Styrylchromones: Biological Activities and Structure-Activity Relationship

Styrylchromones (SC) are a group of oxygen-containing heterocyclic compounds, which are characterized by the attachment of a styryl group to the chromone core. SC can be found in nature or can be chemically synthesized in the laboratory. As their presence in nature is scarce, the synthetic origin is the most common. Two types of SC are known: 2-styrylchromones and 3-styrylchromones. However, 2-styrylchromones are the most common, being more commonly found in nature and which chemical synthesis is more commonly described. A wide variety of SC has been described in the literature, with different substituents in different positions, the majority of which are distributed on the A- and/or B-rings. Over the years, several biological activities have been attributed to SC. This work presents a comprehensive review of the biological activities attributed to SC and their structure-activity relationship, based on a published literature search, since 1989. The following biological activities are thoroughly revised and discussed in this review: antioxidant, antiallergic, antiviral, antibacterial, antifungal, anti-inflammatory, and antitumoral, affinity and selectivity for A3 adenosine receptors, neuroprotective, and α-glucosidase inhibition. In general, SC are composed by a promising scaffold with great potential for the development of new drugs.

Modulation of Human Neutrophils’ Oxidative Burst by Hydroxylated 2-Styrylchromones: The Relevance of the Catechol Group

2-Styrylchromones (2-SC) are a group of oxygen-containing heterocyclic compounds, which are characterized by the attachment of a styryl group to the C-2 position of their chromone core. Over the years, several biological activities have been attributed to 2-SC, such as antioxidant, anti-inflammatory, antimicrobial, antiviral, and antitumor activities [1,2]. Nonetheless, there are no reports in the literature about the effect of 2-SC on human neutrophils’ oxidative burst. Therefore, the present study aims to evaluate the modulation of human neutrophils’ oxidative burst by a panel of hydroxylated 2-SC, previously obtained by chemical synthesis, and to analyze the structure–activity relationship [3]. For that purpose, freshly isolated neutrophils from human blood were stimulated with phorbol-12-myristate-13-acetate, and a chemiluminescence method was applied to evaluate the oxidative burst, using luminol as a probe [4]. Considering the OH substituents present on the B-ring of 2-SC, the tested compounds can be divided into the following three groups: group 1, with a catechol group (C-3′ and C-4′); group 2, with an OH at C-4′; group 3, without any substitution on the B-ring. The 2-SC from group 1 were the most active, with IC50 values in the order of 1 µM. In conclusion, the catechol B-ring appears to play an important role in the modulation of human neutrophils’ oxidative burst by 2-SC.

Crystal structure and Hirshfeld surface analysis of 4-(2,6-dichlorobenzyl)-6-[(E)-2-phenylethenyl]pyridazin-3(2H)-one

The title pyridazinone derivative, C19H14Cl2N2O, an important pharmacophore with a wide variety of biological applications is not planar, the chlorophenyl and pyridazinone rings being almost perpendicular, subtending a dihedral angle of 85.73 (11)°. The phenyl ring of the styryl group is coplanar with the pyridazinone ring [1.47 (12)°]. In the crystal, N—H...O hydrogen bonds form inversion dimers with an R 2 2(8) ring motif and C—H...Cl hydrogen bonds also occur. The roles of the intermolecular interactions in the crystal packing were clarified using Hirshfeld surface analysis, and two-dimensional fingerprint plots indicate that the most important contributions to the crystal packing are from H...H (37.9%), C...H/H...C (18.7%), Cl...H/ H...Cl (16.4%) and Cl...C/C...Cl (6.7%) contacts.

Diethylaminosulfur Trifluoride (DAST)-Mediated Intramolecular Benzannulation of o-Allylchalcones: Synthesis of 3-Fluorotetralins

A concise route for the synthesis of 3-fluorotetralines is described, including: (i) NaBH4-mediated reduction of oxygenated o-allylchalcones and (ii) sequential DAST-mediated intramolecular annulation of the resulting alkenols. A plausible mechanism is proposed and discussed. This protocol provides highly effective regio- and stereocontrolled allyl-enone cross-coupling to construct two stereocenters and one E-configured styryl group.

Synthesis of 4-substituted pyrazole-3,5-diamines via Suzuki–Miyaura coupling and iron-catalyzed reduction

A general and efficient synthesis of 4-substituted-1H-pyrazole-3,5-diamines was developed to access derivatives with an aryl, heteroaryl, or styryl group, which are otherwise relatively difficult to prepare.

Synthesis of mono-(p-dimethylamino)styryl-containing BOPHY dye for a turn-on pH sensor

Mono-substitutional BOPHY 3a with a (p-dimethylamino)styryl group in the α-position was confirmed to be synthesized by the Knoevenagel-type condensation. Dimethylamino-containing BOPHY 3a can be used as a pH probe.

Styrylpyrylium Salts: and NMR High-Resolution Spectroscopy (1D and 2D)

and NMR high-resolution spectroscopy (1D and 2D) (, -COSY, HSQC, HMBC) for four styrylpyrylium perchlorates were carried out and signal attributions are reported. Chemical shifts observed on NMR spectra for the styrylpyrylium salts were compared with net atomic charge for carbon obtained by AM1 semiempirical calculations. The position of the styryl group present low effect on chemical shifts for carbon atoms, while the presence of methyl group led to the unshielding of the substituted carbon.