Cytotoxic and apoptosis-inducing ent-kaurane-type diterpenoids from the Japanese liverwort Jungermannia truncata NEES

ent-Kaurane diterpenoids induce apoptosis and ferroptosis through targeting redox resetting to overcome cisplatin resistance

Reactive oxygen species (ROS) induction is an effective mechanism to kill cancer cells for many chemotherapeutics, while resettled redox homeostasis induced by the anticancer drugs will promote cancer chemoresistance. Natural ent-kaurane diterpenoids have been found to bind glutathione (GSH) and sulfhydryl group in antioxidant enzymes covalently, which leads to the destruction of intracellular redox homeostasis. Therefore, redox resetting destruction by ent-kaurane diterpenoids may emerge as a viable strategy for cancer therapy. In this study, we isolated 30 ent-kaurane diterpenoids including 20 new samples from Chinese liverworts Jungermannia tetragona Lindenb and studied their specific targets and possible application in cancer drug resistance through redox resetting destruction. 11β-hydroxy-ent-16-kaurene-15-one (23) possessed strong inhibitory activity against several cancer cell lines. Moreover, compound 23 induced both apoptosis and ferroptosis through increasing cellular ROS levels in HepG2 cells. ROS accumulation induced by compound 23 was caused by inhibition of antioxidant systems through targeting peroxiredoxin I/II (Prdx I/II) and depletion of GSH. Furthermore, compound 23 sensitized cisplatin (CDDP)-resistant A549/CDDP cancer cells in vitro and in vivo by inducing apoptosis and ferroptosis. Thus, the ent-kaurane derivative showed potential application for sensitizing CDDP resistance by redox resetting destruction through dual inhibition of Prdx I/II and GSH in cancer chemotherapy.

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Thirty ent-kaurane diterpenoids were isolated from the Chinese liverworts, Jungermannia tetragona.

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11β-hydroxy-ent-16-kaurene-15-one (23) was identified to induce apoptosis and ferroptosis for the first time.

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Compound 23 could disorder the intracellular redox system by directly targeting Prdx I/II and GSH.

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Compound 23 could sensitize A549/CDDP cancer cells in vitro and in vivo through redox resetting destruction.

Chemical Composition and Cytotoxic Evaluation of the Essential Oil of Phyllogonium viride (Phyllogoniaceae, Bryophyta)

The present study aimed to determine the chemical composition and biological activity of the essential oil obtained from Phyllogonium viride Brid. (Phyllogoniaceae, Bryophyta), whose samples were collected in southern Brazil. For the first time, the cytotoxic activity of the essential oil of P. viride in breast and colorectal tumor cells (MCF-7 and HCT-116) was evaluated, as well as the cytotoxic potential of this oil in non-tumoral cells of human immortalized keratinocytes (HaCaT) via MTT assay. The compounds majorly found in P. viride essential oil were β-bazzanene (20.30 %), β-caryophyllene (17.06 %), β-chamigrene (14.02), and germacrene B (11.72 %). Treatment with P. viride essential oil in the different tested cell lines did not induce any toxicity in most of the tested concentrations. These data contribute to generating new scientific information about this understudied plant species. Furthermore, the chemical characterization of the compounds present in the essential oil of P. viride can lead to greater elucidation of its biotechnological potential.

Diterpenoids From the Argentine and Malaysian Liverworts Anastrophyllum and Jungermannia Species

We are engaged in the ongoing investigation into the chemical constituents of liverworts in our search for novel compounds and biologically active substances. In the present study, two new rosane diterpenoids were isolated from the Argentine liverwort Anastrophyllum species, together with known aromadendrane sesqui- and rosane diterpenoids. Two new ent-kaurene and 4 ent-kaurene diterpenoids were isolated from the Malaysian liverwort Jungermannia species. Their structures were determined using nuclear magnetic resonance spectroscopy techniques, circular dichroism spectroscopy, and chemical transformation.

