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Rationale: Flavonols are a class of flavonoids, consist of two aromatic rings (A and B) connected by a three-carbon bridge, forming a closed pyran ring (C) with a hydroxyl group at position 3. Galangin is a form of flavonols formed with additional hydroxyl groups at ring A positions 5 and 7. The hydroxylation at ring B of galangin may result in resonance and delocalization of electrons and the formation of different derivatives like kaempferol, quercetin, and myricetin. Most of these flavonols have a similarity to 17β-estradiol, the steroid sex hormone which bound to estrogen receptors (ER), a class of nuclear transcription factors involved in the regulation of many complex pathophysiological processes including breast cancer genesis and progression. Various studies have reported that most of the flavonols are antiestrogenic and show anticancer potential, but the mechanisms may be varied like estrogenic, anti-estrogenic, non-estrogenic, and biphasic activities and their mechanisms of action have not been systematically evaluated. Aim: The goal of this study is to ascertain the possible interactions of flavonol derivatives to ER with respect to ring B hydroxylation and the unsaturation degree of the C2′=C3′ bond. Methods: The variations in structure, frontier molecular orbital, molecular electrostatic potential maps, Mullikan charge population of derivatives was determined by Density functional theory (DFT) calculations at B3LYP/6-311G (d,p) level on model molecular systems. A deep insight into these interactions with ER was described by molecular docking studies. Results and discussion: Results shows that the flavonol was found more affinity to ERβ and the efficacy was increased with respect to the OH group on ring B. The hydroxyl group at position 3 and 5 in ring A and C are not found much relevant. The site of ERβ is more hydrophilic while binding ligand and the electropositive and electronegative area of the molecule was increased and reaches a maximum for quercetin with the 3 OH group; after that, it found to diminish. Moreover, the reduced cavity size of ERβ and the replacement of LEU384 with polar HIE475 and MET336 increased the polarity and hydrophilicity of the cavity and led to more electrostatic interaction with ligands. ERα is found to be hydrophobic and the polar interaction between the ligands and ERα is less due to open confirmation of the cavity and bulk empty space. The results also emphasize that myricetin and quercetin require less energy to activate while accounting for the values of Gibbs free energy, the electronic configuration of frontier molecular orbitals, and entropy. Conclusion: The hydroxylation on ring B has a significant importance in the chemical reactivity as well as estrogenic activity of flavonol.

Fluorescent sensors available for metal ions detection have been extensively developed in recent years. However, developing an ultrasensitive fluorescent sensor for highly selectively detecting Al3+ based on cellulose remains a challenge. In this study, an ethylcellulose-based flavonol fluorescent sensor named EC-BHA was synthesized by the esterification of ethylcellulose (EC) with a new flavonol derivative 4-(2-(2,3-bis(ethoxymeothy)phenyl)-3-hydroxy-4-oxo-4-H-chromen-7-yl) benzoic acid (BHA). The fluorescence intensity of EC-BHA exhibited a 180-fold increase at 490 nm after binding with Al3+ and provided an ultralow detection limit of 13.0 nM. The sensor showed some exceptional sensing properties including a broad pH range (4–10), large Stokes shifts (190 nm), and a short response time (3 min). This sensor was successfully applied for determining trace Al3+ in food samples as well as in plant tissue. Moreover, the electrostatic spun film EBP was fabricated by blending EC-BHA with PS (polystyrene) via electrostatic spinning technique and utilized for selective detection of Al3+ as soon as possible. [Display omitted] [ABSTRACT FROM AUTHOR]

A new flavonol derivative 3, 8-dihydroxy-10-methoxy-5-H-isochromeno[4, 3-b]chromen-7-one ( 1) together with four known compounds, glutinone ( 2), luteolin ( 3), acacetin 7-O-α-L-rhamnopyranosyl- (1→6)- β-D-glucopyranoside ( 4), and rutin ( 5) were isolated from the dried roots of Fagopyrum dibotrys. Their structures were determined by UV, IR, MS, 1H, and 13C NMR spectroscopic analysis, including 2D NMR. [ABSTRACT FROM AUTHOR]

Background: Flavonol derivative and phenolic acids derived from the plants function as free radical scavengers, reducing agents, and quenchers for the formation of singlet oxygen. Flavonoids and phenolic constituents also play an important role in various human diseases and disorders primarily through modulation of inflammatory responses., Objective: To estimate the Flavonol Derivatives (FD) and phenolic acids (PA) in Capsicum annuum (CA) and other important phytochemicals having an anti-inflammatory effect., Methods: In the present study, FD and PA were estimated in CA and in vitro anti-inflammatory activity (pilot study) was determined and correlation was established., Results: The results were found to be significant using RP-HPLC. FD and PA were found to be 0.0659±0.0058 and 0.0862±0.0.0134 mg/gram dry weight, respectively. For in vitro anti-inflammatory activity, the inhibition of albumin denaturation and antiproteinase activity was found to be maximum in Quercetin (QE) with 98.230±1.589% and 59.906±1.529%, respectively. Heat-induced hemolysis of erythrocytes was found to be maximum in salicylic acid (SA) (71.830±2.838%). Hypotonicity-induced hemolysis showed significant activity with QE (76.770±3.475%). Lipoxygenase and cyclooxygenase inhibition was found to be maximum in QE with 56.930±4.069% and 61.660±3.135%, respectively., Conclusion: A strong positive correlation of 0.9 was observed between the extract of CA and standard QE and SA against the anti-inflammatory activity. Therefore, the role of FD and PA has been postulated to be an active phytochemical of CA accountable for its anti-inflammatory activity. However further work is desirable to fully elucidate the phytochemicals responsible for their anti-inflammatory activity and to develop better herbal drug formulations., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)