Daisuke Takaoka

Sesquiterpenoids from Cyperus rotundus

Abstract New sesquiterpenoids with 4,5-secoeudesmane and cyperolone carbon skeletons were isolated from Cyperus rotundus , and characterized by spectroscopic analysis. The structures were confirmed by synthesis from (+)-dihydrocarvone and (+)-cyperolone.

Momilactone A and B as Allelochemicals from Moss Hypnum plumaeforme: First Occurrence in Bryophytes

Momilactones A (1) and B (2), which have been identified as phytoalexins in rice, were isolated from extracts of the moss Hypnum plumaeforme. This is the first isolation and identification of momilactones as allelochemicals from a bryophyte. H. plumaeforme produces considerable amounts of momilactones (isolated yield: 8.4 mg/Kg plant for 1; 4.2 mg/Kg for 2). EtOAc extracts from H. plumaeforme and 2 showed growth inhibitory activity against angiosperms, moss, and liverwort plants. On the other hand, the growth of H. plumaeforme was insensitive to its extract and 2. Our finding suggests that momilactones play an important role as allelochemicals in this moss.

(–)-Myltaylenol, a tricyclic sesquiterpene alcohol with a novel carbon skeleton from the liverwort Mylia taylorii

A sesquiterpene alcohol (–)-myltaylenol with a novel carbon skeleton has been isolated from the liverwort Mylia taylorii, and its structure (3), including the absolute configuration, has been determined on the basis of chemical and spectroscopic evidence as well as X-ray analysis of the benzoate derivative (7).

Biotransformation of shiromodiol diacetate, myli-4(15)-en-9-one and myliol by Aspergillus niger.

Microbiol biotransformation of shiromodiol diacetate from Neolitsea serisea koids, and of myli-4(15)-en-9-one and myliol from the liverwort Mylia taylorii, were carried out with Aspergillus niger IFO 4407. A. niger hydroxylated the allyl position (C-2) of shiromodiol diacetate, and one of the geminal dimethyl groups of myli-4(15)-en-9-one and myliol regioselectively. The structures of these transformants were elucidated by spectral analysis and confirmed by X-ray analysis.

Three verrucosane diterpenoids, verrucosane triol and related compounds from the liverwort Mylia verrucosa

Abstract Three new diterpenoids of the verrucosane class were isolated as minor constituents of the methanol extract of the liverwort Mylia verrucosa and their structures shown to be 2β,9α,13β-trihydroxyverrucosane,9α-acetoxy-2β,13β-dihydroxyverrucosane and 2β,13β-dihydroxy-9-oxoverrucosane.

The structure and absolute configuration of (–)-2β,9α-dihydroxyverrucosane isolated from the liverwort Mylia verrucosa : X-ray analysis of the mono-p-bromobenzoate

The structure of dihydroxyverrucosane (I), a novel diterpene-diol isolated from the liverwort Mylia verrucosa has been determined from single-crystal X-ray analysis of the mono-p-bromobenzoate (II) by the heavy-atom method. The crystals were monoclinic, a= 6.670(1), b= 19.269(1), c= 10.379(1)A, β= 112.6(4)°, space group P21, Z= 2. Block-diagonal least-squares refinement based on 1 929 independent reflections converged to R 0.078. The absolute configuration was established by the anomalous dispersion effect. The molecule contains a 3,6,6,5-tetracyclic ring system in which ring B is considerably distorted by fusion with the cyclopropane ring A. Ring C adopts a chair conformation and ring D is a conformation somewhere between a half-chair and β-envelope.

Structure of (–)-neoverrucosan-5β-ol, a diterpenoid from Mylia verrucosa(liverwort) containing a novel carbon skeleton: X-ray crystal and molecular structure of the benzoate

The structure and absolute configuration of a novel diterpene alcohol, (–)-neoverrucosan-5β-ol, isolated from the liverwort Mylia verrucosa has been shown to be (2) on the basis of chemical and spectral evidence and X-ray analysis of the benzoate (6).

Structure of (–)-2,9-dihydroxyverrucosane, a novel carbon skeletal diterpenoid from the liverwort Mylia verrucosa

A novel cabon skeletal diterpene diol isolated from the liverwort Mylia verrucosa has been shown to have the structure (1), containing a novel fused 3,6,6,5-tetracyclic ring system, on the basis of chemical and spectral evidence.

Soluble carbohydrates of liverworts

Abstract Five soluble carbohydrates, (−)- l -bornesitol, (−)- d -mannitol, (+)- d -glucose, (+)-sucrose and (+)-trehalose, have been isolated as their acetyl derivatives from the liverwort, Mylia taylorii. The absolute configuration of these carbohydrates is the same as that of sugars found in vascular plants, although the liverwort sesquiterpenoids are usually enantiomeric relative to those of vascular plants. The soluble carbohydrates in seven other liverwort species have also been analysed by HPLC.

Steryl esters of liverworts

Abstract Fatty acid steryl esters have been isolated from two liverwort species, and the nature of both the sterols and the fatty acids has been determined by analysis using GLC and GC/MS methods.