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Ascorbic acid (vitamin C) is extensively used in a variety of formulations including creams. It is an ingredient of anti-aging cosmetic products alone or along with alpha-tocopherol (vitamin E). In solutions and creams, ascorbic acid is susceptible to air and light and undergoes oxidative degradation to dehydroascorbic acid and further to inactive products. The degradation is influenced by oxygen, temperature, viscosity and pH of the medium and is also catalyzed by metal ions, particularly Cu2+, Fe2+, and Zn2+. This review highlights the stability and modes of stabilization of ascorbic acid in both the cosmetic and pharmaceutical preparations. A number of approaches involved in the stabilization of the vitamin such as the use of antioxidants, stabilizers, synergists, other vitamins, and formulation of multiple emulsions, nanosuspensions, microencapsulation, etc. have been discussed (16) Stability and Stabilization of Ascorbic Acid. Available from: https://www.researchgate.net/publication/321148774_Stability_and_Stabilization_of_Ascorbic_Acid [accessed Jan 28 2018].
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KEYWORDS: Ascorbic acid; stability; stabilization, cosmetic and pharmaceutical preparations.
AbstractAscorbic acid (vitamin C) is extensively used in a variety of formulations including creams. It is an
ingredient of anti-aging cosmetic products alone or along with alpha-tocopherol (vitamin E). In
solutions and creams, ascorbic acid is susceptible to air and light and undergoes oxidative degradation to dehydroascorbic
acid and further to inactive products. The degradation is influenced by oxygen, temperature, viscosity and pH of the medium
and is also catalyzed by metal ions, particularly Cu2+, Fe2+, and Zn2+. This review highlights the stability and modes of stabilization
of ascorbic acid in both the cosmetic and pharmaceutical preparations. A number of approaches involved in the stabilization of
the vitamin such as the use of antioxidants, stabilizers, synergists, other vitamins, and formulation of multiple emulsions,
nanosuspensions, microencapsulation, etc. have been discussed.
Stability and Stabilization of Ascorbic Acid
A Review
INTRODUCTION
Ascorbic acid (AA) is known to play an important role as
an antioxidant due to its presence in the body  uids (1). It
causes an increase in the rate of absorption of iron, calcium
and folic acid and hence reduces allergic reactions,
boosts the immune system, stimulates the formation of bile
in the gallbladder and facilitates the excretion of various
steroids (2). In the body AA plays an essential role in the
production of collagen tissue around bones, teeth, cartilage,
skin and damaged tissue (3). It has shown a prominent
pharmacological effect in a number of disease conditions
such as scurvy, common cold, osteoarthritis, hypertension,
heart diseases, cancer, diabetes mellitus, asthma, wound
healing, pregnancy, gout and eye diseases (4). Because
of all these favourable effects, AA has been used in a
variety of cosmetic and pharmaceutical formulations (5). It
is highly soluble in water and alcohol, and is easily oxidised
to dehydroascorbic acid in its solubilised form (1). The rapid
degradation of AA in aqueous media is still a major factor
in the formulation of its products. It is also reported that AA
oxidation occurs rapidly in an alkaline environment especially
at higher temperatures (>50°C) (6) and its reaction with
oxygen is strongly catalysed by metal ions, particularly cupric
and ferric ions (7, 8). The degradation of AA proceeds both by
aerobic and anaerobic pathways and depends upon many
factors such as oxygen, temperature, light, pH and storage
conditions (1, 3, 9–12).
STABILITY OF AA
The stability of a pharmaceutical formulation, particularly,
the semisolid dosage form depends on its formulation
characteristics and the nature of the active ingredients.
These characteristics are in uenced by the nature and
amount of the excipients to be added and their sensitivity to
the environmental factors to which these dosage forms are
exposed. In the semisolid dosage forms a careful selection
of bases including oil-in-water (o/w) and water-in-oil (w/o)
emulsifying agents, humectants, emollients, etc. would
provide physical stability to the formulation and enhance the
shelf-life of the product. In the selection of these ingredients
the formulator has to take into consideration the nature of
the active ingredient and the possible effect of formulation
ingredients on its stability pro le. The stability of AA and
various modes of its stabilization are discussed in the following
sections:
Vegetables and Fruits
AA is a white crystalline organic compound and can be
synthesized from glucose or extracted from certain natural
sources such as fruits and vegetables to meet the nutrient
requirements of a healthy diet. Plants and most animals
synthesize their own AA but humans lack this ability due to the
de ciency of an enzyme known as L-gulono-gamma-lactone
oxidase (13).
