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Ferulic Acid Stabilizes a Solution of Vitamins C and E and Doubles its Photoprotection of Skin


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Ferulic acid is a potent ubiquitous plant antioxidant. Its incorporation into a topical solution of 15%l-ascorbic acid and 1%alpha-tocopherol improved chemical stability of the vitamins (C+E) and doubled photoprotection to solar-simulated irradiation of skin from 4-fold to approximately 8-fold as measured by both erythema and sunburn cell formation. Inhibition of apoptosis was associated with reduced induction of caspase-3 and caspase-7. This antioxidant formulation efficiently reduced thymine dimer formation. This combination of pure natural low molecular weight antioxidants provides meaningful synergistic protection against oxidative stress in skin and should be useful for protection against photoaging and skin cancer.
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See related Commentaries on pages v and xii
Ferulic Acid Stabilizes a Solution of Vitamins C and E and Doubles
its Photoprotection of Skin
Fu-Hsiung Lin,
Jing-Yi Lin,wRavindra D. Gupta,
Joshua A. Tournas,
James A. Burch,
M. Angelica
Nancy A. Monteiro-Riviere,zJames M. Grichnik,
Jan Zielinski,yand Sheldon R. Pinnell
Duke University Medical Center, Durham, North Carolina, USA; wChang Gung Memorial Hospital, Taipei, Taiwan; zNorth Carolina State University, Raleigh,
North Carolina, USA; yZielinski Research, San Diego, California, USA
Ferulic acid is a potent ubiquitous plant antioxidant. Its incorporation into a topical solution of 15% L-ascorbic acid
and 1% a-tocopherol improved chemical stability of the vitamins (CþE) and doubled photoprotection to solar-
simulated irradiation of skin from 4-fold to approximately 8-fold as measured by both erythema and sunburn cell
formation. Inhibition of apoptosis was associated with reduced induction of caspase-3 and caspase-7. This anti-
oxidant formulation efficiently reduced thymine dimer formation. This combination of pure natural low molecular
weight antioxidants provides meaningful synergistic protection against oxidative stress in skin and should be
useful for protection against photoaging and skin cancer.
Key words: antioxidant/ferulic acid/photoprotection/vitamin C/vitamin E
J Invest Dermatol 125:826 –832, 2005
Ultraviolet (UV) radiation generates oxidative stress in skin
creating photodamage. Mechanistically, a photon of radia-
tion interacts with trans-urocanic acid in skin generating
singlet oxygen (Hanson and Simon, 1998). This reaction
occurs maximally at about 345 nm. Singlet oxygen can
generate the entire oxygen free radical cascade with oxi-
dation of nucleic acids, proteins, and lipids, resulting in skin
cancer and photoaging changes. The body deals with oxi-
dative stress by employing a series of low molecular weight
antioxidants that neutralize the reactive oxygen species
before they can produce oxidative changes in tissues
(Podda and Grundmann-Kollmann, 2001). In skin the pre-
dominant antioxidant is vitamin C; vitamin C protects the
fluids of the body (Shindo et al, 1994). The lipid phase in-
cluding cell membranes and stratum corneum is protected
by vitamin E (Thiele, 2001). Plants make vitamins E and C to
protect themselves from sunlight (Smirnoff et al, 2001; Mu-
nne-Bosch and Alegre, 2002). Most animals make vitamin C
but humans have lost this ability; a necessary gene is mu-
tated (Nishikimi et al, 1994). Therefore, humans typically get
vitamins C and E from diet and/or vitamin supplements.
Body controls related to absorption, metabolism, and dis-
tribution, however, limit the amounts that can eventually be
delivered into skin (Herrera and Barbas, 2001; Padayatty
et al, 2003). Moreover, when these vitamins neutralize oxi-
dative stress in skin, they are used up (Darr et al, 1992). With
daily oral supplements of 3 g vitamin C and 2 g vitamin E,
protection against photodamage in skin is increased ap-
proximately 1.5 times; either vitamin alone is ineffective
(Fuchs and Kern, 1998).
New formulation methods make it possible to augment
protection in skin against photodamage using topical vita-
mins C and E, achieving significantly greater protection than
ever was possible by ingestion. We have previously re-
ported that a stable aqueous solution of 15% vitamin C
(L-ascorbic acid) and 1% vitamin E (a-tocopherol) when
applied topically to skin can provide 4-fold photoprotection
for skin (Lin et al, 2003). The solution must be formulated at
a pH of 3.5 or lower for the vitamin C to be absorbed into
skin: at this pH the vitamin C is protonated and the molecule
is uncharged (Pinnell et al, 2001). The formulation concen-
trations were maximized for percutaneous absorption. Fif-
teen percent L-ascorbic acid saturates skin in 3 d; its tissue
half life is about 4 d (Pinnell et al, 2001). Once inside skin it
cannot be removed by washing or rubbing. Vitamins C and
E interact synergistically to protect each other and increase
overall effectiveness (Pinnell et al, 2001).
In an attempt to improve the stability of this solution of
vitamins C and E, we explored the effectiveness of a series of
known low molecular weight antioxidants that are available in
chemically pure form. Chemical stability was determined after
1moat451C. We have learned that addition of ferulic acid, a
ubiquitous plant antioxidant, provided stability of more than
90% for L-ascorbic acid and 100% for a-tocopherol (Zielinski
and Pinnell, 2004). A concentration of 0.5% gave the best
combination of formulation stability and effectiveness.
