Parkinson's disease is a neurodegenerative condition characterized by slow movement
(bradykinesia), tremors, and muscle stiffness. These symptoms occur due to the degeneration of dopamine-
producing neurons in the substantia nigra region of the brain, leading to reduced dopamine
levels. The development of Parkinson's Disease (PD) involves a combination of genetic and environmental
factors. PD is associated with abnormal regulation of the monoamine oxidase (MAO) enzyme.
Monoamine oxidase inhibitors (MAOIs) are an important class of drugs used to treat PD and
other neurological disorders. In the early stages of PD, monotherapy with MAO-B inhibitors has
been shown to be both safe and effective. These inhibitors are also commonly used as adjuncts in
long-term disease management, as they can improve both motor and non-motor symptoms, reduce
"OFF" periods, and potentially slow disease progression. However, current MAO-B inhibitors come
with side effects like dizziness, nausea, vomiting, light-headedness, and fainting. Therefore, accelerating
the development of new MAO-B inhibitors with fewer side effects is crucial. This review explores
natural compounds that may inhibit monoamine oxidase B (MAO-B), focusing on key findings
from the past seven years. It highlights the most effective heterocyclic compounds against
MAO-B, including thiazolyl hydrazone, pyridoxine-resveratrol, pyridazine, isoxazole, oxadiazole,
benzothiazole, benzoxazole, coumarin, caffeine, pyrazoline, piperazine, piperidine, pyrrolidine, and
morpholine derivatives. The review covers in vitro, in silico, and in vivo data, along with the structure-
activity relationship of these compounds. These findings offer valuable insights for the development
of more effective MAO-B inhibitors and advancements in Parkinson's disease research.