Fatty acids ricinoleic acid incorporation

Castor esters have been found to be nonirritating and noncomedogenic to the skin. Cetyl ricinoleate was found to be an effective noncomedogenic moisturizer (118). Castor-based quaternaries prepared by reaction of a castor fatty acid and a tertiary diamine are used for hair care. The ricinoleic quaternium is incorporated into clear shampoo formulations for foam enhancement and conditioning (119,120). 

Figure 25.1. Proposed biosynthetic pathway of castor oil. Heavy arrows show the key enzyme steps driving ricinoleate into acylglycerols. Two arrows with solid bars show a complete block. Two dashed arrows show the phospholipase C hydrolysis which can be targeted to block the incorporation of non-hydroxyl fatty acids into triacylglycerols to increase presumably the content of ricinoleate in transgenic seed oils.

The incorporation of fatty acids into a polyanhydride chain was investigated using two fatty acids lithocholic acid and ricinoleic acid. Lithocholic acid containing polyanhydrides (Figure 2) were prepared by two step synthesis. Polyanhydrides reached molecular weights of 21000-115000 Da, depending on the polymer composition. Release of model drugs from these polymers showed sustained release of 5FU for almost 3 weeks and triamcinolone for 4 weeks (22). 

Ricinoleic acid is a bifunctional fatty acid containing a hydroxy group along the fatty chain. The presence of both carboxylic and hydroxyl groups allows incorporation of ricinoleic acid into a polymer backbone by formation of an ester bond. The synthesis of poly(ester-anhydride) contains two steps trans-... 

Ricinoleate (R) has many industrial uses. Its only commercial source is castor oil, in which ricinoleate constitutes 90% of the fatty acids (FA) (1). Castor beans contain toxic substances and are hazardous to grow, harvest, and process. Therefore, it is desirable to produce ricinoleate from a transgenic plant lacking these toxic substances. To develop a transgenic plant capable of producing a high level of ricinoleate in its seed oil, it is essential to understand the biosynthesis of castor oil. We previously established the biosynthetic pathway of castor oil and identified the key enzymatic steps of the pathway, which drive the ricinoleate into castor oil (2,3). We report here the identification and quantification of the molecular species of triacylglycerols (TAG, end products), phosphatidylcholines (PC, intermediate) and phosphatidylethanolamines (PE, intermediate) on the pathway incorporated from various [ C]-labeled FA and the comparison of the levels of their incorporation. 

This structural peculiarity, with fatty-acid chains incorporating an unsaturation and a secondary hydroxyl group, opens the potential for direct polymerisation, which also applies to its major ricinoleic fatty acid (albeit in different mechanistic contexts) [11,12]. The three -OH groups appended on this triglyceride have prompted studies on the synthesis of polymers such as polyesters and polyurethanes (PU). 

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