β-Agarofurans and Sesquiterpene Pyridine Alkaloids from Maytenus spinosa

Abstract

Nine new β-dihydroagarofurans (1-9) and four new sesquiterpene pyridine alkaloids (10-13) were isolated from the leaves of Maytenus spinosa. Their structures were determined mainly by 1D- and 2D-NMR spectroscopic studies. The absolute configuration of compound 6 was established using CD spectroscopy. Several derivatives (14-20) were prepared from the sesquiterpene 13. Most of the sesquiterpenoids were tested for anti-HIV activity, but only compound 1 was found to be active.

New sesquiterpene polyol esters from the root bark of Pseudolarix kaempferi

“…3). The large coupling constant (J 8,9 = 12.0 Hz) between H-8 and H-9 suggested that H-9 was b-orientated (Gutierrez-Nicolas et al, 2014). The correlation of H-9/H-1 suggested that H-1 is in the b-orientation (Fig.…”

“…Furthermore, the coupling constant (J 1,2 = 4.0 Hz) between H-1 and H-2 suggested H-2 was equatorial, which means H-2 was b-oriented (Gutierrez-Nicolas et al, 2014). Hence, the structure of compound 2 was identified as 1a, 2a, 15-triacetoxy-8b-furoyloxy-9a-benzoxy-4b, 6b-dihydroxy-b-dihydroagarofuran (Fig.…”

“…3). The value of coupling constant, J 1,2 = 4.0 Hz, indicated a H-1 ax -H-2 eq disposition, which implied H-2 was b-oriented (Gutierrez-Nicolas et al, 2014). Accordingly, the structure of compound 1 was identified as 1a, 15-diacetoxy-2a, 9a-dibenzoxy À8b-isobutanoyloxy-4b, 6b-dihydroxy-b-dihydroagarofuran (Fig.…”

“…Firstly, OH-4 a-orientation. The large coupling constant (J 8,9 = 8.0 Hz) between H-8 and H-9 suggested both H-8 and H-9 were axial oriented (Gutierrez-Nicolas et al, 2014), which in turn implied that H-9 was b-oriented. The correlation of H-9/H-1 confirmed that H-1 was also in the b-orientation (Fig.…”

“…Other 14 known sesquiterpene polyol esters, celangulatin C (3) (Ji et al, 2007), 1a, 2a, 8b-triacetoxy À9a-benzoyloxy-15(2)-methylbutyroyloxy-4b, 6b-dihydroxy-b-agarofuran (4) (PerezVictoria et al, 1999), 1a, 2a-diacetoxy-8b-isobutanoyloxy À9a-benzoyloxy À13-(a-methyl) Àbutanoyloxy À4b, 6b-dihydroxyb-dihydroagarofuran (5) (Wu et al, 2002), celangulin XIX (6) (Zhu et al, 2010), 1a, 2a-diacetoxy-8b-isobutanoyloxy-9a-benzoyloxy-13-nicotinoyloxy-4b, 6b-dihydroxy Àb-dihydroagarofuran (7) , celangulatin D (8) (Ji et al, 2007), ejaponine B (9) , 1a, 6b, 8b, 15-tetracetoxy À2a-hydroxy- 9a-benzoyloxy-b-dihydroagarofuran (10) (Gutierrez-Nicolas et al, 2014), 1b, 2b, 6a-triacetoxy-8b, 12-di-(a-methyl)-butanoyloxy-9a-benzoyloxy-4a-hydroxy Àb-dihydroagarofuran (11) (Wei et al, 2009), 1a, 2a, 6b-triacetoxy À8a-isobutanoyloxyl-9b-benzoyloxy-13 (a-methyl) Àbutanoyloxy-4b-hydroxyb-dihydroagarofuran (12) (Wu et al, 2001a), 1a, 2a, 6b-triacetoxy-8a, 13-diisobutanoyloxyl-9b-benzoyloxy-4b-hydroxyl-b-dihydroagarofuran (13) (Wu et al, 2001a), ejaponine A (14) , 1a, 6b, 8a, 13-tetraacetoxy À9a-benzoyloxy2a-hydroxy-b-dihydroagarofuran (15) (Wu et al, 2001b) and wilforsinines A (16) (Wang et al, 2005) (Fig. S1 in Supplementary data) were also isolated and identified by comparing their spectroscopic data with reported literature data.…”