Antimicrobial milk proteins offer skin care potential

If this indeed is true, it is unlikely that Cleopatra would have been the only woman in history to use milk as a skin care preparation. Milk, and those cosmetic preparations which contain milk, have long been recognised as having a beneficial effect when applied to human skin. One possible and obvious explanation for this apparent effect is the production of lactic acid in sour milk, with its associated drop in pH. Lactic acid is known as an alpha hydroxy acid (AHA), and AHAs are commonly used as active ingredients in numerous skin care products including moisturisers, cleansers, toners, and facial masks. However the benefits to the skin from using milk do not end with it simply being a useful source of lactic acid. Recent research in New Zealand has demonstrated that a specific subfraction of milk protein has pronounced properties far beyond its nutritive qualities. These bioactive proteins may benefit the skin from their functional antimicrobial and anti-inflammatory characteristics, which make for an ideal ingredient in a skin care formulation. Once the casein is removed from the milk (which constitutes 80% of the protein in milk), you can then get to the protein fraction which demonstrates the greatest degree of bioactivity. This includes the bioactive proteins such as lactoferrin and lactoperoxidase, which are well known to the nutraceutical industry, but these bioactives are generally isolated and highly purified during the production. Our data suggests that as a result of this purification process, they may lose some of their specific activity. It was discovered during research into mastitis treatments that functional proteins work best as a synergistic suite of proteins rather than specific isolates. It is believed that this increased functionality occurs either by potentially acting as cofactors for each other or one protein or peptide acting as a superagonist. This research is also supported by the observations from Korhonen et al.,1 who suggested that the milk proteins provide a rich source of precursors of biologically active and stable peptides of which many are either immune modulating or antibacterial. The focus of the research has been around this complex of milk-derived bioactive proteins, which supports the immune system by providing natural protection from inflammation and infection. The company patented the formulation of six milk-based bioactive protein fractions, along with various natural activating compounds that collectively are far more potent than any single fraction alone. This natural suite of bioactive proteins captures the synergistic nature of the bioactives and provides a broad-spectrum activity. As a company, Quantec is not alone in wanting to unlock the potential of these bioactive protein subfractions in milk. Other companies are also investigating the production and functional benefits of protein bioactives. The Tatua Co-operative Dairy Company Ltd and Westland Co-operative Dairy Company Ltd (both of New Zealand) have worked on the production of this class of bioactive proteins. As shown in Table 1, AgResearch Ltd, a research institute in New Zealand has reported numerous synergistic proteins in this fraction.2 Snow Brand Milk Products Co Ltd of Japan has developed a nutritional ingredient from this class of bioactive proteins for the management of bone health and osteoporosis. The Biotene brand, which was recently acquired (Oct 2008) by GSK, also uses two of the proteins from this same functional protein subfraction group for the management and symptomatic relief of dry mouth.

The process

The process of producing the bioactive protein subfraction, known as the cationic fraction, involves fractionating milk through an ion exchange resin, eluting the bound components from the resin using a salt solution, which can be either a one-step high molarity (>1M) salt or a gradient elution (from a lower molarity up to over 1M), collecting the eluted components in a single fraction, and then desalting and purifying the collected fraction. Lactoferrin (Lf), lactoperoxidase (Lp) and other proteins or peptides with isoelectric points (pI) greater than the pH of milk (6.6-6.8) are all purified from milk by this general method. This also includes minor proteins such as angiogenin, chitinase-like protein-1 and quiescin, which can be present in low amounts. Table 1 shows some of those proteins that would be bound and eluted in the cationic fraction as indicated by their isoelectric points. Isoelectric points equal to or greater than 6.8 would be included in the cationic fraction.2 The process results in formulation set of freeze-dried cationic milk proteins. However, to be effective, this cationic subfraction of proteins requires the addition of added activators, such as enzymes and substrates. For example, makers of the Biotene product, GSK, claim the subfraction achieves its functionality through the augmentation of such enzymes as glucose oxidase. Clearly, different ingredient formulations for these cationic protein subfractions and their activator compounds would be required depending on the target end-product application.