Creative Developments
(Cosmetics) Limited
Active Ingredients for Skin Care; Manufacturing Chemist 1997
Copyright John Woodruff
Over
the last few years the main innovations in active ingredients for skin-care have
been in the use of alpha hydroxy acids, ceramides and enhanced delivery
systems. Sun protection has been to the fore and the use of inorganic oxides
has stimulated many new formulations. Many natural materials have moved from
folklore to proven efficacy[Ref 1] and
more compounds of natural origin are introduced than from any other category at
conferences and symposia.
A
review of the papers and posters contributed to the 19th IFSCC Congress [REF 2]
reveal that UV protection and anti-inflammatory responses were considered of
major importance. This may be due in part to the location of the Congress and
the many papers and delegates from Japan and Korea. Skin lightening is
currently of interest in both hemispheres; in the East all exposed areas are treated
while in the West, products are more frequently designed for reducing local
pigmentation.
The
majority of ingredients for reducing skin pigmentation are tyrosinase
inhibitors and a paper at the IFSCC Congress [REF 3] described their action and
an in-vitro method for determining efficacy. As is usual with such tests the
base line is provided by hydroquinone and the test material, an extract from Broussonetia kazinoki (paper
mulberry) and trade named Kazinol F was shown to be more effective than kojic acid,
ascorbic acid and hydroquinone. The anti-erythema and free radical scavenging
activity of Kazinol F was also described and the material shown not to be a
sensitiser nor a primary irritant. Another paper [REF 4] described the skin
whitening effects of Polygonum
cuspidatum (flowering bamboo) which inhibits tyrosinase synthesis and a
third paper reported the results of screening one hundred plant extracts for
tyrosinase inhibition [REf 5]. Morus
alba and Glycyrrhiza glabra
showed >50% inhibitory activity against mushroom tyrosinase at a
concentration of 333mg/ ml. Other workers [REF 6] reported the effects of a
liquorice extract on tyrosinase activity and as an anti-inflammatory and
anti-allergen agent; concluding that the material was ideal as an ingredient
for reducing pigmentation in cosmetic products for sensitive skin.
Another
material shown to be effective [REF 7} is
2.5-dimethyl-4-hydroxy-3[2H]-furanone, (DMHF), an antioxidative compound from
the reaction of L-cysteine/D-glucose. It was shown to be an efficient free
radical scavenger and to have an inhibitory effect on the auto-oxidation of
linolenic acid. In addition, DMHF appeared to prevent the cellular
melanogenesis in cultured murine melanoma cells more effectively than kojic
acid although it was not so effective as the latter for the inhibition of
tyrosinase.
Arctostaphylos uva-ursi
or bearberry is generating a lot of interest in skin whitening products.
C.I.T.Sarl report that an extract of the plant has been shown to inhibit
melanin production in human melanocytes by reducing tyrosinase activity and
test results show it to be more effective than either kojic acid or L-ascorbic
acid. Sederma have also investigated the skin whitening effect of bearberry; it
has combined it with an extract from a mitracarp indigenous to West Africa and
called it Etioline for which a synergistic effect in inhibiting tyrosinase
activity is claimed.
Products
to reduce cellulite continue to grow in popularity and traditionally such
products have been based on seaweed and their derivatives so it is not
surprising that ingredient suppliers are investigating these materials to find
ways of improving their activity. Rhodysterone from Secma is a red seaweed
extract with a lipolytic effect on adipose cells. The efficacy of Rhodysterone
has been tested by both in-vivo and in-vitro methods and the suppliers claim an
improvement in appearance, texture and suppleness of skin when applied to the
thigh area of human volunteers. Exsymol have a number of materials based on
organo-silicone compounds such as methylsilanol mannuronate (Algisium C) and a
mixture of this with caffeine (Cafeisilane C) for slimming and anticellulite
products. Exsymol also supply a theophyllin derivative, methylsilanol
carboxymethyl theophylline alginate or Theophyllisilane C, and publish
extensive literature describing the mechanism of cellulite and cellulite
reduction with test protocols and results. Another company producing
interesting organo-silicone ingredients is The Fanning Corporation. Dimethicone
copolyol eicosanate is the result of complexing silicone with meadowfom seed
oil triglycerides and by controlling the reaction three products with different
solubilities are produced. The water-soluble version has been found to deeply
penetrate the hair shaft with excellent results on hair conditioning. The
oil-soluble version adds emolliency to skin care products and the
water-dispersible version blooms and foams in water making it ideal for bath
products.
Until
recently many suppliers of botanical extracts have claimed an activity and then
attributed the evidence to folklore which is less than adequate to prove
efficacy as required by the 6th Amendment. Some companies are prepared to
investigate the properties of such materials and publish properly validated
test results. Thus a paper presented at the Active Ingredients Conference in
Paris [REF 8] by Alban Muller described the development and testing of an
anticululite ingredient, Slimming Phytomine Biocomplex which included caffeine
from coffee, theophyllin from tea, asiaticosides from an Asian plant, Centella asiatica, and an extract of Aesculus hippocastanum or
horsechestnut.[REF 9] Tests on female volunteers for eight weeks showed a
significant improvement in skin texture, tone and 30% reported a reduction in
the orange peel effect. Laboratoires Phybiotex of the Sederma group also
produce botanically derived materials and substantiate claims by reporting the
results of clinical studies. Phytotal SL complex contains extracts of Sambucus nigra (elderberry), Verbena officinalis (vervain) and Eugenia caryphyllata (clove tree) and
was shown to reduce cellulite when applied in a cream at 5% concentration. The
same company produces Phytotal FM for firming skin and improving tone and
Phytotal VT for combating couperose and improving microcirculation with test
results of clinical trials.
