Sesquiterpene lactones from Smyrnium cordifolium

In addition to previously obtained furanosesquiterpenes, two new eudesmanolides and a new glechomanolide were isolated from the fruits of Smyrnium cordifolium, while the roots gave two new eudesmanolides. The new compounds from the fruits were 1β-acetoxy-eudesman-4(15), 7(11)-dien-8,12-olide, 1β-acetoxy-8β-hydroxy-eudesman-4(15),7(11)-dien-8,12-olide, 1β,10α;4α,5β-diepoxy-8-hydroxy-glechomanolide, those obtained from the roots were smyrnicordiolide and the corresponding 8β-hydroxy derivative belonging to a new type of oxepine derivative.     

Synthesis of substituted septanosyl-1,2,3-triazoles

A carbohydrate-based oxepine, derived from 2-deoxy-d-arabino-hexopyranose, was used to prepare a family of septanosyl-1,2,3-triazoles in four steps. DMDO mediated epoxidation of the oxepine followed by trapping of the intermediate 1,2-anhydroseptanose by sodium azide gave the β-substituted glycosyl azide. The septanosyl azide was then reacted with a number of alkynes under thermal Huisgen or copper(I) mediated reaction conditions. Hydrogenolysis of benzyl protecting groups gave substituted septanosyl-1,2,3-triazoles. The new septanose-based structures were then evaluated as potential glycosidase inhibitors.     

New germacrolide- and heliangolide-type sesquiterpene lactones from Melampodium linearilobum

Chemical analysis of Melampodium linearilobum yielded, besides coumarin, seven germacrolide-type sesquiterpene lactones, linearilobin A to G and two heliangolides, linearilobin H and I. All new sesquiterpene lactones are oxygenated at C-14 and C-15 and differ by the number and types of ester moieties at C-8, C-14 and C-15. M. linearilobum represents the first species within the genus known to produce germacrolides and heliangolides instead of the more common melampolides.     

Three biflavonoids from Daphne odora

Three new biflavonoids, daphnodorins G-I, were isolated from the roots of Daphne odora and their structures established from spectral and chemical means. These are two C-7/C-2″, C-8/C-3″ biflavonoids (upper half: apigenin, lower half: afzelechin), daphnodorins G and H and a spirobiflavonoid, daphnodorin I.     

Alkaloids of Stephania sinica

A new hasubanan alkaloid named as runanine was isolated from Stephania sinica. On the basis of spectral analysis, four methoxyl groups could be located at C-2, C-3, C-7 and C-8, respectively. Its structure was determined to be 1. Two other known compounds, cepharanthine and sitosterol, were also obtained from this plant.     

4-Hydroxydehydromyoporone from infected Ipomoea batatas root tissue

A new sesquiterpenoid, 4-hydroxydehydromyoporone, was isolated from Ceratocystis fimbriata— infected root tissue of Ipomoea batatas. We showed that it was a derivative of myoporane with one hydroxyl group at C-8 and one double bond at C-12 by spectroscopic comparison with known compounds.     

Six new melampolides from Tetragonotheca helianthoides

Chemical analysis of Tetragonotheca helianthoides L. yielded six new melampolide-type sesquiterpene lactones, tetrahelins A–F. All new compounds have the same medium ring skeleton and differ by the ester moieties at C-8 and C-9. Tetrahelin A and B contain the side chain 2-methyl-2,3-diacetoxybutanoate and tetrahelin E 3-hydroxy-3-methylbutanoate. Both ester side chains have previously not been found in sesquiterpene lactones.     

Naphthoquinone dimers and trimers from Euclea natalensis

The naphthoquinone dimers natalenone, 8′-hydroxydiospyrin and euclanone and the trimers galpinone and a compound with MW 562 were isolated from E. natalensis roots. Natalenone is a dehydrodimer of 7-methyl- juglone with the two moieties linked by two CC bonds to give a fused tetracyclic structure, one ring bearing a methylene bridge. Galpinone is a 7-methyljuglone linear trimer, the three units probably being linked C-8-C-6′and C-3′-C-3″. Euclanone is a new dimer of 7-methyljuglone and methylnaphthazarin, isomeric with 8′-hydroxydiospyrin.     

