Phenolic constituents from the leaves of Cratoxylum formosum ssp. pruniflorum

Abstract One (formosumone A, 1 ) new and fifteen ( 2 – 16 ) known phenolic compounds were isolated from the leaves of Cratoxylum formosum ssp. pruniflorumm , a substitute for the popular bitter nail tea (“Kuding Tea”) generally used in Southeast Asia. Their structures were determined by extensive spectroscopic analysis and by comparison with literature data. Compound 1 possesses a rare scaffold of a flavanone coupled with a phloroglucinol moiety, representing the first example of such a scaffold from the Clusiaceae family. Among the isolates, toxyloxanthone B ( 11 ) and vismione D ( 12 ) were found to show remarkable anti-neuroinflammatory effects by inhibiting nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated murine BV-2 microglial cells. Additionally, toxyloxanthone B ( 11 ) exhibited significant neuroprotective effect against β -amyloid 25–35 (A β 25–35 )-induced cell viability decrease in SH-SY5Y neuroblastoma cells.