We were surprised to find that in addition to improving
stability, adding 0.5% ferulic acid to the solution of 15% L-
ascorbic acid and 1% a-tocopherol doubled photoprotec-
tion when applied topically to skin from 4- to 8-fold. In this
article, we detail these photoprotection experiments, show
reduction in thymine dimer formation generated by UV ra-
diation and demonstrate reduction of apoptosis in keratin-
ocytes with lowered caspase-3 and caspase-7 generation.
This work was done in Durham, North Carolina, USA.
Abbreviations: MED, minimal erythema dose; UV, ultraviolet
Copyright r2005 by The Society for Investigative Dermatology, Inc.
Antioxidant protection factor is designed to reflect relative
photoprotection to solar-simulated radiation provided by
daily topical applications of the solution for 4 consecutive
days. Both 0.5% ferulic acid alone and 15% L-ascorbic acid
þ1% a-tocopherol together provided about 4-fold protec-
tion (Fig 1a,b). Similar photoprotection has been previously
reported for 15% L-ascorbic acid þ1% a-tocopherol (Lin
et al, 2003). The combination of 15% L-ascorbic acid, 1% a-
tocopherol, 0.5% ferulic acid provided approximately 8-fold
protection and was statistically different than ferulic acid
alone or the combination of vitamins C and E (Fig 1a,b).
These observations were confirmed by colorimetric meas-
urements of erythema (Fig 1c) and sunburn cell counts (Fig
1d). Colorimetric measurements of combination of vitamins
C, E, and ferulic acid were statistically different from control
and vehicle at all minimal erythema dose (MED) tested; dif-
ferent from ferulic acid alone at 2 ,6, and 8 MED;
and different from combination vitamins C þEat4and
6MED. Sunburn cell counts of combination of vitamins C,
E, and ferulic acid were statistically different from control
and vehicle at all MED tested and different from ferulic acid
alone as well as from the combination of vitamins C þEat
2,4,6, and 8 MED.
In an effort to explore the mechanism of apoptosis in
these experiments, western blots were carried out to de-
termine levels of caspase-3 and its downstream effector,
caspase-7. Figure 2areveals protection by antioxidant so-
lutions of activation of caspase-3 by 4 and 8 MED of
solar-simulated radiation. Figure 2bshows relative quanti-
fication of antioxidant protection of solar-simulated radia-
tion. With 8 MED of irradiation, protection of vitamin C, E,
and ferulic acid is almost complete and is better than
vitamin C and E or ferulic acid alone. Figure 2cshows
activation of caspase-7 by 4 and 8 MED of solar-sim-
ulated radiation and protection by antioxidant solutions.
Figure 2dshows relative antioxidant protection, which is
Figure 1
Photoprotection by topical antioxidant formulations. Skin was pretreated with vehicle, 0.5% ferulic acid, 15% vitamin C and 1% vitamin E, 15%
vitamin C and 1% vitamin E, and 0.5% ferulic acid and irradiated with solar-simulated radiation 2 to 10 minimal erythema dose (MED) at
2MED intervals. Evaluation was carried out 1 d later. (a) Visual erythema of photoprotection provided by antioxidant solutions. (b) Antioxidant
protection factor of antioxidant formulations.
po0.01 vs 0.5% ferulic acid and 15% C þ1% E (n ¼6). (c) Colorimeter measurements of pho-
toprotection by antioxidant solutions.
po0.05 vs control and vehicle,
po0.05 vs 0.5% ferulic acid,
po0.05 vs 15% C þ1% E (n¼6). (d)
Sunburn cell measurements of photoprotection by antioxidant solutions.
po0.01 vs control and vehicle,
po0.01 vs 0.5% ferulic acid and 15%
Cþ1% E (n ¼6).
virtually complete by vitamins C, E and ferulic acid. Figure 3
shows immunohistochemistry of activation of caspase-3 by
4MED of solar-simulated light. Activation occurs in both
epidermis and dermis (Fig 3ac); in epidermis, activation is
particularly strong in the basal layer. Ferulic acid alone (3b)
and vitamins C þE (3c) provide partial protection but vita-
mins C, E, and ferulic acid (3d) provides virtually complete
We have previously demonstrated that topical vitamins
CþE could prevent UV-induced thymine dimer formation
(Lin et al, 2003). In order to determine whether the addition
of ferulic acid augmented this protection, we investigated
the relative dose–response protection of these formulations
(Fig 4). With 4 MED of solar-simulated irradiation, both
control and vehicle-treated skin showed virtually uniform
nuclear fluorescence in both epidermis and papillary dermis
(Fig 4a). After 4 MED, ferulic acid-treated skin was still
positive in approximately 25% of both epidermis and de-
rmis (data not shown). As previously reported, vitamins
CþE almost completely protected skin irradiated with
4MED (data not shown). After 8 MED, ferulic acid-
treated skin was about one third positive (Fig 4b) and
vitamin C þE-treated skin was about 15% positive and
fluorescence was less intense (Fig 4c). Skin treated with
vitamins C, E, and ferulic acid was completely negative
(Fig 4d).
