Skin Care Cosmetics Ingredients Glossary
K
kaolin. Naturally occurring clay mineral (silicate of aluminum) that is used in cosmetics for its absorbent properties.
Kathon CG. See methylchloroisothiazolinone.
kava-kava extract. Extract of the Piper methysticum plant that has analgesic (anti-inflammatory) properties, but can also cause skin irritation and dermatitis (Sources: Alternative Medicine Review, December 1998, pages 458–460; and Clinical Experimental Pharmacology and Physiology, July 1990, pages 495–507).
kawa extract. See kava-kava extract.
kelp extract. See algae.
Kigelia africana extract. Extract of African plant commonly known as the sausage tree. The African lore about this extract is that it can firm breast tissue, but there is no supporting research for this myth. The research on this ingredient is limited and mostly in vitro, but it does appear to have anti-inflammatory and antioxidant properties (Sources: Experimental and Toxicologic Pathology, August 2007, pages 433–438; and Journal of Natural Products, November 2005, pages 1610–1614).
kinetin. (N6-furfuryladenine): A nature-based identical plant growth factor. This molecule is a cytokinin- a essential plant growth factor that delays age-related changes in plants. Although the N6 furfuryladenine in Kinerase is a synthetic product, it is nature identical (has exactly the same structure and activity)as the natural molecule. N6-furfuryladenine in plants promotes cell division and helps to ensure the orderly growth and development of the plant. In vitro studies have shown that the compound may also delay or prevent a range of cellular changes associated with aging of human skin cells, including the following: Alteration in cell morphology, growth rate and size Changes in the organization of the cytoskeleton Changes in the synthesis of macromolecules Accumulation of lipofuscin aging pigments.
kiwi fruit extract. As a food, kiwi has significant antioxidant properties that may even be greater than those of vitamin C. Whether that benefit translates into its use on skin has not been demonstrated. The acid component of the kiwi can be a skin irritant.
kojic acid. By-product of the fermentation process of malting rice for use in the manufacture of sake, Japanese rice wine. There is definitely convincing research, both in vitro and in vivo and in animal studies, showing that kojic acid is effective for inhibiting melanin production. Both glycolic acid and kojic acid, as well as glycolic acid with hydroquinone, are highly effective in reducing the pigment in melasma patients. So why aren’t there more products available containing kojic acid? Kojic acid is an extremely unstable ingredient in cosmetic formulations. Upon exposure to air or sunlight it turns a strange shade of brown and loses its efficacy. Many cosmetics companies use kojic dipalmitate as an alternative because it is far more stable in formulations. However, there is no research showing that kojic dipalmitate is as effective as kojic acid, though it is a good antioxidant. There is a small amount of research showing that kojic acid is a skin irritant.
kola nut. One of the major components of the kola nut is caffeine, which can be a skin irritant. However, kola nut also has a primary amine content that can form nitrosamines, which are potential carcinogens. See caffeine.
kudzu root. Source of isoflavone, genistein, and daidzein, all plant estrogens. It can be a potent antioxidant.
kukui nut oil. Non-volatile oil from a plant native to Hawaii; it has emollient properties for skin (Source: Journal of the Society of Cosmetic Chemists, September–October 1993).