Liverwort sesquiterpenoids

Studies on the Absolute Configuration of Some Liverwort Sesquiterpenoids... 

Within the space of two months, no fewer than five independent syntheses of the liverwort sesquiterpenoid gymnomitrol (144) have been reported. " This must constitute some kind of record. In three of the syntheses " the key building block was the known bicyclic ketone (143) and from that point the three syntheses converged to gymnomitrol (144) (Schemes 14—16). In the... 

Hashimoto, T., Tori, M. and Asakawa, Y. 1989. Drimane-type sesquiterpenoids from the liverwort Makinoa crispata. Phytochemistry 28 3377-3381. 

Gymnomitrol (579), a tricyclic sesquiterpenoid which occurs as a major metabolite of the liverwort Gyrmomitrion obtusum (Lindb.) Pears, contains a rare 4,8-methano-azulene (diquinane) carbon skeleton with five adjacent chiral centers, three of them... 

Sacculatal (155) and its C-9 epimer, isosacculatal, are two diterpenoid dialdehydes which contribute to the pungent odour of the liverwort, Trichocoleopsis sacculata. Their structures bear a resemblance to the sesquiterpenoid drimanes. A diterpenoid analogue of the cadinene group is found in the structure of dihy-droxyserrulatic acid (156), from Eremophila serrulata (Myoporaceae). 

The isolation of -(-)-cuparene (77), and f -(-)-S-cuparenol (78) from the liverwort, Bazzania pompeana, is consistent with the general tendency of this type of plant to produce sesquiterpenoids enantiomeric with those found in higher plants38... 

Lubimin, a phytoalexin found in several Solanaceae, has been assigned the spiro-structure (57) on n.m.r. and biosynthetic evidence,83 whilst the new sesquiterpenoid skeleton of taylorione (58) from the liverwort Mylia taylorii is thought84 to be biosynthesized via an aromadendrene-type precursor which may also generate the co-occurring myliol (59). 

Two more longipinane derivatives (218) and (219) have been isolated from Stevia species.A full paper on the chemistry of vulgarone A (220) and B (221) has been published." In keeping with the general rule that enantiomeric sesquiterpenoids are often found in liverworts, Matsuo have identified the... 

The nor-ketone rudbeckianone (244) has been identified in Rudbeckia lacini-ata A very interesting new sesquiterpenoid ketone, (+)-bicyclohumulenone (245), has been isolated from the leafy liverwort Plagiochila acanthophylla subsp. japonica The structure and absolute stereochemistry of this compound were ascertained by X-ray crystallographic analysis of the mono-p-bromobenzoate of the derived triol (246). This ketone co-occurs with the two enantiomeric sesquiterpenoids (-)-maalioxide (247) and (+)-cyclocolerenone (248). 

A continuing investigation of the sesquiterpenoids from liverworts (Plagiochila species) has revealed the presence of more seco-aromadendrane compounds, namely plagiochilines A (652), B (653), C (654), D (655), E (656), and F (657). Plagiochilide (658) has been found in the Swiss species of P. asplenioides but not in the French version. The presumed precursor of these compounds, (-)-bicyclogermacrene (659), has also been identified in the extracts... 

Further studies on the metabolites of the liverwort Porella platyphylla have resulted in the isolation and structural determination of three more pinguisane-type sesquiterpenoids, namely pinguisanin (665), pinguisanolide (666), and /8-pinguisenediol (667). A very neat synthesis of the unusual sesquiterpenoid... 

Nakagawara, S., Nakamura, N., Guo, Z.-J., Sumitani, K., Katoh, K. and Ohta, Y. (1993) Enhanced formation of a constitutive sesquiterpenoid in cultured cells of a liverwort, Calypogeia granulata Inoue during elicitation effects of vanadate. Plant Cell Physiol., 34,421-9. 

The first enantioselective total synthesis of tetracyclic sesquiterpenoid (+)-cyclomyltaylan-5a-ol, isolated from a Taiwanese liverwort, was accomplished by H. Hagiwara and co-workers. They started out from Hajos-Parrish ketone analogue, (S)-(+)-4,7a-dimethyl-2,3,7,7a-tetrahydro-6/-/-indene-1,5-dione, that could be synthesized from 2-methylcyclopentane-1,3-dione and ethyl vinyl ketone in an acetic acid-catalyzed Michael addition followed by an intramolecular aldol reaction. The intramolecular aldol reaction was carried out in the presence of one equivalent (S)-(-)-phenylalanine and 0.5 equivalent D-camphorsulfonic acid. The resulting enone was recrystallized from hexane-diethyl ether to yield the product in 43% yield and 98% ee. Since the absolute stereochemistry of the natural product was unknown, the total synthesis also served to establish the absolute stereochemistry. 

New drimane sesquiterpenoids include 6p-acetoxyisodrimenin (74), capsico-dendrin, a partially characterized tetramer of cinnamodial (63),45 albicanyl 3,4-dihydroxycinnamate (75), albicanyl 2,4-dihydroxycinnamate (76) (both liverwort constituents),48 and polyveoline (77), an indolosesquiterpenoid.47 Full details of the isolation and structural determination of pebrolide (78) and its congeners (79) and (80) have been published.48 The biosynthesis of pebrolide... 