Antiproliferative and Antimicrobial Activities of Selected Bryophytes

One-hundred and sixty-eight aqueous and organic extracts of 42 selected bryophyte species were screened in vitro for antiproliferative activity on a panel of human gynecological cancer cell lines containing HeLa (cervix epithelial adenocarcinoma), A2780 (ovarian carcinoma), and T47D (invasive ductal breast carcinoma) cells using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and for antibacterial activity on 11 strains using the disc-diffusion method. A total of 99 extracts derived from 41 species exerted ≥25% inhibition of proliferation of at least one of the cancer cell lines at 10 μg/mL. In the cases of Brachythecium rutabulum, Encalypta streptocarpa, Climacium dendroides, Neckera besseri, Pleurozium schreberi, and Pseudoleskeella nervosa, more than one extract was active in the antiproliferative assay, whereas the highest activity was observed in the case of Paraleucobryum longifolium. From the tested families, Brachytheciaceae and Amblystegiaceae provided the highest number of antiproliferative extracts. Only 19 samples of 15 taxa showed moderate antibacterial activity, including the most active Plagiomnium cuspidatum, being active on 8 tested strains. Methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus aureus were the most susceptible to the assayed species. This is the first report on the bioactivities of these 14 species.

Chemical Constituents of Bryophytes: Structures and Biological Activity

Comparatively little attention has been paid to the bryophytes for use in the human diet or medicine in spite of the presence of 23 000 species globally. Several hundred new compounds have been isolated from the liverworts (Marchantiophyta), and more than 40 new carbon skeletons of terpenoids and aromatic compounds were found. Most of the liverworts studied elaborate characteristic odiferous, pungent, and bitter-tasting compounds, of which many show antimicrobial, antifungal, antiviral, allergic contact dermatitis, cytotoxic, insecticidal, anti-HIV, plant growth regulatory, neurotrophic, NO production and superoxide anion radical release inhibitory, muscle relaxing, antiobesity, piscicidal, and nematocidal activities. The biological effects ascribed to the liverworts are mainly due to lipophilic sesqui- and diterpenoids, phenolic compounds, and polyketides, which are the principal constituents of their oil bodies. Some mosses and liverworts produce significant levels of vitamin B₂ and tocopherols, as well as prostaglandin-like highly unsaturated fatty acids. The most characteristic chemical phenomenon of the liverworts is that most of the sesqui- and diterpenoids are enantiomers of those found in higher plants. In this review, the chemical constituents and potential medicinal uses of bryophytes are discussed.

Crystal structure of 2-amino-4-(4-chloro-phenyl)-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile, C16H13ClN2O2

C16H13ClN2O2, monoclinic, C2/c (no. 15), a = 13.7576(10) Å, b = 11.0534(5) Å, c = 19.6232(14) Å, β = 107.776(8)°, V = 2841.6(3) Å3, Z = 8, R gt(F) = 0.0407, wR ref(F 2) = 0.1105, T = 293(2) K.

Crystal structure of 2-amino-4-(3-trifluoromethylphenyl)-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile, C17H13F3N2O2

C17H13F3N2O2, triclinic, P1̅ (No. 2), a = 8.2615(7) Å, b = 8.7262(7) Å, c = 11.6521(9) Å, α = 105.872(7)°, β = 104.107(7)°, γ = 95.738(7)°, V = 771.02(11) Å3, Z = 2, R gt (F) = 0.0548, wR ref (F 2 ) = 0.1332, T = 293 K.

Sesquiterpene glycosides from the roots of Codonopsis pilosula

Three new sesquiterpene glycosides, named codonopsesquilosides A−C (1−3), were isolated from an aqueous extract of the dried roots of Codonopsis pilosula. Their structures including absolute configurations were determined by spectroscopic and chemical methods. These glycosides are categorized as C₁₅ carotenoid (1), gymnomitrane (2), and eudesmane (3) types of sesquiterpenoids, respectively. Compound 1 is the first diglycoside of C₁₅ carotenoids to be reported. Compound 2 represents the second reported example of gymnomitrane-type sesquiterpenoids from higher plants. The absolute configurations were supported by comparison of the experimental circular dichroism (CD) spectra with the calculated electronic CD (ECD) spectra of 1−3, their aglycones, and model compounds based on quantum-mechanical time-dependent density functional theory. The influences of the glycosyls on the calculated ECD spectra of the glycosidic sesquiterpenoids, as well as some nomenclature and descriptive problems with gymnomitrane-type sesquiterpenoids are discussed.

