Normal-phase and reversed-phase silica gel column chromatography and semi-preparative high performance liquid chromatography were applied to study the chemical constituents of the stems and twigs of the Hainan mangrov...Normal-phase and reversed-phase silica gel column chromatography and semi-preparative high performance liquid chromatography were applied to study the chemical constituents of the stems and twigs of the Hainan mangrove plant,Excoecaria agallocha L.A new 3,4-seco-ent-kaurane diterpenoid,named agallochanin acid A(1),and a rare ent-tetranorlabdane diterpenoid,named agallochanin acid B(2),along with four known diterpenoids were isolated.Their structures including absolute configurations were characterized via HR-ESI-MS,extensive 1D and 2D NMR investigations and calculated and experimental electronic circular dichroism(ECD)data.All isolates were tested for their inhibitory effects on NO production in lipopolysaccharide(LPS)-activated BV-2 cells.ent-3,4-Seco-17-oxo-kaur-4(19),15(16)-dien-3-oic acid(3)and ent-15-hydroxy-labda-8(17),13E-dien-3-one(5)exhibited considerable anti-neuroinflammatory activities with IC50 values of(14.32±1.99)and(4.24±0.37)μmol/L.展开更多
Decomposition of stumps in successive rotation of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) plantations was studied using a chronosequence approach. The results showed that decomposition rate constant of Chi...Decomposition of stumps in successive rotation of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) plantations was studied using a chronosequence approach. The results showed that decomposition rate constant of Chi- nese fir stump was 0.02695 as calculated from Olson’s model. The N content of stump increased during the first two-year decomposition. When the dead stump C/N ratio was 463.2 ± 27.3, the stumps started to release N. The pattern of P release was similar to that for N. However, K content of stumps showed a consistent declining trend over time during the whole decomposition. 13C nuclear magnetic resonance spec- troscopy with cross polarization and magic-angle spinning (13C CPMAS-NMR) was used to analyse organic carbon (C) components in decomposing stumps. The 13C CPMAS-NMR spectra of stumps displayed that stump was dominated by cellulose and hemicellulose. The spectra also showed the ac- cumulation of intensity in alkyl C, aromatic C, and carboxyl C spectral regions, which was expected as the labile cellulose and hemicellulose components in O-alkyl C spectral region were selectively decomposed first.展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.82204275,82160653)Hainan Provincial Natural Science Foundation(No.323MS014)。
文摘Normal-phase and reversed-phase silica gel column chromatography and semi-preparative high performance liquid chromatography were applied to study the chemical constituents of the stems and twigs of the Hainan mangrove plant,Excoecaria agallocha L.A new 3,4-seco-ent-kaurane diterpenoid,named agallochanin acid A(1),and a rare ent-tetranorlabdane diterpenoid,named agallochanin acid B(2),along with four known diterpenoids were isolated.Their structures including absolute configurations were characterized via HR-ESI-MS,extensive 1D and 2D NMR investigations and calculated and experimental electronic circular dichroism(ECD)data.All isolates were tested for their inhibitory effects on NO production in lipopolysaccharide(LPS)-activated BV-2 cells.ent-3,4-Seco-17-oxo-kaur-4(19),15(16)-dien-3-oic acid(3)and ent-15-hydroxy-labda-8(17),13E-dien-3-one(5)exhibited considerable anti-neuroinflammatory activities with IC50 values of(14.32±1.99)and(4.24±0.37)μmol/L.
基金This work was supported by the National Natural Science Foundation of China (Grant No.30300054).
文摘Decomposition of stumps in successive rotation of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) plantations was studied using a chronosequence approach. The results showed that decomposition rate constant of Chi- nese fir stump was 0.02695 as calculated from Olson’s model. The N content of stump increased during the first two-year decomposition. When the dead stump C/N ratio was 463.2 ± 27.3, the stumps started to release N. The pattern of P release was similar to that for N. However, K content of stumps showed a consistent declining trend over time during the whole decomposition. 13C nuclear magnetic resonance spec- troscopy with cross polarization and magic-angle spinning (13C CPMAS-NMR) was used to analyse organic carbon (C) components in decomposing stumps. The 13C CPMAS-NMR spectra of stumps displayed that stump was dominated by cellulose and hemicellulose. The spectra also showed the ac- cumulation of intensity in alkyl C, aromatic C, and carboxyl C spectral regions, which was expected as the labile cellulose and hemicellulose components in O-alkyl C spectral region were selectively decomposed first.
