Antitubercular natural products: berberine from the roots of commercial Hydrastis canadensis powder. Isolation of inactive 8-oxotetrahydrothalifendine, canadine, beta-hydrastine, and two new quinic acid esters, hycandinic acid esters-1 and -2.

Berberine (4) is responsible for the activity of an extract of a commercial root sample of Hydrastis canadensis against multiply drug resistant Mycobacterium tuberculosis. Two new quinic acid feruloyl esters, compounds 2 and 3, have been isolated from the same source along with canadine (1c), 8-oxotetrahydrothalifendine (1), and beta-hydrastine (5). These were found to be inactive. The structures of the new compounds were elucidated from spectral (1H, 13C, HMQC, HMBC, and H-H COSY) and chemical evidences.

Wallifoliol, a taxol congener with a novel carbon skeleton, from Himalayan Taxus wallichiana.

A new taxoid, wallifoliol [3], has been isolated, along with five known taxoids (taxol, cephalomannine, 10-deacetylbaccatin III, brevifoliol, 2-acetoxy brevifoliol = taxchinin A) from extracts of the needles of Himalayan Taxus wallichiana. The structure of wallifoliol has been assigned primarily from nmr studies. Wallifoliol [3] is assigned a structure in which rings A and B of the taxane system have undergone putative rearrangements producing a novel skeleton. Wallifoliol is the first diterpene to be found in nature with this particular 5/6/6/6/4 ring system.