Limonoids with Intact Four Rings and γ-Hydroxybutenolide Side Chain. The presence of a y-
Hydroxybutenolide side chain in place of the furan ring is the characteristic of this group of
compounds. Two isomeric constituents, nimocinolides (37 and 38) 134 - and isonimbocinolideI39
(40) have been isolated from neem leaves whereas isonimolicinolide(41) from fresh fruits141
(Table 3). The prefix 'iso' in this case, designates the 23-oxo isomers. The structure elucidation of
37 and 38 was facilitated by the comparison of their spectral data with the furan analogue,
nimocinol (45). The diagnostic chemical shifts in nmr of the γ-¬Hydroxybutenolide are ca. δ 6.9(m)
and δ 6.l(m) for H-22 and H-23, 0 137(d) and δ l45(d) for C-20 and C-22 in 2l-oxo-olides and δ 5.9
(m) and δ 6.0(m) for H-2l and H-22, δ l57(d) and δ l19(d) for C-20 and C-22 in 23-oxo-olides
respectively. Nimocinolides (39 and 40), just like azadirachtol (31), bear C-ll oxygen function.
Nimocinolides showed mild insect growth regulating properties and affected fecundity in
houseflies (Musca domestica) and mosquitoes (Aedes aegypti) at a dosage of 100-500 ppm
(pure neem oil).
Hydroxybutenolide side chain in place of the furan ring is the characteristic of this group of
compounds. Two isomeric constituents, nimocinolides (37 and 38) 134 - and isonimbocinolideI39
(40) have been isolated from neem leaves whereas isonimolicinolide(41) from fresh fruits141
(Table 3). The prefix 'iso' in this case, designates the 23-oxo isomers. The structure elucidation of
37 and 38 was facilitated by the comparison of their spectral data with the furan analogue,
nimocinol (45). The diagnostic chemical shifts in nmr of the γ-¬Hydroxybutenolide are ca. δ 6.9(m)
and δ 6.l(m) for H-22 and H-23, 0 137(d) and δ l45(d) for C-20 and C-22 in 2l-oxo-olides and δ 5.9
(m) and δ 6.0(m) for H-2l and H-22, δ l57(d) and δ l19(d) for C-20 and C-22 in 23-oxo-olides
respectively. Nimocinolides (39 and 40), just like azadirachtol (31), bear C-ll oxygen function.
Nimocinolides showed mild insect growth regulating properties and affected fecundity in
houseflies (Musca domestica) and mosquitoes (Aedes aegypti) at a dosage of 100-500 ppm
(pure neem oil).
| Table 3. Limonoids with all rings intact and containing y-Hydroxybutenolide side chain |
Stru- Name Molecular m.p. Isolated form Ref.
ture Formula Weight (*C) No.
No.
37. Nimocinolide C28H36O7 484 160 Fresh winter leaves 134
38. Isonimocinolide C28H36O7 484 165 Fresh winter leaves 134
39. Nimbocinolide C32H42O9 570 - 165
40. Isonimbocinolide C32H42O9 570 - Fresh winter leaves 139
41. Isonimolicinolide C30H36O9 540 102 Fresh fruits 141
ture Formula Weight (*C) No.
No.
37. Nimocinolide C28H36O7 484 160 Fresh winter leaves 134
38. Isonimocinolide C28H36O7 484 165 Fresh winter leaves 134
39. Nimbocinolide C32H42O9 570 - 165
40. Isonimbocinolide C32H42O9 570 - Fresh winter leaves 139
41. Isonimolicinolide C30H36O9 540 102 Fresh fruits 141
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