Pungent and Bitter, Cytotoxic and Antiviral Terpenoids from Some Bryophytes and Inedible Fungi

Most liverworts elaborate characteristic odiferous, pungent and bitter tasting compounds many of which show antimicrobial, antifungal, antiviral, allergenic contact dermatitis, cytotoxic, insecticidal, anti-HIV, superoxide anion radical release, plant growth regulatory, neurotrophic, NO production inhibitory, muscle relaxant, antiobesity, piscicidal and nematocidal activities. Several inedible mushrooms produce female spider pheromones, strong antioxidant, and cytotoxic compounds. The present paper is concerned with the extraction and isolation of terpenoids from some bryophytes and inedible fungi and their pungent and bitter taste, and cytotoxic and antiviral activity.

Biotransformation of diterpenes

Structural modification of the diterpenes to enhance their pharmaceutical relevance can be efficiently carried out by the application of biotransformational under mild reaction.

Phytochemical and biological studies of bryophytes

The bryophytes contain the Marchantiophyta (liverworts), Bryophyta (mosses) and Anthocerotophyta (hornworts). Of these, the Marchantiophyta have a cellular oil body which produce a number of mono-, sesqui- and di-terpenoids, aromatic compounds like bibenzyl, bis-bibenzyls and acetogenins. Most sesqui- and di-terpenoids obtained from liverworts are enantiomers of those found in higher plants. Many of these compounds display a characteristic odor, and can have interesting biological activities. These include: allergenic contact dermatitis, antimicrobial, antifungal and antiviral, cytotoxic, insecticidal, insect antifeedant, superoxide anion radical release, 5-lipoxygenase, calmodulin, hyaluronidase, cyclooxygenase, DNA polymerase β, and α-glucosidase and NO production inhibitory, antioxidant, piscicidal, neurotrophic and muscle relaxing activities among others. Each liverwort biosynthesizes unique components, which are valuable for their chemotaxonomic classification. Typical chemical structures and biological activity of the selected liverwort constituents as well as the hemi- and total synthesis of some biologically active compounds are summarized.

The natural diterpene ent-16β-17α-dihydroxykaurane down-regulates Bcl-2 by disruption of the Ap-2α/Rb transcription activating complex and induces E2F1 up-regulation in MCF-7 cells

ent-Kauranes are diterpene-type compounds commonly found in most plant species, especially from the Euphorbiaceae family. These compounds have been studied due to their anti-inflammatory and anti-tumor properties. Regulation of apoptosis, or programmed cell death, is commonly bypassed by tumoral cells, giving rise to uncontrolled proliferating cells, which eventually become carcinogenic. In a previous work, we showed that both mRNA and protein expression levels of the antiapoptotic gene Bcl-2 are reduced in MCF-7 cancer cells by the effect of the natural diterpene ent-16β-17α-dihydroxykaurane (DHK). This effect was not directly associated with the inactivation of NF-κB, as has been shown with other diterpenes compounds. Herein, we report that DHK is dissociating the Ap2α-Rb activating complex, affecting its binding ability for the Bcl-2 gene promoter. These events down-regulate Bcl-2 and is temporally accompanied by the induction of E2F1 and its target pro-apoptotic gene Puma. Disruption of the Rb-Ap2α activation complex was corroborated by chromatin immunoprecipitation and protein immunolocalization, which also revealed that Ap2α sorts out from the nucleus and relocalizes in the cell periphery. Taken together, our study confirms the regulation of Bcl-2 gene transcription by the Ap2α-Rb complex and describes a singular protein relocalization for Ap2α induced by DHK, implicating a new potential therapeutic target to differentially onset apoptosis in tumor cells.

Inflexinol inhibits colon cancer cell growth through inhibition of nuclear factor-kappaB activity via direct interaction with p50

Kaurane diterpene compounds have been known to be cytotoxic against several cancer cells through inhibition of nuclear factor-kappaB (NF-kappaB) activity. Here, we showed that inflexinol, a novel kaurane diterpene compound, inhibited the activity of NF-kappaB and its target gene expression as well as cancer cell growth through induction of apoptotic cell death in vitro and in vivo. These inhibitory effects on NF-kappaB activity and on cancer cell growth were suppressed by the reducing agents DTT and glutathione and were abrogated in the cells transfected with mutant p50 (C62S). Sol-gel biochip and surface plasmon resonance analysis showed that inflexinol binds to the p50 subunit of NF-kappaB. These results suggest that inflexinol inhibits colon cancer cell growth via induction of apoptotic cell death through inactivation of NF-kappaB by a direct modification of cysteine residue in the p50 subunit of NF-kappaB.

