Topical compositions comprising protected functional thiols

Details Topical compositions comprising protected functional thiols Topical compositions comprising protected functional thiols

2001-01-05

2002-12-17

Dees, Jose′ G. (Department: 1616)

Drug, bio-affecting and body treating compositions

Live hair or scalp treating compositions

Uv protectant

C424S070100, C424S401000, C424S543000, C424S200100

Reexamination Certificate

active

06495125

ABSTRACT:

TECHNICAL FIELD
The present invention relates to topical compositions for treating amino acid based substrates. The topical compositions comprise cosmetic or therapeutic actives that have been bound to a protected thiol which acts as a molecular ‘hook’ to impart “permanent” benefits to the amino acid based substrates. The amino acid based substrates can include, for example, proteinaceous materials such as keratin, as found in human hair, animal fur, velus hair on skin, finger and toe nails; various animal body parts, such as horns, hooves and feathers; other naturally occurring protein containing materials, such as wool; and synthetic polymers. Of particular interest are compositions which deliver and attach cosmetic actives to human hair.
BACKGROUND OF THE INVENTION
It is well known in the art that amino-acid based fibers, particularly hair, can be treated with agents that deliver one or more cosmetic benefits, such as conditioning, styling or setting. The conventional cosmetic products which have been known and used commercially have relied upon two key factors: deposition and retention. The cosmetic actives must first be physically deposited onto the hair fiber where the active imparts a benefit to a sufficient degree. Secondly, it is essential that the cosmetic actives be retained on the hair beyond the completion of the treatment. For example, when hair is rinsed to remove unwanted excess composition (e.g., a conditioner) a sufficient amount of the cosmetic active (humectant, moisturizer, etc.) remains bonded to the hair so as to maintain the desired cosmetic benefits.
The bonding of the cosmetic active material to the hair is generally of the nature of physico-chemical intermolecular forces, e.g., physisorption. Such physical forces comprise, for example, hydrogen bonding, electrostatic interactions, van der Waals interactions and the like. As an example, cationic cosmetic agents, generally of the quaternary ammonium type, are known to bond to hair by virtue of the interaction of their cations with anionic amino acid residues within keratin, e.g., glutamic acid, aspartic acid, cysteic acid etc. A major problem, however, with physisorption is the inevitable short lived retention of the cosmetic agent on hair. This is due to the relatively weak physical forces which bind the cosmetic to hair and which are easily disrupted by other treatments, e.g. washing. And, given the frequent need for treating hair, performance retention is difficult to achieve and generally does not last in excess of the period between washes.
One approach that has been disclosed in the art to overcome the above problem to provide truly durable or “permanent” cosmetic benefits to hair that are retained through multiple washes is to utilize molecular “hooks” to chemically bond cosmetic actives to hair keratin, e.g., chemisorption. Chemisorption results in a permanent juncture that is essentially resistant to physical wear from subsequent washings or physical abrasion. Two conventional approaches to achieve chemisorption comprise the use of either electrophilic reactive moieties or thiol reactive moieties attached to the cosmetic active. Electrophilic reactive moieties are designed to react with thiol functional groups present in hair and thiol reactive moieties are designed to react with electrophilic functional groups within the hair to create a covalent bond.
U.S. Pat. No. 5,523,080 issued to Gough et al. on Jun. 4, 1996, U.S. Pat. No. 5,211,942 issued to Deppert et al. on May 18, 1993, and UK Patent Application GB2197887 published on Jun. 2, 1988, all disclose the use of electrophilic moieties. These electrophilic chemistries include the use of azlactone, (haloalkyl)trialkylammonium salts, and acyl halides. All of these molecular hooks have potential to react with hair via an electrophilic mechanism which necessitates sufficient nucleophilic functional groups present within the keratin structure with which to react to a sufficient degree to achieve the desired durable benefits. For hair, this poses a dilemma in that it is generally known that hair does not naturally possess a sufficient concentration of nucleophilic functional groups under consumer mild conditions to drive the reaction. However, it is also generally known that by chemically reducing the disulfide bonds present within the cystine amino acid residues of hair, in a manner analogous to cold waving, sufficient quantities of nucleophilic cystine residues can be produced. Pre-reduction of hair, to enable the chemical reaction with suitable electrophilic cosmetic actives, is illustrated below in reactions (a) and (b). Ker represents keratin protein, R—X represents an alkyl halide electrophilic cosmetic active, R represents a cosmetic agent and X
—
is a halide anion such as bromide or chloride.
While electrophilic cosmetic actives have been demonstrated effective at providing durable cosmetic benefits to hair, the approach has disadvantages that arise from the required pre-to reduction step. First, the reduction step is known to be a very harsh chemical process that imparts considerable damage to hair. Second, the effective reducing agents are typically mercaptans of low molecular weight and are odiferous. The pre-reduction process generates unpleasant malodor that remains on the hair for greater than a week time in most instances. Thirdly, in addition to unpleasant malodor and resulting hair damage, the required pre-reduction imparts an additional step to the process with attendant added inconvenience to the user.
U.S. Pat. No. 5,087,733 and U.S. Pat. No. 5,206,013 both issued to Deppert et al. on Feb. 11, 1992 and Apr. 27, 1993 respectively, as well as U.S. Pat. No. 4,973,475 issued to Schnetzinger and Ciaudelli on Nov. 27, 1990, describe the use of quaternary ammonium thiols which fall under the general class of nucleophilic reactive actives. Such nucleophilic actives are generally intended to react with cystine amino acid residues present within hair via formation of a mixed disulfide covalent linkage as is demonstrated in the chemical equation (c).
R—SH+Ker—S—S—Ker→Ker—S—S—R+Ker—SH
  (c)
Ker represents keratin and R—SH represents a suitable nucleophilic active where R is a cosmetic agent and —SH representing a nucleophilic moiety. It is generally known that thiols are the preferred nucleophilic reactive moieties that possess enough reactive strength to chemically bond with the disulfide bond of cystine, Ker—S—S—Ker, under safe and mild consumer conditions (e.g., relatively non toxic, less than 120° F., pH 2 to 11). Most other prospective nucleophilic molecular handles are either highly toxic (e.g., selenols), or are unreactive under mild conditions (e.g., alkoxides with pKa~15).
There are two major drawbacks to the use of nucleophilic thiols as reactive moieties to form covalent bonds with keratin. First, thiol nucleophilic moieties are known to be unstable in the presence of air. Atmosphere induced oxidation of the thiols to the corresponding, and unreactive, disulfide as is shown in the following equation (d) where R—SH represents a suitable nucleophilic cosmetic active R being an alkyl cosmetic agent and —SH representing the nucleophilic moiety:
R
⁢
—SH
+
R
⁢
—SH
⁢
→
Oxidation
⁢
 
⁢
R
⁢
—S—S—R
(
d
Such oxidative deactivation of the nucleophilic thiol moieties severely limits their mode of usage. Thus, nucleophilic thiols are generally not stable enough to be utilized as such in a large majority of current product forms, i.e., re-sealable hair care packages widely used for shampoos, rinse-off conditioners etc. Second, the nucleophilic thiol moiety has very little affinity for hair keratin and has very low aqueous solubility, both of which hinder its performance in generating durable cosmetic benefits, especially when attached to hydrophobic, insoluble cosmetic actives, i.e., hydrocarbon conditioners, in-soluble polymers etc.
Despite major efforts, however, the art has not yet provided molecular “hooks” that provide durable cosmetic benefits to hair that last beyond twent

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