76 SAPONIFIABLE LIPIDS 



have been isolated from saponified suberin and their structures established. Phloionic 

 acid is also found in cutin. 



OHOH 



I I 



HO(CH2)8CHCH(CH2)7COOH phloionolic acid 

 HOCH2(CH2)2oCOOH phellonic acid 



OHOH 



I I 



HOOC(CH2)7CHCH(CH2)7COOH phloionic acid 



HOOC(CH2)2oCOOH phellogenic acid 



Cutinic acid and cutic acid of cutin have been assigned the empirical formulas C13H22O3 

 and C26H50O6 and are evidently also hydroxy acids. It seems likely that cutin and suberin 

 are complex polymeric esters similar to the etholides but possibly having additional ester 

 linkages to other constituents of cuticle or cork such as lignin, cellulose, or tannins. 

 Since the cutin and suberin acids which have more than one hydroxyl group may also form 

 cross-linked polymers. 



A group of relatively low molecular weight esters of acetylenic acids is character- 

 istic of the family Compositae. Long-chain acetylenic C18 acids have already been men- 

 tioned as occurring in some triglycerides. The Compositae compounds are methyl esters 

 of Cio acids. Two of the most widespread compounds in the family are the following: 



O 



II 



CH3CH = CH - C = C - C=C - CH = CH COCH3 



matricaria ester 



O 



II 

 CH3CH2CH2C = C - CeC - CH = CH COCH3 



lachnophyllum ester 



The composites also contain acetylenic alcohols and hydrocarbons which will be described 

 in Chapter 6. Several reviews on natural acetylenic compounds have appeared recently 

 (3, 4, 5, 6). 



PHOSPHOLIPIDS OR PHOSPHATIDES 



Several different types of phosphorus-containing lipids are found in plants. All are 

 esters of phosphoric acid and long chain fatty acids. The simplest phospholipids are the 

 phosphatidic acids which have fatty acid groups and phosphoric acid esterified with glyc- 

 erol: 



1} 



HXOCR 

 RfCOCH 



H^0P03H2 



