Clerodane‐Type Diterpenoids from the Taiwanese Liverwort Schistochila Acuminata

Abstract

Three cis‐clerodane‐type acids 3‐5 and one methyl ester 9 were identified from the liverwort Schistochila acuminata. The two new acids 3 and 5 were 12E and 12Z geometric isomers and the methyl ester 9 was first reported from nature.

Clerodane diterpenes: sources, structures, and biological activities

“…For instance, both 3-methylenepent-4-ene ( 156–158 ) and 3-methylpenta-2,4-diene ( 164–167 ) side chains are found in type I subtype IIa. Interestingly, compounds 164–166 with a Δ 12 Z double bond were isolated from both Schistochila acuminate and Heteroscyphus planus , 45–47 while heteroscyphol ( 167 ) with an assigned Δ 12 E double bond was found only in Heteroscyphus planus . 47 …”

A New Seco-Clerodane-Type Diterpenoid from Bornean Liverwort Schistochila acuminata

“…In this investigation, two populations of Bornean S. acuminata were analyzed where seco-clerodane-, clerodane-as well as dolabellanetype diterpenoids were isolated. A population from Mount Trus Madi gave one new seco-clerodane (1) and two known clerodanes (2, 3), while population from Mount Alab gave three known clerodanes (2, 3, 4) and one dolabellane-type compound (5), as shown in Figure 1. Here we report the spectral evidence for the new compound and discuss the chemosystematic significance of these findings.…”

“…HSQC and 13 C-DEPT experiments coupled with 13 C-and 1 H-NMR signals of compound 1 showed the presence of a conjugated carboxylic acid at  C 172.0 (C), two pairs of olefinic carbons at  C 144.2 (CH),  H 7.40 (1H, d),  C 137.0 (C),  C 128.7 (CH),  H 5.41 (1H, td),  C 127.9 (CH),  H 5.93 (1H, d), three vinylidenes at  C 147.9 (C),  C 116.3 (CH 2 ),  H 5.00 (2H, br s),  C 145. 5 (Table 1). Thus, degrees of unsaturation could be attributed to five double bonds, one carboxylic acid and a monocyclic ring.…”

“…The NOESY correlations observed between H-7/H-10, H-10/H 3 -17, H-7/H 3 -17 and H 3 -17/H 3-20, as well as the same biosynthetic pathway with the co-occurring compounds 2-4, proposed the  configuration of methyl groups at C-8 and C-9. Thus, compound 1 was identified as schistochilic acid D. The other known diterpenoids were identified as (-)-3,13(16),14cis-clerodatrien-18-oic acid (2) [5], (-)-3,12E,14-cis-clerodatrien-18-oic acid (3) [5], cis-3,14-clerodadien-13-ol (4) [6] and 12 hydroxydolabella-(3E,7E)-diene (5) [7]. Liverwort populations of this species collected from different localities showed chemical differences.…”