Plant Derived Compounds and their Synthetic analogs against

1
Plant Derived Compounds and their Synthetic
analogs against Yellow Fever Mosquito Aedes
Aegypti Kumudini M. Meepagala1, Julia W.
Pridgeon, George Sturtz, James J. Becnel, and
Stephen O. Duke
2
NPURU Oxford MS
Collaborative Research work between NPURU in
Oxford, MS and CMAVE in Gainesville, FL
3
NPURU Oxford MS
Objective of Collaboration

• To identify and develop safe, environmentally
  benign insecticides to protect the deployed
  military personnel from vector borne diseases.
• 1. To develop adulticides
• 2. To develop repellents

4
NPURU Oxford MS
Two approaches have been chosen in search for
insecticides
Collection and screening of plant families
with known insecticidal properties and isolation
of compounds
Synthesis of libraries of known natural product
based insecticides eg. amides, furans, Methylenedi
oxy analogs
5
NPURU Oxford MS
Approach at USDA NPURU
In search for effective, environment friendly,
insecticides we have screened some natural
products isolated from plant extracts belonging
to various families. egAsteraceae, Apiaceae and
Rutaceae
6
NPURU Oxford MS

• Rationale
• Secondary metabolites are produced by plants as
  part of the natural defense mechanism.
• They also play a significant role in defending
  the plants from insects, fungi, bacteria, and
  other plants.
• We have postulated that this is one area to
  explore in order to search for such insecticides.

7
NPURU Oxford MS
Each chemical was given a DWFP log number before
testing. The testing was carried out to see
adulticide activity upon topical application
8
NPURU Oxford MS
Toxicities of compounds 58-69 against Aedes
aegypti (7-10 )days old)by topical application
9
NPURU Oxford MS

• AT-05-24 and AT-05-27-2 have been isolated from
  the same plant
• They are cis/trans isomers.
• Further synthetic modifications are in progress
• 119-2 and 123-1 are synthetic analogs based on a
  natural product.
• Structural optimization is also in progress.

10
NPURU Oxford MS
Larvicides
11
Several natural product based compounds were
synthesized Each compounds required about 12
synthetic steps All the steps yielded gt80
yield These were tested on mosquito larvae by
Dr. Pridgeon at MFRU
12
(No Transcript)
13
Indoxacarb Insecticide developed by Du Pont.
57-1 and 57-2 do not have halogens and similar
to a natural product.
14
NPURU Oxford MS
Structures of the tested compounds
15
NPURU Oxford MS
Piperidines that have been synthesized and tested
Chemical Name/Number LD50 (ug/insect)
NPURU-1 1.057383 NPURU-2 3.299732
NPURU-3 1.581581 NPURU-4 7.356252
PIPERINE 7.00832 (from Piper nigrum)
16
NPURU Oxford MS
Mode of action of some of these insecticides

• Many commercial insecticides are AChE inhibitors.
• Some of these have been tested in our lab for
  this activity using
• a rapid TLC assay
• This method can also be used to detect the
  presence of insecticides
• in crude plant extracts.

This assay is based upon a color reaction Used
AChE from electric eel.
17
NPURU Oxford MS
Test for AChE inhibitory activity
1.Plant extracts or pure samples are spotted on a
TLC plate and elute with an appropriate
solvent. 2. The plates are allowed to dry and
spray with AChE solution and incubate at 37 0C
for 20 min. 3. Then the plates are sprayed with
a solution of ?-naphthyl acetate and fast blue
4. White spots will be seen in a dark purple
background where the inhibitors are present. 5.
Galanthanime isolated from daffodil bulbs is used
as a positive control.
18
NPURU Oxford MS
19
NPURU Oxford MS
AChE inhibitors are seen as white spots in a
purple background
20

• Acknowledgements
• Raffaella Purcaro (Graduate Student, Naples,
  Italy)
• Jason Martin (Physical Sci. Technician)
• Jennifer Cox (student worker)
• Amarette Aube( student worker)