Studies On Chemical Constituents And Bioactivity Of Three Abies Plants

Abies plants have proven to be an excellent source of terpenoids, whose characteristic are various structure types, diverse substituted positions, and multiple chiral centers, frequent rearrangement. The chemical constituents of Abies plants have shown many kinds of activities, including insect juvenile hormone, antitumor, antibacterial, anti-ulcerogenic, anti-inflammatory, and CNS (central nervous system) activities. In continuation of our research program for bioactive terpenoids derived from the plants of Abies genus, we examined Abies fabri, Abies recurvata, Abies nukiangensis).Investigations on chemical constituents of three Abies plants led to the isolation and elucidation of185compounds, and50compounds were identified as new ones. As the main chemical constituents, terpenoids included45triterpenes,48diterpenes,17sesquiterpenes,11monoterpenes,8tetraterpenes, and2pentaterpenes.Eight tetraterpenoids (AF-73-AF-80) were fractionated and identified from Abies fabric, formed by Diels-Alder cycloaddition between a lanostane triterpenoid [(24E)-lanosta-8,24-diene-3,23-dion-26-oic acid] and a monoterpenoid, and the absolute configuration were assigned by electronic circular dichroism. In addition, two novel pentaterpenes (AF-81-AF-82) were isolated from Abies species for the first time. Because similar abietane diterpenes were obtained from this plant, the pentaterpenes were pesumed as adducts of Diels-Alder reaction of a lanostane triterpenoid and a abietane diterpenoid.A new norditerpene (AF-26) and a new nortriterpene (AN-1) were isolated from Abies fabri and Abies nukiangensis, respectively. And the norditerpene contained a three-membered, oxygen-containing ring, and the C-23of the nor-triterpene is the first example of the nortriterpene bearing a8(14â†'13)abeo-17,13-friedo moiety, their structures were confirmed by X-ray. One9,10-seco-abietane diterpene (AF-27) and two triterpenes (AF-1-AF-2) with novel spirolactone were also obtained, and the stereochemistry of the two triterpenes was determined by the means of extensive analysis of NMR techniques and X-ray crystallography.We summarized the NMR spectroscopy rules of lanostane and cycloartane triterpenoids of Abies genus.All the isolated diterpenes were assessed for their inhibitory effects against LPS-induced NO production in RAW264.7macrophages, and compound AF-43showed strongest effects, with an IC50value of24.2uM. Triterpenoids, tetraterpenoids, and pentaterpenoids were assessed for their cytotoxic activities against human tumor cells, AF-81exhibited potent effects against HCT116and ZR-75-30, with IC50values of1.12and1.30, respectively.