Ferulic acid not only provides increased stability to a so-
lution of vitamins C þE, but also adds a substantial
synergistic photoprotection, essentially doubling its
efficacy. Moreover it provides additional protection against
thymine dimer formation that should prove useful for pre-
vention of skin cancer. These studies support the hypoth-
eses that UV radiation produces apoptosis by triggering the
caspase cascade in both epidermis and dermis, and topical
vitamins C, E, and ferulic acid can protect against caspase
Ferulic acid is a potent phenolic antioxidant found ubiq-
uitously and at high concentrations in plants (Graf, 1992;
Rice-Evans et al, 1996; Ou and Kwok, 2004). It serves to
cross-link polysaccharides and proteins during lignin cell
wall synthesis (Wallace and Fry, 1994; Mathew and Abra-
ham, 2004) and may be important for the health effects of
bran; corn bran contains 3.1% ferulic acid (Mathew and
Abraham, 2004). It is abundant in the diet and has low tox-
icity (Ou and Kwok, 2004; Zhao et al, 2004). Ferulic acid is a
potent antioxidant with synergistic interactions with ascor-
bic acid (Trombino et al, 2004). It readily forms a resonance
stabilized phenoxy radical which accounts for its potent
antioxidant potential (Graf, 1992). Ferulic acid protected
membranes from lipid peroxidation and neutralized alkoxyl
and peroxyl radicals (Trombino et al, 2004). It protected
against iron-induced oxidative damage (Hynes and O’Coin-
ceanainn, 2004). Ferulic acid scavenged hydroxyl radical
(Ogiwara et al, 2002; Wenk et al, 2004), nitric oxide (Wenk
et al, 2004), peroxynitrite (Pannala et al, 1998; Dinis et al,
2002), and superoxide radical (Kaul and Khanduja, 1999;
Kikuzaki et al, 2002). It was antimutagenic (Yamada and
Tomita, 1996; Ferguson et al, 2003), protected against
menadione-induced oxidative DNA damage (Burdette et al,
2002) and demonstrated anticarcinogenic effects in animal
Figure 2
Activation of caspase-3 and ca-
spase-7 by solar-simulated irra-
diation and relative protection
by antioxidant formulations. Skin
was pretreated with vehicle, 0.5%
ferulic acid, 15% vitamin C and 1%
vitamin E, 15% vitamin C and
1% vitamin E, and 0.5% ferulic
acid and exposed to 4 and 8
minimal erythema dose (MED).
Levels of of caspase-3, caspase-
7, and a-tubulin were determined
after 24 h. Relative caspase-3 or
caspase-7 levels corrected for
a-tubulin are presented (n ¼3).
(a) Western blot of caspase-3 after
4and 8 MED and relative
antioxidant protection. (b) Densito-
metric levels of caspase-3 and rel-
ative antioxidant protection (n ¼3).
(c) Western blot of caspase-7 after
4and 8 MED and relative
antioxidant protection. (d) Densito-
metric levels of caspase-7 and rel-
ative antioxidant protection (n ¼3).
models of pulmonary (Lesca, 1983) and colon carcinoma
(Kawabata et al, 2000; Wargovich et al, 2000). Topical
application inhibited 12-O-tetradecanoylphorbol-13-ace-
tate (TPA)-induced ornithine decarboxylase activity and de-
creased TPA-induced skin tumor formation (Huang et al,
1988). Topical application of ferulic acid inhibited UVB-in-
duced erythema (Saija et al, 2000). In a mouse model of
multiple sclerosis, oral ferulic acid had a striking effect on
syncytin-mediated inflammation and death of oligodendro-
cytes induced by redox reactants (Antony et al, 2004).
Ferulic acid absorbs UV radiation with an absorption max-
imum at 307 nm (log e¼4.19) (Graf, 1992). Theoretically this
absorption could result in a sunscreen effect providing top-
ical protection against UV radiation. Our studies revealed no
evidence of a dose–response effect to support a sunscreen
mechanism (Fig 5).
The mechanism of ferulic acid’s stabilizing effect on vi-
tamins C and E is unknown. It would not be expected to
directly protect these vitamins since its redox potential
(0.595) is appreciably higher than vitamin C (0.282) or vita-
min E (0.48) (Lu and Liu, 2002). Since it provides protection
against vitamin C degradation, it may preferentially interact
with pro-oxidative intermediates, or serve as a sacrificial
substrate. It is also possible that its interactions may be
enhanced at the low pH of the formulation. Ferulic acid’s
effect on photoprotection is most likely related to its anti-
oxidant activity. It had no appreciable effect on ascorbic
acid absorption (data not shown).
Ferulic acid augments the protection of vitamins C þE
previously demonstrated to prevent UV-induced thymine
dimer formation when applied topically to skin (Lin et al,
2003). A recent study of actinic keratoses and squamous
cell carcinomas of skin using laser capture microdissection
reveals 8-oxo guanine mutations in the basal germinative
layer and thymine dimer mutations at suprabasal locations
(Agar et al, 2004). The results support the hypothesis that
UVA-induced oxidative DNA modifications are responsible
for the carcinogenic mutations in stem cells and UVB-in-
duced mutations promote the carcinogenic process. The
hypothesis fits with the superficial penetration of UVB and
the deeper penetration of UVA into skin. Although we have
not yet been able to measure the effect of antioxidants on
UV-induced 8-oxo guanine formation, protection would be
predicted. The demonstrated protection of topical applica-
tion of vitamins C, E, and ferulic acid against UV-induced
thymine dimer formation supports its use for the prevention
of skin cancer.