Tri1 Encodes the Cytochrome P450 Monooxygenase for C-8 Hydroxylation during Trichothecene Biosynthesis in Fusarium sporotrichioides and Resides Upstream of Another New Tri Gene

Many Fusarium species produce one or more agriculturally important trichothecene mycotoxins, and the relative level of toxicity of these compounds is determined by the pattern of oxygenations and acetylations or esterifications on the core trichothecene structure. Previous studies with UV-induced Fusarium sporotrichioides NRRL 3299 trichothecene mutants defined the Tri1 gene and demonstrated that it was required for addition of the oxygen at the C-8 position during trichothecene biosynthesis. We have cloned and characterized the Tri1 gene from NRRL 3299 and found that it encodes a cytochrome P450 monooxygenase. The disruption of Tri1 blocks production of C-8-oxygenated trichothecenes and leads to the accumulation of 4,15-diacetoxyscirpenol, the same phenotype observed in the tri1 UV-induced mutants MB1716 and MB1370. The Tri1 disruptants and the tri1 UV-induced mutants do not complement one another when coinoculated, and the Tri1 gene sequence restores T-2 toxin production in both MB1716 and MB1370. The DNA sequence flanking Tri1 contains another new Tri gene. Thus, Tri1 encodes a C-8 hydroxylase and is located either in a new distal portion of the trichothecene gene cluster or in a second separate trichothecene gene cluster.     

Germacranolides from Viguiera microphylla

Three new germacranolides, including two heliangolides (niveusin C-2′,3′-epoxide and 1,2-dehydroniveusin C-2′,3′-epoxide) and a germacrolide (3β-hydroxy-8β-epoxyangeloyloxycostunolide-1β,10α-epoxide) were isolated from Viguiera microphylla. Their structures were established by spectroscopic analyses, including extensive ¹H NMR and ¹³C NMR decoupling experiments and chemical transformations. X-ray diffraction analysis confirmed the structure of niveusin C-2′,3′-epoxide.     

Fusarium Tri8 Encodes a Trichothecene C-3 Esterase

Mutant strains of Fusarium graminearum Z3639 produced by disruption of Tri8 were altered in their ability to biosynthesize 15-acetyldeoxynivalenol and instead accumulated 3,15-diacetyldeoxynivalenol, 7,8-dihydroxycalonectrin, and calonectrin. Fusarium sporotrichioides NRRL3299 Tri8 mutant strains accumulated 3-acetyl T-2 toxin, 3-acetyl neosolaniol, and 3,4,15-triacetoxyscirpenol rather than T-2 toxin, neosolaniol, and 4,15-diacetoxyscirpenol. The accumulation of these C-3-acetylated compounds suggests that Tri8 encodes an esterase responsible for deacetylation at C-3. This gene function was confirmed by cell-free enzyme assays and feeding experiments with yeast expressing Tri8. Previous studies have shown that Tri101 encodes a C-3 transacetylase that acts as a self-protection or resistance factor during biosynthesis and that the presence of a free C-3 hydroxyl group is a key component of Fusarium trichothecene phytotoxicity. Since Tri8 encodes the esterase that removes the C-3 protecting group, it may be considered a toxicity factor.     

Phragmalin-type limonoids with NF-κB inhibition from Chukrasia tabularis var. velutina

Chemical investigation on Chukrasia tabularis var. velutina led to the identification of eight new phragmalin-type limonoids (1–8), as well as 20 known analogues. Compounds 1–4 are a rare class of C-15-acyl phragmalin-type limonoids, and particularly compounds 2–4 also possess a δ-lactone ring formed between C-16 and C-30. All the isolates were evaluated for inhibitory effects on NF-κB production, and four of which showed significant inhibitions.     

Flavonoids and Isoflavonoids of Millettia dura and Millettia ferruginea: Phytochemical review and chemotaxonomic values

The phytochemical information on Millettia dura Dunn, M. ferruginea (Hochst.) Baker and M. ferruginea subsp. darassana (Cufod.) J.B. Gillett was reviewed. All the three taxa elaborate mainly isoflavones (33 reported), occurring in the flowers, seeds/seed pods, stem bark and root bark. Out of the 33 isoflavones reported, some 19 (ca. 58%) contain prenyl at C-8 or its modification as 2,2-dimethylchromene ring at C-7/C-8, occurring in all the three taxa. Except for three isoflavones isolated from M. ferruginea subsp. darassana, all the isoflavones of these taxa are 5-deoxygenated. In these taxa, oxygenation at C-6 is a common feature, while isoflavones with C-8 oxygenation are rare, only three reported, and all of these from M. dura. There are 7 rotenoids reported from these taxa, and occur almost entirely in the seeds/seedpods of these plants. The major rotenoid with methylenedioxy group at C-2/C-3, millettone and its 12a-hydroxy derivative, millettosine, occur only in M. dura, this appears to distinguish M. dura from M. ferruginea.     

