hydroquinone

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hydroquinone

 [hi″dro-kwin´ōn]
a topical agent used to bleach hyperpigmented skin.

hydroquinone

/hy·dro·quin·one/ (hi″dro-kwĭ-nōn´) the reduced form of quinone, used topically as a skin depigmenting agent.

hydroquinone

(hī′drō-kwĭ-nōn′, -kwĭn′ōn′) also

hydroquinol

(-kwĭn′ôl′, -ōl′)
n.
A white crystalline phenol, C6H6O2, used as an antioxidant, photographic developer, stabilizer, and reagent.

hydroquinone

[hī′drōkwin′ōn]
a dermatological bleaching agent.
indications It is prescribed to reduce pigmentation of the skin in certain conditions in which an excess of melanin causes hyperpigmentation.
contraindications Sunburn, prickly heat, other irritation of the skin, or known hypersensitivity to this drug prohibits its use.
adverse effects Among the more serious adverse effects are tingling, erythema, burning, and severe inflammation of the skin.

hydroquinone (hīdrōkwin´ōn),

n 1. a reducing agent used as an inhibitor in resin monomers to prevent polymerization during storage.
n 2. one of the two chemicals used as reducing agents in film-developing solutions. It is made from benzene (paradihydroxybenzene) and is sensitive to thermal changes. Above 70° F (21° C), the action of hydroquinone is rapid; below 60° F (15.5° C), hydroquinone becomes inactive. Its action is to control the contrast of the film.

hydroquinone

thought at one time to be the toxic component of Xanthium spp., a now discredited view.
References in periodicals archive ?
Strzalka, "Plastoquinol and [alpha]-tocopherol quinol are more active than ubiquinol and [alpha]-tocopherol in inhibition of lipid peroxidation," Chemistry and Physics of Lipids, vol.
Caption: Figure 3: Scheme of a chain radical reaction in a system containing an azo initiator MeO-AMVN, CL molecules, and a chain-breaking inhibitor of quinol nature (based on [4, 10, 15-18]).
Such compounds were dubbed SkQ ions, that is, conjugates of penetrating Skulachev ions (Sk) and quinols (Q); these constructs were tested in vitro and in vivo [20, 61-74].
Chain-breaking antioxidants, such as tocopherols or quinols, react with peroxyl radicals much faster than the bisallylic hydrogen atom of a fatty acid, and thereby can prevent the chain propagation.
Ultimately, if the extent of the autooxidation is very high, the stoichiometry of the quenching of peroxyl radicals by quinols may be even close to zero [78, 87].
The antioxidant potency of HPMC was lower than that of the quinols and slightly higher than that of [alpha]-tocopherol, although the duration of the induction period was much shorter.
2] (Figure 7(a)), and amphiphilic short-tail quinols lacking penetrating cation moieties, decPQ[H.
In simplest biphasic micellar systems the antioxidant potencies of quinols and [alpha]-tocopherol were shown to be comparable [78, 92, 101].
According to the here presented data, all the tested quinols were equally highly effective in protecting CL from peroxidation, as indicated by negligible slopes of absorbance increase at 234 nm in their presence; see Figures 5-8 and 10, as well as the Table 1.
In our experiments, [alpha]-tocopherol, a reference antioxidant for such calculations, could not block the oxidation of CL completely, unlike quinols.
Hence, almost all radicals were quenched before getting the opportunity to oxidize a fatty acid, so that quinols essentially prevented the propagation of lipid oxidation.
Hence, although all the quinols got fully oxidized at the end of the lag phase, the duration of the inhibitory action of plastoquinols (this work) and several other quinols [19] was approximately two times shorter than the respective duration for ubiquinols, which, in turn, was almost as long as the duration of the protective effect of [alpha]-tocopherol.