Agariblazeispirol C from the cultured mycelia of the fungus, Agaricus blazei, and the chemical conversion of blazeispirol A

Agariblazeispirol C, which has a unique steroidal skeleton, has been isolated from the cultured mycelia of Agaricus blazei (Agaricaceae). The structure of agariblazeispirol C was established to be (23S,24S)-13,23-cyclo-25-hydroxy-14β-methyl-18-nor-des-A-ergosta-5,7,9,11,17(20)-pentaen-22-one by comparison of extensive 1D and 2D NMR spectral data with those of agariblazeispirols A and B. At the same time, agariblazeispirol C was synthesized by the reaction of blazeispirol A with BF₃·OEt₂ along with some interesting compounds.     

Schilancidilactones A and B: two novel tetranortriterpenoids with an unprecedented skeleton from Schisandra lancifolia

Schilancidilactones A (1) and B (2), two novel tetranortriterpenoids possessing an unprecedented skeleton, have been isolated from the stems of Schisandra lancifolia. Their structures were elucidated on the basis of extensive spectroscopic analysis. The relative configurations of 1 were further determined by single-crystal X-ray crystallography. Compounds 1 and 2 were tested for their cytotoxicity against four tumor cell lines NB4, A549, SH-SY5Y, and PC-3, and compound 1 was further tested for its anti-HIV-1 activity.     

Chloctanspirones A and B, novel chlorinated polyketides with an unprecedented skeleton, from marine sediment derived fungus Penicillium terrestre

Two novel chlorinated sorbicillinoids named chloctanspirones A (1) and B (2), possessing an unprecedented bicyclo[2.2.2]octane-2-spiro cyclohexane skeleton, together with their quasi-precursors terrestrols K (3) and L (4), two additional new chlorinated compounds, were isolated from a marine sediment derived fungus Penicillium terrestre. Their structures including absolute stereochemistries were elucidated by analysis of NMR, MS data, and TDDFT CD calculations. The cytotoxic effects of 1-4 were preliminarily evaluated in HL-60 and A-549 cells. Compound 1 was active against both HL-60 and A-549 cells with IC₅₀s 9.2 and 39.7 μM, respectively, while 2 showed weaker activity only against HL-60 cells (IC₅₀ 37.8 μM).     

Calyciphylline G, a novel alkaloid with an unprecedented fused-hexacyclic skeleton from Daphniphyllum calycinum

Calyciphylline G (1), a novel Daphniphyllum alkaloid with an unprecedented fused-hexacyclic skeleton containing a 5-azatricyclo[6.2.1.0^1,5]undecane ring, has been isolated from the stem of Daphniphyllum calycinum (Daphniphyllaceae), and the structure and relative stereochemistry were elucidated on the basis of spectroscopic data.     

Suffruticosine, a novel octacyclic alkaloid with an unprecedented skeleton from Securinegasuffruticosa (Pall.) Rehd.

A novel securinega alkaloid, suffruticosine (1), was isolated from the leaves and barks of Securinegasuffruticosa. The structure of 1, characterized by a fused complex octacyclic system, was elucidated by combined spectroscopic techniques, especially 2D NMR and CD spectral analyses.     

Neoverataline A and B, two antifungal alkaloids with a novel carbon skeleton from Veratrum taliense

Bioassay-guided fractionation of the ethanol extract of the roots and rhizomes of Veratrum taliense yielded two new and thirteen known steroidal alkaloids. The structures of the two new compounds, neoverataline A and B, were established by extensive spectroscopic analyses to be 3,4-secocevane-4,9-olid-14,15,16,20-tetra-ol-3-oic acid and 3,4-secocevane-4,9-olid-7,14,15,16,20-penta-ol-3-oic acid, respectively, and are a novel carbon skelton. All of the fifteen alkaloids were subjected to in vitro antifungal assays, which showed that the verazine- (veramitaline, stenophylline B, stenophylline B-3-O-β-d-glucopyranoside, veramiline-3-O-β-d-glucopyranoside) and jerveratrum-type (jervine, jervine-3-O-β-d-glucopyranoside) alkaloids exhibited strong antifungal activities against the phytopathogenic fungus Phytophthora capisis with MICs of 160, 120, 160, 80, 80 and 120 μg·L⁻¹, respectively. Furthermore, the verazine-type alkaloids stenophylline B, stenophylline B 3-O-β-d-glucopyranoside and veramiline 3-O-β-d-glucopyranoside were shown to also inhibit the growth of another fungal phytopathogen Rhizoctonia cerealis with MICs of 160, 120 and 120 μg mL⁻¹. The MICs of triadimefon (an antifungal agrochemical used herein as a positive control) against P. capisis and R. cerealis were 120 and 80 μg mL⁻¹, respectively. A preliminary structure-activity relationship regarding these alkaloids has been formulated.     

