New Sesquiterpenoids from the New Zealand Liverwort Chiloscyphus subporosus

Abstract

The liverworts contain various types of lipophilic terpenoids and aromatic compounds.1,2) Their chemical constituents are valuable as chemosystematic and genetic markers.1,2) Additionally, it is known that geographic differences in the main components are occasionally observed in the same species. [1][2][3] We have already reported the isolation and structural determination of a number of terpenoids and aromatic compounds with novel skeletons.1,2) As part of a search for novel compounds and biologically active substances in the Hepaticae, we are studying the chemical constituents of the southern hemispheric liverworts. A number of endemic liverwort species have been found in New Zealand, which are not related to those found in Japan. 4)The New Zealand liverwort Chiloscyphus subporosus (MITT.) J. J. ENGEL & R. M. SCHUST. was chemically analyzed to give a new aromadendrane-type sesquiterpenoid (1) and an aromadendrane-guaianolide-type dimer (2), together with 5,8-epidioxy-6-eudesmene (3) and ent-spathulenol 5) (4). Here we report on the isolation and structural characterization of the new compounds. Results and DiscussionA combination of chromatography on silica gel, Sephadex LH-20, and preparative HPLC of the ether extract of C. subporosus resulted in the isolation of compounds 1-4.The IR spectrum of 1 showed the presence of a g-lactone) and the electron impact mass spectrometry (EI-MS) confirmed the molecular ion peak at m/z 232. Fig. 1. The long-range 1 H-13 C correlations were observed by the heteronuclear multiple bond correlation (HMBC) spectrum of 1, as shown in Fig. 1. Consequently, the structure of 1 was clarified to be 4(15)-aromadendren-12,5-olide. The phase-sensitive nuclear Overhauser enhancement and exchange spectroscopy (PH-NOESY) spectrum of 1 showed NOEs between i) H-13 and H-6, H-7, ii) H-10 and H-8a, iii) H-14 and H-2a, and iv) H2a and H-3a. However, its PHNOESY spectrum did not provide clear information on the stereochemistry. X-Ray crystallographic analysis demonstrated the stereochemistry of 1 by its ORTEP drawing, as shown in Fig. 2. Accordingly, the stereostructure of 1 was established to be 4(15)-aromadendren-12,5a-olide or its enantiomer.The IR spectrum of compound 2 showed absorption as- A new aromadendrane-type sesquiterpenoid, 4(15)-aromadendren-12,5a a-olide and an aromadendrane-guaianolide dimer have been isolated from the New Zealand liverwort Chiloscyphus subporosus. Their structures were established by extensive NMR techniques and X-ray crystallographic analysis.

Sesquiterpenoids and Artificial 19-Oxygenated Steroids from the Formosan Soft Coral Nephthea erecta

“…The 13 C NMR displayed 15 carbon resonances, and the DEPT spectrum (Table 1) was consistent with the presence of a methine [δ C 71.4 (CH)], a quaternary carbon [δ C 81.5 (qC)] bearing a peroxide ring, a quaternary carbon [δ C 70.7 (qC)] bearing a hydroxyl, and trisubstituted olefinic carbons [δ C 124.2 (CH) and 149.5 (qC)], as well as four methyls, four methylenes, three methines, and four quaternary carbons. The above data of 1 were similar to those of 5R,8R-epidioxy-6-eudesmene, 14 except for the presence of a tertiary hydroxyl at C-11. This was supported by the HMBC spectrum, which shows correlations from H 3 -12 and H 3 -13 to C-11 (Figure 1).…”

Diterpenoids and Aromatic Compounds from the Three New Zealand Liverworts Jamesoniella kirkii, Balantiopsis rosea, and Radula Species

“…[4][5][6][7] Here, we report on the isolation and structural elucidation of new aromatic compounds and known diterpenoids as well as bibenzyl derivatives from three New Zealand liverworts, Balantiopsis rosea BERGGREN, Jamesoniella kirkii STEPH., and an unidentified Radula species.…”

A novel eudesmene sesquiterpenoid from Schisandra sphenanthera stems

“…The results were consistent with the stereochemistry of 1 as established by the NOESY experiments. The NOESY correlations between Me-14 and Me-15, Me-14 and H-8, as well as between Me-15 and H-8, positioned these protons on the same side of the molecule and revealed the D-orientation of the peroxide group, similar to that of 5D,8D-epidioxy-6-eudesmene [12]. Finally, the structure of 1 was elucidated and named schisansphene A.…”