VitaScope®

Roche Vitamins Inc. Newsletter on Vitamins and Specialty Ingredients for the Personal Care Industry

Spring 2002 Volume 5  Number 1

With the spring season upon us, one can envision extensive outdoor activities. Unfortunately, skin, hair and nails will be more exposed to environmental stresses, especially UV light, during such activities.

Over the last three decades the awareness of sun damage and the use of sun care products has increased considerably. Although the UVB and UVA filters used in almost all products can block most of the UV light, there is a certain amount of the UV light that penetrates the skin and contributes to the formation of UV induced free radicals. Free radicals have been associated with cancer, aging and age-related health problems. According to a new study conducted at the University of Illinois, Vitamins E and C are necessary in providing enhanced skin protection.

In this issue we review the attributes of the antioxidants Vitamin E and the new stable Vitamin C form, STAY-C® 50, in providing such improved protection, in combination with Parsol® MCX (a UVB filter) and Parsol® 1789 (the broad spectrum UVA filter).

We will also review a new market survey on the purchase preferences of consumers when buying sun care products, providing marketing insight into successful product launches.

David Djerassi

Anna Gripp

Alan Marks

Contributing Editor: Kerry Hanson*,  University of Illinois, Urbana-Champaign

Photodamage is cumulative, resulting from repetitive UV-induced photoreactions within the skin, which taken individually may seem trivial, but over the course of one's lifetime cause extensive damage to the cells of the skin. Case in point: one sunburn in childhood may seem simply inconvenient and uncomfortable, but also dramatically increases the risk of skin cancer later in life. Concurrent with advances in technology has come an understanding that UV radiation also induces effects, like immune suppression, lipid oxidation and mitochondrial activity in the skin, that are not detectable by eye following a day spent at the beach. And most worrisome, these effects, similar to tanning and sunburn, are responsible for photoaging, actinic keratosis and/or skin cancers.

Recent research shows that such photodamage occurs, in part, due to photoreactions involving reactive oxygen species (ROS) in the skin. ROS are energetically excited derivatives of molecular oxygen, and include singlet oxygen ( 1O2), hydrogen peroxide (H2O2), superoxide (O2- •) and nitric oxide (NO). ROS react and destroy lipid membranes, induce inflammatory cytokines and trigger apoptosis. In addition, many of the visible signs of aging are attributed to ROS-induced photodamage that accumulates over a lifetime.

Although sunscreens do an excellent job at preventing erythema, their ability to provide complete photoprotection, which includes protection against the generation of UV-induced ROS in the skin, has remained elusive in large part due to technology limitations. With recent advances in ultrafast (10-15s) laser technology, however, new imaging methods are now conveniently available that allow the researcher to explore skin chemistry and biology with submicron spatial resolution and submillimeter depth-penetration within the skin.

In our lab, we developed a two-photon fluorescence imaging method to identify the subcellular regions within live human skin that generate ROS following UV irradiation. We were interested in understanding how lightly pigmented skin responds following irradiation equivalent to 2 hours of noonday North American summer sun — an exposure time easily and often obtained by many in the summer. We then tested the effects of a broadspectrum sunscreen containing octyl methoxycinnamate (OMC) and Parsol 1789 upon UV-induced ROS levels generated within the stratagranulosum, spinosum and basale viable epidermal layers. Topical application of the tested sunscreens reduces the amount of ROS generated in the viable epidermis by blocking UV radiation in the stratum corneum by the amount consistent with SPF values. For example, the SPF 8 sunscreen yields 84.8% reduction in ROS, whereas SPF 15 sunscreen yields 90.1% reduction of ROS (Figure 1).

his indicates that, although sunscreens can reduce the amount of ROS generated, they offer incomplete photo-protection, still allowing incident UV photons to penetrate to the viable epidermis and generate destructive ROS. With this in mind, we looked towards sunscreen formulations supplemented with antioxidants for added protection.

We tested the bioconvertible antioxidant precursors Vitamin E Acetate and Stay-C 50 (Sodium Ascorbyl Phosphate), at 2.5% each. These molecules are stable in the product and are bioconverted to the antioxidants Vitamins E and C, respectively, by natural esterase and phosphatase enzymes within the epidermis. Supplementing the SPF 8 sunscreen formula with Vitamin E Acetate reduced ROS generation considerably. Addition of STAY-C 50 to the sunscreen containing Vitamin E Acetate resulted in reducing the amount of ROS further (Figure 2, Figure 3).

Addition of both Vitamin E Acetate and STAY-C 50 to the SPF 15 formula containing OMC and Parsol 1789, reduced the amount of ROS generated in the viable epidermal layers, by up to 95.5% (Figure 4, Figure 5).

The addition of the bioconvertible antioxidants Vitamin E Acetate and and Stay-C50 (Sodium Ascorbyl Phosphate) improved sunscreen photoprotection by converting to the antioxidants Vitamins E and C, respectively. As a result, the ROS that are generated by the residual UV photons, which were not absorbed by the sunscreen molecules in the stratum corneum, were quenched. Therefore, the photoprotective properties of the conventional sunscreens containing UVB and UVA filters were enhanced.

STAY—C50 is a stable form of ascorbic acid. It is a sodium salt of the monophosphate ester of ascorbic acid.

It's most important attributes are:

• A source of vitamin C
• In vivo Antioxidant
• Stable to water and oxygen
• Optimal stability at pH 6.5-8

Topical application of this ingredient is important because of the low levels of Vitamin E present in the skin, and its depletion by UV light and ozone.

The most important attributes are:

• Protects skin from environmental stress (blocks lipid peroxidation, in vivo antioxidant, protects against ozone)
• Moisturizes skin from within
• Enhances skin smoothness with continuous use

The most important attributes are:

• Protection against UVB
• One of the most tested and widely used UV filters worldwide
• deal for use in sun care and all other personal care products

Parsol 1789 (avobenzone) is a broad spectrum UVA filter.

The important attributes of Parsol 1789 are:

• Provides broad-spectrum protection throughout the entire UVA spectrum (320-400 nm)
• In combination with UVB filters, it can provide protection throughout the UV spectrum (290-400 nm)
• Used in sun care and daily skin care products at levels of 2-3% and at 0.2%-0.5% in hair care products
• Easy to formulate into personal care and cosmetic products
• Approved worldwide for UVA protection

A daily protective moisturizer compounded with UVB and UVA filters (Parsol MCX and Parsol 1789), Vitamin E and STAY-C 50 (Roche stable Vitamin C) for enhanced protection against UV damage and UV induced free radicals.

Major Attributes:

• Protection against UVB radiation (290-320 nm)
• Protection against the entire UVA spectrum (320-400 nm)
• Critical wavelenght — 377nm
• Protection against UV induced free radicals
• Deep moisturization of skin
• Ideal for daily use

A nationwide market survey conducted among 1008 men and women in February 2000, has shown that 63% of the respondents view the presence of the antioxidant vitamins E and C, in skin care and sun care products as important factor in their purchasing decision. There was a difference between men and women with 68% of the women favoring the presence of vitamins. There was no appreciable difference between the various age groups, or the regions of residence.