Zinc ascorbate has superoxide dismutase-like activity and in vitro antimicrobial activity against Staphylococcus aureus and Escherichia coli

BACKGROUND Acne vulgaris is a common dermatological disease, and its pathogenesis is multifactorial. OBJECTIVE We examined whether the ascorbic acid derivative zinc ascorbate has superoxide dismutase (SOD)-like activity. SOD is an enzyme that controls reactive oxygen species production. In addition, the in vitro antimicrobial activity of zinc ascorbate against the Gram-positive bacterium Staphylococcus aureus and the Gram-negative bacterium Escherichia coli was tested either alone or in combination with a variety of antimicrobial agents; their fractional inhibitory concentration index was determined using checkerboard tests. METHODS The SOD-like activity was measured in comparison with other ascorbic acid derivatives (ascorbic acid, magnesium ascorbyl phosphate, and sodium ascorbyl phosphate) and zinc. The antimicrobial susceptibility of twelve strains each of S. aureus and E. coli isolated from patients with dermatological infections was tested, in comparison to a type strain of S. aureus and E. coli. RESULTS Zinc ascorbate had significant (P < 0.001) SOD-like activity compared with other ascorbic acid derivatives and zinc. Moreover, it showed antimicrobial activity against a type strain of S. aureus and E. coli, and its concentration (0.064% and 0.128% for S. aureus and E. coli, respectively) was sufficiently lower than the normal dose (5%) of other ascorbic acid derivatives. Furthermore, combinations of zinc ascorbate with clindamycin, erythromycin, and imipenem against S. aureus (average fractional inhibitory concentration, 0.59-0.90), and with imipenem against E. coli (average fractional inhibitory concentration, 0.64) isolated from patients with dermatological infections showed an additive effect. CONCLUSIONS Our results provide novel evidence that zinc ascorbate may be effective for acne treatment.