Neue pyron-derivate aus Helichrysum-arten

The investigation of five further Helichrysum species afforded in addition to known compounds nine α-pyrone derivatives all also being phloroglucinol derivatives. Furthermore, a new toxol derivative has been isolated. The structures were elucidated by extensive NMR studies and by some chemical transformations. The chemotaxonomic situation is discussed briefly.     

Neue phloroglucin-derivate aus Leontonyx-arten sowie weitere verbindungen aus vertretern der tribus inuleae

The investigation of several South African species of the tribe Inuleae afforded in addition to known compounds 16 new constituents. From Leontonyx a group of 9 new phloroglucinol derivatives, from Stoebe species two new p-hydroxyacetophenone, two thymol and two coumaric acid derivatives and from Relhania a new euparine-derivative were isolated. The structures are elucidated mainly by spectroscopic methods. The chemotaxonomic aspects are discussed briefly. The phloroglucinol derivatives, which in part are derived from geraniol, seem to be especially characteristic.     

Petiolins A-C, phloroglucinol derivatives from Hypericum pseudopetiolatum var. kiusianum

Two new phloroglucinol derivatives possessing chromane skeleton, petiolins A (1) and B (2), and a new phloroglucinol derivative containing a dihydrofuran ring, petiolin C (3), were isolated from aerial parts of Hypericum pseudopetiolatum var. kiusianum. The gross structures of 1-3 were elucidated by spectroscopic data, and the relative stereochemistry of 3 was elucidated by NOESY data. Petiolins A-C (1-3) showed modest cytotoxicity, while petiolin C (3) exhibited antifungal activity.     

Synthesis of 4-arylcoumarins from Coutarea hexandra

The structures assigned to the 5,7-dimethoxy-4-arylcoumarins isolated from Coutarea hexandra have been confirmed by synthesis, via Pechmann condensation of phloroglucinol and an ethyl benzoylacetate derivative, the hydroxy groups of which were protected either by benzylation or by methylenedioxy group formation.     

Neue phloroglucin-derivate aus Helichrysum natalitium und Helichrysum bellum

Helichrysum natalitium afforded four new phloroglucinol derivatives, while from H. bellum two further compounds of this type have been isolated; H. platypterum yielded two known derivatives. The new structures were elucidated by spectroscopic methods and some chemical transformations. The chemotaxonomical situation is briefly discussed.     

Neue flavone und phloroglucin-derivate aus Helichrysum herbaceum und Helichrysum chrysargyrum

The investigation of two further South African Helichrysum species afforded five new flavones and six new phloroglucinol derivatives. The structures were elucidated by spectroscopic methods and some chemical transformations. The chemotaxonomic situation is discussed briefly.     

Prostaglandin E2 production and induction of prostaglandin endoperoxide synthase-2 is inhibited in a murine macrophage-like cell line,RAW 264.7, by Mallotus japonicus phloroglucinol derivatives

An aqueous acetone extract obtained from the pericarps of Mallotus japonicus (MJE) was observed to inhibit prostaglandin (PG) E₂ production in a lipopolysaccharide (LPS)-activated murine macrophage-like cell line, RAW 264.7. Six phloroglucinol derivatives isolated from MJE exhibited inhibitory activity against PGE₂ production. Among these phloroglucinol derivatives, isomallotochromanol showed the strongest inhibitory activity, with an IC₅₀ of 1.0 μM. MJE and its phloroglucinol derivatives did not effect the enzyme activity of either prostaglandin endoperoxide synthase (PGHS)-1 or PGHS-2. However, induction of PGHS-2 in LPS-activated macrophages was inhibited by MJE and its phloroglucinol derivatives, whereas the level of PGHS-1 protein was not affected. Moreover, RT-PCR analysis showed that MJE and its phloroglucinol derivatives significantly suppressed PGHS-2 mRNA expression. Therefore, the observed inhibition of PGHS-2 induction by MJE and its phloroglucinol derivatives was likely due to a suppression of PGHS-2 mRNA expression. These results suggest that MJE and its phloroglucinol derivatives have the pharmacological ability to suppress PGE₂ production by activated macrophages.     

Inhibitory effects of phloroglucinol derivatives from Mallotus japonicus on nitric oxide production by a murine macrophage-like cell line,RAW 264.7, activated by lipopolysaccharide and interferon-γ

An aqueous acetone extract of the pericarps of Mallotus japonicus (MJE) inhibited nitric oxide (NO) production by a murine macrophage-like cell line, RAW 264.7, which was activated by lipopolysaccharide (LPS) and interferon-γ (IFN-γ). Seven phloroglucinol derivatives isolated from MJE exhibited inhibitory activity against NO production. Among these phloroglucinol derivatives, isomallotochromanol exhibited strong inhibitory activity toward NO production, exhibiting an IC₅₀ of 10.7 μM. MJE and the phloroglucinol derivatives significantly reduced both the induction of inducible nitric oxide synthase (iNOS) protein and iNOS mRNA expression. NO production by macrophages preactivated with LPS and IFN-γ for 16 h was also inhibited by MJE and the phloroglucinol derivatives. Furthermore, MJE and the derivatives directly affected the conversion of L-[¹⁴C]arginine to L-[¹⁴C]citrulline by the cell extract. These results suggest that MJE and the phloroglucinol derivatives have the pharmacological ability to suppress NO production by activated macrophages. They inhibited NO production by two mechanisms: reduction of iNOS protein induction and inhibition of enzyme activity.     

