Plants are present ubiquitously on Earth as faunal diversity. Both interact
with each other at one or another stage. This interaction can be positive or negative for
plants. Interaction for the purpose of pollination is classified as positive interaction
whereas faunal diversity (mostly arthropods) is attacking plants to fulfill their food
requirement. To defend themselves against this attack by herbivorous animals, plants
synthesize some bioactive compounds. Plants release these compounds either to kill or
repel these herbivorous animals. Hence it is a direct approach to counter these attacking
animals. An indirect approach is also used by some plants where plants produce nectar
to attract ants. These ants feed on this nutritious nectar and defend the plants from
herbivorous insects that eat the plant’s leaves. Compounds synthesized by plants can
have noxious odors, and excessive stimulation and some compounds become toxic
after ingestion. Ingestion of these compounds can cause many problems such as
vomiting, nausea hallucinations convulsions, and even death of the organism.
Keywords: Alkaloid compounds, Plant defense system, Phytochemicals, Phenolics, Terpenoids.