Novel alkaloids, paxdaphnines A and B with unprecedented skeletons from the seeds of Daphniphyllum paxianum

Two novel Daphniphyllum alkaloids with unprecedented skeletons, namely paxdaphnines A (1) and B (2), have been isolated from the seeds of Daphniphyllum paxianum. Paxdaphnine A (1) is a 19-nor-Daphniphyllum alkaloid with highly caged skeleton, and paxdaphnine B (2) is the first 1,19-bisnor-Daphniphyllum alkaloid. The relative structures of 1 and 2 were elucidated by spectral methods, and their unique biosynthetic pathway postulated. The absolute structure of 1 was determined by X-ray diffraction of the iodide derivative (1a) of 1, and the absolute stereochemistry of 2 was proposed by correlation with the biosynthetic pathway for 1.     

Three novel quassinoids, javanicolides A and B, and javanicoside A, from seeds of Brucea javanica

Two novel quassinoids, javanicolides A and B, and one novel quassinoid glucoside, javanicoside A were isolated from the seeds of Brucea javanica Merr. (Simaroubaceae), along with four known quassinoids, yadanziolides A and D, and bruceins D and E, and two known quassinoid glucosides, yadanziosides D and L. Their structures were elucidated by the analysis of spectral data and chemical evidence.     

Mekongenines A and B, two new alkaloids from Bousigonia mekongensis

Mekongenine A (1) possessing an unprecedented structure constituted from the union of a rare 2,7-seco eburnamine half and an aspidospermine alkaloid, together with a new bisindole alkaloid, mekongenine B (2), consisting of an eburnamine-aspidospermine type skeleton, was isolated from Bousigonia mekongensis. Their structures were elucidated by means of spectroscopic methods and those of 2 were further confirmed by X-ray diffraction. The absolute configurations of 1 and 2 were determined by comparison of quantum chemical TDDFT calculated and experimental ECD spectra. Mekongenines A (1) and B (2) exhibited cell growth inhibitory activities against various human cancer cell lines.     

Multistalides A and B, two novel sesquiterpenoid dimers from Chloranthus multistachys

Two novel sesquiterpenoid dimers, multistalides A and B (1-2), were isolated from the whole plant of Chloranthus multistachys. Their structures were established on the basis of spectroscopic analysis, and the absolute configuration of 1-2 was determined by CD exciton chirality method.     

Briaexcavatins A and B, novel briaranes from the octocoral Briareum excavatum

Two novel briaranoidal derivatives, designated as briaexcavatins A (1) and B (2), along with two known metabolites, excavatolides B and C (3 and 4), were isolated from the octocoral Briareum excavatum. Both compounds 1 and 2 possess unprecedented 5,6-epoxy moiety in the 10-membered ring. Diterpenoid 1 possesses a novel pentacyclic skeleton with a ε-lactone. The structures of diterpenoids 1 and 2 were elucidated by interpretation of spectral data and the absolute stereochemistry was established by application of modified Mosher’s method on 3.     

Swiemahogins A and B, two novel limonoids from Swietenia mahogani

Two novel limonoids, swiemahogins A (1) and B (2) isolated from the twigs and leaves of Swietenia mahogany, are the first examples of andirobin and phragmalin types of limonoids, of which the D-ring δ-lactone is demolished and a rare γ-lactone is fused to the C-ring at C-8 and C-14. Their structures were elucidated by extensive spectroscopic means, and that of 1 was confirmed by single-crystal X-ray diffraction.     

Dilospiranes A and B: diterpenes featuring novel carbocyclic units from the brown alga Dilophus spiralis

Dilospiranes A and B (1 and 2), two diterpenes featuring unprecedented carbocycles, were isolated from the organic extract of the brown alga Dilophus spiralis, collected from the coast of Elafonissos Island, Greece. The structures and the relative configurations of the isolated natural products were determined on the basis of extensive analyses of their spectroscopic data.     

