Zealand Liverwort Research Articles

Distribution of terpenoids and aromatic compounds in New Zealand liverworts

Distribution of terpenoids and aromatic compounds in New Zealand liverworts

Total synthesis of both enantiomers of clavigerins B and C

The first total synthesis of both enantiomers of clavigerins B and C, insect antifeedant sesquiterpenes isolated from New Zealand liverwort Lepidolaena clavigera, has been achieved. The synthesis features Ireland-Claisen rearrangement for construction of bicyclo[3.1.1]heptene skeleton. By comparison of the optical rotations of both enantiomers with those of natural clavigerins, the absolute configurations of natural clavigerins B and C were unambiguously determined to be 1S,3S,6S,8S,9R.

Directed Magnesiation of Polyhaloaromatics using the Tetramethylpiperidylmagnesium Reagents TMP2Mg⋅2 LiCl and TMPMgCl⋅LiCl

AbstractA convenient and efficient functionalization of polyhaloaromatics via regioselective magnesiation has been developed. Starting from simple, inexpensive but structurally challenging arenes, metallation by magnesium amide bases was achieved under mild conditions. The desired Grignard reagents were stable towards aryne formation, were obtained in good yields within short reaction times and could be reacted with a variety of typical electrophiles, providing attractive, functionalized building blocks in good to excellent yields. As an application we have prepared the antimicrobial natural product 2,6‐dichloro‐3‐phenethylphenol isolated from the New Zealand liverwort Riccardia marginata. This synthesis involves a mixed bimetallic compound prepared via metallation of a phenylboronic acid pinacol ester derivative and subsequent selective cross‐coupling.

Novel Prenyl Bibenzyls from the New Zealand Liverwort Marsupidium epiphytum

The ether extract of the New Zealand liverwort Marsupidium epiphytum gave four new prenyl bibenzyl derivatives, along with a known prenyl bibenzyl derivative which has been isolated from the Ecuadorian liverwort Lethocolea glossophylla; their structures were determined by 2D-NMR spectrum. The chemical constituents of Marsupidium epiphytum are highly characteristic since they elaborate dihydrooxepin type compounds and prenyl type bibenzyls. These structures are closely related to those found in Radula spp. (Radulaceae), although bibenzyls with two prenyl groups have not been isolated from the Radula spp. Although Marsupidium spp. are different from Radula spp. morphologically, the constituents are closely related. This is the first example of isolation of prenyl bibenzyl derivatives from M. epiphytum, a species which has not previously been investigated phytochemically.

Concise Synthesis of (±)-Perrottetinene with Bibenzyl Cannabinoid

Scheme 1. Retrosynthetic analysis of (±)-perrottetinene (4) Cannabinoids are widely distributed in nature and have been isolated from Indian hemp Cannabis sativa, which has been used as both a medicine and a psychotomimetic drug since ancient times (Figure 1). These compounds possess analgesic, antiemetic, psychotropic, and anti-inflammatory properties. They also have potential therapeutic applications in the treatment of asthma and glaucoma. Among these, ∆-tetrahydrocannabinol (1) (∆-THC) and ∆-tetrahydrocannabinol (2) (∆-THC) are the major psychopharmacological active constituents of marijuana (hashish). Their analogues have also attracted medical interest because of their promising biological and pharmacological activities including anthemetic, analgesic, and psychotropic effects. Additionally, hexahydrocannabinol (3) has attracted considerable attention since clinical tests have shown that these compounds have a similar psychotropic activity to natural ∆-tetrahydrocannabinol (1). Currently, synthesized ∆-tetrahydrocannabinol (2) (∆-THC) and its derivatives have been used as the medicines, Marinol and Cesamet, for patients with chemotherapy-induced nausea and vomiting (CINV), who have failed to respond adequately to conventional antiemetic treatments. Structurally related perrottetinene (4) and perrottetinenic acid (5) with a bibenzyl cannabinoid nucleus were isolated from the extract of the New Zealand liverwort Radula marginata (Figure 2). The structures of these natural products were determined using spectroscopic analysis. Interestingly, most of the naturally occurring tetrahydrocannabinols 1-3 possessed a trans-fused ring junction between cyclohexene (or cyclohexane) and the pyranyl ring, whereas perrottetinene (4) and perrottetinenic acid (5) exhibited a cis-stereochemisty. Although the total synthesis of perrottetinene (4) has already been reported in a 9-step process, simple and more concise synthetic approaches are still needed. A new methodology was reported for synthesizing a variety of benzopyrans and canabinoid analogues starting from substituted resorcinols and α,β-unsaturated aldehydes utilizing ethylenediamine diacetate as a catalyst. Naturally occurring hexahydrocannabinol (3) was synthesized using this methodology as a key step. As an expansion of the synthesis of benzopyrans and cannabinoid, (±)-perrottetinene (4) was concisely synthesized in this study.

