US EPA

4674230 

Journal Article 

Food-grade antimicrobials potentiate the antibacterial activity of 1,2-hexanediol 

Yogiara; Hwang, SJ; Park, S; Hwang, JK; Pan, JG 

2015 

1 

Letters in Applied Microbiology
ISSN: 0266-8254
EISSN: 1472-765X 

Blackwell Publishing Ltd 

60 

5 

431-439 

English 

25631558 

10.1111/lam.12398 

WOS:000352572700004 

UNLABELLED: Preservative agents determining the shelf life of cosmetic products must have effective antimicrobial activity while meeting safety requirements for topical use. In this study, we determined the antimicrobial activity of 1,2-hexanediol against several Gram-positive and Gram-negative bacteria. Antimicrobial susceptibility tests have shown that 1,2-hexanediol exhibits broad-spectrum activity against Gram-positive and Gram-negative bacteria with MICs of 0·5-2% (v/v). The bactericidal concentration of 1,2-hexanediol was ranging from 1 to 2 × MIC as demonstrated by time-kill curve assay. A membrane depolarization assay showed that 1,2-hexanediol disrupted the cytoplasmic membrane potential. A checkerboard assay indicated that the effective concentration of 1,2-hexanediol was reduced up to 0·25-0·5 × MIC when combined with macelignan and octyl gallate against Gram-positive bacteria. However, this combination was not effective against Gram-negative bacteria. A turbidity reduction assay demonstrated that the combination of a high concentration of 1,2-hexanediol with food-grade antimicrobial compounds could trigger lytic activity towards Bacillus cereus cells. The remaining cell turbidity was 24·6 and 22·2% when 2% of 1,2-hexanediol was combined with 8 mg l(-1) octyl gallate or with 32 mg l(-1) macelignan respectively. This study showed that food-grade antimicrobial compounds may be used in combination with 1,2-hexanediol to increase its efficacy as a preservative agent in cosmetics.

SIGNIFICANCE AND IMPACT OF THE STUDY: The antimicrobial activity of 1,2-hexanediol against Gram-positive and Gram-negative bacteria was potentiated with food-grade antimicrobials including xanthorrhizol, macelignan, panduratin A and octyl gallate, which have already been reported to display anti-inflammatory and other beneficial activities related to cosmetics. Therefore, the combination of 1,2-hexanediol and these food-grade antimicrobial agents would have benefits not only for increasing the antimicrobial activity but also in cosmetics use. 

Antimicrobial activity; Antibacterial activity; Food; Gram-positive bacteria; Cosmetics; Shelf life; Minimum inhibitory concentration; Antimicrobial agents; Inflammation; Gram-negative bacteria; Cytoplasmic membranes; xanthorrhizol; Turbidity; Preservatives; Depolarization; Membrane potential; Bacillus cereus