chemical substances normally occuring in nature. Or a chemical that's the just like a naturally occuring one. They may be used as pesticides for instance.
Enzymes, bodily hormones, pheromones, etc., which either occur obviously or tend to be made to be the same as natural substances. Biochemicals have many environment-friendly programs, such as for example all-natural pesticides that really work in non-lethal methods as repellents or by disrupting the mating patterns associated with the bugs.