RESUMEN
Three new diterpenes, stellejasmins A (1) and B (2) and 12-O-benzoylphorbol-13-heptanoate (3), were isolated from the roots of Stellera chamaejasme L. The structures of 1-3 were elucidated by extensive NMR and mass spectroscopic analyses. Compounds 1 and 2 are the first derivatives containing a hydroxy group at C-2 in the family of daphnane and tigliane diterpenes. The presence of a chlorine atom in 1 is unique in the plant metabolite. Compound 3 has an odd-number acyl group, which is biosynthetically notable. Human immunodeficiency virus (HIV) LTR-driven transcription activity was tested with 1-3 and 17 known diterpenes isolated from S. chamaejasme L. and Wikstroemia retusa A.Gray. Among these, gnidimacrin (4), stelleralide A (5), and wikstroelide A (20) were highly potent, with EC50 values of 0.14, 0.33, and 0.39 nM, respectively. The structure-activity relationship (SAR) was investigated using 20 natural and eight synthetic diterpenes. This is the first SAR study on natural daphnane and tigliane diterpenes.
Asunto(s)
Fármacos Anti-VIH/síntesis química , Fármacos Anti-VIH/farmacología , Diterpenos/síntesis química , Diterpenos/farmacología , VIH/efectos de los fármacos , Forboles/química , Latencia del Virus/efectos de los fármacos , Diterpenos/química , Modelos Moleculares , Simulación del Acoplamiento Molecular , Forboles/farmacología , Extractos Vegetales/química , Extractos Vegetales/farmacología , Raíces de Plantas/química , Relación Estructura-Actividad , Thymelaeaceae/química , Wikstroemia/químicaRESUMEN
Amyloid fibril formation is associated with protein misfolding disorders, including neurodegenerative diseases such as Alzheimer's, Parkinson's, and Huntington's diseases. Familial amyloid polyneuropathy (FAP) is a hereditary disease caused by a point mutation of the human plasma protein, transthyretin (TTR), which binds and transports thyroxine (T(4)). TTR variants contribute to the pathogenesis of amyloidosis by forming amyloid fibrils in the extracellular environment. A recent report showed that epigallocatechin 3-gallate (EGCG), the major polyphenol component of green tea, binds to TTR and suppresses TTR amyloid fibril formation. However, structural analysis of EGCG binding to TTR has not yet been conducted. Here we first investigated the crystal structure of the EGCG-V30M TTR complex and found novel binding sites distinct from the thyroxine binding site, suggesting that EGCG has a mode of action different from those of previous chemical compounds that were shown to bind and stabilize the TTR tetramer structure. Furthermore, EGCG induced the oligomerization and monomer suppression in the cellular system of clinically reported TTR variants. Taken together, these findings suggest the possibility that EGCG may be a candidate compound for FAP therapy.