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FUNCTIONAL CHARACTERISTICS
OF COSMETICS INGREDIENTS

The skin

The skin: Epidermis

• Outer layer of the skin
• Provides a physical barrier against
– microorganisms (germs)
– substances entering the body

• Some parts such as feet soles and palms have thicker
epidermis
• Contains cells melanocytes
–
–
–
–

Cells that produce a substance called melanin
Melanin is a skin pigment and gives skin its colour
The more the melanin, the darker the skin
Melanin provides protection against sunlight (ultraviolet
light)
– Melanin production increases with exposure to sunlight
• tan

The dermis
• Thicker layer under the epidermis
• Mostly consists of connective tissue
• Contains blood vessels, lymphatic vessels and
nerve fibres
...

– Expansion or cooling of blood vessels to allow or
prevent heat loss

• Provides sensitivity to the environment

Hair follicles and sebaceous glands
• Hair follicles
–
–
–
–

hair follicles contain cells that produce hair
Hair follicles and hair are found over most of the skin
Exceptions: palms, soles, lips, eyelids (aprt from eyelashes
A pore is the opening of the hair follicle

• Sebaceous (oil) glands are found in part of the hair follicle
...

– Sebum travels up the hair follicle and onto the surface of the skin
where it is often rubbed off by clothing or washed off in the shower
...

– Sebaceous glands become most active when certain hormones are
released at puberty
...

– When we are hot, they release sweat to the
surface of the skin
...


• Apocrine sweat glands found in the armpits
and groin area produce an oily fluid which
when it comes into contact with bacteria
result in body odour
...

• As the skin ages, and is exposed to sunlight,
chemicals etc
...

• Cross-linking makes the collagen insoluble and
inflexible
...


Structural lipids:-ceramides
• Ceramides located between skin cells
– make up the bulk of the lipid layer which holds the skin's
cells together in a firm, smooth structure
...


• A drop in the level of ceramides results in the skin
losing its structure and texture becoming dry and
hard, leading in turn to fine lines and wrinkles
...

• Synthesized skin-identical ceramides became
commercially available in the 1990s
...

• These fats have long been known to be necessary
for the body's functioning
– their deficiency results in the skin losing moisture and
leading to hardening and drying
...

• Important constituent of products for intensive
skincare
...

• Petrolatum is widely used as a classic moisturizer
...


Emollients
• Emollients smooth skin by filling spaces
between skin flakes with droplets of oil
• Not usually occlusive unless applied heavily
...


Emollients
• Fatty acids: fatty acids and fatty alcohols exert
their benefits through effects on the skin
barrier
...


Proteins
• like emollients, protein shrink on the skin
leaving a film that softens the skin, stretches
out some of the fine wrinkles, and avoids
water loss
...

• Water originates in the deeper epidermal layers and moves upward
to hydrate cells in the upper layer of the skin (stratum corneum),
eventually being lost to evaporation
...


Humectants
• Chemically, all humectants have something in
• common: hydroxyl groups participate in
hydrogen bonding with water
• Humectants include:
– Glycerin
– Sorbitol
– Propylene glycol
– hexylene and butylene glycol
– MP Diol,
– Urea
– alpha hydroxy acids (e
...
, lactic acid)

Humecants
• Glycerin: glycerin is by fare the most popular of all
humectants used in personal care products
...


• Sorbitol: Sorbitol, available as powder or a 70% aqueous
solution, is typically used in toothpastes and many other
personal care products
...
5%
...
g
...

• Propylene Glycol, one of the most widely used
ingredients in cosmetics
...

• Permeates skin better than glycerin, but causes
more sensitivity reactions
...

• Propylene glycol further enhances the performance of
Sodium PCA in absorbing and retaining moisture in the
skin
...

• When employed in makeup emulsions, they
can reduce streaking
• Their relatively high cost has limited their
usage
...

• Urea & alpha-hydroxy acids (AHA’s)
• AHA’s, such as lactic acid or glycolic acid,
appear to increase cohesion of the stratum
corneum cells, thereby reducing roughness
and scaling
...

• These substances are weak hygroscopic acids that absorb moisture
from the atmosphere and also help in exfoliation (removal) of dead
cells on the surface layer of the skin
...

• These products can only remove superficial lines and wrinkles
which appear at a young age but cannot act as a cure at
middle/advanced age and hence cannot be called an anti-aging or
age defying treatment
...
A
faintly yellow, solid, plastic resin resembling
albumen
...

• Temporary protection of minor cuts, scrapes, burns and
sunburns
...

• Treatment and prevention of diaper rash and to help
protect/seal out wetness
...
e
...

• Sunscreen is particularly important in children, as 85% of all sun
exposure occurs before the age of 18
...

• If a sunscreen has a label of a 15 SPF, then with its use over a 15-hour
period, the skin will have absorbed only 1 hour’s worth of ultraviolet
light
...

• Other agents which block the sun include zinc oxide, titanium oxide,
magnesium silicate, kaolin, ferric oxide, red petrolatum, and
magnesium oxide
...


Zinc oxide
• White powder used in skin ointments for
ultraviolet protection and diaper rash
treatment
...


PABA
• Para-aminobenzoic Acid (PABA)
Found in Vitamin B complex
...

• Can cause allergic reactions
...

