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New Pyrazolo[3,4-b]pyrazines: Synthesis and Biological Activity. -A variety of new pyrazolopyrazines and related heterocycles are synthesized and evaluated for their antifungal and antiparasitic activities. The key intermediate (IIIa) is obtained via reaction of 5-amino-4-nitrosopyrazole (I) with malononitrile. -(EL-KASHEF, H. S.; EL-EMARY, T. I.; GASQUET, M.; TIMON-DAVID, P.; MALDONADO, J.; VANELLE, P.; Pharmazie 55 (2000) 8, 572-576; Dep. Chem., Fac. Sci., Assiut Univ., Assiut 71516, Egypt; EN)

Summary  Asparagine metabolism in sunflower (Helianthus annuus) was investigated by cDNA cloning, sequence characterization and expression analysis of three genes encoding different isoforms of asparagine synthetase (AS, EC 6.3.5.4).  The AS‐coding sequences were searched for in leaves, roots and cotyledons by using a methodology based on the simultaneous amplification of different cDNAs. Three distinct AS‐coding genes, HAS1, HAS1.1 and HAS2, were identified.  HAS1 and HAS1.1 are twin genes with closely related sequences that share some regulatory features. By contrast, HAS2 is a singular sequence that encodes an incomplete AS polypeptide and shows an unusual regulation. The functionality of both the complete HAS1 and the truncated HAS2 proteins was demonstrated by complementation assays. Northern analysis revealed that HAS1, HAS1.1 and HAS2 were differentially regulated dependent on the organ, the physiological status, the developmental stage and the light conditions.  Asparagine synthetase from sunflower is encoded by a small gene family whose members have achieved a significant degree of specialization to cope with the major situations requiring asparagine synthesis.

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Experimentally, superoxide dismutase (SOD) protects against cytotoxological and histotoxological effects of superoxide anions, which play a fundamental role where inflammatory processes are involved. Currently, only bovine copper containing SOD (Cu-SOD) is available for clinical application in the treatment of patients with various arthritic diseases. The intramuscular route is the principal route to administer usual dosages of bovine Cu-SOD 4 to 32mg, 2 or 3 times weekly. A single dose corresponds to an optimal dose ranging from 30 to 200 micrograms/kg, determined from an established dose-response curve. After intramuscular injection of bovine Cu-SOD 8, 16 and 32mg the peak plasma concentration occurs 4 to 8 hours postdose and is 0.05, 0.16 and 0.39 mg/L, respectively. Clinically this metallo-protein is particularly effective for the treatment of inflammation and toxicity resulting from ionising irradiations, ischaemia and tumours. The major advantages of liposomally encapsulated bovine Cu-SOD are its improved pharmacokinetic characteristics, leading to a longer plasma half-life and a slower release of free bovine Cu-SOD. In humans, bovine Cu-SOD (free or liposomal), although a foreign protein, is well tolerated and produces no acute or delayed toxic effects.