This issue’s patents focus on skin cleansing concepts from antibacterial and anti-acne soaps to washes that deposit sunscreen on the skin
1. Liquid soap having enhanced antibacterial activity
US Patent 10,144,908
Application No 14/784,178
Granted 4 December 2018
The patent describes an aqueous soap composition that provides biocidal activity against Gram-positive bacteria, in particular Staphylococcus aureus, in relatively short contact periods.
The applicants claim that soap compositions have antibacterial benefits largely associated with the removal of organisms from the skin through their cleansing action. Additionally, such compositions commonly have biocidal action against many Gram-negative bacteria but activity against Gram-positive bacteria such as S. aureus is considerably more limited, and is especially problematic in the case of high pH9-11 liquid soap products.
The soap forms from 10-55% by weight of the final composition and comprises alkali metal or alkanol ammonium salts of lauric and oleic fatty acids.
A water-soluble silver compound is incorporated in the liquid soap for its biocidal activity and – of the many discussed – silver oxide and silver sulfate appear to be preferred.
Their preferred level of addition is in the ratio of 1:1,200-1:200,000 to that of the fatty acid soap. In a preferred embodiment, the silver-containing compositions are used in combination with essential oil antimicrobial actives thymol and terpineol.
Preferably, thymol is present up to 0.2% and terpineol at up to 0.5% in the total composition, which may also contain skin benefit agents, rheology modifiers, preservatives and other materials that enhance its aesthetic and stability properties.
The composition as described is effective against S. aureus, S. epidermidis and corynebacteria with contact times of 10-30 seconds before being rinsed from the skin.
2. Personal cleansing compositions containing zinc amino acid/trimethylglycine halide
US Patent 10,188,112
Application No 14/650,952
Granted 29 January 2019
The applicants suggest that it is extremely difficult to provide liquid personal wash compositions with sunscreen components that may be readily deposited on the skin. One significant problem is that the sunscreen agents will generally be solubilised by the surfactant and, while they may be deposited during lathering, they will be removed by rinsing. The patent describes a personal cleansing composition containing a zinc X halide that can be used to deliver zinc salts to reduce or prevent sunburn, kill bacteria, or reduce perspiration.
The cleansing composition is in liquid form and can be formulated to be a body wash/shower gel, shampoo or conditioner. The surfactant can be a surfactant or a combination of surfactants; many possible combinations are cited but are not an important part of the patent claim.
Essential to the claim is a complex of zinc ion, X residue and halide ion, where X refers to amino acid or trimethylglycine and the complex is present in an amount to provide at least 0.36% weight of the composition of zinc.
It is thought that the formation of the zinc X halide proceeds via formation of the zinc halide then coordination of X residues around a central zinc. For example, zinc oxide reacts with lysine hydrochloride in water to form zinc chloride, which then reacts with lysine to form a clear solution of Zn-lysine-chloride complex.
The interaction of zinc and X converts the insoluble ZnO to a highly soluble complex at approximately neutral pH. In the skin, which contains charged molecules such as proteins and fatty acids, the complex will flocculate, forming a precipitate that deposits on the skin.
When the complex is disrupted on the skin, free zinc ions are released, which can hydrolyse to form amorphous zinc hydroxide precipitate on the skin, and zinc ions can kill skin bacteria, thereby reducing odour. As the amount of water increases, the complex hydrolyses to distribute a relatively insoluble zinc-containing precipitate that typically contains one or more of zinc oxide, zinc cysteine, zinc hydroxide, or other zinc-containing compounds.
This precipitate is unique in that it will allow deposition on the skin and this reaction is atypical since, in most cases, dilution will increase the solubility of an ionic complex. The patent describes the chemistry of the complex formation in great detail and the reasoning behind the claims for sun protection and antibacterial properties.
3. Use of an essential oil of Origanum majorana as an agent for treating and/or preventing greasy skin and/or the associated aesthetic skin defects
US Patent 10,231,921
Application No 14/785,970
Granted 19 March 2019
The patent describes an essential oil of Origanum majorana as an agent for preventing or treating greasy skin and the associated aesthetic skin defects when included in a cosmetic cleansing composition.
Greasy or hyperseborrhoeic skin is characterised by excessive secretion and excretion of sebum, and is often associated with dilated pores. The appearance and visibility of the pores and shininess of the skin is associated with dilation of the pores, hence the interest in finding active agents for their reduction.
Such skin is also often associated with a desquamation defect and it may be desired to stimulate the desquamation mechanism in order to promote epidermal renewal and restore or reinforce a healthy physiological state of the skin. Moreover, such grease-prone skin may be associated with the development of Propionibacterium acnes, which prefers to grow in oxygen-deprived environments, such as at the bottom of a hair follicle or an obstructed sebaceous duct.
Essential oil of Origanum majorana can advantageously be obtained from the aerial part of the plant and preferably at the end-of-flowering stage. It comprises more than 18% by weight of cis-4-thujanol and more than 16% by weight of carvacrol relative to the total weight of the constituents of the essential oil.
The oil is added at up to 1% by weight to a cosmetically acceptable cleansing composition.
Tests are described that show such compositions reduce the growth of P. acnes microorganisms and, consequently, treat the skin disorders and imperfections associated with their growth. Such compositions are also shown to improve desquamation by reducing cohesion between the layers of cells in the stratum corneum; they likewise reduce dilated pores and the production of sebum.
4. Cleansing composition for skin or hair
US Patent 10,196,587
Application No 15/594,154
Granted 5 February 2019
Assignee Kao Corporation
The patent describes a cleansing composition for skin or hair that can provide a good durability of foam and rinse feel, and give good combability and softness when applied to hair, as well as giving a moist feeling when applied to skin.
The cleansing composition comprises an internal olefin sulfonate of 16-18 carbon atoms, a moisturising agent, an organic solvent and ingredients to improve its marketing claims, aesthetic properties and product stability.
An internal olefin sulfonate is obtained by sulfonating an internal olefin (an olefin having a double bond inside the olefin chain) as the raw material, followed by neutralisation and then hydrolysis. Upon completion of the reactions, the products may be purified by extraction, washing and the like.
The cleansing composition may contain additional surfactants and specific examples include anionic, nonionic amphoteric and cationic surfactants.
These are selected according to whether foam generation, density and stability is to be improved or whether hair conditioning or skin moisturising is the principal target and many examples are given.