Porphyric Insecticides - Chlorophyll Biosynthesis and Technological Applications - page 429

Table 18.15 Effects of ALA, and substituted quinolines on Proto accumulation and larval
mortality in T . ni

Proto content
(nmol/100 mg protein)

Larval mortality after 6 days
in the greenhouse (%) Entry Treatment a

1.0b b 1 Control 0.0a

2 ALA 1.7c 0.0a

3 8-Hydroxyquinoline 1.0a 0.0a

4 Above + ALA 1.9c 0.0a

5 8-Hydroxy-5-nitroquinoline 0.7a 0.0a

6 Above + ALA 3.0d 0.0a

7 8-Hydroxy-7-(4-sulfo-1-

naphtylazo)-5-sulfonic acid

1.8c 1.7a

8 Above + ALA 41.8 g 76.7b

9 8-Hydroxyquinoline-5-

sulfonic acid

1.8c 0.0a

10 Above + ALA 32.1f 81.7b

Correlation coefficient 0.85

Level of significance 1 %

Adapted from Gut et al. ( 1993 )
a Treatment consisted of control diet lacking any added ALA or modulator, diet containing 4 mM
ALA, 3 mMmodulator or 4 mM ALA + 3 mMmodulator, in a randomized complete block design
with three replicates. Percent larval death was arcsine transformed prior to statistical analysis
b

Means followed by the same letter within a column are not significantly different at the 5 % level
of significance

reduction in activity (Table 18.15 , # 7, 8). The presence of a sulfonyl group at
position 5 of the macrocycle was an essential requirement for activity. The main
effect of this substitution was a significant increase in the electrostatic positive
charge binding volumes around the sulfonic acid group.
Moving the exocyclic OH group from position 8 to position 1 and moving the
endocyclic N atom from position 1 to position 2, as in isocarbostyril, an
oxypyridine compound, also resulted in substantial insecticidal activity in compar-
ison to 8-hydroxyquinoline (Table 18.14 , # 13, 14; Table 18.15 #, 3, 4). This change
resulted in an increase in the magnitude of the dipole moment from 2.33 D to
3.53 D, as well as an increase in electron density (from 0.16 to 0.23 kcal/mol) in the
unoccupied molecular orbitals in isocarbostyril. Addition of a hydroxyl group at
position 5, as in 1,5-isoquinolinediol, diminished considerably the observed insec-
ticidal activity (Fig. 18.7 ; Table 18.14 , # 11, 12). This was accompanied by a
decrease in dipole moment and further increase in electron density of the unoccu-
pied molecular orbitals.

18.6.5 Structure-Activity Relationship
of Substituted Pyrroles

Structure-activity relationships of three substituted pyrroles were investigated
(Fig. 18.7 ). As was generally observed for the other templates, porphyric insecticidal