Three New Indole Alkaloids from Trigonostemon lii

Abstract

Three unprecedented indole alkaloids, trigonoliimines A-C (1-3) with a unique polycyclic system, were isolated from the leaves of Trigonostemon lii Y. T. Chang. The structures of 1-3 were determined by the spectroscopic, computational, and CD exciton chirality approaches. Trigonoliimine A showed modest anti-HIV-1 activity (EC(50) = 0.95 microg/mL, TI = 7.9).

Antiviral chlorinated daphnane diterpenoid orthoesters from the bark and wood of Trigonostemon cherrieri

“…Numerous structurally interesting compounds such as flavonoidal alkaloids (Kanchanapoom et al, 2002), indole alkaloids (Tan et al, 2010;Zhu et al, 2010), phenanthrenes (Kokpol et al, 1990) and an array of daphnane-type diterpenoids (Chen et al, 2010a;Dong et al, 2011a;Jayasuriya et al, 2000Jayasuriya et al, , 2004Li et al, 2011;Lin et al, 2010;Soonthornchareonnon et al, 2005;Zhang et al, 2010a) have been isolated from this genus. Daphnane-type diterpenoids of Trigonostemon have been shown to possess insecticidal (Jayasuriya et al, 2000(Jayasuriya et al, , 2004, acaricidal (Soonthornchareonnon et al, 2005), cytotoxic (Chen et al, 2010b;Dong et al, 2011b;Lin et al, 2010) and antiviral (Zhang et al, 2010b) properties.…”

Enantioselective Arylative Dearomatization of Indoles via Pd-Catalyzed Intramolecular Reductive Heck Reactions

“…Following this hypothesis, we investigated the intramolecular asymmetric arylative dearomatization of Nsubstituted indoles via palladium-catalyzed reductive Heck reactions ( Figure 1). 8,9 The new dearomatization strategy provides a facile approach to chiral indolines bearing C2-quaternary stereocenters, 10 which are frequently occurring core structures of bioactive natural products, such as trigonoliimine C, 11 (-)-isatisine A, 12 and hinckdentine A. 13 Herein, we wish to present our findings of highly enantioselective Pd-catalyzed arylative dearomatization of a variety of indole derivatives.…”

“…To our delight, the desired product 2a was isolated in lower yields but with excellent enantioselectivities when the reactions were performed in CH 3 CN or DCE (1,2-dichloroethane) ( Table 1, entries [3][4]. Gratifyingly, the yield was remarkably improved to 79% in methanol and the excellent enantioselectivity was retained ( [8][9][10][11]. However, the results were significantly improved when HCO 2 Na was used as a hydride source, leading to product 2a in 85% yield and 97% ee value (Table 1, entry 13).…”

Chemical Constituents of Plants from the Genus Trigonostemon

“…was tested by a microtiter syncytium formation infectivity assay. Compound 54 showed modest anti-HIV-1 activity, with an EC 50 value of 0.95 mg/ml and TI of 7.9 [17].…”

“…Highly aromatized tetranorditerpenes, 45 and 46, were isolated from T. chinensis and T. lii. [17]. Carboline alkaloids 48 -53 were isolated from the roots and stems of T. lii, whereas, unprecedented indole alkaloids with a unique fused-hexacyclic ring system (two five-, three six-, and one seven-membered ring), 54 -56, were isolated from the leaves of T. lii.…”