• These molecules may react with other molecules thus
creating more unstable compounds and setting off a
chain reaction that can damage cells and cause
breakdown of immune system
...


• The ideal antioxidant should be:
– nontoxic, nonirritant,
– effective at low concentration under the expected conditions of
storage and use,
– soluble in the medium and stable
...


• Some of the commonly used antixidants for emulsified
systems include alkyl gallate such as ethyl, propyl or dodecyl
gallate, butylated hydroxyanisole (BHA), butylated
hydroxytoluene (BHT), Vitamin E (Tocopheryl acetate)

6/5/2021

PHT 312

34

Co-enzyme Q10
• Co-enzyme Q10 has two important roles: it is an essential part of the
cellular respiration system located in the mitochondria, and it is an
antioxidant
...

• CoQ10 is sometimes called a "biomarker of aging" because its level
correlates so well with aging
...

• CoQ10-depleted skin may also be more prone to the damage by free
radicals, which are particularly abundant with exposure of the skin to
the elements
...

• A small molecule that can relatively easily penetrate into skin cells
...

• A lack of vitamin A can cause skin to become dry and
hardened
...
It helps
heal wounds and scar tissue, Fractures; prevents scurvy; builds
resistance to infection; aids in the prevention treatment of the
common cold; gives strength to blood vessels; aids in the
absorption of iron
...

• It is also one of the major antioxidant nutrients
...

• Moreover, Vitamin C has been shown to help slow the production
of hyperpigmentation ( age spots ) while providing some UV
protection
...


Wheatgerm oil
• Wheatgerm Oil (Triticum aestivum)
• This oil has a nutty aroma and is extracted by pressing
or solvent extraction from the wheat "germ
...

• It helps relieve dermatitis symptoms, promotes skin
cell formation, and improves blood circulation
...


Sunflower Oil
• Sunflower seeds are expressed to produce this
light oil which is high in linoleic acid, Vitamins
A, B complex, D, and E, as well as calcium,
zinc, potassium, iron, and phosphorus
...


Liposomes
• Liposomes are typically manufactured from various fatty substances
• used to encapsulate, or to create a sphere around, cosmetic
materials
...

• The liposome wall is very similar, physiologically, to the material of
cell membranes
...

• In the process, the liposomes release their load of active materials
into the cells
...


Emulsifiers
• Added to make the aqueous phase and the oil
phase ingredients mix
• Emulsifiers are surfactants
• Many types
• To be discussed in study of emulsions

Preservatives
• Preservatives are chemicals with antimicrobial action
...

• Contamination due to microorganisms can result in
problems such as
–
–
–
–
–

color and odor change
gas production
Hydrolysis
pH change
eventually breaking of emulsion
...
2% released forlmaldehyde
• “Contains formaldehyde” must be in label if
>0
...

• Methylchloroisothiazolinone (5-chloro-2-methyl-4isothiazolin-3-one)
• Known by the registered trade name Kathon CG when
used in combination with methylisothiazolinone
• May be used in combination with other preservatives
such as
– ethylparaben, benzalkonium chloride or 2-bromo-2nitropropane-1,3-diol
...


Paraben free
• Phenoxyethanol
• phenoxypropanol

Preservatives harmful effects
• Safety concerns because preservatives may be
cytotoxic, cause skin irritation and contact
sensitization and other medical issues
• Preservative levels may be reduced or
eliminated to have preservative-free (selfpreserving) products based on the
physicochemical composition of the formula
and the use of multifunctional ingredients
with antimicrobial activity
...

Purpose of fragrances
1
...
To make consumers “shop” with their nose
The way most fragrance ingredients impart
scent is through a volatile reaction,

Fragrance adverse effects
•
•
•

•
•
•

Fragrances in skin-care products are among the most
common cause of sensitizing and allergic reactions
...

The unseen irritant reaction hurts the skin's ability to
reduce wrinkles, firm skin, or maintain youthful look
Hence regulated
Some ingredients banned/restricted

Fragrances
•
•
•
•
•
•
•

Linalool
Citronellol
Cinnamal
Limonene
Geraniol
Eugenol
Lavender oil (Lavandula
angustifolia)
• Rose flower extract (Rosa
damascene)
• Bergamot oil (Citrus bergamia)
• Ylang-ylang oil (Canaga
odorata)

• Lemon (Citrus limon)
• Lime (Citrus aurantifolia or
Citrus medica)
• Orange (Citrus sinensis)
• Tangerine (Citrus tangerine)
• Peppermint (Mentha piperita)
• Spearmint (Mentha spicata)
• Menthol
• Cinnamon (Cinnamomum)

Fragrances
•
•
•
•
•

Each fragrance material CAS# is checked against authoritative lists
of:
carcinogens, mutagens, or reproductive toxicants (CMRs);
persistent, bioaccumulative, and toxic chemicals (PBTs);
and other hazards
...


•

(Natural Complex Substances (NCSs), including essential oils and
extracts, are chemical mixtures subject to special requirements that
allow only very low levels of listed chemicals)

Colour
• D&C
This abbreviation preceding the name of a color means
that the Food and Drug Administration (FDA) has
certified it as safe for use in drugs and cosmetics, but
not in food
...

– D&C colors are usually synthetic
...




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