quality:correction, linguistic:paraphrasing
Contribution in modern medicine

Quinine, which is found naturally in the bark of the cinchona tree, is known to be used by Quechuas people for malaria -like symptoms.

When chewed, coca acts as a mild stimulant and suppresses hunger, thirst, pain, and fatigue; it is also used to alleviate altitude sickness. Coca leaves are chewed during work in the fields as well as during breaks in construction projects in Quechua provinces. Coca leaves are the raw material from which cocaine, one of Peru's most historically important exports, is chemically extracted.