**5. Conclusion**

Natural products originate as secondary metabolites Plants possess different indigenous defensive mechanisms to cope with certain environmental stresses. Secondary metabolites are natural tools used by plants to combat biotic and abiotic stresses. Microorganisms can produce several antibiotics and other pharmaceutically important drugs to treat bacterial and fungal infections. The secondary metabolites from natural products help us to understand their classes, sources, pharmacological importance and examples associated with the secondary metabolites derived from plants, fungi, and bacteria.
