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Pyrrolidone carboxylic acid (PCA), the primary constituent of the natural moisturizing factor (NMF),1 including its derivatives – such as simple2 and novel3 esters as well as sugar complexes4 – is the subject of great interest and research regarding its capacity to moisturize the stratum corneum via topical application.
Creams and lotions containing the sodium salt of PCA are widely reported to aid in hydrating the skin and ameliorating dry flaky skin conditions.5,6 In addition, the zinc salt of L-pyrrolidone carboxylate is a longtime cosmetic ingredient due to antimicrobial and astringent qualities. This column briefly addresses the role of PCA in skin health.7
Dry skin
In a comprehensive literature review from 1981, Clar and Fourtanier reported conclusive evidence that PCA acts as a hydrating agent and that all the cosmetic formulations with a minimum of 2% PCA and PCA salt that they tested in their own 8-year study enhanced dry skin in short- and long-term conditions given suitable vehicles (no aqueous solutions).6
In a 2014 clinical study of 64 healthy white women with either normal or cosmetic dry skin, Feng et al. noted that tape stripped samples of stratum corneum revealed significantly lower ratios of free amino acids to protein and PCA to protein. This was associated with decreased hydration levels compared with normal skin. The investigators concluded that lower NMF levels across the depth of the stratum corneum and reduced cohesivity characterize cosmetic dry skin and that these clinical endpoints merit attention in evaluating the usefulness of treatments for dry skin.8
In 2016, Wei et al. reported on their assessment of the barrier function, hydration, and dryness of the lower leg skin of 25 female patients during the winter and then in the subsequent summer. They found that PCA levels were significantly greater during the summer, as were keratins. Hydration was also higher during the summer, while transepidermal water loss and visual dryness grades were substantially lower.9
Atopic dermatitis
A 2014 clinical study by Brandt et al. in patients with skin prone to developing atopic dermatitis (AD) revealed that a body wash composed of the filaggrin metabolites arginine and PCA was well tolerated and diminished pruritus. Patients reported liking the product and suggested that it improved their quality of life.10
Later that year, Jung et al. characterized the relationship of PCA levels, and other factors, with the clinical severity of AD. Specifically, in a study of 73 subjects (21 with mild AD, 21 with moderate to severe AD, 13 with X-linked ichthyosis as a negative control for filaggrin gene mutation, and 18 healthy controls), the investigators assessed transepidermal water loss, stratum corneum hydration, and skin surface pH. They found that PCA levels and caspase-14 were lower in inflammatory lesions compared with nonlesional skin in subjects with AD. These levels also were associated with clinical AD severity as measured by eczema area and severity index scores as well as skin barrier function.11
PCA as a biomarker
In 2009, Kezic et al. determined that the use of tape stripping to cull PCA in the stratum corneum was effective in revealing that PCA concentration in the outermost skin layer is a viable biomarker of filaggrin genotype.12
Raj et al. conducted an interesting study in 2016 in which they set out to describe the various markers for total NMF levels and link them to the activities of plasmin and corneocyte maturation in the photoexposed cheek and photoprotected postauricular regions of healthy white, black African, and albino African women in South Africa. PCA levels were highest among the albino African group, followed by black African and then white participants. The investigators also found that bleomycin hydrolase was linked to PCA synthesis, as suggested by higher bleomycin levels in albino African participants. In this group, corneocyte maturation was also observed to be impeded.13
The next year, the same team studied stratum corneum physiology and biochemistry of the cheeks in 48 white women with sensitive skin. The goal was to ascertain the connections between bleomycin hydrolase and calpain-1, PCA levels, corneocyte maturation, and transglutaminase and plasmin activities. Capsaicin sensitivity was observed in 52% of subjects, with PCA levels and bleomycin hydrolase activity found to be lower in the capsaicin-sensitive panel and correlated in subjects not sensitive to capsaicin. The researchers concluded that reduced levels of PCA, bleomycin hydrolase, and transglutaminase combined with a larger volume of immature corneocytes suggest comparatively poor stratum corneum maturation in individuals with sensitive skin.14
Other uses
In 2012, Takino et al. used cultured normal human dermal fibroblasts to show that zinc l-pyrrolidone carboxylate blocked UVA induction of activator protein-1, diminished matrix metalloproteinase-1 synthesis, and spurred type I collagen production. The researchers suggested that such results suggest the potential of zinc PCA for further investigation as an agent to combat photoaging.7
Conclusion
. Recent research suggests that it may serve as an important biomarker of filaggrin, NMF levels, and skin hydration. In addition, new data point to its usefulness as a gauge for ADs. More investigations are necessary to ascertain the feasibility of adjusting PCA levels through topical administration and what effects topically applied PCA may have on various skin parameters.