AA along with its derivatives is added to foods and fruit
FORMULATION
MUHAMMAD ALI SHERAZ*, MARIUM FATIMA KHAN, SOFIA AHMED, SADIA HAFEEZ KAZI, IQBAL AHMAD
*Corresponding author
Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, 51, Deh Tor, Toll Plaza,
Super Highway, Gadap Road, Karachi-74600, Pakistan
H&PC Today - Household and Personal Care Today Vol. 10(3) May/June 2015
23
the studies
related to the
stabilization of
AA.
STABILIZATION OF
AA
In order to
achieve maximum
stability of AA in
various foods,
cosmetics and
pharmaceutical
formulations, different strategies have been employed, some
of which are briey described below:
Use of Other Vitamins in Combination with AA
AA is known to be one of the important members of the
water-soluble vitamin group. It has been reported that AA
acts synergistically with other water- and fat-soluble vitamins
including alpha-tocopherol (vitamin E) (TP) (31). In recent
years, AA has been successfully used in a number of cosmetic
and dermatological formulations along with TP. They are
specically indicated for topical applications such as skin
depigmentation and ability to take part in proline and lysine
hydroxylation in collagen biosynthesis (3). The stabilizing
effect of TP on the photodegradation of AA has been studied
using UV spectrometry. Similarly, the stability of AA in o/w
creams in the presence of vitamins including riboavin (RF),
nicotinamide (NA) and TP has been investigated by Ahmed
et al. (31), Jung et al. (37), Kim et al. (38) and the results
showed the highest stability of AA with TP.
Use of Stabilizers / Preservatives / Synergists
The photosensitivity of AA makes it highly unstable for use
in cosmetic (9) and pharmaceutical preparations (26) and
hence it requires the use of appropriate stabilizing agents. As
mentioned above, TP acts as a synergist with AA, by acting as
an electron donor to restore the tocopheroxyl radical (7, 39).
TP rst functions as the primary antioxidant that reacts with
an organic free ascorbyl radical in the physiological system
and is then converted back to ascorbate through the redox
cycle (40). The interaction of AA with a redox partner such as
TP has been found to be useful to slow down its oxidation and
prolong its physiological action (3, 41, 42).
The instability of AA in various formulations also leads to the
use of stabilizers or preservatives such as citric acid (CT),
boric acid (BA) or tartaric acid (TA). A study was designed
to determine the effects of CT, TA and BA on the stabilization
of AA in various o/w cream formulations in the light and
in the dark. The results indicated a marked decrease in
the rate of degradation of AA by these stabilizers both
in the light and in the dark. The order of stabilization was
found as CT>TA>BA (20). Similarly, a decrease in the rate
of degradation of AA in w/o creams has been observed
in the presence of CT indicating that the change of phase
does not affect the efcacy of the stabilizer (21). In the AA
formulations, these agents act simultaneously as antioxidants
(29, 43, 44), preservatives or synergists (45) that may lead to
the stabilization of the formulations. CT has been found to
be a naturally occurring antioxidant in carcinogenesis (46)
and lipid peroxidation (47) whereas BA acts as a complexing
agent for hydroxyl compounds including AA (9, 20, 48–52)
juices for the improvement of nutritional quality (14, 15).
The degradation of AA in orange, grape, pomegranate
juices and sour cherry nectar with or without the addition of
hydrogen peroxide (H2O2) has been studied at 20, 30 and
40°C (16). In another stability study for the determination of
the retention of AA in homogenized raw fruits and vegetables
stored under routine conditions, raw collard greens (Brassica
oleracea var. viridis), clementine (Citrus clementina hort. ex
Tanaka) and potatoes (Solanum tuberosum) were selected
as the representatives of foods to be sampled in a USDA’s
National Food and Nutrient Analysis Program (NFNAP) (17).
The retention of AA was also studied in dried guava during
storage at 30, 40 and 50°C and with different water activity
values that resulted in the degradation of AA by a pseudo-rst
order reaction (18).
Cosmetic and Pharmaceutical Formulations
AA has found wide applications in the eld of cosmetics
and pharmacy. In cosmetic preparations AA is used for its
anti-ageing, depigmentation (19) and antioxidant properties
(20–22) along with its ability to reduce wrinkles by promoting
collagen synthesis (23). Because of these favourable effects,
AA has long been used in cosmetic preparations (5, 24).
AA is sensitive to light (9, 25–30) and is degraded to form
dehydroascorbic acid and 2,3-diketogulonic acid on UV
irradiation by photooxidation and subsequent hydrolysis (27)
(Figure 1).