Novel Terpenoids from the New Zealand Liverworts Jamesoniella colorata and Bazzania novae-zelandiae

Diethylether extracts of New Zealand liverworts Jamesoniella colorata and Bazzania novae-zelandiae were investigated to reveal novel terpenoids. The former extract afforded a new modified clerodane-type diterpenoid, and the latter gave a degraded clerodane (rearranged drimane) type sesquiterpenoid. The structures of those new compounds were established by 2D NMR spectra.

Sesqui- and diterpenoids from three New Zealand liverworts: Bazzania novae-zelandiae, Gackstroemia sp. and Dendromastigophora sp.

Two new sesquiterpenoids, 1 and 2, were isolated from the unidentified liverwort Gackstroemia species, and three known sesquiterpenoids, 3–5, and a known sesqui- (6) and diterpenoid (7) were isolated from Bazzania novae-zelandiae and the unidentified Dendromastigophora species, respectively. Their structures were determined by spectroscopic analysis.

Pungent Aromatic Compound from New Zealand Liverwort Hymenophyton flabellatum

Ether extract of the New Zealand liverwort Hymenophyton flabellatum produced a pungent principle. The structure has been identified as known compound, 1-(2,4,6-trimethoxy-phenyl)-but-2(E)-en-1-one by means of its spectral data, previously isolated from the fern Arachinoides standishii. Further isolation of the extract of this species afforded eight aromatic compounds whose structures were determined by spectral analysis. Those compounds were shown to be biogenetically and structurally related to the pungent compound of this species.

Chemical Constituents of Selected Japanese and New Zealand Liverworts

Liverworts are rich sources of biologically active substances. Recent topics relating to the chemical constituents found in several Japanese and New Zealand liverworts and their biological activity and chemosystematics are discussed.

Insect Antifeedant Sesquiterpene Acetals from the Liverwort Lepidolaena clavigera. 2. Structures, Artifacts, and Activity

Clavigerin A ( 1) was isolated from the New Zealand liverwort Lepidolaena clavigera and shown to be a polyoxygenated bergamotane sesquiterpene with an unusual ring system. L. clavigera shows infraspecific variation, since 1 was the only clavigerin detected in a North Island collection, whereas the previously reported clavigerins B ( 2) and C ( 3) were found in South Island collections with no sign of 1. Three new clavigerins, 4- 6, were identified, but these are artifacts formed by alcoholysis of the acetoxy acetal group of the clavigerins 2 and 3, with either the extraction solvent ethanol or the RP column eluent methanol. The insect antifeedant and cytotoxic activities of these compounds are reported, and it is proposed that they act as hidden 1,4-dicarbonyl compounds.

Photoprotective pigments in red and green gametophytes of two New Zealand liverworts

Gametophytes of Jamesoniella colorata (Jungermanniaceae) and Isotachis lyallii (Isotachi‐daceae) produce red leaves in exposed habitats, but green leaves in shaded environments. To understand the functional significance of this colour polymorphism, the anatomy, pigment composition, optical properties, and kinetics of chlorophyll a fluorescence were compared for red and green gametophytes. Both colour morphs were structurally similar, but the red leaves held unidentified red pigment(s) firmly associated with the cell wall. Green morphs contained more chlorophylls and carotenoids, and had higher ratios of chlorophylls to carotenoids, than did the red morphs. Red leaves absorbed 10% more photosynthetically active radiation, with a maximum at 540 nm, than did the green leaves. Under high irradiance, the red leaves maintained higher apparent quantum efficiencies for photosynthesis, and had larger photochemical and non‐photochemical quenching values. The data indicate that red gametophytes have the greater potential to mitigate the damaging effects of high irradiance.

Bazzanane Sesquiterpenoids from the New Zealand Liverwort Frullania falciloba.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

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

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

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

Three new aromatics were isolated from the New Zealand liverwort Balantiopsis rosea. A new bibenzyl was isolated from an unidentified Radula species, together with known bibenzyls. Jamesoniella kirkii yielded three known ent-isopimarane and two ent-kaurane diterpenoids. Their structures were confirmed by NMR techniques, chemical reaction, and X-ray crystallographic analysis.