Dr. Baumann is a private practice dermatologist, researcher, author, and entrepreneur in Miami. She founded the Cosmetic Dermatology Center at the University of Miami in 1997. Dr. Baumann wrote two textbooks, “Cosmetic Dermatology: Principles and Practice” (New York: McGraw-Hill, 2002) and “Cosmeceuticals and Cosmetic Ingredients” (New York: McGraw-Hill, 2014), as well as a New York Times Best Sellers book for consumers, “The Skin Type Solution” (New York: Bantam Dell, 2006). Dr. Baumann has received funding for advisory boards and/or clinical research trials from Allergan, Evolus, Galderma, and Revance. She is the founder and CEO of Skin Type Solutions Franchise Systems LLC. Write to her at dermnews@mdedge.com.
References
1. Björklund S et al. Soft Matter. 2014 Jul 7;10(25):4535-46.
2. Hall KJ, Hill JC. J Soc Cosmet Chem. 1986;37(6):397-407.
3. Tezuka T et al. Dermatology. 1994;188(1):21-4.
4. Kwoya Hakko Kogyo Co. Pyrrolidone carboxylic acid esters containing composition used to prevent loss of moisture from the skin. Patent JA 48 82 046 (1982).
5. Org Santerre. l-pyrrolidone carboxylic acid-sugar compounds as rehydrating ingredients in cosmetics. Patent Fr 2 277 823 (1977).
6. Clar EJ, Fourtanier A. Int J Cosmet Sci. 1981 Jun;3(3):101-13.
7. Takino Y et al. Int J Cosmet Sci. 2012 Feb;34(1):23-8.
8. Feng L et al. Int J Cosmet Sci. 2014 Jun;36(3):231-8.
9. Wei KS et al. J Cosmet Sci. 2016 May-Jun;67(3):185-203.
10. Brandt S et al. J Drugs Dermatol. 2014 Sep;13(9):1108-11.
11. Jung M et al. J Dermatol Sci. 2014 Dec;76(3):231-9.
12. Kezic S et al. Br J Dermatol. 2009 Nov;161(5):1098-104.
13. Raj N et al. Int J Cosmet Sci. 2016 Dec;38(6):567-75.
14. Raj N et al. Int J Cosmet Sci. 2017 Feb;39(1):2-10.
Pyrrolidone carboxylic acid (PCA), the primary constituent of the natural moisturizing factor (NMF),1 including its derivatives – such as simple2 and novel3 esters as well as sugar complexes4 – is the subject of great interest and research regarding its capacity to moisturize the stratum corneum via topical application.
