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.
Examination of bioactive mother-liquors from previous large s c a l e experimnts on the antimicrobial agents from the Nigerian medicinal plant, ENthrira mildbraedii, led t o the isolation and s t r u c t u r a l characterization of two new pterocarpans, erybraedin D and E. Erybraedin D was i n i t i a l l y isolated as its apparently a r t i f a c t u a l hemiethyl phthalate ester. m t h new pterocarpans possess marginal antimicrobial potency in *. The genus ENthrina contains numerous a t t r a c t i v e species distributed i n t r o p i a l and subtropical Extracts of the leaves, bark and r m t s have a significant history of use i n indigenous medical practice for the treatment of various diseases including applications l i k e l y t o include microbial i n f e~t i o n s .~ I n previous studies from t h i s laboratory, we have shown that the roots of many species contain flavanoids, p a r t i c u l a r pterocarpans, .rhich possess s u f f i c i e n t potency innagainst human pathogens t o r a t i o n a l i z e the l c c a l p c p l l a r i t y of extracts a s medicament^.^ Other laboratories have made a n a l q o u s finding^.^ I n particular, we have recently sharn t h a t Ervthrina mildbraedii, c o l l e c t e d i n northern Nigeria, possessed several antimicrobial agents, three new t o the l i t e r a t u r e . These are erythrabyssin-I1 i l l , isoneorautenol (21, and erybraedins A i3), B (41, and C (51.' While examining the mother-liquors from the above study, we detected two q u i t e minor antimicrobial agents which were not identical with the above andwhich proved t o he new to the l i t e r a t u r e . This paper describes t h e i r properties and t h e i r s t r u c t u r a l characterization Erybraedin D hemiethyl phthalate (61 was isolated a s a gum: i r CHC13/max an-' : g, A=-HI, 7.73 IZH, m, Ar-HI; EIMS m/z ( r e l . int., 8 ) : 390 159.21, 375 I l O O ) , 319 03.91, 185
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