Cardiolipin (CL) is a unique phospholipid with a very interesting chemical and specific ultrastructural characteristics. It is a highly acid dimer of phosphatidylglycerol (PG) and phosphatidic acid (PA), containing four acyl chains; three glycerols and two phosphate headgroups. Due to deprotonation of one of these phosphate groups, cardiolipin is negatively charged in physiological pH [1,2].
Cardiolipin (CL) is known as mitochondria-specific phospholipid since it is almost exclusively biosynthesized and located in the inner mitochondrial membranes. The name “cardiolipin” is derived from fact that it was first found and isolated from animal heart. Cardiolipin is considered to be intimately linked to mitochondrial bioenergetic process. It plays a functional role in mitochondrial membrane stability and dynamics, interacts with a number of inner mitochondrial membrane metabolite carriers, enzymes and proteins. During apoptosis in presence of H2O2, CL-bound Cytochrome c catalyzes the peroxidation of cardiolipin, releasing Cytochrome c, which is a death-inducing protein. CL peroxidation and depletion have important implications to age-related mitochondrial dysfunction, resulting in a number of pathophysiological conditions, such as hypo/hyperthyroid states [3-7], heart ischemia–reperfusion [8-12], nonalcoholic fatty liver disease [13], diabetes [14,15], Barth syndrome [16,17] and aging [18-21]. According Birk et al. [22], the main functions of cardiolipin are: “(i) to support spatial organization of mitochondrial cristae; (ii) to create the proton trap necessary for sustaining the proton gradient and ATP synthesis by the F0F1 ATP synthase; (iii) to act as a scaffold for assembly of respiratory complexes and super-complexes to facilitate optimal electron transfer among the redox partners.”
Extensive studies [23-29] of pharmacological, toxicological, and therapeutic effects have shown that the incorporation of doxorubicin in cardiolipin liposomes improved the antitumor activity of doxorubicin, while the histopathologic lesions in cardiac tissue of mice significantly decreased. It has been reported that cardiolipin-containing liposomes have lower (at least 2-fold lower than that observed with conventional doxorubicin) cardiotoxicity associated with doxorubicin by altering the pharmacokinetics and tissue distribution of the drug in mice [29]. Also, it has been indicated that cardiolipin provides two types of binding possibility for drugs; one mostly exposed at the surface, and the other deeply buried in the membrane [30,31]. Hence, the cardiolipin-liposomes has been suggested as a convenient carrier for doxorubicin delivery to increase the therapeutic index of the drug [23].
Cardiolipin is a negatively charged lipid. Cellsome® made from cardiolipin lipid catalog containing many different types of saturated and unsaturated cardiolipin based liposomes made from 0.5 up to 100 percent of cardiolipin.