Creams and lotions containing the sodium salt of PCA are widely reported to aid in hydrating the skin and ameliorating dry flaky skin conditions.5,6 In addition, the zinc salt of L-pyrrolidone carboxylate is a longtime cosmetic ingredient due to antimicrobial and astringent qualities. This column briefly addresses the role of PCA in skin health.7
Dry skin
In a comprehensive literature review from 1981, Clar and Fourtanier reported conclusive evidence that PCA acts as a hydrating agent and that all the cosmetic formulations with a minimum of 2% PCA and PCA salt that they tested in their own 8-year study enhanced dry skin in short- and long-term conditions given suitable vehicles (no aqueous solutions).6
In a 2014 clinical study of 64 healthy white women with either normal or cosmetic dry skin, Feng et al. noted that tape stripped samples of stratum corneum revealed significantly lower ratios of free amino acids to protein and PCA to protein. This was associated with decreased hydration levels compared with normal skin. The investigators concluded that lower NMF levels across the depth of the stratum corneum and reduced cohesivity characterize cosmetic dry skin and that these clinical endpoints merit attention in evaluating the usefulness of treatments for dry skin.8
In 2016, Wei et al. reported on their assessment of the barrier function, hydration, and dryness of the lower leg skin of 25 female patients during the winter and then in the subsequent summer. They found that PCA levels were significantly greater during the summer, as were keratins. Hydration was also higher during the summer, while transepidermal water loss and visual dryness grades were substantially lower.9
Atopic dermatitis
A 2014 clinical study by Brandt et al. in patients with skin prone to developing atopic dermatitis (AD) revealed that a body wash composed of the filaggrin metabolites arginine and PCA was well tolerated and diminished pruritus. Patients reported liking the product and suggested that it improved their quality of life.10
Later that year, Jung et al. characterized the relationship of PCA levels, and other factors, with the clinical severity of AD. Specifically, in a study of 73 subjects (21 with mild AD, 21 with moderate to severe AD, 13 with X-linked ichthyosis as a negative control for filaggrin gene mutation, and 18 healthy controls), the investigators assessed transepidermal water loss, stratum corneum hydration, and skin surface pH. They found that PCA levels and caspase-14 were lower in inflammatory lesions compared with nonlesional skin in subjects with AD. These levels also were associated with clinical AD severity as measured by eczema area and severity index scores as well as skin barrier function.11
PCA as a biomarker
In 2009, Kezic et al. determined that the use of tape stripping to cull PCA in the stratum corneum was effective in revealing that PCA concentration in the outermost skin layer is a viable biomarker of filaggrin genotype.12
Raj et al. conducted an interesting study in 2016 in which they set out to describe the various markers for total NMF levels and link them to the activities of plasmin and corneocyte maturation in the photoexposed cheek and photoprotected postauricular regions of healthy white, black African, and albino African women in South Africa. PCA levels were highest among the albino African group, followed by black African and then white participants. The investigators also found that bleomycin hydrolase was linked to PCA synthesis, as suggested by higher bleomycin levels in albino African participants. In this group, corneocyte maturation was also observed to be impeded.13
The next year, the same team studied stratum corneum physiology and biochemistry of the cheeks in 48 white women with sensitive skin. The goal was to ascertain the connections between bleomycin hydrolase and calpain-1, PCA levels, corneocyte maturation, and transglutaminase and plasmin activities. Capsaicin sensitivity was observed in 52% of subjects, with PCA levels and bleomycin hydrolase activity found to be lower in the capsaicin-sensitive panel and correlated in subjects not sensitive to capsaicin. The researchers concluded that reduced levels of PCA, bleomycin hydrolase, and transglutaminase combined with a larger volume of immature corneocytes suggest comparatively poor stratum corneum maturation in individuals with sensitive skin.14
Other uses
In 2012, Takino et al. used cultured normal human dermal fibroblasts to show that zinc l-pyrrolidone carboxylate blocked UVA induction of activator protein-1, diminished matrix metalloproteinase-1 synthesis, and spurred type I collagen production. The researchers suggested that such results suggest the potential of zinc PCA for further investigation as an agent to combat photoaging.7
Conclusion
. Recent research suggests that it may serve as an important biomarker of filaggrin, NMF levels, and skin hydration. In addition, new data point to its usefulness as a gauge for ADs. More investigations are necessary to ascertain the feasibility of adjusting PCA levels through topical administration and what effects topically applied PCA may have on various skin parameters.
Dr. Baumann is a private practice dermatologist, researcher, author, and entrepreneur in Miami. She founded the Cosmetic Dermatology Center at the University of Miami in 1997. Dr. Baumann wrote two textbooks, “Cosmetic Dermatology: Principles and Practice” (New York: McGraw-Hill, 2002) and “Cosmeceuticals and Cosmetic Ingredients” (New York: McGraw-Hill, 2014), as well as a New York Times Best Sellers book for consumers, “The Skin Type Solution” (New York: Bantam Dell, 2006). Dr. Baumann has received funding for advisory boards and/or clinical research trials from Allergan, Evolus, Galderma, and Revance. She is the founder and CEO of Skin Type Solutions Franchise Systems LLC. Write to her at dermnews@mdedge.com.