Similarly, chemical oxidation has also been found as a
major cause of AA degradation in the dark (9, 20, 21,
31) thus making it difficult to be used in cosmetics and
pharmaceutical formulations. The contact of AA with
metals in solution form has been reported to form free
radicals which are then converted to molecular oxygen
that oxidizes AA in solution. The rate of oxidation has
been found to increase with pH, oxygen content and
concentration of metal ions in the solution (32, 33). In
an attempt to study the stability of AA in pure water
solutions (without buffers), it has been observed that the
rate of oxidation is pH dependent, showing a minimum
at pH 2.5 to 3.0 and a maximum at pH 4.0. The pH
adjustment is necessary to preserve the physical, chemical
and therapeutic properties of AA because fruit juices
containing this vitamin have pH values ranging from 2.5 to
5.0 (34).
A number of derivatives of AA such as sodium ascorbate
and ascorbyl palmitate are used as antioxidants in
cosmetics and pharmaceutical preparations (29, 35).
However, they lack the biological activity similar to that of
AA (5, 36); therefore, this review particularly emphasizes
Figure 1. Degradation of ascorbic acid (AA) upon UV irradiation by photooxidation and subsequent hydrolysis.
H&PC Today - Household and Personal Care Today Vol. 10(3) May/June 2015
24
to use the latter in dermocosmetic products (71). It has
been stated that the stability of AA may be achieved by
preparing a solid-in-oil-nanosuspension (SONS) having
medium chain triglycerides such as sucrose erucate (i.e.
lipophilic surfactant) and sucrose monolaureate (i.e.
hydrophilic surfactant) stored at 25°C, protected from light.
A lipase-based enzymatic technique has been used to
degrade a formulation phase making it easier for AA to be
extracted. The results showed that the entire encapsulated
AA (95.3%) has been successfully extracted from the SONS
with the addition of a medium-chain triglyceride. Hence
the SONS showed increased stability of AA due to low
moisture contents (65).
Use of Solvents
In aqueous solution AA undergoes rapid oxidation (1)
but its stability is increased in acidic and weakly alkaline
media upon the addition of acetonitrile. It has been
observed that acetonitrile decreases the rate of AA
degradation to four fold at a concentration of 0.2%
while at a concentration of 2.0% the rate of reaction
reaches to the least value and remains unchanged upon
further addition of acetonitrile (58). This may be due to
a change in the polarity of the medium to inhibit the
rate of degradation of ionized AA. The effect of ethanol
on the stabilization of AA was also studied and the
results indicated a markedly lower effect of this solvent
compared to acetonitrile (58).
Effect of Viscosity, Dielectric Constant and pH
The rate of a chemical reaction may be affected by a
number of factors including the pH, viscosity and dielectric
constant of the medium which can greatly influence the
stability of oxidisable substances (72, 73). A study has been
performed to determine the effect of different humectants
such as ethylene glycol, propylene glycol and glycerine
in cream formulations containing AA. The humectants
showed stabilizing effect on the degradation of AA,
depending upon their viscosity, in the order of ethylene
glycol>propylene glycol>glycerine (9). A study of the rate
of photolysis of AA in aqueous and organic solvents has
been carried out using UV irradiation. It has been observed
that there is a linear relation between the rate of photolysis
and the solvent dielectric constant or the reciprocal
of viscosity. Hence an increase in the solvent dielectric
constant or a decrease in solvent viscosity leads to an
increase in the rate of photolysis. This should be taken into
consideration during the formulation of pharmaceutical
preparations containing AA (50). As stated earlier the rate
of photolysis of AA in cream formulations is also affected
by pH and redox potential of AA (e.g. E° at pH 5.0 = +0.127
V and at pH 7.0 = +0.058 V) and is due to the change in
the ionization of AA. An increase in the viscosity of creams
is also known to affect the physical stability of AA in cream
formulations. It has been reported that the higher the
viscosity of the medium the lower will be the degradation
of AA. Therefore, a careful selection of excipients including
emollients and humectants is of utmost importance to
improve the stability of AA (21).
Microencapsulation
Microencapsulation and emulsification are the widely
used techniques for the stabilization of AA in formulations
particularly at a concentration of 1–5% (18, 69, 74).
and enhances its level in plasma (53). Stabilization of AA
is also achieved by using other antioxidants such as DL-
methionine, mannitol, sorbitol, sucrose, dextrose, sodium
thiosulphate, halide salts, triplet quenchers, metal-
complexing agents and various viscosity enhancing agents
(54, 55). For the maximum stability of AA in solutions the
use of metaphosphoric acid is also reported (56, 57) with
greater efficacy than that of CT, perchloric, acetic, and
orthophosphoric acids (57, 58). In another study palmitic
acid (PA), an emulsifier, has been observed to exert a
greater stabilizing effect against the degradation of
AA in creams than the myristic and stearic acid (9). The
drugs prepared in the form of extruded granules with low
substituted hydroxyl propyl cellulose (L-HPC) and water
have been investigated using AA and thiamine nitrate
(TN) as model drugs. D-Mannitol is used as the control
additive for a comparison with L-HPC. The percentage of
AA remaining after a storage period of 14 days at 60°C in
a closed glass bottle was 57% in D-mannitol granules and
89% in L-HPC granules, showing higher stability of AA in
L-HPC granules (33).
