Natural Product Biomolecules - Organic Chemistry Concepts: An EFL Approach - page 155

FIGURE 8.8
Hydrolysis of complex carbohydrates.
8.3 LIPIDS
The class name lipid refers to different compound types with various struc-
tures which have different functional groups. However, all lipids have
large hydrocarbon content and are relatively non-polar. This makes them
soluble in relatively non-polar organic solvents. It is this solubility, rather
than a structural or chemical feature, that makes lipids different from other
biomolecules.
As shown in Figure 8.9 , lipids are classified as simple or complex. This depends
on whether or not they have an ester group. The presence of an ester means they
can undergo base hydrolysis.
FIGURE 8.9
General classification of lipids.
Figure 8.10 shows two structurally different classes of simple lipids: steroids and
eicosanoids. These have nothing in common except the physical property of
similar solubility and no ester group. Other classes of simple lipids are terpenes
and fat-soluble vitamins. These are not shown here.
Figure 8.10 also shows how complex lipids have the common feature of an ester
group. They are further subdivided based on whether or not glycerol (1,2,3-
propanetriol) is the alcohol portion of the ester.