References
1. Björklund S et al. Soft Matter. 2014 Jul 7;10(25):4535-46.
2. Hall KJ, Hill JC. J Soc Cosmet Chem. 1986;37(6):397-407.
3. Tezuka T et al. Dermatology. 1994;188(1):21-4.
4. Kwoya Hakko Kogyo Co. Pyrrolidone carboxylic acid esters containing composition used to prevent loss of moisture from the skin. Patent JA 48 82 046 (1982).
5. Org Santerre. l-pyrrolidone carboxylic acid-sugar compounds as rehydrating ingredients in cosmetics. Patent Fr 2 277 823 (1977).
6. Clar EJ, Fourtanier A. Int J Cosmet Sci. 1981 Jun;3(3):101-13.
7. Takino Y et al. Int J Cosmet Sci. 2012 Feb;34(1):23-8.
8. Feng L et al. Int J Cosmet Sci. 2014 Jun;36(3):231-8.
9. Wei KS et al. J Cosmet Sci. 2016 May-Jun;67(3):185-203.
10. Brandt S et al. J Drugs Dermatol. 2014 Sep;13(9):1108-11.
11. Jung M et al. J Dermatol Sci. 2014 Dec;76(3):231-9.
12. Kezic S et al. Br J Dermatol. 2009 Nov;161(5):1098-104.
13. Raj N et al. Int J Cosmet Sci. 2016 Dec;38(6):567-75.
14. Raj N et al. Int J Cosmet Sci. 2017 Feb;39(1):2-10.
Pyrrolidone carboxylic acid (PCA), the primary constituent of the natural moisturizing factor (NMF),1 including its derivatives – such as simple2 and novel3 esters as well as sugar complexes4 – is the subject of great interest and research regarding its capacity to moisturize the stratum corneum via topical application.
Creams and lotions containing the sodium salt of PCA are widely reported to aid in hydrating the skin and ameliorating dry flaky skin conditions.5,6 In addition, the zinc salt of L-pyrrolidone carboxylate is a longtime cosmetic ingredient due to antimicrobial and astringent qualities. This column briefly addresses the role of PCA in skin health.7
Dry skin
In a comprehensive literature review from 1981, Clar and Fourtanier reported conclusive evidence that PCA acts as a hydrating agent and that all the cosmetic formulations with a minimum of 2% PCA and PCA salt that they tested in their own 8-year study enhanced dry skin in short- and long-term conditions given suitable vehicles (no aqueous solutions).6
In a 2014 clinical study of 64 healthy white women with either normal or cosmetic dry skin, Feng et al. noted that tape stripped samples of stratum corneum revealed significantly lower ratios of free amino acids to protein and PCA to protein. This was associated with decreased hydration levels compared with normal skin. The investigators concluded that lower NMF levels across the depth of the stratum corneum and reduced cohesivity characterize cosmetic dry skin and that these clinical endpoints merit attention in evaluating the usefulness of treatments for dry skin.8
In 2016, Wei et al. reported on their assessment of the barrier function, hydration, and dryness of the lower leg skin of 25 female patients during the winter and then in the subsequent summer. They found that PCA levels were significantly greater during the summer, as were keratins. Hydration was also higher during the summer, while transepidermal water loss and visual dryness grades were substantially lower.9
Atopic dermatitis
A 2014 clinical study by Brandt et al. in patients with skin prone to developing atopic dermatitis (AD) revealed that a body wash composed of the filaggrin metabolites arginine and PCA was well tolerated and diminished pruritus. Patients reported liking the product and suggested that it improved their quality of life.10
Later that year, Jung et al. characterized the relationship of PCA levels, and other factors, with the clinical severity of AD. Specifically, in a study of 73 subjects (21 with mild AD, 21 with moderate to severe AD, 13 with X-linked ichthyosis as a negative control for filaggrin gene mutation, and 18 healthy controls), the investigators assessed transepidermal water loss, stratum corneum hydration, and skin surface pH. They found that PCA levels and caspase-14 were lower in inflammatory lesions compared with nonlesional skin in subjects with AD. These levels also were associated with clinical AD severity as measured by eczema area and severity index scores as well as skin barrier function.11
PCA as a biomarker