Formulation of Multiple Emulsions
Multiple w/o/w emulsions are vesicular systems in which small
water droplets are entrapped within oil drops, and then
dispersed in the aqueous phase (59). They may be used as
a potent drug and cosmetic vehicles to prolong the action
after administration (60–63). The w/o emulsions containing
AA complexed with surfactants have been reported
(64–66). In a separate formulation, AA is added into the
inner aqueous phase of the w/o/w emulsion using parafn
oil at a concentration of 1% and a two step method for the
preparation of the emulsion. Stability studies on AA have been
performed at different temperatures, such as 8°C (refrigerator),
25°C (oven) and 40°C (oven) at 75% RH (stability cabin) for a
period of 28 days to foresee the changes in these formulations.
Different parameters, such as pH, globule size, electrical
conductivity and effect of centrifugation (simulating gravity)
have been evaluated during the stability studies. Multiple
emulsion formulations have been found to be stable at lower
temperatures (i.e. 8° and 25°C) during the study period with
no phase separation in all the samples (67). Another study has
been conducted using a high concentration of AA up to 30%
in the dispersed phase of w/o emulsions, with their continuous
phase containing rened soybean oil or Moringa oleifera oil
and a food-grade hydrophobic emulsier. All the w/o emulsions
appeared stable for more than 30 days at 4°C or 25°C with
slight increase in the average droplet diameter and without
any phase separation. AA retention ratio of these emulsions
followed rst-order kinetics showing good stability (68).
In order to study the effect of composition on AA
formulations such as surfactant/co-surfactant associations
and the use of different oils on the physicochemical
characteristics of the system, a polyglycoside
microemulsion has been developed which showed
good stability. It can protect AA from degradation with
enhanced penetration ability into the skin for topical
application. The study also revealed that the control of
pH and electrolyte concentration is necessary for the
stabilization of AA in the formulations (69, 70).
Formulation of Nanosuspensions
Since AA is not as stable as its derivatives such as tetra-
isopalmitoyl ascorbic acid (IPAA), it is often, recommended
H&PC Today - Household and Personal Care Today Vol. 10(3) May/June 2015
25
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Both w/o and w/o/w emulsification methods have
been used for encapsulation of AA (3, 67–69, 74–76). In
order to improve AA microencapsulation by complex
coacervation, both gelatine and gum arabic have
been used as encapsulating agents. In a w/o emulsion
using corn oil, a 30% solution of AA and polyglycerol
polyricinoleate (PGPR 90) as surfactant has been made for
making coacervation of a hydrophilic core material. The
encapsulation was carried out successfully in the double
emulsion with the complex coacervation thus confining
AA to a more stable microcapsule form rather than in
solution. It suggests the option of controlled release
under specific conditions and masking the acidic taste
of AA (77). Microencapsulated AA is also reported to
be more stable to colour change (18). Starch and beta-
cyclodextrin encapsulated AA delays its degradation
during storage at a temperature of 38°C and relative
humidity of 84% (18).
CONCLUSION
The stability of air sensitive drugs such as AA has always
been a problem for the formulator. Various approaches
have been adopted to achieve stabilization of AA in
cosmetic preparations. These include the use of stabilizers,
antioxidants, preservatives, synergists, emulsifiers etc. The
techniques of entrapment of AA in multiple emulsions and
encapsulation in nanosuspensions have shown significant
improvement in the stabilization of AA. The control of
medium pH, polarity and viscosity also prolong the shelf-life
of AA in cosmetic preparations.
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H&PC Today - Household and Personal Care Today Vol. 10(3) May/June 2015
... High dose (millimolar concentration) of ascorbic acid has been shown to be cytotoxic against oral cancer cells [7][8][9]. However, formulating ascorbic acid is difficult due to its instability in the bulk aqueous system [10]. Several approaches have been adopted to preserve its stability and enhance its delivery to the target site, such as formulation of multiple emulsion, and microparticles including nanoparticles [10][11][12]. ...
... However, formulating ascorbic acid is difficult due to its instability in the bulk aqueous system [10]. Several approaches have been adopted to preserve its stability and enhance its delivery to the target site, such as formulation of multiple emulsion, and microparticles including nanoparticles [10][11][12]. Furthermore, nanoparticulate systems have been reported to improve drug accumulation, drug uptake and drug absorption across biological barriers [13,14]. ...