Sederma
has recently introduced Cyclolipase which is claimed to control lipolysis of
subcutaneous fat by the action of lipase, caffeine and AMP and has mixed an
extract of Sambucus nigra
(elderberry) with glyceryl polyacrylate and ethoxydiglycol to prepare a
material trade-named Redulite that is claimed to attack the problem of
retention of interstitial water by hypodermal adipose tissue. It needs to be
used at from 15 - 20% to be effective and the mechanism is mainly due to
osmotic pressure. Polyacrylate and methacrylate gels are also used as
moisturisers and have been found effective as antimicrobial compounds so such
ingredients are multifunctional. A paper presented at the S.C.S. Symposium on
microbiological matters [REF 10] described the use of Osmocide, a polyacrylate
gel, as a possible means of preparing preservative-free cosmetics or of greatly
enhancing the activity of existing preservatives enabling lower levels to be
used. [REF 11]
A
totally different approach to treating cellulite was the subject of a paper
given at the 19th IFSCC Congress. A cream containing barium-hexaferrite
particles was claimed to produce a static magnetic field, the strength and
depth of penetration of the magnetic field depending on the concentration of
particles. [REF 12] Studies showed that the electromagnetic field could
penetrate to a depth of from 0.1 to 0.5mm and there was a statistically
positive increase in blood flow in the microcirculatory system. The paper
describes the extensive studies necessary to prove slimming and anticellulite
action of topically applied preparations and should stimulate many good ideas
to those interested in the subject.
Anti-free
radical activity is another term which is often seen and seldom quantified,
especially under conditions of actual use such as in the final cosmetic
composition. Ever since the free radical theory of cell damage and skin ageing
was introduced in the late eighties botanical extract manufacturers have
claimed an effect for various materials. In a paper presented at the Active
Ingredients Conference in Paris by Thomas Herling [Ref 13] the skins
susceptibility to oxidative damage and its own defensive and post-damage repair
mechanisms were described. Herling then proposed an in-vitro method for
determining the Radical Protection Factor (RPF) of a cosmetic formulation using
Electron Paramagnetic Resonance Spectroscopy. The RPF depends on the test
radical concentration and the concentration of the antioxidant system in the
cosmetic formulation and is a value which describes the radical scavenging
activity of the complete product. The same authors also describe a method of
measuring the Antioxidative Factor (AOF) of the skin. It is an in-vivo method and measures the rate
of decay of a test radical in the skin which is dependent on the nature and
concentration of the test radical and the properties of the skin and Herling
has found a correlation between RPF and AOF.
Enhanced
delivery systems were described in Manufacturing Chemist, March 1996 and since
then further advances have been made including the introduction of
nanocrystalline materials from Nanophase Technologies Corporation. NTC has
developed a vapour condensation process which, it is claimed, produces
nanocrystalline particles which are spherical and have a narrow particle size
distribution. The particles themselves may be prepared from titanium dioxide or
zinc oxide and used as inorganic sunscreen agents or be iron oxide suitable for
use in decorative cosmetics. Other metallic or ceramic materials may be used
and the nanocrystals supplied in a variety of cosmetic oils or in aqueous
dispersions.
REF
1. Press release on the Internet
REF
2 19th IFSCC Congress, Sydney, Australia,
1996.
REF
3 The Depigmentation effect of a new
material extracted from paper mulberry and its comparison by three colorimetric
instruments. Ha J.H, Jo N.S, Lee H.K, Kim J.I, Lee B.G, Park W.J, Pacific
Corp., Korea
REF
4 Development of active cosmetic
agents for skin whitening: inhibitory effects of flowering bamboo (Polygonum cuspidatum) on
melanogenesis of B16 melanoma cells. K.Obayashi et al. Noevir Co. Ltd., Shiga
Central Laboratory, Yokaich, Shiga, Japan
REF
5 Biological screening of
100 plant extracts for cosmetic use (II) Inhibitory activities of tyrosinase
and DOPA autooxidation. Jeong Ha Kim1 et al.R & D Centre, Koreana Cosmetics
Co.
REF
6 Application of liquorice
extract and its derivatives to skin care products. Masato Tagawa et al, Nikko
Chemicals Ltd.
REF
7 Anti-melanogenesis effect of 2,5-dimethyl-4-hydroxy-3 [2H]-furanone. Che-Ok
Jeonet al. Kim Pacific Corp. & Speciality Chemical Research Institute,
Korea.
REF
8 The Active Ingredients Conference, Paris 1996.
REF
9 Slimming Phytoamine
Biocomplex; Muller.A.
REF
10 Society of Cosmetic Scientists (UK) Symposium 1996, Microbial contamination,
determination and eradication.
REF
11 Physical methods for the preservation of cosmetic products; Dr. Karl
Lintner, Sederma SA.
REF
12 A new direction in cosmetics: physics instead of chemistry. Effect of a
static magnetic field on human skin; Zastrow L. et al. Benckiser Cosmetics,
International Research Centre, Monaco.
Ref
13 Free radical scavenging activity of cosmetics; Herling T et al, Institute
for Dermatological Research, Berlin.