Chemical composition, antifungal and antitumor properties of ether extracts of Scapania verrucosa Heeg. and its endophytic fungus Chaetomium fusiforme

An endophytic fungus Chaetomium fusiforme was obtained from a liverwort, Scapania verrucosa. A comparison of the constituents of the ether extracts between S. verrucosa and the C. fusiforme culture was investigated by gas chromatography-mass spectrometry (GC/MS). The yield of ether extract based on dried plant material was 0.6% and 59 compounds were found in S. verrucosa. (+)-Aromadendrene (9.12%), hexadecanoic acid (6.92%), 6-isopropenyl-4,8a-dimethyl-1,2,3,5,6,7,8,8a-octahydro-naphthalen-2-ol (5.97%), s-tetrachloroethane (5.61%) and acetic acid (5.30%) were found to be the most abundant components among the 49 characterized compounds in S. verrucosa, which represented 84.64% of the total extract. However, the constituents of the cultured endophyte extract contained mainly acetic acid (35.05%), valeric acid, 3-methyl-, methyl ester (21.25%), and butane-2, 3-diol (12.24%). Although the extracts of S. verrucosa and its endophyte showed little chemical composition correlation, both of them demonstrated antifungal and antitumor activities. Furthermore, C. fusiforme has displayed a wider range of antimicrobial and antitumor activities, which were better than the host plant. These results could support the suggestion of endophytes as an alternative of the host for medicinal activity.

ent-kaurane diterpenoids from the liverwort Jungermannia atrobrunnea

Three new rearranged ent-kaurane-type diterpenoids (1-3) and seven new ent-kaurane-type diterpenoids (4-10) have been isolated from the liverwort Jungermannia atrobrunnea. Their structures were determined by extensive spectroscopic techniques and X-ray crystallographic analysis. The absolute configurations of these compounds were clarified by CD spectroscopic studies. Compound 1 is the first example of a rearranged ent-kaurane diterpenoid possessing a peroxide bridge.

Recent Advances of Biologically Active Substances from the Marchantiophyta

The Marchantiophyta (liverworts) produce a number of terpenoids, aromatic compounds and acetogenins, several of which show interesting biological properties, such as antimicrobial, antifungal, allergenic contact dermatitis, insecticide, insect antifeedant, cytotoxic, piscicidal, muscle relaxing, plant growth regulatory, anti-HIV and DNA polymerase β inhibitory, anti-obesity and neurotrophic activities. The isolation and chemical structures of the active compounds are discussed.

Kaurane diterpenoids from Isodon excisus inhibit LPS-induced NF-kappaB activation and NO production in macrophage RAW264.7 cells

As part of an ongoing search for plant-derived compounds that inhibit the activation of NF-kappaB, the methanol extract of the aerial parts of Isodon excisus was found to have significant inhibitory effects on the activation of NF-kappaB in murine macrophage RAW264.7 cells. Bioactivity-guided isolation of the extract yielded five new diterpenoids, excisusin A-E (1-5), along with seven known compounds, inflexarabdonin I (6), inflexarabdonin G (7), inflexin (8), inflexanin A (9), inflexanin B (10), inflexinol (11), and inflexarabdonin A (12). The structures were determined by analysis of the spectroscopic data including 2D NMR. All of the isolates were evaluated for their inhibitory effects on LPS-induced NF-kappaB activation and nitric oxide production in RAW264.7 cells.

Biologically active compounds from bryophytes

Liverworts produce a great variety of lipophilic terpenoids, aromatic compounds, and acetogenins. Many of these constituents have characteristic scents, pungency, and bitterness, and display a quite extraordinary array of bioactivities and medicinal properties. These expressions of biological activity are summarized and discussed, and examples are given of the potential of certain lead compounds for structure-activity studies and synthesis.

Induction of apoptosis by carbazole alkaloids isolated from Murraya koenigii

In the current study, we isolated 10 carbazole alkaloids from the plant species Murraya koenigii (Rutaceae), and examined their effects on the growth of the human leukemia cell line HL-60. Three carbazole alkaloids, mahanine (6), pyrayafoline-D (7) and murrafoline-I (9), showed significant cytotoxicity against HL-60 cells. Fluorescence microscopy with Hoechst 33342 staining revealed that the percentage of apoptotic cells with fragmented nuclei and condensed chromatin was increased in a time-dependent manner after treatment with each alkaloid. Interestingly, each carbazole alkaloid induced the loss of mitochondrial membrane potential. In addition, both caspase-9 and caspase-3 were also time-dependently activated upon treatment with the alkaloids. Caspase-9 and caspase-3 inhibitors suppressed apoptosis induced by these alkaloids. The results suggest that these three alkaloids induced apoptosis in HL-60 cells through activation of the caspase-9/caspase-3 pathway, through mitochondrial dysfunction.