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Background: Chemotherapy is commonly used in oral cancer therapy, especially as the disease advances. However, it is associated with terrible adverse effects and the occurrence of chemoresistance which causes treatment failure. Thus, discovering a new potential anticancer agent and developing a safe, effective and non-invasive drug delivery are necessary. Objective: The objective of the current study is to develop ascorbic acid-loaded poly(lactic-co-glycolic) acid (AA-PLGA) nanoparticles incorporated into polyacrylic acid gel intended to treat oral cancer. Materials and methods: Double emulsion solvent evaporation method was used to fabricate AA-PLGA nanoparticles. Optimisation was carried out in the primary emulsion based on multilevel factorial design by testing at varying surfactant types and concentrations. The optimised nanoparticles formulation was further incorporated into different concentrations of polyacrylic acid gel, and compared with a mucoadhesive polyacrylic acid-based commercial product (Kin Care) as a reference. The optimised AA-PLGA nanoparticles were subjected to cytotoxic assay against the SCC-25 cell line. Results: For the optimised formulation, we observed particle size of 252 ± 2.98 nm, polydispersity index (PDI) of 0.151 ± 0.02, zeta potential of -20.93 ± 0.87 mV, and encapsulation efficiency of 69.73 ± 1.07%. Polyacrylic acidpolymer with a strength of 1% was chosen as the optimum gelling agent for AA-PLGA nanoparticles-in-gel formulation. Cytotoxicity study of the optimised nanoparticle demonstrated significant (p-value < 0.05) reduction of cancer cell viability in a dose-dependent manner with a half-maximal inhibitory concentration value of 2.42 mg/mL. Conclusion: The results of the present study support the feasibility of AA-PLGA nanoparticles-in-gel formulation for oral cancer therapy.
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Background: 5-Fluorouracil (5-FU) is a routine anticancer agent for several cancer types, its short half-life requires continuous administration in high doses. This results in toxic side-effects to the normal tissues in the body. Vitamin C is an antioxidant which believed to impart cyto-protection to normal tissues in cancer patients treated with chemotherapeutic drugs. Aim of the Study: To assess the potential benefit of vitamin C administration 24 hours after 5-FU treatment compared to its immediate supplementation on normal fibroblast cell line. Materials and Methods: Fibroblast cell line (WI-38) was divided into 5 groups. Group I not treated (control group), group II treated with 5-FU only and group III received vitamin C only. Groups IV and V received 5-FU with vitamin C simultaneously and after 24 hours of 5-FU administration, respectively. The viability of cells in all groups was determined using MTT assay. MDA Quantification Assay was used to determine lipid peroxidation. Flow cytometry was used for evaluation of the cell cycle and cell death. All recorded data was statistically analyzed. Results: Cells in group IV seems like group II fewer and rounded while in group V some of them adherent spindle and the others rounded non-adherent. The least viability was noted in group II. MDA levels were significantly lower in groups III compared to all the other groups. Cell cycle analysis revealed the presence of statistically significant differences between groups in different phases of the cycle. Flowcytometry analysis showed the highest apoptosis in groups II and IV. Conclusion: Co-treatment of normal fibroblasts with vitamin C along with 5-FU reduces cell death and lipid peroxidation while enhancing viability and proliferation in treated fibroblasts, indicating healing and repair. Vitamin C administration 24 hours after 5-FU is more effective in reducing cell death and lipid peroxidation compared to its concomitant administration with 5-FU.
... Also, HYP was shown to be more effective than VC (600 µM) since lower concentrations of HYP presented similar protective effects in human spermatozoa. Previous studies reported that VC stability is influenced by pH, temperature, oxygen, and the presence of metal ions, such as copper and iron [82,83]. VC decomposes rather quickly in an aqueous medium, and its oxidation is highly favoured in neutral or basic conditions, being the lowest rate of oxidation observed at pH 3 [84]. ...
