Hinokiflavone

Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease with high mortality rate but effective therapeutics are still lacking.Phosphodiesterase-4 (PDE4) inhibitors were reported to be promising anti-IPF agents.Herein, series of biflavonoids isolated from Selaginella uncinate were found to be PDE4 inhibitors and the most active amentoflavone gave a half maximal inhibitory concentration (IC₅₀) of 12 nmol/L, which was further validated by isothermal titration calorimetry with K_d of 23 nmol/L.Besides, co-crystal structure of PDE4-amentoflavone was determined and gave a different binding pattern from roflumilast with multiple H-bonds between it and key residues such as Asn321/Thr333/Gln369/Gly371.So far, this was the first reported co-crystal structure of amentoflavone with its potential binding target in despite of the extensive investigations of this common natural biflavonoid.Furthermore, amentoflavone exhibited remarkable anti-IPF effects in vivo and in vitro, suggesting it as a novel anti-fibrotic agent by targeting PDE4.

Abstract: Some active substances in Phyllanthus emblica not only endow Phyllanthus emblica with specific biol. functions but also provide its astringency.It is not a good choice to directly remove these active substances to improve the astringency.In order to clarify the astringent active substances in Phyllanthus emblica and their interaction mechanism with oral protein, the composition and structure of the active substances in Phyllanthus emblica were identified by UHPLC-Q-exactive-orbitrap-MS technol., and the main astringent substances were identified.Combining turbidity and electronic tongue measurement technol. by tracking the morphol. changes of the main astringent substances and the products of protein, a method for studying the interaction between the astringent substances of Phyllanthus emblica and protein in vitro was established.Further, the interaction mechanism between the astringent substance of Phyllanthus emblica and protein was analyzed at the mol. level by fluorescence scanning and CD.The results showed that 29 active substances were identified from Phyllanthus emblica by accurate quality measurement and comparison, and ellagic acid was identified as the main astringent active component in Phyllanthus emblica.On this basis, according to the relationship between the astringent taste of ellagic acid and the turbidity of ellagic acid/amylase mixture, a method for in vitro study of Phyllanthus emblica was successfully developed (R² = 0.9954), which provided a premise for in vitro study on the formation and determination of astringent taste of Phyllanthus emblica.Fluorescence quenching and CD anal. showed that ellagic acid induced the conformational change of protein mol. and revealed that the interaction between ellagic acid and protein of Phyllanthus emblica was the main cause of astringency.The results provide inspiration for exploring the astringent components of Phyllanthus emblica and the formation mechanism of astringency.