Broussonetia zeylanica 3,4’-dihydroxy-2,3’-bipyridine

Only three constituents have been reported from Broussonetia zeylanica, all by a group at the University of Peradeniya in Sri Lanka [89-91]. A major alkaloid, 8-hydroxyquinoline-4-carbaldehyde (55), was identified as an antimicrobial agent active against Staphyllococus aureus and Candida albicans (the levels of activity were not specified) [89] and then two minor compounds, 3,4 -dihydroxy-2,3 -bipyridine (56) and 3,4-bis(8-hydroxyquinolin-4-yl)-y-butyrolactone (broussonetine, 57), were reported, Fig. (10) [90,91]. However, the structure of 3,4 -dihydroxy-2,3 -bipyridine (56) was revised to 8-hydroxyquinoline-4-carbaldehyde oxime (58) by synthesis [92,93]. Also, it was noted that an artefactual origin of this oxime (58) could not be ruled out due to the presence of the corresponding aldehyde (55) [93]. 

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