Obliquin derivatives and other constituents from Australian Helichrysum species

The investigation of three Australian Helichrysum species afforded in addition to known compounds three new obliquin derivatives, eight cinnamic acid derivatives, a tremetone derivative, a styrene derivative, two lignans, two caryophyllene derivatives and an azulene. The structures were elucidated by highfield ¹H NMR.     

Neue germacranolide aus Calea urticifolia

The investigation of Calea urticifolia afforded eight new germacranolides. While five are heliangolides, three are of a new type and have some unusual structural features. The structures are elucidated by extensive ¹H-NMR studies and some chemical transformations. In addition, a new isoeugenol and an unusual phloroglucinol derivative were isolated; the structure of the latter could only be established after some chemical transformations. Other Calea species contain typical C₁₇ acetylenes only, also present in other species of the subtribe Galinsoginae. So far, the results on Calea indicate that the genus is chemically heterogenous.     

6-Acyl-4-aryl/alkyl-5,7-dihydroxycoumarins as anti-inflammatory agents

A series of coumarin derivatives were synthesized in two steps from phloroglucinol. The anti-inflammatory activities of these derivatives were evaluated by means of inhibiting NO production in LPS-induced RAW 264.7 cells. Derivatives 3, 8, 10, 11, and 13 exhibited low micromolar levels of anti-inflammatory activities, and these derivatives also protected DNA against hydroxyl radical attack. Coumarin derivative 8 was the most potent derivative among those tested herein against NO production in LPS-induced RAW 264.7 cells with an IC(50) value of 7.6 microM, and it effectively reduced the hydroxyl radical production by 50% at 100 microM in the electron spin resonance study.     

A daucanolide further farnesene derivatives from Ageratum fastigiatum

A reinvestigation of Ageratum fastigiatum afforded, in addition to known compounds, several new farnesene derivatives including some tetrahydropyrane derivatives. Furthermore a sesquiterpene lactone derived from daucane and a minor derivative of the ent-labdanes isolated previously were isolated. The structures were elucidated by spectroscopic methods.     

Cuauthemone sesquiterpenoids from Blumea alata

The investigation of five Blumea species afforded, in addition to known compounds, several cuauthemone derivatives, most of them being 7,11-epoxides, some thymol derivatives, an eremophilane epoxide and a himachalane diol. From Pterocaulon virgatum a further himachalane derivative was isolated. The structures were elucidated by spectroscopic methods and in part by partial synthesis.     

Phloroglucinol derivatives of Hagenia abyssinica

Four phloroglucinol derivatives have been isolated from Hagenia abyssinica (Bruce) Gmel. The structure (IV) and partial structures (V), (VI) and (VII) are proposed. All are mixtures of isobutyryl (iB), isovaleryl (iV) and 2-methylbutyryl (2-MeB) side chain homologues. The two latter acyl groups have been detected for the first time in kousso.     

Humulene derivatives from Heterotheca villosa

The aerial parts of Heterotheca villosa afforded, in addition to known compounds, eleven new humulene derivatives. The roots gave a new umbelliferone derivative. The structures were elucidated by high-field NMR spectroscopy.     

Phloroglucinol derivatives from Mallotus pallidus

From the leaves of Mallotus pallidus were isolated five phloroglucinol derivatives, namely pallidusol, dehydropallidusol, pallidol, mallopallidol and homomallopallidol. Their structures were determined by means of spectroscopic methods of analysis.     

A phloroglucinol derivative of Dryopteris abbreviata

A new phloroglucinol derivative, abbreviatin BB, has been isolated from Dryopteris abbreviata. Its structure was elucidated to be methylene-bis-met     

Non-acetalic thapsane sesquiterpenoids from Thapsia villosa var. minor

The benzene extract from the roots of T. villosa var. minor has afforded the new thapsane derivatives 15-acetoxythapsan-14-al, (1S)-1-senecioyloxy-6(14)-thapsen-15-ol, (1S,6R)-1-senecioyloxy-6,14-epoxythapsan-15-ol and its acetate. Their structures were deduced from spectral data and chemical transformation into known hemiacetalic thapsane derivatives. Acid rearrangement of the epoxythapsane acetate gave a 6-epi-formyl derivative and a bicyclo[4.4.0]decadiene derivative.     

Neue acetylenverbindungen aus chrysothamnus parryl

The investigation of Chrysothamnus parryi afforded, in addition to known compounds, several new matricaria ester derivatives. The structures were elucidated by spectroscopic methods and some chemical transformations. Furthermore, a naphthol derivative was isolated. Chemotaxonomic aspects are discussed briefly.     

Future meetings

The investigation of one representative of the genus Morithamnus afforded, in addition to several known compounds, a new ent-labdane derivative, a new hydroxy-ent-kauranol and three tremetone derivatives. The structures were elucidated by spectroscopic methods. The chemotaxonomic situation is discussed briefly.