L-carnosine, known as beta-alanine-L-histidine, is a dipeptide containing two amino acids, alanine and histidine. It is an antioxidant, a chelator of toxic metals, a buffer, etc. L-carnosine may neutralize lactic acid and surprisingly the human muscle contains 20 mM carnosine while mouse muscle contains only 1 mM.
The authors have studied the effect of l-carnosine on human fibroblasts and neoplastic (cancerous cells). Two parameters that were studied were the effects of l-carnosine on cell doubling and the length of time that cell populations continued to live, which are measurements of cell aging.
Hayflick and Moorhead started studying human fibroblasts in test tubes over 30 years ago and they found that cell populations doubled about 50-70 times and then begin to decline. This is felt to be a manifestation of cell aging or senescence when cells no longer form an organized pattern, contain abnormal granules, and fail to divide.
Human muscle contains a concentration of 20 mM of carnosine. Cells grown at 30 mM of carnosine, with glucose and pyruvate, have a longer survival. Cells grown with carnosine consistently have the appearance of being younger than they actually are. When carnosine is removed from culture in which fibroblasts are being grown the cells start to look older or senescent.
Carnosine is toxic to neoplastic cells when pyruvate is absent. Anserine is similar to carnosine in being cytotoxic to neoplastic cells dependent on the absence of pyruvate. Histidine is cytotoxic to certain neoplastic cells without regard to the presence or absence of pyruvate.
Carnosine was tested on both rodent embryonic stem cells (ES) and rodent teratocarcinoma (EC) cells. Both of these primitive cells are able to differentiate into many different types of cells. ES cells differentiate into many different cells useful to the body, while EC cells can differentiate into different types of cancer cells. Carnosine inhibits only the EC cells in the absence of pyruvate.
CONCLUSION: L-carnosine in the culture media of human fibroblasts prolongs the life of the cells and seems to slow the aging process. Aging cells seem to be rejuvented in the presence of l-carnosine and, in the absence of pyruvate, L-carnosine is toxic to cancer cells. D-carnosine does not show these effects. L-carnosine may have anti-cancer effects in vivo. Further studies need to be conducted on the ability of l-carnosine to delay aging and protect cells from neoplastic transformation.
NOTE: Fibroblasts are primitive connective tissue cells. L-carnosine is the natural form of carnosine. D-carnosine is the synthetic form of carnosine. Read more about the use of histidine and carnosine in fatty liver