Friedrich O. Snyckers

An oxindole from the roots of Capparis tomentosa

Abstract The structure of 3-hydroxy-3-methyl-4-methoxyoxindole isolated from the roots of Capparis tomentosa has been determined by spectrometric methods.

Synthesis and antimicrobial activity of a series of caespitin derivatives.

Chemical modification of the naturally occurring phlorophenone antimicrobial agent caespitin is described. These modifications include variations in the phenone side chain, substitution with prenyl, allyl, and benzyl in the 4-position of the phlorophenone nucleus, and ring cyclizations via etherification to give furan and chroman compounds. Several of these derivatives show enhanced in vitro potency over caespitin. Studies on the development of microbial resistance against these compounds show that no or very little resistance developed after several passes of these compounds in representative microbial strains.

A pentacyclic triterpene acid, with anti-ulcer properties, from Cussonia natalensis

Abstract The structure of 23-hydroxy-3-oxo-urs-12-en-28-oic acid, isolated from the twigs and leaves of Cussonia natalensis , has been determined by spectrometric methods.

Studies on the constituents of Asclepiadaceae plants. Part 67. Further studies on glycosides with a novel sugar chain containing a pair of optically isomeric sugars, D- and L-cymarose, from Cynanchum africanum

Two new glycosides named cynafoside-C (3) and -D (4) were isolated from Cynanchum africanum R. BR. (Asclepiadaceae), and their structures were deduced on the basis of spectral and chemical evidence. The absolute configurations of cymarose, oleandrose, and digitoxose included in compounds (3) and (4) were each determined by h.p.l.c. analysis of their carbamoyl derivatives on a chiral column after acidic hydrolysis of the glycosides. A unique feature is that cynafoside-C (3), as well as cynafoside-A (1) and B (2), contains a pair of optically isomeric sugars, D-and L-cymarose, in the sugar chain.