Manoyl Oxide Diterpenoids from Grindelia scorzonerifolia

Abstract

Two new norditerpenoids, 4beta-hydroxy-19-normanoyl oxide (1) and 4alpha-hydroxy-18-normanoyl oxide (2), the new 18-O-alpha-l-arabinopyranosylmanoyl oxide (3a), and the known diterpenoids jhanol (4) and 18-hydroxy-13-epi-manoyl oxide (5) were isolated, together with other common plant constituents from an Argentine collection of Grindelia scorzonerifolia. The structures of the new compounds were established by extensive 1D and 2D NMR techniques and chemical transformations. Structural features of compounds 2 and 4 were verified by X-ray crystallographic analyses. The insecticidal effect of compound 3a was evaluated against the polyphagous pest Spodoptera frugiperda. Pupal and adult malformations leading to death occurred when 3a was incorporated in a larval diet at a concentration of 100 ppm.

8,15-Epoxylabdane and norlabdane diterpenoids from Eragrostis viscosa

“…To our knowledge, this is the first time that 8,15-epoxylabdane has been found as a natural product (usually, the epoxy link is C-8 and C-13 or C-9 and C-13) (Ziegler and Spiteller, 1992;Carreras et al, 1996;Mebe, 2001;Ybarra et al, 2005;Argyropoulou et al, 2009).…”

Labdane-type diterpenoids from Croton laevigatus

“…The 1 H and 13 C NMR spectroscopic data (Tables 1 and 2) of 7 resembled those of 18-hydroxy-13-epimanoyl oxide. 17 The major difference was that the methyl H 3 -17 signals and methylene group H 2 -12 signals in the known compound were replaced by the oxymethylene group H 2 -17 signals (d H 3.00 and 3.36, d, J ¼ 11. 1 Hz,each 1H;4.28 and 4.44,d,J ¼ 12.4 Hz,each 1H;d C 63.9) and the oxymethine group H-12 signals (d H 4.09, t, J ¼ 3.5 Hz, 1H; d C 69.3) in 7.…”

“…The 1 H-1 H COSY experiment showed connectivity of three moieties: I: 1 CH 2 -2 CH 2 -3 CH 2 ; II: 5 CH-6 CH 2 -7 CH 2 ; and III: 9 CH-11 CH(O)-12 CH 2 . The HMBC correlations from CH 3 -19 (d H 0.79, 3H, s) to C-3 (d C 35.1), C-5 (d C 44.4), and C- 18 (d C 15.7); from H [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]each 1H,d,J ¼ 11.2 Hz) to C-3, C-5, and C-19 (d C 17.7); and from H 2 -2 (d H 1.50 and 1.60, each 1H, m) to C-4 (d C 37.5) indicated that C-4 connected units I and II together. The HMBC correlations from CH 3 -20 (d H 0.96, 3H, s) to C-1 (d C 41.4), C-5, and C-9 (d C 66.0) and from H 2 -1b (d H 0.96, 1H, m) to C-9 suggested that C-10 (d C 35.9) connected units I and III together.…”

“…The HMBC correlations from CH 3 -20 (d H 0.96, 3H, s) to C-1 (d C 41.4), C-5, and C-9 (d C 66.0) and from H 2 -1b (d H 0.96, 1H, m) to C-9 suggested that C-10 (d C 35.9) connected units I and III together. Furthermore, the HMBC correlations from H-9 (d H 1.57, 1H, d, J ¼ 2.0 Hz) to C- 17 (d C 78.5),1H,td,J ¼ 5.2,2.4 Hz) and H 2 -6 (d H 1.32 and 1.60, each 1H, m) to C-8 (d C 80.1), and from H [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]each 1H,d,J ¼ 9.6 Hz) to C-7 (d C 33.3), C-9, IR spectrum showed absorption bands for hydroxyl (3422 cm À1 ), ester carbonyl (1735 cm À1 ) and olen (1676 cm À1 ) functionalities. The 1 H and 13 C NMR spectroscopic data (Tables 1 and 2) of 3 resembled those of 1 and 2, sharing the same AB rings, and also belongs to nor-labdane-type diterpene series.…”

“…Moreover, the 1 H and 13 C NMR spectroscopic data also showed an extra acetyl group signal at d H 2.13 (s, 3H; d C 20.9, 171.1). The HMBC experiment demonstrated correlations of H [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]J ¼ 11.2,1.2 Hz;4.38,d,J ¼ 11.2 Hz) to C-21 (d C 171.1), which indicated the acetoxyl group attached to C-17 in 3. The NOESY spectrum showed correlations of H-9 to H-5 and H 2 -17 to CH 3 -20, which indicated that the H 2 -17 was b-oriented, and the 8-OH and H-9 were a-oriented.…”