486
loss, erythema and epidermal thickness in mouse skin. Furthermore, topical application of the fraction 3 increased the activity of catalase and suppressed cyclooxygenase-2 (COX-2) and proliferating cell nuclear antigen (PCNA) expression in
mice exposed to UVB.
Kim et al. (2004) investigated the anti-aging effects of dietary intake of isoflavones on photoaged (UV-irradiated) hairless female mouse skin for 4 weeks. The
isoflavone oral administration resulted in better appearance and less wrinkling of
the skin and higher amount of collagen deposit. The isoflavones also suppressed the
UV-increased metalloproteinases (MMP-1) expression.
Isoflavones bind to estrogen receptors preferentially to 24 and transactivate 25
estrogen receptor-β that is the predominant receptor in the skin (Thornton et al.
2003a, b). In addition, isoflavones also have an effect on the skin, which is independent of estrogen receptor binding. Genistein, the soybean isoflavone is suggested to
prevent photoaging through inhibiting the UV-induced epidermal growth factor
receptor tyrosine kinase activity and its effect on several other signal transduction
pathways in human (Kang et al. 2003). Genistein prevented UV-B irradiation
induced skin damage when applied to the human reconstituted skin (Moore et al.
2006). Subcutaneous administration of genistein aglycone in mature ovariectomized rats has shown to improve skin (wound) healing and tensile strength with a
greater effect than raloxifene and estradiol (Marini et al. 2010).
Equol, an isoflavandiol estrogen metabolized from daidzein, contains a chiral
carbon and exists as enantiomers, S- and R- equol, where both enantiomers can
specifically bind to 5α- dihydrotestosterone (DHT) stimulating androgen receptors
(ARs) in the keratinocytes of the epidermis/dermis, fibroblasts, and sebocytes.
Equol ability to stimulate collagen was tested on human dermal monolayer fibroblasts, where collagen deposition was quantified by collagen type 1 C-terminal peptide by ELISA assays. Equol effect on cell viability was similar to that of
17β-estradiol as shown by MTT assay. Equol could stimulate collagen deposition at
different concentrations at significantly higher levels compared to 17β-estradiol
(Lephart et al. 2005). Equol, also protects against UV induced skin damage
(Widyarini et al. 2005).
Soy isoflavone emulsion could rejuvenate the structure of mature skin by topical
application in a placebo-controlled study, through increasing the number of dermal
papillae after 2 weeks, since flattening of the dermal-epidermal junction is most
considered as important reproducible change in skin aging (Südel et al. 2005).
In a Brazilian study, estrogen and isoflavones were tested on 35 postmenopausal
women for 24 weeks of topical application. Both drugs improved the histomorphometrical parameters; but estrogen was more effective than isoflavones (Moraes
et al. 2009). Isoflavones can be absorbed effectively through the skin and thus, can
exert good protection against photoaging and photodamage (Huang et al. 2008). In
fact, Minghetti et al. 2006 suggested that topical administration could lead to circulating isoflavone levels sufficiently to have systemic effects. Bifidobacteriumfermented soy milk (BFS) extract containing genistein and daidzein was tested on
the skin of hairless mice by topical application for 6 weeks and it improved the
elasticity and viscoelasticity of mouse skin, increased hyaluronic acid content and
S. Das et al.
loss, erythema and epidermal thickness in mouse skin. Furthermore, topical application of the fraction 3 increased the activity of catalase and suppressed cyclooxygenase-2 (COX-2) and proliferating cell nuclear antigen (PCNA) expression in
mice exposed to UVB.
Kim et al. (2004) investigated the anti-aging effects of dietary intake of isoflavones on photoaged (UV-irradiated) hairless female mouse skin for 4 weeks. The
isoflavone oral administration resulted in better appearance and less wrinkling of
the skin and higher amount of collagen deposit. The isoflavones also suppressed the
UV-increased metalloproteinases (MMP-1) expression.
Isoflavones bind to estrogen receptors preferentially to 24 and transactivate 25
estrogen receptor-β that is the predominant receptor in the skin (Thornton et al.
2003a, b). In addition, isoflavones also have an effect on the skin, which is independent of estrogen receptor binding. Genistein, the soybean isoflavone is suggested to
prevent photoaging through inhibiting the UV-induced epidermal growth factor
receptor tyrosine kinase activity and its effect on several other signal transduction
pathways in human (Kang et al. 2003). Genistein prevented UV-B irradiation
induced skin damage when applied to the human reconstituted skin (Moore et al.
2006). Subcutaneous administration of genistein aglycone in mature ovariectomized rats has shown to improve skin (wound) healing and tensile strength with a
greater effect than raloxifene and estradiol (Marini et al. 2010).
Equol, an isoflavandiol estrogen metabolized from daidzein, contains a chiral
carbon and exists as enantiomers, S- and R- equol, where both enantiomers can
specifically bind to 5α- dihydrotestosterone (DHT) stimulating androgen receptors
(ARs) in the keratinocytes of the epidermis/dermis, fibroblasts, and sebocytes.
Equol ability to stimulate collagen was tested on human dermal monolayer fibroblasts, where collagen deposition was quantified by collagen type 1 C-terminal peptide by ELISA assays. Equol effect on cell viability was similar to that of
17β-estradiol as shown by MTT assay. Equol could stimulate collagen deposition at
different concentrations at significantly higher levels compared to 17β-estradiol
(Lephart et al. 2005). Equol, also protects against UV induced skin damage
(Widyarini et al. 2005).
Soy isoflavone emulsion could rejuvenate the structure of mature skin by topical
application in a placebo-controlled study, through increasing the number of dermal
papillae after 2 weeks, since flattening of the dermal-epidermal junction is most
considered as important reproducible change in skin aging (Südel et al. 2005).
In a Brazilian study, estrogen and isoflavones were tested on 35 postmenopausal
women for 24 weeks of topical application. Both drugs improved the histomorphometrical parameters; but estrogen was more effective than isoflavones (Moraes
et al. 2009). Isoflavones can be absorbed effectively through the skin and thus, can
exert good protection against photoaging and photodamage (Huang et al. 2008). In
fact, Minghetti et al. 2006 suggested that topical administration could lead to circulating isoflavone levels sufficiently to have systemic effects. Bifidobacteriumfermented soy milk (BFS) extract containing genistein and daidzein was tested on
the skin of hairless mice by topical application for 6 weeks and it improved the
elasticity and viscoelasticity of mouse skin, increased hyaluronic acid content and
S. Das et al.