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Background/aims: Oxidative Stress (OS) is reported as one of the main causes of male infertility. Infertile couples often resort to assisted reproductive technology (ART) to achieve parenthood. However, preparation for ART protocols increases the exposer of gametes to OS. Thus, it is crucial to find suitable preservation media that can counteract the OS-induced damages in spermatozoa. In this work, we tested and compared the efficiency of vitamin C (VC) and hyperoside (HYP) as potential antioxidant supplements for sperm preservation media. Methods: We evaluated the cytotoxicity of HYP (0, 5, 50, 100, and 500 µM) in spermatozoa. After incubation of sperm cells with VC (600 µM) and HYP (100 and 500 µM), in the presence and absence of H2O2 (300 µM), the following parameters were assessed: total sperm motility and vitality, OS biomarkers expression, total antioxidant capacity (TAC) of the media, percentage of DNA fragmentation, mitochondrial membrane potential (MMP), and metabolite quantification of the media by proton nuclear magnetic resonance (1H-NMR). Results: The supplementation with VC (600 µM) and HYP (100 and 500 µM) did not induce any deleterious effects to the physiology and metabolism of the spermatozoa, after 1-hour of treatment. In the presence of H2O2 (300 µM), both VC and HYP were able to prevent some of the deleterious effects of H2O2 in sperm, which were represented by an increase in sperm motility, a decrease in DNA fragmentation, and a decreasing trend in lipid peroxidation levels. However, these antioxidants were not able to prevent the decrease of MMP associated with H2O2 treatment, nor were able to prevent the conversion of pyruvate into acetate (a reaction promoted by H2O2). Conclusion: The supplementation of sperm preservation media with VC and HYP could be beneficial for the preservation of sperm physiology. From the antioxidant conditions tested, the supplementation of media with HYP (100 µM) demonstrated the best results regarding sperm preservation, evidencing the higher antioxidant capacity of HYP compared to VC. Nevertheless, none of the antioxidants used was able to prevent the metabolic alterations promoted by H2O2 in spermatozoa.
... Ascorbic acid is recognized as performing a significant role as an antioxidant in the human body [72]. This compound is crucial in food processing because any change in vitamin C level shows that the quality of the food has deteriorated after processing and during storage [73]. ...
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Anthocyanins are secondary metabolites and water-soluble pigments belonging to the phenolic group, with important functions in nature such as seed dispersal, pollination and development of plant organs. In addition to these important roles in plant life, anthocyanins are also used as natural pigments in various industries, due to the color palette they can produce from red to blue and purple. In addition, recent research has reported that anthocyanins have important antioxidant, anticancer, anti-inflammatory and antimicrobial properties, which can be used in the chemoprevention of various diseases such as diabetes, obesity and even cancer. However, anthocyanins have a major disadvantage, namely their low stability. Thus, their stability is influenced by a number of factors such as pH, light, temperature, co-pigmentation, sulfites, ascorbic acid, oxygen and enzymes. As such, this review aims at summarizing the effects of these factors on the stability of anthocyanins and their degradation. From this point of view, it is very important to be precisely aware of the impact that each parameter has on the stability of anthocyanins, in order to minimize their negative action and subsequently potentiate their beneficial health effects.
... In Poland, wild rose fruits are the only plants that are superior to blackcurrant in terms of vitamin C content [2,8,27]. Vitamin C is very sensitive in comparison to other vitamins, and at the same time, is the least durable upon exposure to oxygen, UV radiation, pH or heavy metal ions, and is highly sensitive to damage by temperature and the time of exposure of the factors mentioned above [28]. Therefore, optimal antioxidant properties are found in the raw form. ...
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The number of consumers seeking safe and health-beneficial foods is systematically increasing. Consumers demand more environmentally friendly and safe food options coming from organic farming. Blackcurrants fruits are a perfect source of biological active compounds, such as vitamin C, polyphenols and flavonoids as well anthocyanins. Organic agricultural practices have modified the level of bioactive compounds in blackcurrant fruits. The novelty and the aim of the presented study was to compare the concentrations of selected health-promoting antioxidants in fruits of three blackcurrants (‘Ben Adler’, ‘Tiben’ and ‘Titania’) grown in organic and conventional orchards in Poland. For bioactive compound determination, the high-performance liquid chromatography (HPLC) method was used. The obtained results showed that organic blackcurrant fruits contained significantly more vitamin C (9.4 mg/100 g f.w.), total polyphenols (189.2 mg/100 g f.w.), total phenolic acids (10.3 mg/100 g f.w.), and total flavonoids (178.8 mg/100 g f.w.), as well anthocyanins (167.9 mg/100 g f.w.), compared to conventional ones. The selected cultivars and the years of cultivation system affect the concentration of the measured polyphenols, with strong interactions between these factors. The experiment confirms the hypothesis that organic blackcurrants should be a very important part of well-balanced, healthy diet.
... The amount of AA required in the diet varies according to species, size, age, breeding condition, and the form of AA administered [3]. In its pure form, ascorbic acid is unstable in alkaline environments, where its oxidation is accelerated, leading to its loss at rates influenced by factors including temperature, oxygen, light, and pH, among others [11]. Therefore, it is important to develop new technologies capable of protecting this molecule against premature degradation, increasing its stability and bioavailability. ...
