Primarily used for tooth abcesses, it is also active against acne, some insects, tuberculosis, and MRSA. It is primarily found in foods such as cashew nuts, cashew apples, and cashew shell oil, but also in mango, garden geranium.
The side chain with three unsaturated bonds was the most active against Streptococcus mutans, the tooth decay bacterium, in test tube experiments. The number of unsaturated bonds were not material against Propionibacterium acnes, the acne bacterium. Eichbaum claims that one part to 200,000 to as high as 2,000,000 parts of solution of anacardic acid is lethal to gram positive bacteria in 15 minutes in vitro. Somewhat higher ratios killed tubercle bacteria of tuberculosis in 30 minutes. Heating these anacardic acids converts them to the alcohols (cardinols) but does not destroy their activity unless high heat is used, which decarboxylates them. It is said that the people of the Gold Coast use cashew leaves and bark for a toothache.
Anacardic acid is the main component of cashew nutshell liquid (CNSL), and finds use in the chemical industry for the production of cardanol, which is used for resins, coatings, and frictional materials. Cardanol is used to make phenalkamines, which are used as curing agents for the durable epoxy coatings used on concrete floors.
The first chemical analysis of the oil of the cashew nut shell from the Anacardium occidentale was published in 1847. It was later found to be a mixture rather than one chemical, sometimes the plural anacardic acids is used.
Anacardic acid kills MRSA cells more rapidly than totarol.