Recent studies substantiating the shortcomings of sun-
screen protection support the need for a different approach
Figure 3
Immunochemistry of activated caspase-3 after solar-simulated ir-
radiation. Skin was pretreated with 0.5% ferulic acid, 15% vitamin C
and 1% vitamin E, or 15% vitamin C and 1% vitamin E, and 0.5%
ferulic acid and exposed to 4 minimal erythema dose. After 24 h
formalin-fixed tissues were stained with antibodies to activated ca-
spase-3. (a) Vehicle-treated irradiated skin; (b) 0.5% ferulic acid-treated
irradiated skin. (c): 15% vitamin C and 1% vitamin E-treated irradiated
skin; (d) 15% vitamin C and 1% vitamin E, and 0.5% ferulic acid-treated
irradiated skin.
Figure 4
Immunochemistry of thymine dimers after solar-simulated irradi-
ation. Skin was pretreated with vehicle, 0.5% ferulic acid, 15% vitamin
C and 1% vitamin E, or 15% vitamin C and 1% vitamin E, and 0.5%
ferulic acid and exposed to 4 or 8 minimal erythema dose (MED).
After 24 h formalin-fixed tissues were stained with antibodies to thy-
mine dimers. (a) Vehicle-treated skin after 4 MED; (b) 0.5% ferulic
acid-treated skin after 8 MED; (c) 15% C and 1% vitamin E-treated
skin after 8 MED; (d) 15% vitamin C and 1% vitamin E, and 0.5%
ferulic acid-treated skin after 8 MED.
to photoprotection. Sun protection factor is measured at 2
mg per cm
, yet in actual use, sunscreen application is only
0.4–0.5 mg per cm
(Wulf et al, 1997; Autier et al, 2001).
Since SPF is an exponential measurement, at reduced lev-
els, relative photoprotection of any sunscreen is no more
than 3–4-fold. In addition, SPF is a measurement of UVB
only and reveals nothing about UVA photoprotection,
protection necessary to protect against oxidative stress.
Indeed a recent study of three high SPF broad-screen sun-
screens revealed that at 2 mg per cm
application, UVA-
induced free radical formation was reduced only 55% with
even worse protection when application levels were de-
creased (Haywood et al, 2003). Sunscreens are designed to
be shields for the skin, protecting the skin by absorbing
harmful UV radiation. Since they work at the surface of the
skin, they are easily removed by washing or rubbing. Anti-
oxidants, in contrast, are designed to work not only at the
skin’s surface but also inside skin. Following topical appli-
cation, once the skin is saturated with L-ascorbic acid, it
remains with a half-life of about 4 d (Pinnell et al, 2001).
Approximately one third of UVA-induced oxidative stress in
skin occurs at the surface of skin (Ou-Yang et al, 2004).
Vitamin E is delivered to the surface of skin through sebum
to protect the stratum corneum from this oxidative insult
(Thiele, 2001). Direct topical application of antioxidants
would be expected to facilitate this protection. Using both a
properly formulated topical combination antioxidant prod-
uct containing vitamins C and E with ferulic acid, and also
a broad-spectrum sunscreen, would be expected to pro-
vide optimal photoprotection. Since they work by different
mechanisms, they should be supplemental (Darr et al,
Materials and Methods
L-ascorbic acid, DL-a-tocopherol, and
ferulic acid were pur-
chased from Sigma (St Louis, Missouri). Aqueous solutions were
prepared in a vehicle containing diethylene glycol monoethyl ether,
1,2-propanediol, Brij-35, and phenoxyethanol at pH 3.
Treatment and irradiation procedure The experimental design
has previously been published in detail (Lin
et al
, 2003). Experi-
ments were performed on weanling white Yorkshire pigs in accord
with the guidelines prepared by the Committee on Care and Use of
Laboratory Animals of the Institute of Laboratory Resources, Na-
tional Research Council (National Institutes of Health, publication
No. 86–23, revised 1996). Unless otherwise noted, 500 mL aliquots
of vehicle; 0.5%
ferulic acid; 15% L-ascorbic acid, 1% DL-a-
tocopherol, and 15% L-ascorbic acid, 1% DL-a-tocopherol, 0.5%
ferulic acid were applied to patches of back skin (7.5 10
cm) daily for 4 d. A 1000 W solar simulator (Lightning Cure 200,
Hamamatsu, Japan) fitted with a WG295 Schott filter to eliminate
wavelengths less than 295 nm delivered UV radiation to the skin’s
surface through a liquid light guide at an intensity of 5 mW per cm
of UVB and about 40 mW per cm
of UVA as measured by a
radiometer (IL1700, International Light, Newburyport, Mississippi).
MED was determined as the lowest dose resulting in erythema with
perceptible borders (40 mJ per cm
of UVB). Each patch was given
solar-simulated irradiation in triplicate from 2 to 10 MED at
2MED intervals. Evaluation was carried out 24 h later.
