Bioactive Enmein-Type ent-Kaurane Diterpenoids from Isodon phyllostachys

Area of Science:

• Natural Products Chemistry
• Medicinal Chemistry
• Pharmacology

Background:

• Isodon species are a rich source of bioactive ent-kaurane diterpenoids.
• Enmein-type diterpenoids exhibit diverse biological activities.

Purpose of the Study:

• To isolate and characterize new enmein-type ent-kaurane diterpenoids from Isodon phyllostachys.
• To evaluate the cytotoxic and anti-inflammatory potential of these compounds.

Main Methods:

• Isolation and purification of compounds using chromatographic techniques.
• Structure elucidation via Nuclear Magnetic Resonance (NMR) and High-Resolution Electrospray Ionization Mass Spectrometry (HRESIMS).
• Determination of absolute and relative configurations using single-crystal X-ray diffraction.

Main Results:

• Thirty-two enmein-type ent-kaurane diterpenoids were identified, with 13 being novel.
• Compounds 1 and 2 represent the first reported 3,20:6,20-diepoxyenmein-type ent-kauranoids.
• Compounds 11, 15, 20, and 21 displayed potent cytotoxic activity against human cancer cell lines (IC50: 1.2–5.0 μM).
• Compounds 3, 11, 15, 17, 20, 21, 25, and 29 exhibited strong inhibition of nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated RAW264.7 cells (IC50: 0.74–4.93 μM).

Conclusions:

• The aerial parts of Isodon phyllostachys are a valuable source of structurally diverse enmein-type ent-kaurane diterpenoids.
• The newly discovered and isolated compounds possess significant anticancer and anti-inflammatory properties, warranting further investigation.