Aminopiperidine derivatives, Compound 1a and 1b, are novel small molecules that inhibit C-14 reduction catalyzed by Erg24p in ergosterol synthesis of Candida albicans. We evaluated the properties of the in vitro and in vivo activities of these compounds against pathogenic fungi and compared their activities with those of fluconazole. Compound 1a and 1b exhibited potent in vitro activities against clinically important fungi such as Candida species, including both of fluconazole-resistant strains of C. albicans and non-albicans Candida, Aspergillus fumigatus, and Cryptococcus neoformans. Against C. albicans, its mode of action was fungistatic. Furthermore, orally administered Compound 1b clearly prolonged the survival of infected mice in systemic lethal infection caused by C. albicans. These results suggest that aminopiperidine derivative is a promising lead compound for an orally available novel antifungal drug with a broad spectrum.
Chitosanases which degrade chitosan to glucosamine oligomers have been purified from several microorganisms, including bacteria (7,15,18,(21)(22)(23), fungi (4,19) and actinomycetes (5,8,(12)(13)(14)16,17).We found a thermostable chitosanase produced by Amycolatopsis sp.14).Although strain Cs0-2 is mesophile, it produced thermostable chitosanase (CsO-2 chitosanase).We also isolated a mesophile actinomycete, strain K-O1, producing a thermostable chitosanase (K-O1 chitosanase) different from Cs0-2 chitosanase.In this paper, we report on the identification of strain K-O1 and some properties of K-O1 chitosanase.Strain K-O1 was isolated from soil by the same method as the case of strain Cs0-2, and maintained on Bennet agar slants (14).Strain K-01 was identified in the following way: The isomeric form of diaminopimelic acid and sugars were determined by chromatography of whole-cell hydrolyzates on Cellulose glass plates (Merck, Darmstadt, Germany) as described by Becker et al. ( 1) and Staneck and Roberts (20).The mycolic acid was examined by the method of Goodfellow et al. ( 6).The phosphatidylethanolamine of the cell membrane was examined by the method of Minnikin et al. (11).Degradation tests of casein, xanthin, hypoxanthin, tyrosine, urea, and cellobiose were examined by the method of de Boer et al. (3).Lysozyme resistance was determined by the method of Berd (2).Chitosanase production by strain K-O1 was done in the following way: As seed culture, a loopful of the organism was inoculated into 20 ml of Bennet's liquid medium in a 100-ml Erlenmeyer flask, and was then incubated on a rotary shaker
In the early stage of ripening of cherry-tomato fruits (Lycopersicon esculentum var. cherry), the lectin activity increased logarithmically and reached a plateau at day 10 after flowering. During purification of lectin from ripe and unripe fruits, a 42-kDa protein was found abundantly in unripe fruits. The protein cross-reacted with anti-cherry-tomato-lectin serum, retained chitin-binding ability, but showed no lectin activity. Comparative studies between the structure of the lectin and the 42-kDa protein were done. N-Terminal amino acid sequences of the lectin, peptides derived from the S-pyridylethylated lectin, and fragments generated by limited proteolysis of the native lectin showed that the lectin was comprised of three domains, Hyp-rich, Cys-rich, and Gln-rich, and the alignment of them was as this order from the N-terminus. Studies on the 42-kDa protein showed that it contained two of the three domains, Cys-rich and Gln-rich, but the amino acid sequence analysis showed that the protein should be a product of another gene.