Evaluation of antioxidant protection factor, erythema, and
sunburn cells Antioxidant protection factor was calculated as the
ratio of the MED in antioxidant-treated skin in comparison with
untreated skin. Erythema was measured by colorimeter evaluation
in the ‘‘a’’ mode (ColorMouse Too, Color Savvy Systems Ltd,
Springboro, Ohio) of 8 12 in enlargements of skin photographs.
Each spot and adjacent unirradiated skin was measured in trip-
licate. The difference between irradiated and unirradiated skin
determined the erythema. Sunburn cells were determined in for-
malin-fixed 8 mm punch biopsy sections stained with hematoxylin
and eosin. When irradiation damage was extensive, the number 35
sunburn cells per mm were used as an upper limit.
Evaluation of caspase-3 and caspase-7 For western blotting,
cell protein was extracted from freeze-fractured skin in a solution
containing 1% NP-40%, 1% sodium deoxycholate, 0.3% SDS,
0.15 M NaCl, 2 mM EDTA, 50 mM sodium fluoride, 10 mM sodium
phosphate, pH 7.2, and a pre-formed protease inhibitor mixture
(Sigma). Protein extract (50 mg) mixed with mercaptoethanol and
SDS-PAGE sample buffer was heated at 1001C for 5 min, and
separated on 12% SDS-polyacrylamide gel, electrotransferred to
PVDF membrane (Millipore, Bedford, Massachusetts), blocked in
TBS (100 mM Tris-HCl, pH 7.5, and 150 mM NaCl) containing 0.1%
Tween-20% and 5% milk for 1 h at room temperature and incu-
bated with primary antibody: rabbit anti-human cleaved caspase-
3, or cleaved caspase-7 diluted 1:1000 (Cell Signaling Technology,
Beverly, Massachusetts) overnight at 41C. After reaction with
horseradish peroxidase-conjugated goat anti-rabbit IgG, immuno-
complexes were visualized using ECL (Amersham Pharmacia
Figure 5
Effect of dosage on photoprotection provided by vitamins C, E,
and ferulic acid. Skin was pretreated by 75, 150, and 250 mL of 15%
vitamin C, 1% vitamin E, and 0.5% ferulic acid and irradiated with
solar-simulated radiation 1 to 5 minimal erythema dose (MED) at
1MED intervals. Evaluation was carried out 1 d later. (a) Colorimeter
measurements of photoprotection by vitamins C, E, and ferulic acid
(n ¼3). (b) Sunburn cell measurements of photoprotection by vitamins
C, E, and ferulic acid (n ¼3).
Biotech, Piscataway, New Jersey). For internal control, the blots
were stripped and reprobed with anti-atubulin monoclonal anti-
body (Santa Cruz Biotechnology, Santa Cruz, California). Densi-
tometry was performed using Kodak ID image analysis software
(Kodak, Rochester, New York).
Formalin-fixed skin was prepared for caspase-3 or caspase-7
immunocytochemistry by following manufacturer’s protocol. Brief-
ly, sections were deparaffinized/hydrated, heated in 10 mM sodium
citrate buffer (pH 6) for antigen unmasking, incubated in 1% hy-
drogen peroxide, followed by incubation with 5% horse serum.
Sections were incubated with primary antibody solution (1:200 di-
lution) overnight at 41C, followed by biotin-labeled anti-rabbit IgG
secondary antibody according to ABC biotin/avidin method (Vector
Laboratories, Burlingame, California). Finally, sections were incu-
bated in peroxidase substrate solution (DAB, Vector Laboratories),
and counterstained with hematotoxylin.
Evaluation of thymine dimers The procedure was modified from
the method described by Mitchell
et al
(2001). Briefly, sections
were deparaffined/rehydrated and washed with phosphate-buff-
ered saline (PBS), denatured in 0.1 N NaOH/70% EtOH for 5 min,
dehydrated in EtOH, air dried, and incubated with protease XXV
(Labvision, Fremont, California) at 371C for 7 min. After washing
with PBS, sections were blocked with 5% goat serum for 20 min,
washed, incubated with anti-thymine dimer, clone KTM53 diluted
1:200 (Kamiya Biomedical Company, Seattle, Washington) at 371C
for 1 h, followed by anti-mouse IgG conjugated with fluorescein
isothiocyanate diluted 1:200 at 371C for 30 min. Sections were
visualized using Olympus BX41fluorescence microscope coupled
with a Q-Fire camera.
Statistics Results are expressed as mean SD. The p-values
were calculated by two-tailed Student’s
This research was supported in part by NIH Grant R43CA83538. This
research was presented in part as posters at the 65th Annual Meeting
of the Society of Investigative Dermatology, Providence, Rhode Island
4/28-5/1 2004. Thanks to Doren Madey, PhD for help in preparation of
the manuscript. Sheldon Pinnell is a consultant for SkinCeuticals, Gar-
land, Texas. Jan Zielinski, PhD is president of Zielinski Laboratory, San
Diego, California.
DOI: 10.1111/j.0022-202X.2005.23768.x
Manuscript received January 7, 2005; revised February 10, 2005;
accepted for publication February 15, 2005
Address correspondence to: Sheldon R. Pinnell, MD, The J. Lamar
Callaway Professor Emeritus of Dermatology, Duke University, Box
3135 Duke University Medical Center, Durham, North Carolina 27710,
USA. Email:,
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... Under certain conditions, nano-encapsulation of ascorbic acid can be realized through ion gelation of chitosan or complex coacervation with anionic polymers [10,11]. On the other hand, some bioactive compounds with low molecular weight can protect ascorbic acid by scavenging the pro-degradation factors of ascorbic acid in the solution [12]. Stable ascorbic acid needs to be accurately delivered to the desired site, and released from the carrier at a desired rate and time. ...