Tricalysiosides H-O: Ent-kaurane glucosides from the leaves of Tricalysia dubia

Eight ent-kaurane glucosides, named tricalysiosides H-O, were isolated from Tricalysia dubia. Tricalysioside H possessed a hydroxyl group at the 1-position, to which the glucose moiety was attached. The structure was first elucidated by means of spectroscopic data analysis and finally confirmed by X-ray crystallography. Since acid hydrolysis of 1 gave D-glucose, the aglycone was proved to have an enantio-kaurane type skeleton. The structures of tricalysiosides I-O were mainly elucidated from analysis of spectroscopic evidence.

Four ent-kaurane-type diterpenoids from Croton tonkinensis Gagnep

From the leaves of the endemic Vietnamese medicinal plant Croton tonkinensis GAGNEP. (Euphorbiaceae) the four new ent-kaurane-type diterpenoids ent-1alpha,14alpha-diacetoxy-7beta-hydroxykaur-16-en-15-one (1), ent-1alpha,7beta-diacetoxy-14alpha-hydroxykaur-16-en-15-one (2), ent-18-acetoxy-14alpha-hydroxykaur-16-en-15-one (3), and ent-(16S)-18-acetoxy-7beta-hydroxykauran-15-one (4) were isolated. Their structures were elucidated by spectroscopic analyses.

Cytotoxic Diterpenoids from Vietnamese Medicinal Plant Croton tonkinensis GAGNEP

Six new ent-kaurane-type diterpenoids were isolated from the leaves of the endemic Vietnamese medicinal plant Croton tonkinensis GAGNEP. (Euphorbiaceae) together with three known ent-11alpha-acetoxy-7beta,14alpha-dihydroxykaur-16-en-15-one (1), ent-kaur-16-en-15-one 18-oic acid (5) and ent-18-hydroxykaur-16-ene (7). Their structures were determined by spectroscopic analyses to be ent-7beta-acetoxy-11alpha-hydroxykaur-16-en-15-one (2), ent-18-acetoxy-11alpha-hydroxykaur-16-en-15-one (3), ent-11alpha-acetoxykaur-16-en-18-oic acid (4), ent-15alpha,18-dihydroxykaur-16-ene (6), ent-11alpha,18-diacetoxy-7beta-hydroxykaur-16-en-15-one (8), and ent-(16S)-1alpha,14alpha-diacetoxy-7beta-hydroxy-17-methoxykauran-15-one (14). ent-Kaurane-type diterpenoids from Croton tonkinensis 2-4, 6, and 9-13, were tested for toxicity in the brine shrimp lethality assay. Compounds 9, 10, and 12 demonstrated significant activity, compounds 2, 3, 6, and 11 showed weak activity, and compounds 4 and 13 were inactive.

Kaurene Diterpene Induces Apoptosis in Human Leukemia Cells Partly through a Caspase-8-Dependent Pathway

Defects in apoptosis signaling pathways contribute to tumorigenesis and drug resistance, and these defects are often a cause of failure of chemotherapy. Thus, a major goal in chemotherapy is to find cytotoxic agents that restore the ability of tumor cells to undergo apoptosis. We previously found that an Ent-kaurene diterpene, Ent-11alpha-hydroxy-16-kauren-15-one (KD), induced apoptosis in human promyelocytic leukemia HL-60 cells. Here, we found that caspase-8, an apoptotic factor, is involved in KD-induced apoptosis. Although treatment of HL-60 cells with KD resulted in the activation of caspase-8 and -9, a caspase-8-specific inhibitor but not a caspase-9-specific inhibitor attenuated KD-induced apoptosis. Expression of a catalytically inactive caspase-8 partly attenuated KD-induced apoptosis. Treatment with KD led to a time-dependent cleavage of Bid, a substrate of caspase-8, as well as to the proteolytic processing of procaspase-8, indicating that KD treatment induces apoptosis through a caspase-8-dependent pathway. Moreover, overexpression of the drug resistance factor Bcl-2, which is frequently overexpressed in many tumors, failed to confer resistance to KD-induced cytotoxicity. Thus, KD may be a promising experimental cytotoxic agent that possibly points to new strategies to overcome a drug resistance.

