Isolation and structural elucidation of chemical constituents ofAmanoa almerindae

Chemical constituents of Avicennia alba. Isolation and structural elucidation of new naphthoquinones and their analogues.

Three new naphthoquinones and their analogues, named avicequinone-A (1), -B (2), -C (3), and avicenol-A (4), -B (5), -C (6), respectively, were isolated from the stem bark of Avicennia alba (Avicenniaceae) collected in Singapore, and their structures were elucidated by means of spectral methods. Gillan and co-workers have proposed that the structures of the new phytoalexins isolated from Avicen...

Chemical constituents of Micromelum minutum. Isolation and structural elucidation of new coumarins.

The chemical constituents of an acetone extract of the stems of Micromelum minutum Wight et Arn (Rutaceae), collected at Nakorn-Rachasima province in Thailand, were studied. Six new coumarins, named micromarin-A (1), -B (2), -C (3), -F (4), -G (5), and -H (6), were isolated along with six known coumarins, and their structures were elucidated by chemical and spectroscopic methods.

ISOLATION AND STRUCTURAL ELUCIDATION OF THE FIRST KNOWN C-HOMOPROTOBERBERINE

A novel C-homoprotoberberine alkaloid, Hediamine (2), has been isolated from the roots of Berberis actinucantha (Berberidaceae). Conclusive proof for the structure of hediamine was obtained by its comparison with the isomeric lactam (4), by chemical transformation, and by means of spectroscopic techniques (UV, IR, MS, NMR).

isolation and structural elucidation of natural products in euphorbia erythradenia

Fermentation, Isolation, Structural Elucidation and Biological Activities

A fermentation broth of an unidentified fungus (N983-46) was found to produce DNAgyrase inhibitors, CJ-12,371 (1) and CJ-12,372 (2). Following isolation by solvent extraction and silica gel and ODS(reverse phase) chromatographies, the structures were determined to be novel spiro-ketal compounds with S-connguration at position C-l. CJ-12,371 and CJ-12,372 inhibit both DNA supercoiling and relaxa...