... The oxidation-reduction potential of ferulic acid (0.595) is significantly higher than that of ascorbic acid (0.282), thus the former protect effect on ascorbic acid is indirect. There is a hypothesis that ferulic acid preferentially reacts with pro-oxidant intermediates or acts as a sacrificial substrate [12]. As mentioned above, low-molecular-weight stabilizers can inhibit the degradation of ascorbic acid to a certain extent, but it is hard to mask the acidic taste of ascorbic acid. ...
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The L-enantiomer of ascorbic acid is commonly known as vitamin C. It is an indispensable nutrient and plays a key role in retaining the physiological process of humans and animals. L-gulonolactone oxidase, the key enzyme for the de novo synthesis of ascorbic acid, is lacking in some mammals including humans. The functionality of ascorbic acid has prompted the development of foods fortified with this vitamin. As a natural antioxidant, it is expected to protect the sensory and nutritional characteristics of the food. It is thus important to know the degradation of ascorbic acid in the food matrix and its interaction with coexisting components. The biggest challenge in the utilization of ascorbic acid is maintaining its stability and improving its delivery to the active site. The review also includes the current strategies for stabilizing ascorbic acid and the commercial applications of ascorbic acid.
... dithiothreitol) [49] and formulation designs (e.g. ascorbic acid, ferulic acid and tocopherol) [82,83]. ...
Mitragynine is a promising candidate for pain relief and opiate replacement but the investigations for drug delivery are lacking. This study aims to investigate the potential of mitragynine to be delivered through the skin with an emphasis on developing and validating a gradient HPLC-UV analytical method to determine mitragynine in the samples collected during in vitro skin permeation studies. The optimised method involves a gradient elution using a C18 column with a mobile phase comprising acetonitrile and 0.1%v/v of formic acid (0 – 1 min: 30:70 to 70:30 (v/v) and hold up to 4 min; 4 – 6 min: return to 30:70 (v/v) and hold up to 10 min) at a flow rate of 1.2 mL/min. This method was validated based on the standards set by the International Council on Harmonisation guidelines. The method showed mitragynine elution at ∼4 min with adequate linearity (R² ≥ 0.999 for concentration ranges of 0.5 – 10 and 10 – 175 μg/mL) and acceptable limits of detection and quantification at 0.47 and 1.43 μg/mL, respectively. The analytical performance is robust with excellent precision and accuracy. This method was used to evaluate the in vitro skin permeation of mitragynine (5%w/v) from simple solvent systems over 48 hr. The results showed a cumulative amount of mitragynine permeated at ∼11 μg/cm² for dimethyl sulfoxide and ∼4 μg/cm² for propylene glycol. The study not only addressed the issues of the currently available HPLC-UV methods that limit the direct application but also affirmed the potential of mitragynine to be delivered through the skin.
... Topical formulation of ASC was stabilized by several emulsions with α-tocopherol, boric acid, citric acid, and tartaric acid (Rozman and Gasperlin, 2006;Ahmad et al., 2015). Ferulic acid stabilized aqueous solution of 15% ASC and 1% Vit-E improved 8-fold photoprotection for skin to solar simulated irradiation (Lin et al., 2005). A deep eutectic solvent of ASC and choline chloride (1:2) maintained its antioxidant properties up to 6 months (Silva et al., 2018). ...
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L-Ascorbic acid (ASC), commonly known as vitamin C, acts as an anti-oxidant in the biological system. It is extensively used as an excipient in pharmaceutical industry, food supplements in fruit juices, and food materials due to its free radicals scavenging activity. Main drawback of ASC is its poor aqueous stability owing to the presence of lactone moiety that is easily oxidized to dehydroascorbic acid and further degraded. To improve aqueous stability and inhibit oxidative degradation, ASC was co-crystallized to constitute binary eutectic compositions with mono and di-saccharides such as glucose, sucrose, lactose, and mannitol. The eutectics were confirmed by their (single) lower melting endotherm compared to ASC and sugars, although Powder X-ray diffraction (PXRD) and Fourier transform Infrared spectroscopy (FT-IR) data confirmed the characteristics of their physical mixture. Scanning electron microscope (SEM) images of the binary eutectics confirmed their irregular morphology. The ASC eutectics exhibited improved shelf-life by 2–5-fold in weakly acidic (pH 5) and neutral (pH 7) aqueous buffer medium, whereas the eutectic with glucose enhanced shelf-life only by 1.1–1.2-fold in acidic medium (pH 3.3 and 4). Notably, stabilizing effect of the sugar eutectics decreased with increasing acidity of the medium. In addition, higher binding energy of the disaccharide eutectics partially supports the aqueous stability order of ASC in the neutral pH medium due to more number of non-bonded interactions than that of monosaccharides.
