Production, stability, and antioxidative and antimicrobial activities of two L-ascorbate analogues from phycomyces blakesleeanus: D-erythroascorbate and D-erythroascorbate glucoside.
D-erythroascorbate (D-EAA), a five-carbon analogue of L-ascorbate (L-AA), and D-erythroascorbate monoglucoside (D-EAAG) are accumulated in Phycomyces blakesleeanus grown on glucose (99.5 and 1084 μg/g mycelial dry weight, respectively) and also excreted into the culture medium. Both compounds showed UV spectral properties and ionization constants similar to those of L-AA. D-EAAG was much more stable to aerobic oxidation than D-EAA and L-AA at acidic pH. D-EAAG is synthesized from D-erythroascorbate by a mycelial glucosyltransferase activity that uses UDP-glucose as glucose substrate donor with K(m) = 2.5 mM and 41.3 μM for D-EAA. This glucosyltransferase activity was maximal in the stationary growth phase in parallel with maximal production of D-EAAG. The presence of D-arabinose or D-arabinono-1,4-lactone in the culture medium produces the maximal accumulation of D-EAA and D-EAAG (about 30- and 4-fold with respect to that obtained in glucose culture). Both compounds showed greater antioxidant activity than L-AA and other standard antioxidants, with a capacity similar to that of L-AA to inhibit the growth of Escherichia coli.
Gutierrez-Larrainzar
Marta
M
Departamento de Biología MolecularUniversidad de León, E-24071 León, Spain.
de Castro
Cristina
C
del Valle
Pilar
P
Rúa
Javier
J
García-Armesto
María Rosario
MR
Busto
Félix
F
de Arriaga
Dolores
D
D000890:Anti-Infective Agents / Q000494:pharmacology*; D000975:Antioxidants / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000737:chemistry / Q000494:pharmacology; D003470:Culture Media; D004355:Drug Stability; D005960:Glucosides / Q000096:biosynthesis / Q000737:chemistry / Q000494:pharmacology*; D005964:Glucosyltransferases / Q000378:metabolism; D010800:Phycomyces / Q000201:enzymology / Q000378:metabolism*
D000890:Anti-Infective Agents; D000975:Antioxidants; D003470:Culture Media; D005960:Glucosides; C555525:erythroascorbate glucoside; C005056:isoascorbic acid; D005964:Glucosyltransferases; D001205:Ascorbic Acid