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This paper provides dynamic insight into the aggregation profile of systems containing six different phospholipid species, cholesterol, and vitamin C thru Coarse-Grain Molecular Dynamics (CGMD) simulations. The simulation used 42 systems, and each system was composed of 220 molecules of each phospholipid species, a varied number of cholesterol molecules (0, 11, 22, 33, 66, 88), and 10 vitamin C molecules. The phospholipid species were DLPE, DOPE, DLiPE, DOPS, DLiPS, and DLiPC. We found curved bilayer, toroidal bilayer, concave micelle, disc-like bilayer, planar bilayer, and liposome structures in the systems during the 40 ns simulation. The systems with a ratio cholesterol:phospholipid between 15% and 40% formed liposomes regardless of the phospholipid species. Cholesterol is positioned in the liposome bilayer while vitamin C is encapsulated in the aqueous core of liposomes for all cholesterol compositions. The cholesterol influences the liposome formation of various phospholipid species and the encapsulation of vitamin C in the liposome structure.
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Chapter
Ascorbic acid is an essential water-soluble vitamin, commonly known as vitamin C. It is abundantly available among animals and plants naturally. Only very few species of the animals such as guinea pigs, human beings, and most of the primates require ascorbic acid in their diet. Humans are unable to synthesize vitamin C endogenously because of the deficiency of an enzyme, L-gulono-gamma-lactone oxidase that catalyzes the terminal step in ascorbic acid biosynthesis. It acts as an essential cofactor, electron donor during collagen hydroxylation, which boosts the maturation of intracellular and extracellular collagen production. Ascorbic acid is a promising nutraceutical found naturally in food imparting medical or health benefits. It is also called l-ascorbic acid which acts as a powerful antioxidant and free radical scavenger that protects tissues, cell membranes, and DNA from oxidative damage. This chapter also covers the various sources, extraction, and characterization, mode of action, safety, and toxicity associated with ascorbic acid including its health benefits.
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Background: Reactive oxygen species generated by ultraviolet light result in photocarcinogenic and photoaging changes in the skin. Antioxidants protect skin from these insults. Objective: This study defines formulation characteristics for delivering L-ascorbic acid into the skin to supplement the skin's natural antioxidant reservoir. Methods: L-ascorbic acid or its derivatives were applied to pig skin. Skin levels of L-ascorbic acid were measured to determine percutaneous delivery. Results: L-ascorbic acid must be formulated at pH levels less than 3.5 to enter the skin. Maximal concentration for optimal percutaneous absorption was 20%. Tissue levels were saturated after three daily applications; the half-life of tissue disappearance was about 4 days. Derivatives of ascorbic acid including magnesium ascorbyl phosphate, ascorbyl-6-palmitate, and dehydroascorbic acid did not increase skin levels of L-ascorbic acid. Conclusions: Delivery of topical L-ascorbic acid into the skin is critically dependent on formulation characteristics.
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Ascorbic acid degradation in orange, grape and pomegranate juices, and sour cherry nectar was studied at 20, 30 and 40 °C, with or without the addition of hydrogen peroxide (H2O2). Analysis of kinetic data suggested that the degradation fitted better to a zero-order model than a first-order model. Rate constants increased slightly in the presence of 0.5 ppm H2O2. However, increasing H2O2 concentration from 0.5 to 5 ppm caused a substantial increase in the degradation rates of ascorbic acid. Anthocyanins markedly accelerated the degradation of ascorbic acid in sour cherry nectar and pomegranate juice, especially at 5 ppm H2O2 concentration. Degradation was slowest in orange juice, with or without the addition of H2O2. Activation energies were lowest for grape juice (26.2 kJ mol−1) and highest for pomegranate juice (71.0 kJ mol−1) in the presence of 0.5 ppm H2O2.
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Ascorbic acid (vitamin C) is an essential nutrient involved in many physiological functions. In addition to its vitamin activities, the use of ascorbic acid has extended to other medical and industrial applications. Most of these make use of its reducing properties. In animals and plants, ascorbic acid can provide protection against oxidative damage from environmental chemicals, ionising radiation and ultraviolet light. However, ascorbic acid in solution is very unstable. It may undergo auto-oxidation and decompose rapidly to produce many degradation products. Some of these oxidation and degradation products have destructive pro-oxidant effects, including lipid peroxidation, cytotoxicity, mutagenesis and adduct formation with proteins and nucleic acid. Various methods have been attempted to stabilise ascorbic acid in solution. An isotonic ascorbic acid solution stabilised by a borate-EDTA buffering system has been prepared. This solution is very stable with respect to ascorbate content, colouring, clearness, and pH value. It contains ascorbate: 5 mM, berate: 320 mM, EDTA: 3 mM, and sodium ion: 155 mM, and has a pH value of 7.4. Results from in vitro and in vivo experiments indicate that this solution is not toxic to cultured cells or laboratory animals. It is suitable for nutritional, biochemical, and medical applications.
