UPLC-MSE guided isolation of CHCl3 extract
from the fruits of Trichilia connaroides yielded
two new mexicanolide-type limonoids trichanolide F (1) and trichanolide G (2) along with a known compound
carapanolide U (3). The structures of the limonoids were
characterized by extensive spectroscopic analysis (MS, IR, 2D NMR).
These limonoids (1–3) were evaluated
for their antifeedancy against Spodoptera litura F.
To further explore and draw the meaningful structure activity relationship
studies, secophragmalin-type limonoids, namely, secotrichagmalin B,
C (4, 5) and semisynthetic derivatives (5a–5l) were also screened for antifeedancy.
The results revealed that trichanolide F (1) displayed
highest antifeedant index (AFI) and caused larval mortality at 24
h. Derivative 5b caused larval toxicity, whereas 3, 5a, 5d, and 5g lead
to pupal mortality and 2, 5f, 5k, and 5l caused adult deformities. Overall, the study
provided new insights into the antifeedant potential of isolated and
chemically modified limonoids from T. connaroides for the control of spodopteran pests.