Two novel tetracycles,cassibiphenols A and B from the flowers of Cassia siamea

Chemical investigation of the flowers of Cassia siamea (Leguminosae), resulted in the isolation of two novel tetracycles connecting 5-(2-hydroxypropyl)benzene-1,3-diol, cassibiphenols A (1) and B (2). The structures were elucidated by analysis of the 1D, 2D NMR, and HRMS spectra. Synthesis of a tetracyclic core of 1 and 2 led to determine the absolute configuration of 1 and C-12 of 2.     

Pestalustaines A and B,unprecedented sesquiterpene and coumarin derivatives from endophytic fungus Pestalotiopsis adusta

Pestalustaines A (1) and B (2), one unique sesquiterpene possessing an unusual 5/6/7-fused tricyclic ring system and one unprecedented coumarin derivative bearing 6/6/5/5-fused tetracyclic ring system, were isolated from the plant-derived Pestalotiopsis adusta. Their structures with absolute configurations were established by extensive NMR analysis, X-ray crystallography, and CD spectra associated with TD-DFT calculation. Hypothetical biosynthetic pathways for compounds 1 and 2 are proposed. Compounds 1 and 2 showed weak to moderate cytotoxic activities against three human tumor cell lines HeLa, HCT116, and A549, whose IC₅₀ values were ranged from 21.01 to 55.43?μM.     

Uragogin and blepharodin, unprecedented hetero-Diels-Alder adducts from Celastraceae species

Uragogin and blepharodin were isolated from Crossopetalum uragoga and Maytenus magellanica, respectively. They represent the first examples of a triterpene-neolignan ester and a heptacyclic arylpropanoid-nor-triterpenephenol, hetero-Diels-Alder adducts built with dioxane bridges. Their proposed biosynthetic route is discussed.     

Volvalerenone A, a new type of mononorsesquiterpenoid with an unprecedented 3,12-oxo bridge from Valeriana officinalis

Volvalerenone A (1), a new type of mononorsesquiterpenoid with an unprecedented 5/6/6 tricyclic ring system, was isolated from the roots of Valeriana officinalis, the official species of valerian used in Europe. The structure of volvalerenone A was elucidated based on its spectroscopic and single-crystal X-ray crystallography data. The absolute configuration was assigned by the computational method. A possible biosynthetic pathway of volvalerenone A was also proposed. Preliminary biological studies showed that volvalerenone A had weak inhibitory activity on acetylcholine esterase (AChE), and no enhancing activity on nerve growth factor (NGF)-mediated neurite outgrowth in PC12 cells was observed at 50 μM.     

Daphnilongerine, an unprecedented fused pentacyclic ring system alkaloid from Daphniphyllum longeracemosum Rosenth.

An unusual yuzurine-type alkaloid daphnilongerine (1), with an unprecedented fused pentacyclic skeleton in addition to seven known ones, daphnigracine (2), daphnezomine R, daphnigraciline, yuzurine, longistylumphyllines A, daphnilongeranin C, and calycinine A, was isolated from the fruits of Daphniphyllum longeracemosum. The structure and relative stereochemistry of 1 were determined by spectroscopic analysis.     

Penicillones A and B, two novel polyketides with tricyclo [5.3.1.0] undecane skeleton, from a marine-derived fungus Penicillium terrestre

Two novel polyketides, penicillones A (1) and B (2), with tricyclo [5.3.1.0^3,8] undecane skeleton, were isolated from Penicillium terrestre. Their structures and relative stereochemistries were determined on the basis of spectroscopic methods. The absolute configuration of 2 was established by the modified Mosher’s method, while that of 1 was deduced from the similar CD absorptions of 1 and 2. Compound 1 showed weak cytotoxicities against P338 and A-549 cell lines, while 2 was inactive against P388.     

Emervaridione and varioxiranediol, two new metabolites from the endophytic fungus, Emericella variecolor

Two new compounds, emervaridione and varioxiranediol, together with the three known compounds, stellatic acid, ergosterol and dihydroterrein, were isolated from the endophytic fungus, Emericella variecolor. The structures of emervaridione and varioxiranediol were established from spectroscopic and X-ray crystallographic analysis.