... Ferulic acid is able to absorb UVA (cis-ferulic acid-peak at 317 nm; trans-ferulic acid-236 and 322 nm). 10 Until recently, this compound was used synergistically together with other antioxidants such as vitamin C and E, increasing their effectiveness and participating in their regeneration processes. 11 After oral administration, the bioavailability of ferulic acid in the skin is relatively low. 12 Formulas enriched with ferulic acid gain several times higher antioxidant and photoprotective efficacy than those without it. ...
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Introduction: Continuous production of reactive oxygen species, induced by UV radiation, is one of the main mechanisms contributing to skin photoaging. Therefore, the use of novel superior antioxidants, which ferulic acid belongs to, is an innovative treatment option. The aim of this study was to evaluate the effect of 14% ferulic acid peel on skin hydration, topography, the level of melanin, and the severity of erythema, in people with skin photoaging symptoms. Methods: 20 women aged 45 to 60, received 8 treatments of chemical peeling in 1-week intervals. Efficacy was measured using The Multi Probe Adapter (MPA) Systems (Courage + Khazaka electronic GmbH, Köln, Germany). The measurements were taken before, 8, and 12 weeks after the first treatment. Additionally, the photo documentation was made with Fotomedicus (Elfo) and VISIA® Complexion Analysis System (Canfield Scientific, Inc.). Results The objective evaluation showed statistically significant improvement in all measured skin parameters (P<0,05). The best results of skin hydration and melanin level were observed right after the end of the series (P<0,001). The best improvement in erythema reduction was noted a month after the last treatment (P<0,0001). At the control, untreated point none of the probes showed statistically significant changes. Conclusion: In conclusion, a series of treatments with 14% ferulic acid peel has a significant bleaching, erythema-reducing, and moisturizing activity. The results achieved by apparatus, are reflected by photo documentation. The effects achieved during a series persist over time.
... They had observed that the stabilization of the ROS and resonating permission are the mechanisms behind this photoprotective activity of the gel extract (Alencar Filho et al., 2020). Phytomolecules like Kaempferol and kaempferol analogs (Monici et al., 1994), Quercetin and quercetin analogs (Saija, 2003;Gonçalves et al., 2019), Tricin , Stigmasterol (Bayer et al., 2011), β-Sitosterol (Bayer et al., 2011), Ferulic acid (Lin et al., 2005;Peres et al., 2018), p-Coumaric acid , and Chlorogenic acid which were earlier reported from Alternanthera brasiliana (L.) Kuntze, may be responsible for this photoprotective property of the gel extract. ...
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Ethnopharmacological relevance: The genus Alternanthera ( Amaranthaceae ) comprises 139 species including 14 species used traditionally for the treatment of various ailments such as hypertension, pain, inflammation, diabetes, cancer, microbial and mental disorders. Aim of the review: To search research gaps through critical assessment of pharmacological activities not performed to validate traditional claims of various species of Alternanthera. This review will aid natural product researchers in identifying Alternanthera species with therapeutic potential for future investigation. Materials and methods: Scattered raw data on ethnopharmacological, morphological, phytochemical, pharmacological, toxicological, and clinical studies of various species of the genus Alternanthera have been compiled utilizing search engines like SciFinder, Google Scholar, PubMed, Science Direct, and Open J-Gate for 100 years up to April 2021. Results: Few species of Alternanthera genus have been exhaustively investigated phytochemically, and about 129 chemical constituents related to different classes such as flavonoids, steroids, saponins, alkaloids, triterpenoids, glycosides, and phenolic compounds have been isolated from 9 species. Anticancer, antioxidant, antibacterial, CNS depressive, antidiabetic, analgesic, anti-inflammatory, and immunomodulator effects have been explored in the twelve species of the genus. A toxicity study has been conducted on 3 species and a clinical study on 2 species. Conclusions: The available literature on pharmacological studies of Alternanthera species reveals that few species have been selected based on ethnobotanical surveys for scientific validation of their traditional claims. But most of these studies have been conducted on uncharacterized and non-standardized crude extracts. A roadmap of research needs to be developed for the isolation of new bioactive compounds from Alternanthera species, which can emerge out as clinically potential medicines.
... It is postulated that ferulic acid protects L-ascorbic acid and alpha-tocopherol, undergoing oxidation before the others in the formula. 25 There have been no studies evaluating the use of topical antioxidants for the treatment of AK and CFC. The present study demonstrated a beneficial and safe effect of the combination of 15% L-ascorbic acid, 1% alpha-tocopherol, and 0.5% ferulic acid in reducing the number of AKs, consequently controlling CFC activity. ...
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Background Several treatments are available for skin with advanced photodamage, which is characterized by the presence of actinic keratoses (AK). Objectives Evaluate the efficacy of using sunscreen with photolyase compared to regular sunscreen, as well as to compare the combination of a topical formulation of antioxidants versus placebo in the treatment of advanced photodamage. Methods This was a randomized, double-blind, factorial clinical trial. Participants with AKs on their forearms were randomized to apply regular sunscreen (SC) or sunscreen with photolyase (SC+P) on both forearms during the day. One of the forearms in each group was randomized again to receive topical antioxidants (AOx), and the other forearm received a placebo cream (both for night application). The four groups were SC/AOx, SC/placebo, SC+P/AOx, and SC+P/placebo. The duration of treatment was 8 weeks. Primary outcomes were total AK clearance, decrease in Forearm Photoaging Scale (FPS), and AK severity scores. Secondary outcomes were reduction in AK count, partial clearance rate, and safety. Results Forty participants (80 forearms) were included. All groups showed significant improvement in outcomes at week eight. There were no significant differences between SC and SC+P for either outcome. AOx led to a significant reduction in AK count (22%; p < 0.05). Partial clearance was obtained in 18 (47.4%) forearms treated with AOx and in 9 (23.7%) treated with placebo (p < 0.05). All groups reduced the FPS score, without significant differences among them. Conclusions There is no difference in the treatment of advanced photodamage skin when comparing the use of sunscreen with photolyase and regular sunscreen, and topical antioxidants were more efficient in reducing AK count than placebo. Study limitations Short interval of follow-up and absence of re-evaluation in the absence of treatment were limitations of the present study.