Some new pinguisane sesquiterpenoids have been isolated from liverwort species. These include dehydropinguisanin (820), dehydropinguisenol (821), and pinguisenal... 

An examination of the sesquiterpenoid constituents of the liverwort Plagiochila semidecurrens has resulted in the isolation of ovalifoliene (=plagiochiline C) (671), hanegokidial (672), and ovalifolienalone (673). A related and wide ranging investigation of other Plagiochila species... 

Taylorione (683), an unusual ent-l,10-secoaromadendrane sesquiterpenoid from the leafy liverwort Mylia taylorii, has been synthesized from (+)-A -carene. ... 

Mastteophorenes. The M. are atropisomeric dimeric sesquiterpenoid biaryls from the liverwort Mastigo-phora diclados, co-occurring with their monomeric phenolic precursors, related with herbertene derivatives. M. A C,oH4204, Mr 466.65, crystalline, mp. 258 -261 °C, [a]p -65.3° (CHCI3). M. B is the atropiso-mer, mp. 210°C, [a], -39.1° (CHCI3). 

Sesquiterpenes (sesquiterpenoids). A structurally highly diverse class of terpenoids with 15 carbon atoms skeleton derived biosynthetically from famesyl pyrophosphate (FPP) ( famesol, isoprene rule, ter-penes). More than 70 different ring systems are formed by enzyme-catalyzed cyclization of the linear parent structure these cyclic structures can be further modified by 1,2- and 1,3-hydride shifts, renewed cycliza-tions, hydroxylations, and other subsequent reactions. S. are widely distributed in plants, fiingi, and animals but are less common in bacteria. Specific biosynthetic routes are often characteristic for certain organisms. Thus, basidiomycetes preferentially use humulene as the basis for the syntheses of protoilludanes, illu-danes, lactaranes, hirsutanes, and related S. skeletons. Individual S. systems are also known for liverworts and marine organisms. In addition, liverworts often contain the optical antipodes of S. known from plants. 

Wurzel G, Becker H (1990) Sesquiterpenoids from the Liverwort Ricciocarpos natans. Phytochemistry 29 2565... 

Connolly JD, Thornton IMS (1973) Sesquiterpenoid lactones from the liverwort Frullania tamarisci. Phytochem 12 631-632 Culberson CF (1969) Chemical and botanical guide to lichen products. University of North Carolina Press, Chapel Hill Dahlquist I, Fregert S (1980) Contact allergy to atranorin in lichens and perfumes. Contact Dermatitis 6 111-119 Dahlquist I, Fregert S (1981) Atranorin and oak moss contact allergy. Contact Dermatitis 7 168-169 Fernandez de Corres L (1984) Contact dermatitis from frullania ... 

Albicanal (288) and (-)-drimenol (289) are simple drimane sesquiterpenoids isolated from the liverwort, Diplophyllum serrulatum, and many other liverworts and higher plants. The latter compound was incubated with M. plumbeus and R. arrhizus. The former microorganism converted 289 to 6,7a-epojQ - (290), 3p-hydroxy- (291), and 6a-drimenol (292) in the yields of 2%, 7%, and 50%, respectively. On the other hand, the latter species produced only 3p hydroxy derivative (291) in 60% yield (Aranda et al., 1992) (Figure 20.90). 

Furusawa, M., 2006. Microbial biotransformation of sesquiterpenoids from crude drugs and liverworts Production of functional substances. PhD thesis. Tokushima Bunri University, Tokushima, Japan, pp. 1-156. 

Hashimoto, T., Y. Noma, Y. Goto, S. Takaoka, M. Tanaka, andY. Asakawa, 2003c. Biotransformation of sesquiterpenoids from the liverwort Plagiochila species. Proceedings of 47th TEAC, pp. 139-141. 

The structure of sesquiterpenoid, (+)-l(10)-aristolene (=calarene) (36) from the crude drug Nardostachys chinensis was similar to that of nootkatone. 2-Oxo-l(10)-aristolene (38) shows antimelanin inducing activity and excellent citrus fragrance. On the other hand, the enantiomer (37) of 36 and (+)-aristolone (41) were also found in the liverworts as the natural products. In order... 

Plagiochiline A (104) that shows potent insect antifeedant, cytotoxicity, and piscidal activity are very pungent 2,3-secoaromadendrane sesquiterpenoids having 1,1-dimethyl cyclopropane ring, isolated from the liverwort Plagiochilafruticosa. Plagiochilide (105) is the major component of this liverwort. In order to get more pungent component, the lactone (105, 101 mg) was incubated with... 

Furusawa, M., T. Hashimoto, Y. Noma, and Y. Asakawa, 2005b. The structure of new sesquiterpenoids from the liverwort Reboulia hemisphaerica and their biotransformation. Pioc. 49th TEAC 235-237. 

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