Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2014
Publication Date: 1/1/2015
Publication URL: http://handle.nal.usda.gov/10113/5642488
Citation: Compton, D.L., Laszlo, J.A., Evans, K.O. 2015. Phenylpropanoid esters of lesquerella and castor oil. Industrial Crops and Products. 6:9-16.
Interpretive Summary: This research describes a method for making bio-based sunscreen and antioxidant ingredients for cosmetics and skin care products. Our mission is to develop new, value added, bio-based chemicals and products that replace those made from petroleum and reduce the effects of climate change. The natural plant component ferulic acid was attached to lesquerella oil, a new crop oil being developed in the southwestern US as an alternative to imported castor oil (which is associated with the toxin, ricin). The new method proves the concept of making the feruloylated lesquerella oil without the need for organic solvent or other harsh chemicals. The feruloylated lesquerella oil absorbs UVA and UVB radiation comparable to commercially used, petroleum-based ingredients and is a potential antioxidant that can be used by other researchers in investigating the protection of model cell membranes with natural antioxidants.
Technical Abstract: Lesquerella (LO) and castor oil (CO) were esterified at the secondary hydroxyl groups of their 14-hydroxyeicos-cis-11-enoic fatty acids and 12-hydroxyoctadec-cis-9-enoic fatty acids, respectively, with 4-acetoxy-3-methoxycinnamic acid (acetoxyferulic acid). The unconventional esterifications were conducted under inert nitrogen atmospheres without solvent at 175 – 200 °C in sealed ampules. 1H NMR was used to measure the degree of acetoxyferuloyl esterification using a modified esterification number (EN). Reactions at 200 °C resulted in ~ 43% conversions to the acetoxyferuloylated LO and CO but promoted significant degradation/loss of the acetoxyferulic acid as evidenced by the low quantity of acetoxyferulic acid found in the reaction products as determined by HPLC. Reactions at 175 °C resulted in significantly lower conversions to the acetoxyferuloylated LO and CO, 9 – 17%, but did not result in as severe acetoxyferulic acid degradation. The addition of tin (II) 2-ethylhexanoate catalyst to the 175 °C reactions increased esterification conversion to ~ 45% without significant loss of acetoxyferulic acid to degradation. The acetoxyferuloylated LO and CO were selectively deacylated at the aromatic acetate using excess pyrrolidine without affecting the aliphatic esters to give feruloylated LO and CO. The feruloylated LO and CO absorbed ultraviolet (UV) radiation from 280 – 360 nm with a 'max at 327 nm, bridging the absorbance gap of commercial UV absorbing ingredients. The feruloylated LO and CO are also presumably good antioxidants and are potential candidates for incorporation into lipid bilayers to protect liposomes and their contents from reactive oxygen species.