Germination improves seed functionality due to increased phytochemicals and associated antioxidant activities. These effects are enhanced with a suitable inductor which is applied at appropriate time and dose. The aim of the present work was to evaluate the effect of germination + UV-B elicitation on the chemical compositions, antioxidant activities (AoxA), total phenolic (TPC), total anthocyanin (TA), and γ-aminobutyric acid (GABA) contents in blue maize seeds. The application of UV-B radiation (wavelengths of 280 - 311 nm) during 37.0 h was an effective elicitor. Germinated-elicited blue maize flour (GEBMF) had higher proteins (+29.1%), dietary fibres (+22.0%), and AoxA (ABTS: +133.9%; DPPH: +173.4%) than unprocessed blue maize flour (UBMF). The increase in AoxA was closely related to the observed increase in TPC (+587.2%), TA (+29.9%), and GABA (+199.9%). Therefore, GEBMF could be used as a source of proteins, dietary fibres, and natural antioxidants in the formulation of new functional foods and beverages. These results could also contribute to the use and conservation of blue maize, an underutilised cereal.
This chapter presents a basic skin regimen to protect from photodamage and to reverse the appearance of aging. The four necessary steps are cleansing, exfoliation, protection, and treatment. Proper cleansing is an essential component of skincare. The inclusion of medications as components of cleansers can be effective in actually treating the skin. Exfoliation is the rejuvenation treatment providing the most immediate improvement in appearance. The single most effective therapy for aging skin is sun protection. The ability of a sunscreen to prevent UVB‐mediated erythema is measured by the internationally accepted standard sun protection factor, the ratio of equivalent exposure by UVB in sunscreen‐protected compared with unprotected skin. Retinoids are the "gold standard" for reversing photoaging of the skin. The skin naturally uses nutritional antioxidants to protect itself from photodamage and topical application has been investigated. Ferulic acid is a potent antioxidant present in the cell walls of grains, fruits, and vegetables.
Tocopherols and tocotrienols, which differ only in the degree of saturation of their hydrophobic prenyl side chains, are lipid-soluble molecules that have a number of functions in plants. Synthesized from homogentisic acid and isopentenyl diphosphate in the plastid envelope, tocopherols and tocotrienols are essential to maintain membrane integrity. α-Tocopherol is the major form found in green parts of plants, while tocotrienols are mostly found in seeds. These compounds are antioxidants, thus they protect the plant from oxygen toxicity. Tocopherols and tocotrienols scavenge lipid peroxy radicals, thereby preventing the propagation of lipid peroxidation in membranes, and the ensuing products tocopheroxyl and tocotrienoxyl radicals, respectively, are recycled back to tocopherols and tocotrienols by the concerted action of other antioxidants. Furthermore, tocopherols and tocotrienols protect lipids and other membrane components by physically quenching and reacting chemically with singlet oxygen. The scavenging of singlet oxygen by α-tocopherol in chloroplasts results in the formation of, among other products, α-tocopherol quinone, a known contributor to cyclic electron transport in thylakoid membranes, therefore providing photoprotection for chloroplasts. Moreover, given that α-tocopherol increases membrane rigidity, its concentration, together with that of the other membrane components, might be regulated to afford adequate fluidity for membrane function. Furthermore, α-tocopherol may affect intracellular signaling in plant cells. The effects of this compound in intracellular signaling may be either direct, by interacting with key components of the signaling cascade, or indirect, through the prevention of lipid peroxidation or the scavenging of singlet oxygen. In the latter case, α-tocopherol may regulate the concentration of reactive oxygen species and plant hormones, such as jasmonic acid, within the cell, which control both the growth and development of plants, and also plant response to stress.
As the outermost layer of skin, the stratum corneum (SC) is continuously exposed to an oxidative environment, including air pollutants, ultraviolet radiation, chemical oxidants, and aerobic microorganisms. Human SC reveals characteristic antioxidant and protein oxidation gradients with increasing antioxidant depletion and protein oxidation towards the outer layers. SC antioxidants, lipids, and proteins are oxidatively modified upon treatments with ultraviolet A/ultraviolet B, ozone, and benzoyl peroxide. α-Tocopherol represents the predominating SC antioxidant with respect to its concentration and its unique susceptibility to the various oxidative challenges tested. In sites rich in sebaceous glands, α-tocopherol is physiologically delivered to the surface via secretion of sebum. Oxidative damage in the human SC represents an early pathophysiological event preceding barrier disruption and inflammation in environmentally challenged skin. Furthermore, oxidative gradients in SC proteins may have implications for the process of desquamation in human skin.