Bazzanane Sesquiterpenoids from the New Zealand Liverwort Frullania falciloba

Two new bazzanane-type sesquiterpenoids have been isolated from the New Zealand liverwort Frullania falciloba. Their structures were confirmed by NMR and CD spectroscopy and chemical reactivity.

Lipid Constituents of the New Zealand Liverwort Plagiochila circinalis

The major constituent of the ether extract of the New Zealand liverwort Plagiochila circinalis afforded five new fatty acid esters of sterol or triterpenoid. Their structures were unequivocally determined, while the purification was not completed. They were shown to be cycloart-24-en-3β-yl α-linolenate, stigmasteryl γ-linolenate, cycloart-24-en-3β-yl arachidonate, 4α, 14α-dimethyl-8, 24(28)-ergostadien-3β-yl arachidonate and 4α, 14α-dimethyl-8, 24(28)-ergostadien-3β-yl eicosapentaenoate. Cycloart-24-en-3β-yl eicosapentaenoate which has been found in the Malagasy liverwort Mastigophora diclados, was also isolated from the title species.

Induction of Apoptosis by Newent-Kaurene-Type Diterpenoids Isolated from the New Zealand LiverwortJungermanniaSpecies

Some diterpenoids show various biological activities, including anti-inflammatory, anti-HIV and anti-tumor activity. Previously, we have focused our research on the apoptosis-inducing properties of diterpenoids and found that some ent-kaurene-type diterpenoids induced apoptosis in human leukemia HL-60 cells. In this study, we have investigated the induction of apoptosis in HL-60 cells by the novel ent-kaurene-type diterpenoids, jungermannenones A (JA), B (JB), C (JC) and D (JD), isolated from the New Zealand liverwort Jungermannia species. Treatment of the cells with each compound for 12 h resulted in cytotoxicity (IC (50) values: A, 1.3; B, 5.3; C, 7.8; D, 2.7 microM) and caused DNA fragmentation and nuclear condensation, both biochemical markers of the induction of apoptosis. Treatment with the compounds resulted in activation of caspases, including caspase-3 and caspase-8. A broad-spectrum inhibitor of caspases, Z-Asp-CH (2)-DCB, attenuated the cytotoxicity induced by these compounds, suggesting that JA, JB, JC and JD induced apoptosis through a caspase-dependent pathway. JA and JD inhibited the activity of nuclear factor-kappaB, which is a transcriptional factor of anti-apoptotic factors. Thus, some of these new ent-kaurene-type diterpenoids may be promising candidates for anti-tumor agents.

New sesquiterpenoid from the New Zealand liverwort Lepidozia spinosissima

A new cyclogorgonane–type sesquiterpenoid, 1,5-cyclo-3,6-gorgonadien-15,11-olide was isolated from the New Zealand liverwort Lepidozia spinosissima, together with three known sesquiterpenoids. Their structures were established by the extensive NMR techniques and chemical reaction.

Sesquiterpenes from the New Zealand Liverwort Lepidolaena hodgsoniae

NMR studies have shown that seven new sesquiterpenoids, 3, 4, 5a, and 7-10, isolated from dried samples of the New Zealand liverwort Lepidolaena hodgsoniae have the same substituted cyclopentapyran ring system as the previously described insecticidal sesquiterpene diene hodgsonox (1), which has been reported only from this plant. In all but one compound, 10, the 1,1-disubstituted double bond of hodgsonox has migrated into an endocyclic position, but only two, 5a and 9, have the double bonds in conjugation. These seven new compounds represent a variety of different oxidation levels. Two of the new derivatives, 9 and 10, were isolated only from an aged sample and are presumably artifacts. The only other terpenoid isolated in significant quantity was (7R,10R)-calamenene (2).

Novel cytotoxic kaurane-type diterpenoids from the New Zealand Liverwort Jungermannia species

Novel cytotoxic rearranged kaurene- and ent-kaurene-type diterpenoids against HL-60 cells have been isolated from the unidentified New Zealand liverwort Jungermannia species together with previously known ent-kaurane-type diterpenoids. Their structures were determined by extensive NMR techniques, chemical degradation and X-ray crystallographic analysis.