Carnosic acid is an abietane diterpenoid that is abieta-8,11,13-triene substituted by hydroxy groups at positions 11 and 12 and a carboxy group at position 20. It is isolated from rosemary (Rosmarinus officinalis) and common sage (Salvia officinalis) and exhibits anti-angiogenic, antineoplastic, antioxidant and anti-HIV activity. It has a role as an antioxidant, an antineoplastic agent, a HIV protease inhibitor, an angiogenesis modulating agent, a food preservative, an anti-inflammatory agent, an apoptosis inducer and a plant metabolite. It is a monocarboxylic acid, a member of catechols, an abietane diterpenoid and a carbotricyclic compound. It is a conjugate acid of a carnosate.