2-(2-Phenylethyl)chromones from Chinese eaglewood

An Overview of 2‐Styrylchromones: Natural Occurrence, Synthesis, Reactivity and Biological Properties

“…[14] The results showed moderate activity in the former case (58.3 ± 2.8 %) and absence of activity in preventing neurotoxicity in the last cell line tested. For comparison, the standard fluoxetine showed neuroprotective activity of 92.5 ± 3.2 and 93.7 ± 2.1 % at the same concentration for glutamate-induced and corticosterone-induced neurotoxicity, respectively.…”

“…[13] 6,4′-Dihydroxy-3′-methoxy-2-styrylchromone (5, Figure 3) was isolated from the ethanol extract of Chinese eaglewood as a yellow amorphous solid and fully characterized by NMR, MS and IR spectroscopy. [14] In 2013, the five 5,7,4′-trihydroxy-2-styrylchromones 6-10 ( Figure 3) were isolated from an ethanol extract of the shed bark of Platanus x acerifolia. [15] Meanwhile, derivative 6 has also been isolated from heartwood of Juniperus chinensis (by heating at reflux in methanol) [16] and from an ethanol extract of the bulbils of Dioscorea bulbifera.…”

“…In the first one, 1-(2-hydroxyphenacylidene)triphenylphosphorane (15, R 1 = R 2 = R 3 = H), prepared through the reaction between 2-acetoxyphenacyl bromide (14) and triphenylphosphine, followed by ester hydrolysis, underwent condensation with cinnamoyl chloride in the presence of pyridine and toluene at reflux. [26] The formed o-cinnamoyl ester 16 (R 1 = R 2 = R 3 = H) underwent an intramolecular Wittig reaction to give the parent 2-SC, in 65 % yield.…”

“…Under photolytic conditions under nitrogen, (E)-3-benzyloxy-6-methyl-2-styrylchromones 43, dissolved in benzene in a Pyrex glass reactor, underwent isomerization and cyclization to afford linear tricyclic tetrahydropyran[3,2-b]chromanones 44 in 20-29 % yields. [87] Under similar conditions, 3-methoxy-6-methyl-2-styrylchromone 45, dissolved in dry methanol, furnished a mixture of the (Z)-2-SC (Z) 14). [43] A review on the photochemistry of chromones and bischromones, which includes the photoinduced H-abstraction from 2-SCs, has been published.…”

“…[12] The natural 5,7,4′-trihydroxy-2-styrylchromone (6, Figure 3) exhibited weak inhibitory activity against acetylcholinesterase with an IC 50 value of 78.35 ± 1.15 μM in comparison with the positive control berberine (IC 50 0.67 ± 0.02 μM). However, a good inhibitory activity against butyrylcholinesterase was observed (6 IC 50 28.80 ± 1.57 μM; berberine IC 50 14.04 ± 1.46 μM) and also against the -site amyloid precursor protein cleaving enzyme 1 (BACE1, 6 IC 50 6.25 ± 0.16 μM; quercetin IC 50 26.94 ± 0.10 μM). [16] Several 6-iodinated 2-SCs were synthesized and screened for their application as in vivo imaging probes of -amyloid plaques in Alzheimer's disease.…”