Lindenane-Based Sesquiterpenoid Hetero-Oligomers with Diverse Skeletons and Extracellular Regulated Protein Kinases Inhibitory Activity from <i>Sarcandra glabra</i>

Sarcglabtenes A-G (<b>1</b>-<b>7</b>), seven lindenane-based sesquiterpenoid hetero-oligomers with six unprecedented skeletons, along with five new biosynthetic analogues sarcglabtenes H-L (<b>8</b>-<b>12</b>), were isolated from <i>Sarcandra glabra</i>. Their structures including absolute configurations were comprehensively elucidated using HR-MS, NMR, ECD, and single crystal X-ray diffraction. Structurally, sarcglabtenes A-G are lindenane hetero-oligomers including a geranyl homogentisic acid (<b>1</b>/<b>2</b>), geranylgeranyl <i>p</i>-toluquinone (<b>3</b>/<b>4</b>), germarane (<b>5</b>), campholenal (<b>6</b>/<b>7</b>) derivatives, for which plausible biosynthesis pathways are also proposed. In bioassays, <b>1</b>-<b>4</b> exhibited cytotoxic activity against five cancer cell lines, and in particular, <b>4</b> acted as extracellular-regulated protein kinase (Erk) inhibitor of the MAPK signaling pathway involved in apoptosis.