In 2009, Kezic et al. determined that the use of tape stripping to cull PCA in the stratum corneum was effective in revealing that PCA concentration in the outermost skin layer is a viable biomarker of filaggrin genotype.12
Raj et al. conducted an interesting study in 2016 in which they set out to describe the various markers for total NMF levels and link them to the activities of plasmin and corneocyte maturation in the photoexposed cheek and photoprotected postauricular regions of healthy white, black African, and albino African women in South Africa. PCA levels were highest among the albino African group, followed by black African and then white participants. The investigators also found that bleomycin hydrolase was linked to PCA synthesis, as suggested by higher bleomycin levels in albino African participants. In this group, corneocyte maturation was also observed to be impeded.13
The next year, the same team studied stratum corneum physiology and biochemistry of the cheeks in 48 white women with sensitive skin. The goal was to ascertain the connections between bleomycin hydrolase and calpain-1, PCA levels, corneocyte maturation, and transglutaminase and plasmin activities. Capsaicin sensitivity was observed in 52% of subjects, with PCA levels and bleomycin hydrolase activity found to be lower in the capsaicin-sensitive panel and correlated in subjects not sensitive to capsaicin. The researchers concluded that reduced levels of PCA, bleomycin hydrolase, and transglutaminase combined with a larger volume of immature corneocytes suggest comparatively poor stratum corneum maturation in individuals with sensitive skin.14
Other uses
In 2012, Takino et al. used cultured normal human dermal fibroblasts to show that zinc l-pyrrolidone carboxylate blocked UVA induction of activator protein-1, diminished matrix metalloproteinase-1 synthesis, and spurred type I collagen production. The researchers suggested that such results suggest the potential of zinc PCA for further investigation as an agent to combat photoaging.7
Conclusion
. Recent research suggests that it may serve as an important biomarker of filaggrin, NMF levels, and skin hydration. In addition, new data point to its usefulness as a gauge for ADs. More investigations are necessary to ascertain the feasibility of adjusting PCA levels through topical administration and what effects topically applied PCA may have on various skin parameters.
Dr. Baumann is a private practice dermatologist, researcher, author, and entrepreneur in Miami. She founded the Cosmetic Dermatology Center at the University of Miami in 1997. Dr. Baumann wrote two textbooks, “Cosmetic Dermatology: Principles and Practice” (New York: McGraw-Hill, 2002) and “Cosmeceuticals and Cosmetic Ingredients” (New York: McGraw-Hill, 2014), as well as a New York Times Best Sellers book for consumers, “The Skin Type Solution” (New York: Bantam Dell, 2006). Dr. Baumann has received funding for advisory boards and/or clinical research trials from Allergan, Evolus, Galderma, and Revance. She is the founder and CEO of Skin Type Solutions Franchise Systems LLC. Write to her at dermnews@mdedge.com.
References
1. Björklund S et al. Soft Matter. 2014 Jul 7;10(25):4535-46.
2. Hall KJ, Hill JC. J Soc Cosmet Chem. 1986;37(6):397-407.
3. Tezuka T et al. Dermatology. 1994;188(1):21-4.
4. Kwoya Hakko Kogyo Co. Pyrrolidone carboxylic acid esters containing composition used to prevent loss of moisture from the skin. Patent JA 48 82 046 (1982).
5. Org Santerre. l-pyrrolidone carboxylic acid-sugar compounds as rehydrating ingredients in cosmetics. Patent Fr 2 277 823 (1977).
6. Clar EJ, Fourtanier A. Int J Cosmet Sci. 1981 Jun;3(3):101-13.
7. Takino Y et al. Int J Cosmet Sci. 2012 Feb;34(1):23-8.
8. Feng L et al. Int J Cosmet Sci. 2014 Jun;36(3):231-8.
9. Wei KS et al. J Cosmet Sci. 2016 May-Jun;67(3):185-203.
10. Brandt S et al. J Drugs Dermatol. 2014 Sep;13(9):1108-11.
11. Jung M et al. J Dermatol Sci. 2014 Dec;76(3):231-9.
12. Kezic S et al. Br J Dermatol. 2009 Nov;161(5):1098-104.
13. Raj N et al. Int J Cosmet Sci. 2016 Dec;38(6):567-75.
14. Raj N et al. Int J Cosmet Sci. 2017 Feb;39(1):2-10.