What are active constituent of capsicum that protect plant from inauthentic and insect?

Question

and how to extract them

Answer 1

It is the amount of capsaicin or capsaicinoid compounds in the capsicum species that makes them an effective deterrent  insecticide.  These compounds can be effectively extracted by drying and grinding capsicum plants high in the active ingredients. This is the way pepper spray is made. To actually extract them chemically would take a knowledge of chemistry and a chemical laboratory.

Answer 2

spray the plant by using medicine Malayan