Insect Control: Biological and Synthetic Agents - Index of

eported, but this is rather nonspecific (Dai et al.,
1999), and more specific enzyme-linked immunosorbent
assays (ELISAs) have been developed that
will give detection from 0.5 to 1000 ppb for azadirachtin
and close relatives (Schutz et al., 1997,
Hemalatha et al., 2001). Additionally, monoclonal
antibodies to azadirachtin produced by phage
display techniques are currently being assessed
(Robertson, Mordue (Luntz), Mordue, and Porter,
unpublished data). The most accurate and sensitive
5: Azadirachtin, a Natural Product in Insect Control 189
Figure 2 Examples of minor products related to azadirachtin from neem seeds. The essential difference of structure that makes
an azadirachtol or meliacarpin is indicated by an arrow. Marrangin is the chief insecticidal compound of the marrango tree
(Azadirachta excelsa). The names azadirachtin A, azadirachtin B, etc., are sometimes used. These are incorrect names. For the
correct chemical names for all teiterpernoids and limonoids, see Kraus (2002).
Figure 3 Rearrangement products from azadirachtin and 3-tigloylazadirachtol. These compounds, of much lower activity than
the others illustrated, are formed by reaction between the epoxide ring and the hydroxyl group at C7.
analytical method, but also the most costly in equipment,
is liquid chromatography–mass spectrometry
(Schaaf et al., 2000; Pozo et al., 2003).
5.3.4. Stability and Persistence
Azadirachtin is soluble in polar organic solvents
(methanol, ethanol, acetone, chloroform, ethyl acetate)
and slightly soluble in water (1.29 g l 1 ). Aqueous
solutions are usually made by dissolving first