound. The half maximal inhibitory concentration (IC50) of quercetin against dengue virus was 35.7 μg mL-1 when it was used after virus adsorption to the cells. The IC50 decreased to 28.9 μg mL-1 when the cells were treated continuously for 5 h before virus infection and up to 4 days post-infection. The SI values for quercetin were 7.07 and 8.74 μg mL-1, respectively, the highest compared to all bioflavonoids studied. Naringin only exhibited anti-adsorption effects against DENV-2 with IC50 = 168.2 μg mL-1 and its related SI was 1.3. Daidzein showed a weak anti-dengue activity with IC50 = 142.6 μg mL-1 when the DENV-2 infected cells were treated after virus adsorption. The SI value for this compound was 1.03. Hesperetin did not exhibit any antiviral activity against DENV-2. The findings obtained from Foci Forming Unit Reduction Assay (FFURA) were corroborated by findings of the qRT-PCR assays. Quercetin and daidzein (50 μg mL-1) reduced DENV-2 RNA levels by 67% and 25%, respectively. There was no significant inhibition of DENV-2 RNA levels with naringin and hesperetin. Results from the study suggest that only quercetin demonstrated significant anti-DENV-2 inhibitory activities. Other bioflavonoids, including daidzein, naringin and hesperetin showed minimal to no significant inhibition of DENV-2 virus replication. These findings, together with those previously reported suggest that select group of bioflavonoids including quercetin and fisetin, exhibited significant inhibitory activities against dengue virus. This group of flavonoids, flavonol, could be investigated further to discover the common mechanisms of inhibition of dengue virus replication.

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Antiviral activity of four types of bioflavonoid against dengue virus type-2

The European Pharmacopoeia

Hydrophobic deep eutectic solvents in microextraction techniques–A review

Chemistry and biological activity of secondary metabolites in Euphorbia from Iran.

Flavonoids are an interesting group of natural polyphenolic compounds that exhibit extensive bioactivities such as scavenging free radical, antitumor and antiproliferative effects. The anticancer and antiviral effects of these natural products are attributed to their potential biomedical applications. While flavonoids complexation with DNA is known, their bindings to RNA are not fully investigated. This study was designed to examine the interactions of three flavonoids; morin (Mor), apigenin (Api) and naringin (Nar) with yeast RNA in aqueous solution at physiological conditions, using constant RNA concentration (6.25 mM) and various pigment/RNA (phosphate) ratios of 1/120 to 1/1. FTIR, UV-visible spectroscopic methods were used to determine the ligand binding modes, the binding constant and the stability of RNA in flavonoid-RNA complexes in aqueous solution. Spectroscopic evidence showed major binding of flavonoids to RNA with overall binding constants of K(morin) = 9.150 x 10(3) M(-1), K(apigenin)=4.967 x 10(4) M(-1), and K(naringin)=1.144 x 10(4) M(-1). The affinity of flavonoid-RNA binding is in the order of apigenin>naringin>morin. No biopolymer secondary structural changes were observed upon flavonoid interaction and RNA remains in the A-family structure in these pigment complexes.

RNA binding to antioxidant flavonoids.

Matrix solid-phase dispersion (MSPD) methodology as a quick and easy extraction method has been developed to extract oleuropein from Olea europaea leaves. This method has been compared with conventional maceration and Soxhlet extraction (SOXE) methods. Variables affecting MSPD, such as the sorbent material, the ratio of sample to sorbent material, elution solvent, and volume of the elution solvent, have been fully evaluated and optimized. Oleuropein was successfully extracted by silica sorbent with 350 microL of dichloromethane-methanol (70 + 30, v/v) as the elution solvent. The calibration curve showed good linearity (r2 = 0.9985) and precision (RSD <4.5%) in the concentration range of 0.5-100 microg/mL for oleuropein. The LOD and LOQ were 0.14 and 0.5 microg/mL, respectively. The recoveries were in the range of 88.0-94.0% with RSD values ranging from 6.0 to 9.8%. The extraction yields obtained by the MSPD method were comparable with those obtained by the maceration and SOXE methods. The reported MSPD extraction method was revealed to be eco-friendly, simpler, and faster than conventional methods used to quantify oleuropein in O. europaea leaves.

Rapid screening of oleuropein from olive leaves using matrix solid-phase dispersion and high-performance liquid chromatography.

The oil obtained by hydrodistillation of the aerial parts of Satureja atropatana Bung., endemic in Iran, and S. mutica Fisch. et C.A. Mey. was analyzed by GC/MS. Thirty-seven compounds representing 99.3% of the oil of S. atropanata were identified, among them carvone (21.5%), menthol (18.1%), 1,8-cineol (13.1%), methyl chavicol (11.1%) and menthone (10.5%) being the major ones. The oil of S. mutica was characterized by higher amount of menthol (37.4%), menthone (17.2%) and 1,8-cineol (9.3%) among the 39 components comprising 95.1% of the total oil detected. Both oils were richer in oxygenated monoterpenes than sesquiterpenes.

Comparison of the Volatile Oils of Satureja atropatana Bung. and Satureja mutica Fisch. et C.A. Mey. from Iran

The chemical composition of essential oil of Cyperus rotundus L. grown in Iran was studied by hydrodistillation and GC and GC-MS. Analysis of the chemical composition of the oil showed the predominance of sesquiterpene compounds, with the presence of monoterpenes. Twenty-two compounds were identified from oil of C. rotundus, of which cyperene (37.9 %) and cyperotundone (11.2 %) were the major components.

Chemical Composition of the Essential Oil of Cyperus rotundus L. from Iran

Hydrophobic deep eutectic solvent based on centrifugation-free dispersive liquid–liquid microextraction for speciation of selenium in aqueous samples: One step closer to green analytical chemistry

Alireza Feizbakhsh

Papers

RNA binding to antioxidant flavonoids.

Rapid screening of oleuropein from olive leaves using matrix solid-phase dispersion and high-performance liquid chromatography.

Comparison of the Volatile Oils of Satureja atropatana Bung. and Satureja mutica Fisch. et C.A. Mey. from Iran

Chemical Composition of the Essential Oil of Cyperus rotundus L. from Iran

Hydrophobic deep eutectic solvent based on centrifugation-free dispersive liquid–liquid microextraction for speciation of selenium in aqueous samples: One step closer to green analytical chemistry