Two new sesquiterpenoids and one new p-coumaroyl-triterpenoid derivative from Myrcia guianensis

• Three new compounds were isolated from Myrcia guianensis . • The isolation of unusual chlorine-containing sesquiterpenoid is reported. • The biogenesis of the new sesquiterpenoids is proposed. Two new sesquiterpenoids (1 and 2) and one new p-coumaroyl-triterpenoid derivative (3), along with five known sesquiterpenoids (4–8), seven triterpenoids (9–15), and two steroids (16 and 17) were isolated from Myrcia guianensis . Compound 1 [6-methyl-5-(2-hydroxy-3-chloro-5-methyl phenyl)-heptan-2-one] contains a chlorine atom attached to C-10, which seems to be the first report of a chlorine-containing sesquiterpenoid in the Myrtaceae family. The biogenesis of the two new sesquiterpenoids (1 and 2) are proposed herein, whereas the isolation of these sesquiterpenoids and triterpenoids from M. guianensis may present chemophenetic relevance to consolidate the genus Myrcia within the Myrtaceae family.