Radical-scavenging activity of butylated hydroxytoluene (BHT) and its metabolites.
To clarify the radical-scavenging activity of butylated hydroxytoluene (BHT), a food additive, stoichiometric factors (n) and inhibition rate constants (kinh) were determined for 2,6-di-tert-butyl-4-methylphenol (BHT) and its metabolites 2,6-di-tert-butyl-p-benzoquinone (BHT-Q), 3,5-di-tert-butyl-4-hydroxybenzaldehyde (BHA-CHO) and 3,5-di-tert-butyl-4-hydroperoxy-4-methyl-2,5-cyclohexadiene-1-one (BHT-OOH). Values of n and kinh were determined from differential scanning calorimetry (DSC) monitoring of the polymerization of methyl methacrylate (MMA) initiated by 2,2'-azobis(isobutyronitrile) (AIBN) or benzoyl peroxide (BPO) at 70 degrees C in the presence or absence of antioxidants (BHT-related compounds). The n values declined in the order BHT (1-2) > BHT-CHO, BHT-OOH (0.1-0.3) > BHT-Q ( approximately 0). The n value for BHT with AIBN was approximately 1.0, suggesting dimerization of BHT. The kinh values declined in the order BHT-Q ((3.5-4.6) x 10(4) M(-1)s(-1)) > BHT-OOH (0.7-1.9 x 10(4) M(-1)s(-1)) > BHT-CHO ((0.4-1.7 x 10(4) M(-1)s(-1)) > BHT ((0.1-0.2 x 10(4) M(-1)s(-1)). The kinh for metabolites was greater than that for the parent BHT. Growing MMA radicals initiated by BPO were suppressed much more efficiently by BHT or BHT-Q compared with those initiated by AIBN. BHT was effective as a chain-breaking antioxidant.
Fujisawa
Seiichiro
S
Department of Oral Diagnosis, Meikai University School of Dentistry, 1-1, Keyakidai, Sakado City, Saitama 350-0283, Japan. fujisawa@dent.meikai.ac.jp
Kadoma
Yoshinori
Y
Yokoe
Ichiro
I
D000975:Antioxidants / Q000737:chemistry / Q000378:metabolism; D002084:Butylated Hydroxytoluene / Q000737:chemistry* / Q000378:metabolism*; D016166:Free Radical Scavengers / Q000737:chemistry* / Q000378:metabolism*; D007700:Kinetics; D015394:Molecular Structure; D011108:Polymers / Q000737:chemistry
D000975:Antioxidants; D016166:Free Radical Scavengers; D011108:Polymers; D002084:Butylated Hydroxytoluene