Karlheinz Seifert

Triterpenoid saponins from the roots of Zygophyllum species

Two new triterpenoid saponins, 3-O-[beta-D-2-O-sulphonylglucopyranosyl]-quinovic acid-28-O-[beta-D-glucopyranosyl] ester (zygophyloside G), 3-O-[alpha-L-arabinopyranosyl-(1-->2)-beta-D-quinovopyranosyl++ +]-quinovic acid-28-28-O-[beta-D-glucopyranosyl] ester (zygophyloside H), and seven known saponins have been isolated. The structures were established primarily on the basis of NMR spectroscopy. The assignment of all NMR signals was performed by means of 1H-1H COSY-45, NOESY, TOCSY, 13C APT, HMQC and HMBC experiments. The determination of the glycosylation sites was possible by the HMBC experiments.

Triterpenoid saponins from Zygophyllum species

Abstract From the roots of Zygophyllum coccineum and the aerial parts of Z. album and Z. dumosum, the new triterpenoid saponin 3-O-[β-d-2-O-sulphonylquinovopyranosyl]-quinovic acid -27-O-[β- d -glucopyranosyl ] ester (zygophyloside F) has been isolated. The known saponins, 3-O-[β- d -quinovopyranosyl ]- quinovic acid 27-O-[β- d -glucopyranosyl ] ester and 3-O-[β- d -quinovopyranosyl ]- quinovic acid, were isolated from the aerial parts of Z. dumosum. The structures were determined primarily on the basis of NMR spectroscopy. The assignment of the NMR signals were performed by means of 1H1H COSY −45°, HMQC, HMBC and TOCSY experiments.

Furanocembranoids from the Soft Corals Sinularia asterolobata and Litophyton arboreum

The new cembranoid diterpene danielid (1) along with 3α‐ethoxyfuranocembranoid 2, pukalide (3), 13α‐acetoxypukalide (4), furanocembranoid 5, and furanosesquiterpene 6 have been isolated from the soft coral Sinularia asterolobata. The furanocembranoid diterpene 11β,12β‐epoxypukalide (7) and the sesquiterpene (−)‐bicyclogermacrene (8) have been obtained from the soft coral Litophyton arboreum. The structures were elucidated primarily by NMR spectroscopy. The furanocembranoids 2, 4, and 5 show good antiproliferative activities against the cell lines L‐929 and K‐562, and weak cytotoxic effects on HeLa cells.

Total synthesis of yahazunol, zonarone and isozonarone

Abstract The synthesis of the marine natural products zonarone and isozonarone was achieved via (+)-albicanic acid, a sesquiterpene of the drimane type. Coupling of the appropiate drimane-synthon with lithiated hydroquinone ethers led to sesquiterpene arenes, which were further modified to the target molecules. Stereoselective epoxidation followed by regioselective opening of the oxirane ring yielded yahazunol.

Synthesis and pharmacological activities of some sesquiterpene quinones and hydroquinones

Synthesis of protected siphonodictyal C was achieved via drim-7-en-11-al. Some sesquiterpene quinones and hydroquinones were tested for their pharmacological activities in assays in search of antiproliferative, cytotoxic, antiphlogistic, antirheumatic and anti-inflammatory drugs. Wiedendiol B is a ten times stronger cyclooxygenase-2 inhibitor than the reference compound indomethacine. Cyclooxygenase-2 inhibitors are drugs with antiphlogistic and antirheumatic activity.

Inhibition of juvenile hormone biosynthesis in Gryllus bimaculatus by Glycosmis pentaphylla leaf compounds

The EtOAc fraction of Glycosmis pentaphylla leaf extract inhibits the juvenile hormone III-biosynthesis in vitro of corpora allata from 3 day old females of the field cricket Gryllus bimaculatus. The bioactive compound which is responsible for this activity was identified as the quinazolone alkaloid arborine. This alkaloid showed also a larvicidal activity against the mosquito Culex quinquefasciatus.

SYNTHESIS OF (+)-CORONARIN E

The labdane-type diterpenoid (+)-coronarin E (5) has been synthesized in 7 steps from (−)-sclareol (1) for the first time.

Terpenes from the Soft Corals Litophyton arboreum and Sarcophyton ehrenbergi

The new cembrane diterpene (3E,11E)‐cembra‐3,8(19),11,15‐tetraene‐7α‐ol (1), nephthenol (2), and all‐trans‐peridinin (3) have been isolated from the soft coral Litophyton arboreum. The tetraterpene 3, (+)‐7,8‐epoxy‐7,8‐dihydrocembrene C (4), emblide (5), sarcophytoxide (6), sarcoglaucol‐16‐one (7), guajacophine (8), and 1,4‐peroxymuurol‐5‐ene (9) have been obtained from the soft coral Sarcophyton ehrenbergi. The compounds were characterized primarily by NMR spectroscopy. Some of the terpenes were tested for their antiproliferative activity against the cell lines HUVEC and K‐562 and for cytotoxicity against the cell line HeLa, and they showed moderate activities.

Cembranoid diterpenes and a briarane diterpene from corals

Two new cembrane diterpenes (+)-polydactylide (1) and (+)-7α,8β-dihydroxydeepoxysarcophine (2) together with (+)-sarcophine (3) and (+)-sarcophytoxide (4) have been isolated from the soft coral Sinularia polydactyla. The new cembrane diterpene (−)-7β-hydroxy-8α-methoxydeepoxysarcophine (5) has been obtained from the soft coral Sarcophyton trocheliophorum and the known briarane diterpene briaexcavatolide W (6) from the gorgonian coral Briareum sp. The structures were determined primarily by NMR spectroscopy. The assignment of NMR signals was performed by means of 1H–1H COSY, ROESY, HMQC and HMBC experiments.

Polyodonine, a prefuranic labdane diterpene from Marrubium polydon

Abstract The new prefuranic labdane diterpene 9 α ,13 R ;15,16-diepoxy-12-oxo-labd-14-en-19,6β-olide (polyodonine) has been isolated from the aerial parts of Marrubium polydon . The known 3-O-(β- d -glucopyranosyl)-3β-hydroxystigmast-5-ene and the flavone glucosides 7-O-[β- d -(6-O-p- coumaroyl)-glucopyranosyl]-apigenin and 7-O-[β- d -(3,6-di -O-p- coumaroyl)-glucopyranosyl]-apigenin were also obtained from the same source. The structure of polydonine has been determined primarily on the basis of NMR spectroscopy.