The microbiological transformation of two 15beta-hydroxy-ent-kaurene diterpenes by Gibberella fujikuroi

The incubation of 15beta-hydroxy-3-oxo-ent-kaur-16-ene (1) with the fungus Gibberella fujikuroi afforded 11beta-hydroxy-3,15-dioxo-ent-kaurane (6), 11beta,15beta-dihydroxy-3-oxo-ent-kaur-16-ene (8), 7beta,11beta,15beta-trihydroxy-3-oxo-ent-kaur-16-ene (9), 7alpha,11beta-dihydroxy-3,15-dioxo-ent-kaurane (7), and 7alpha,11beta,15beta-trihydroxy-3-oxo-ent-kaur-16-ene (10). The incubation of 15beta-hydroxy-ent-kaur-2,16-diene (3) with the same fungus yielded 7alpha,11beta-dihydroxy-15-oxo-ent-kaur-2-ene (12), 7alpha,11beta,15beta-trihydroxy-ent-kaur-2,16-diene (13), 7beta,15beta-dihydroxy-ent-kaur-2,16-dien-19,6-olide (14), 1beta,7beta,15beta-trihydroxy-ent-kaur-2,16-dien-19-oic acid (15), 7alpha,11beta,16alpha-trihydroxy-15-oxo-ent-kaur-2-ene (17), and 7alpha,15beta,17-trihydroxy-11beta,16beta-epoxy-ent-kaur-2-ene (19). These results indicated that a 3-oxo group in ent-kaur-16-ene derivatives inhibits the oxidation at C-19, typical of the biosynthetic pathway of gibberellins and kaurenolides, while a 2,3-double bond or a 15beta-OH does not. In both substrates a 15beta-alcohol directs hydroxylations at C-11(beta) and C-7(alpha), while in those with a 2,3-double bond the functionalization of C-1(beta) is favored.

ent-Kaurane diterpenoids from croton tonkinensis inhibit LPS-induced NF-kappaB activation and NO production

Four ent-kaurane diterpenoids including two known, ent-7alpha,14beta-dihydroxykaur-16-en-15-one (1) and ent-18-acetoxy-7alpha-hydroxykaur-16-en-5-one (2), and two new, ent-1beta-acetoxy-7alpha,14beta-dihydroxykaur-16-en-15-one (3) and ent-18-acetoxy-7alpha,14beta-dihydroxykaur-16-en-15-one (4), were isolated from the leaves of Croton tonkinensis in a search for inhibitors of NF-kappaB activation and nitric oxide production. These ent-kauranoids inhibited LPS-induced NF-kappaB activation in murine macrophage RAW264.7 cells at IC50 values between 0.07 and 0.42 microM. Consistently, the ent-kauranoids markedly reduced LPS-induced NO production in a comparable concentration-dependent manner.

Volatile components of selected species of the liverwort genera Frullania and Schusterella (Frullaniaceae) from New Zealand, Australia and South America: a chemosystematic approach

The volatile components of 25 taxa of the liverwort family Frullaniaceae from New Zealand, Australia and South America have been analyzed by GC-MS. The present Frullania species are chemically divided into five major types: (1) sesquiterpene lactones, (2) sesquiterpene lactones-bibenzyls, (3) bibenzyls, (4) 2-alkanone and (5) triterpene types; the latter two chemo-types are newly proposed for the genus. Schusterella chevalierii, belonging to the Frullaniaceae, is closely related chemically to the sesquiterpene lactone type of the Frullania species since it elaborates two eudesmanolides, beta-cyclocostunolide and dihydro-beta-cyclocostunolide as major components.

New ent-Kaurene-Type Diterpenoids Possessing Cytotoxicity from the New Zealand Liverwort Jungermannia Species

Two new ent-kaurene-type and a new rearranged ent-kaurene-type diterpenoids possessing cytotoxicity against a human leukemia cell line have been isolated from the New Zealand liverwort Jungermannia species, together with previously known ent-kaurene-type diterpenoids. Their structures were established based on extensive NMR techniques.