1. Field of the Invention
This invention relates to products that reduce damage that is caused to skin by the sun, and in particular, to products containing olive-leaf extract together with vitamin components.
2. Description of the Related Art
Ultraviolet radiation causes oxidative damage to the skin, including immunosuppression, which can cause skin cancer, alter the behavior of skin cancer, typically by making the cancer more aggressive, or cause photoaging. Much of this damage is preventable if clothing covers the skin, or where this is not practical, by topical products. UVA (340-400 nm) is linked to accelerated skin aging, causing DNA strand breakage and oxidation of nucleic acids, and UVB (290-320 nm) is a carcinogen. Standard sunscreens, however, while providing protection against UVB, do not fully protect against long-wave UV light (UVA) that is present at higher levels in sunlight and is not filtered by glass. Because of the growing incidence of skin cancer, there is an increased need for topical products that are more protective than standard sunscreens.
Both systemic antioxidants (e.g., oral vitamin C and vitamin E) and topical antioxidants (topical vitamin E and vitamin C) have been proposed as photoprotectants. A stable topical ascorbic acid solution has been developed (U.S. Pat. No. 5,140,043; Pinnell et al., Dermatol. Surg. 27:137-142, 2001) that is capable of traversing the stratum corneum of the skin, and thus resists being washed off of the skin, and provides both photoprotective and anti-inflammatory effects. Related commercial products exist that provide a) 20% L-ascorbic acid, or b) 15% L-ascorbic acid, 2% zinc sulfate and 1% xcex1-tocopherol (vitamin E) (SkinCeuticals, Inc., Dallas, Tex.). Concentrations of about 5-25% L-ascorbic acid resulted in maximum levels of L-ascorbic acid in the skin, where a reservoir of L-ascorbic acid remained even without daily application to the skin.
One problem with antioxidant solutions is that they are inherently unstable (chemical instability and color instability), since antioxidants work by giving up an electron to neutralize oxidative damage and stop the reactive process. Thus, heat, light, air, metal contamination, and other generators of reactive oxygen can destroy antioxidants in solution.
While vitamin E has been shown to be useful in skin-treatment, its stability is also difficult to ensure. Stable aqueous solutions of lipophilic xcex1-tocopherol at concentrations as high as 5% have been developed using bioflavonoid antioxidants and emulsifiers such as Tween 20, 60, 80 and Brij 30 and 72 at concentrations from 1-50%. This has allowed formulations of previous solutions of 15% L-ascorbic acid, 2% zinc sulfate and 1% xcex1-tocopherol.
Extracts of various plant parts have been used for many different types of products, including products for the treatment of skin. The reduced incidence of certain cancers in the Mediterranean region has been attributed in part to the high consumption of olive oil in the Mediterranean diet. Virgin olive oil, obtained from the olive fruits, has long been known to have anti-inflammatory effects.
Historically, olive leaf has been used as a remedy for treating fevers and malaria. Several reports have shown that olive plant has the capacity to lower the blood pressure in animals and increase the blood flow in coronary arteries, relieve arrhythmia, and prevent intestinal muscle spasms.
Certain biophenolic molecules, such as oleuropein and hydroxytyrosol, known as the xe2x80x9cbitter principlexe2x80x9d in olive oil, inhibit pro-oxidative processes, which is the primary reason for the stability of virgin olive oil, and these compounds also increased the ability of human low density lipoprotein (LDL) to resist oxidation and reduced the plasma levels of total, free and ester cholesterol. Similarly, the specific phenolic compounds in olive oil and other olive plant parts have been found to have a marked antiedematous effect and to inhibit the enzyme myeloperoxidase, with oleuropein having the greatest inhibitory activity. Oleuropein has been shown to have cytotoxic effects on tumor cell lines, and to inhibit or delay the rate of growth of a range of bacteria and microfungi, including pathogens such as Salmonella, Staphylococcus, and Haemophilus influenzae. 
Solid phase extraction methods have been used to separate phenolic components from olive fruit, as has a solid-liquid extraction procedure with diatomaceous earth and various eluents. In the extraction of the active ingredients from olive plants, there are several problems related to separation of the active fraction from the inactive fraction, as well as to purification of the active fraction.
Leaves of the olive (Oleo europaea), as well as the leaves of a number of other plants, are also known to contain high levels of secoiridoid glucosides such as oleuropein. Previous olive-leaf extracts have generally been obtained using aqueous chromatographic procedures, resulting in a lower oleuropein content, due to residual degradative enzymes present in the aqueous extracts. A typical concentration of oleuropein in such extracts is about 3%-18%.
It is therefore an object of the invention to provide a method for extraction of olive leaves that is nonaqueous and yields a high level of oleuropein. It is a further object of the invention to provide compositions containing this olive-leaf extract that are useful for skin treatment.
Other objects and advantages will be more fully apparent from the following disclosure and appended claims.
The invention herein is a non-aqueous method of extracting olive leaves. The resulting extract is used, preferably together with vitamins C, E and A to form a skin-treatment product that has efficacy as a photoprotectant and anti-oxidant. The invention also includes methods for treatment of skin with the product containing olive-leaf extract.
Other objects and features of the inventions will be more fully apparent from the following disclosure and appended claims.