Eight new clerodane type diterpenoids, named 7-oxo-kolavelool (1), 7α-hydroxykolavelool (2), 6α,7α-dihydroxykolavenol (3), 12-oxo-hardwickiic acid (4), ptycholide I (5), ptycholide II (6), ptycholide III (7), and ptycholide IV (8) were isolated from the MeOH extract of the bark of a Brazilian medicinal plant, Ptychopetalum olacoides. The structures of 1–8 were elucidated by analyzing spectroscopic data and by comparing their NMR data with those of the previously reported compounds kolavelool (1a), kolavenol (3a), hardwickiic acid (4a), and ptychonolide (5a). Compounds 5 and 6 existed as a 1:1 mixture of inseparable epimers at C-15.
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19.
Compound 5 was purified by HPLC and expressed as one sharp peak, but 5 existed as a 1:1 epimeric mixture at C-15, as deduced from its 1H NMR spectrum.
20.
Compound 6 was purified by HPLC and expressed as one sharp peak, but 6 existed as a 1:1 epimeric mixture at C-15, as deduced from its 1H NMR spectrum.
21.
The α,β-unsaturated γ-lactone ring in compound 8 was deduced as a 15,16-butenolide type ring, and existed as a single isomer rather than an epimeric mixture at C-16.
