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Poly(aspartic acids) of different chain lengths (11, 14, 18,24, 30,52, 58, = 115) were prepared, for the use in aminoglycoside-induced nephrotoxicity inhibition studies, some in their pure L-or D-configuration and in pure a-linkage form by the polymerization of a-amino acid Ncarboxyanhydride (NCA) derivatives with a variety of dialkyl aspartate molecules as primary amine initiators. The primary amine chosen served as an internal reference in the 'H NMR spectrum for the estimation of the degree of polymerization (chain length) in these molecules. Poly(aspartic acids) with varying amounts of D and L asymmetric centres and in pure a-linkage form were also prepared. Poly[(a-co-& (L-co-D) aspartic acid] was prepared by a simplified thermal polymerization procedure for biological studies and also to study the tacticity effects in its 13C NMR spectrum. A qualitative correlation was demonstrated between the retention times from gel-permeation chromatographic analysis and the 'H NMR method used to estimate the polymer chain length. * L

A series of derivatives of 5-methoxysterigmatocystin (3a,12c-dihydro-8-hydroxy-6,11-dimethoxy-7H-furol[3',2':4,5]furo[2,3-c]xanthen-7-one) has been prepared and evaluated for antitumor activity. The potency of the parent compound has been associated with the intact bisfurano ring system and with the double bond in the terminal furan ring. It has been shown that new substituents can be introduced in the xanthone portion of the molecule and that the antitumor activity is in some cases preserved.

Hetacillin was oxidized with m-chloroperbenzoic acid to give the corresponding (R)- and (S)-sulfoxides. Ozonization of hetacillin not only oxidized the sulfide but caused unexpected oxidation of the imidazolidine ring to a 2H-imidazoline. The biological spectrum showed the (R)-sulfoxide to be appreciably more active than the (S)-sulfoxide.

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