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Sodium ascorbyl phosphate is a hydrophilic derivative of ascorbic acid, which has improved stability arising from its chemical structure. It is used in cosmetic and pharmaceutical preparations since it has many favorable effects in the skin, the most important being antioxidant action. In order to achieve this, it has to be converted into free ascorbic acid by enzymatic degradation in the skin. In the present work, o/w and w/o microemulsions composed of the same ingredients, were selected as carrier systems for topical delivery of sodium ascorbyl phosphate. We showed that sodium ascorbyl phosphate was stable in both types of microemulsion with no significant influence of its location in the carrier system. To obtain liquid microemulsions appropriate for topical application, their viscosity was increased by adding thickening agents. On the basis of rheological characterization, 4.00% (m/m) colloidal silica was chosen as a suitable thickening agent for w/o microemulsions and 0.50% (m/m) xanthan gum for the o/w type. The presence of thickening agent and the location of sodium ascorbyl phosphate in the microemulsion influenced the in vitro drug release profiles. When incorporated in the internal aqueous phase, sustained release profiles were observed. This study confirmed microemulsions as suitable carrier systems for topical application of sodium ascorbyl phosphate.
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An HPLC method, for the simultaneous determination of the degradation products of ascorbic acid, was employed to investigate the degradation of ascorbic acid in aqueous solution at different pH values. After ascorbic acid aqueous solutions were heated at 100 °C for 2 h, four main degradation products, furfural, 2-furoic acid, 3-hydroxy-2-pyrone, and an unidentified compound, were separated and determined. In an acid aqueous solution, ascorbic acid was converted to 2-furoic acid and 3-hydroxy-2-pyrone via dehydroascorbic acid under aerobic conditions, whereas under anaerobic conditions, ascorbic acid degraded to furfural. Low pH conditions favored the formation of furfural, 2-furoic acid, and 3-hydroxy-2-pyrone; at extremely low pH (i.e., pH 1), the formation of furfural dominated. In an alkaline aqueous solution, the unknown compound became the main degradation product of ascorbic acid; at pH 10, only very small amounts of furfural and 3-hydroxy-2-pyrone with no 2-furoic acid were detected. Our results suggest that, in a hydrogen-ion-catalyzed environment, the anaerobic degradation of ascorbic acid to furfural is the main degradation pathway in an aqueous solution. Keywords: Ascorbic acid; dehydroascorbic acid; degradation; furfural; 2-furoic acid; 3-hydroxy-2-pyrone; HPLC
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Jellies, prepared from strawberry, blackberry, apple and orange juice, were fortified with ascorbic acid at 0, 35, and 70 mg/100 mL. After storage at room temperature, the jellies were sampled at intervals up to 32 wk for color measurement. The ascorbic acid did produce lighter products as shown by higher Hunter L values. The hues were shifted towards the yellow as shown by higher theta values. The ascorbic acid was well retained in the jellies. Whether the lightness and hue changes are desirable is probably a matter of individual preference.
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This paper constitutes a study of the interaction between ascorbate, diketogulonate, manganous ion, oxygen and illuminated flavins (or other sensitizers). When ascorbate is chosen as the substrate, the resulting photoxidation assumes a peculiar two-step course. This happens because traces of ascorbate inhibit the photoxidation of diketogulonate and oxygen retards the photoxidation of small amounts of ascorbate. Sensitized photo-reactions which are inhibited by high concentrations of oxygen are affected by the addition of various organic compounds. Of these, the herbicides 3-(p-clilorophenyl)-1,1-dimethylurea (CMU) and 3-(3, 4-dichlorophenyl)-1,1-dimethylurea (DCMU) interfere nearly exclusively with flavin sensitized photoreactions, while other inhibiting compounds tested, such as tryptophane and tyrosine, do not display a similar selectivity for only one dye. A second even more rigid specificity concerns the role of manganous ions. Diketogulonate is oxidized through the action of light excited flavin or of traces of alkali in the dark only when Mn⁺⁺ is available. No other metal tested had this ability.
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Retention of ascorbic acid (vitamin C) in dried guava during storage was studied. The effects of storage temperature: 30°C, 40°C, 50°C and water activity (aw): 0.43, 0.75, 0.84, 0.97 were investigated. The degradation of ascorbic acid follows a pseudo-first-order reaction. The rate constant increased about four to six fold when storage condition was changed from aw=0.43–0.97. The rate constants and corresponding water activities are related by a second-order polynomial equation. The effect of temperature on the rate constant followed the Arrhenius relationship. The activation energy of ascorbic acid degradation is found to be in the range 3.4–11.0 kcal/mol. An empirical equation, based on temperature, water activity and rate constant, is developed to predict shelf life of dried guava in respect of ascorbic acid retention.