Butylatedhydroxytoluene
(BHT) is a crystalline stable solid, but it is light-sensitive and reactive to
acid chlorides, acid anhydrides, and oxidizing agents. BHT is used as anantioxidant in many products including food, pharmaceuticals, rubbers, paint,
and petroleum products. Its antioxidant mechanism was well studied and
divided into two steps. In the first step, it forms a stable phenoxyl radical,
which further forms the parent and a quinone methide (QM). QM is a reactive
electrophilic species that easily forms adducts with nucleophiles or polymerize
in the next step.
Adduct formation between the nucleophilic groups of the
active pharmaceutical ingredients with QM in pharmaceutical formulations is
very much possible. In food preservation, BHT reacts with atmospheric
oxygen preferentially rather than oxidizing food materials, thereby protecting
them from decomposition. It is used to preserve food odor, color, and flavor.. Many polymerization
inhibitors (e.g., phenols) work best in the presence of oxygen because they
intercept peroxyl radicals and decelerate oxygen consumption while stopping
chain propagation. 4-MP is an inhibitor of this type. 4-MP has tremendous
ability to quench peroxyl radicals and alkyl radicals via hydrogen abstraction
mechanism, which leads to the formation of a phenoxyl radical .
The
phenoxyl radical is less reactive because it is stabilized by the resonance
effect. The antimicrobial activity of phenolic compounds is highly dependent
upon the chemical structure of the molecules. The bactericidal actions of
substituted phenols and the normal alkyl derivatives of p-chlorophenols were
examined against Gram-negative and Gram-positive bacteria. The
antibacterial potential of essential oils of sweet basil Ocimum basilicum L.
(Lamiaceae) containing 1.8% 4-MP and methanol extracts was evaluated for
controlling the growth range of food-borne pathogenic bacteria. It was
reported that BHT at high levels as well as at lower levels found in foods
might have anti-cancer properties, possibly by damaging free radicals or by
stimulating the production of enzymes that detoxify carcinogens. On the other
hand 4-MP is carcinogenic to the fore-stomach.
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