Tri16 Is Required for Esterification of Position C-8 during Trichothecene Mycotoxin Production by Fusarium sporotrichioides

We previously characterized Tri1, a gene required for hydroxylation of the C-8 position during trichothecene mycotoxin biosynthesis in Fusarium sporotrichioides NRRL 3299. Sequence analysis of the region surrounding Tri1 revealed a gene, named Tri16, which could encode an acyltransferase. Unlike the wild-type parent strain NRRL 3299, which accumulates primarily T-2 toxin along with low levels of diacetoxyscirpenol (DAS) and neosolaniol (NEO) and trace amounts of 8-propionyl-neosolaniol (P-NEO) and 8-isobutyryl-neosolaniol (B-NEO), mutants containing a disruption of Tri16 were blocked in the production of the three C-8 esterified compounds T-2 toxin, P-NEO, and B-NEO and accumulated the C-8-hydroxylated compound NEO along with secondary levels of DAS. These data indicate that Tri16 encodes an acyltransferase that catalyzes the formation of ester side groups at C-8 during trichothecene biosynthesis. We also report the presence of a Tri16 ortholog in Gibberella pulicaris R-6380 that is likely linked to a presumably inactive ortholog for Tri1.     

Degradation of n-alkanes and polycyclic aromatic hydrocarbons in petroleum by a newly isolated Pseudomonas aeruginosa DQ8

A bacterial isolate, designated as DQ8, was found capable of degrading diesel, crude oil, n-alkanes and polycyclic aromatic hydrocarbons (PAHs) in petroleum. Strain DQ8 was assigned to the genus Pseudomonas aeruginosa based on biochemical and genetic data. The metabolites identified from n-docosane as substrate suggested that P. aeruginosa DQ8 could oxidize n-alkanes via a terminal oxidation pathway. P. aeruginosa DQ8 could also degrade PAHs of three or four aromatic rings. The metabolites identified from fluorene as substrate suggested that P. aeruginosa DQ8 may degrade fluorene via two pathways. One is monooxygenation at C-9 of fluorene, and the other is initiated by dioxygenation at C-3 and C-4 of fluorene. P. aeruginosa DQ8 should be of great practical significance both in bioremediation of oil-contaminated soils and biotreatment of oil wastewater.     

Sesquiterpene lactones of Piptothrix pubens

Eleven sesquiterpene lactones, six of which are new, were identified from Piptothrix pubens. All but one of the compounds contained a C₁₀-diester attached at C-8. The taxonomic implications of these results are discussed.     

Murragleinin,a coumarin from Murraya gleinei leaves

A new trioxygenated C-8 prenylated coumarin, 5,6,7-trimethoxy-8-(2′,3′-dihydroxyisopentenyl)-coumarin and the laevorotatory form of mexoticin, sibiricin and phebalosin were isolated from the leaves of Murraya gleinei together with the coumarins meranzin hydrate, meranzin, murralongin, murrangatin and scopoletin, the flavone exoticin, the alkaloid skimianine and the sterol stigmasterol.     

Synthesis of antiproliferative flavones from calycopterin, major flavonoid of Calycopteris floribunda Lamk

Eighteen new analogues of 5,3′-dihydroxy-3,6,7,8,4′-pentamethoxy-flavone, a potent natural cytotoxic and antimitotic flavone, were synthesized from calycopterin, the major flavonoid of Calycopteris floribunda Lamk., a traditional Asian medicinal plant. One of them, the 3′-amino substituted analogue, displayed almost the same activity as the reference compound. Pharmacomodulation at C-3′ on the B-ring, and at C-5,6,7 and 8 on the A-ring allowed to refine structure-activity relationships within the cytotoxic flavones series.     

Diterpenoids from Sideritis varoi subspecies cuatrecasasii: 13C NMR of ent-13-epi-manoyl oxides functionalized at C-12

Several ent-13-epi-manoyl oxides and a new natural product, ent-8α-hydroxylabda-13(16),14-dien-19-oic acid, have been isolated from Sideritis varoi subsp. cuatrecasasii. In addition, a study has been made of some natural and semisynthetic ent-13-epi-manoyl oxides functionalized at C-12.     

Amphidinol C,a major polyketide from an Irish strain of the dinoflagellate Amphidinium carterae

An Irish strain of the dinoflagellate Amphidinium carterae was previously shown to produce antibacterial amphidinol derivatives of unknown masses. Inspection of the major metabolites present in a bulk culture of this strain led to the isolation and structure elucidation of a new amphidinol derivative named amphidinol C featuring an unprecedented tetrahydropyran ring between the positions C-7 and C-11. The structure was determined using extensive analyses of NMR and MS data and comparison with data of analogues. The new ring was proposed to stem from a nucleophilic substitution of the sulphate present on the side chain of Amphidinol B. The major metabolites isolated were tested for their antibacterial and antifungal activities and Amphidinol C showed moderate fungicidal activity against yeast and filamentous fungi at 8–16 µg mL⁻¹.