Keiko Takikawa

Cyclic bis(bibenzyls) and related compounds from the liverworts Marchantia polymorpha and Marchantia palmata

Abstract From the methanol extract of the Indian liverwort Marchantia polymorpha , two new cyclic bis(bibenzyls), isomarchantin C and isoriccardin C, and a new phenanthrene derivative, 2-hydroxy-3,7-dimethoxyphenanthrene, were isolated together with the previously known cyclic bis(bibenzyls) marchantin A, C, D and E, riccardin C and perrottetin E and their structures were established by extensive 1 H NMR spectroscopic examination. Isomarchantin C, isoriccardin C, marchantin C and G, and riccardin C were also isolated from the Indian M. palmata . The two Marchantia species are chemically quite similar.

Prenyl bibenzyls from the liverworts Radula perrottetii and Radula complanata

Abstract A new dihydrobenzofuran and a new chromene derivatives have been isolated from the liverwort Radula perrottetii , together with the known 3,5-dihydroxy-2-(3-methyl-2-butenyl)bibenzyl, 2( R )-2-isopropenyl-6,7-dihydroxy-4-(2-phenylethyl)dihydrobenzofuran, 2,2-dimethyl-7-hydroxy-5-(2-phenylethyl)chromene, 3,5-dihydroxy-6-carbo-methoxy-2-(3-methyl-2-butenyl)bibenzyl, three bis(bibenzyls) and perrottetins E, F and G. The structures of the new compounds have been characterized as 2( R )-2-isopropenyl-6-hydroxy-4-(2-phenylethyl)dihydrobenzofuran and 2,2-dimethyl-7,8-dihydroxy-5-(2-phenylethyl)chromene by 1 H and 13 C NMR spectral analysis and synthesis. The structures of the previously reported chalcone and three prenyl bibenzyls, perrottetins A, B and C, and the other two bibenzyls, isolated from R. perrottetii are revised by analysis of their 1 H and 13 C NMR data, difference NOE experiments and synthesis of their derivatives. Radulanin L, a new bibenzyl with a dihydrooxepin skeleton was isolated from R. complanata together with 2- and 4-(3-methyl-2-butenyl)-3,5-dihydroxybibenzyls and its structure elucidated by comparison of 1 H and 13 C NMR spectral data with those of radulanins A and H. The structures of the previously reported radulanins A and H isolated from R. complanata are confirmed as correct by difference NOE. Some prenyl-containing bibenzyls showed 5-lipoxygenase and calmodulin in hibitory activity and vasopressin antagonist activity. R. perrottetii is a chemically isolated species in the Radulaceae.

Total assignment of 1H and 13C NMR spectra of marchantins isolated from liverworts and its application to structure determination of two new macrocyclic bis(bibenzyls) from Plagiochasma intermedium and Riccardia multifida

Abstract 1 H and 13 C NMR spectra of five marchantins isolated from Marchantia species (Liverwort) have been completely assigned using NOE difference, 13 C- 1 H correlation and long-range proton selective decoupling (LSPD) spectra. The structures of two macrocyclic bis(bibenzyls) have been determined by use of this assignment.

Distribution of novel cyclic bisbibenzyls in Marchantia and Riccardia species

Abstract Marchantins A, B and C, three new cyclic bisbibenzyls with two ether links have been isolated from the liverworts Marchantia polymorpha, M. paleacea var. diptera and M. tosana (Marchantiales). Riccardia multifida (Metzgeriales) also contained two new cyclic bisbibenzyls, riccardins A and B, with an ether and a biphenyl link. The presence of cyclic bisbibenzyls has not been confirmed in Dumortiera hirsuta and Preissia quadrata (Marchantiales). The present chemical data support that D. hirsuta and P. quadrata are not closely allied to Marchantia by flavonoid chemistry and some species of Marchantiales have close affinities to those of Metzgeriales.

Novel bibenzyl derivatives and ent-cuparene-type sesquiterpenoids from Radula species☆

Abstract Four novel prenyl bibenzyls, perrottetin A–D were isolated from the liverwort Radula perrottetii together with a new sesquiterpene phenol, ent-2, 3-dihydroxycuparene and a prenyl dihydrochalcone, and their structures were determined by spectral methods and chemical transformations. Further investigation of the French species R. complanata resulted in the isolation of four new bibenzyls, 3, 4′-dimethoxybibenzyl, 3,5-dihydroxy-4-(2, 3-epoxy-3-methylbutyl)bibenzyl, radulanin H and radulanolide. R. buccinifera was chemically close to R. complanata . The composition of bibenzyls found in R. perrottetii and R. oyamensis were different from that of the other Radula species referred to in the section Radula . Some prenyl bibenzyls showed antimicrobial activity against Streptococcus aureus (20 μg/ml). The allergenic activity of R. complanata is due to (+)-frullanolide from the liverwort Frullania dilatata which is intermingled in R. complanata .

Bibenzyl derivatives from the Australian liverwort Frullania falciloba

Abstract Three new bibenzyl derivatives were isolated from the Australian liverwort Frullania falciloba and their structures were established to be 3,4-methylenedioxy-3′-methoxybibenzyl, 3-hydroxy-4,3′-dimethoxybibenzyl and 3-[4′-methoxybenzyl]-5,6-dimethoxyphthalide by spectral methods and synthesis. The present species belongs to the bibenzyl-type, Chemotype III, in the Frullaniaceae.

Isotachin c and balantiolide two aromatic compounds from the new zealand liverwort balantiopsis rosea

Abstract Isotachin C and balantiolide, two new aromatic compounds, were isolated from the New Zealand liverwort Balantiopsis rosea. Their structures were established to be 2-methoxybenzyl trans-β-methylthioacrylate and 3-[3′,4′-dimethoxybenzyl]-7-hydroxy-5-methoxyphthalide, respectively, by spectral methods. The previously known isotachin A, isotachin B, benzoates, cinnamates and sesquiterpenoids were also found. B. rosea is chemically quite close to Isotachis japonica.

Sesqui- and diterpenoids from the liverworts Porella densifolia subsp. appendiculata and Porella densifolia var. fallax☆

Abstract A new diterpenic acid, ent -kauren-15-one-18-oic acid, was isolated from the Indian liverwort Porella densifolia subsp. appendiculata together with the previously known ent -18-hydroxykauren-15-one and norpinguisone methyl ester. Further investigation of the chemical constituents of the Japanese P. densifolia var. fallax resulted in the isolation of three known ent -kaurane-type diterpenoids. P. densifolia subsp. appendiculata is chemically very close to P. densifolia var. fallax .

Oxidation Reactions of Marchantin A Trimethyl Ether and Some Aromatic Compounds using m-Chloroperbenzoic Acid. Formation of Muconic Acid Ester and m-Chlorobenzoate

On treatment with m-chloroperbenzoic acid, dihydroeugenol methyl ether and marchantin A trimethyl ether afford muconic acid ester derivatives by oxidation of the aromatic ring as well as hydroxylated derivatives; the m-chlorobenzoate of the dihydroeugenol derivative is also observed for the former.