Frutescones H-R (1-11), new sesqui- or monoterpene-based meroterpenoids, were isolated from the aerial parts of Baeckea frutescens. Their structures and absolute configurations were established by means of spectroscopic analyses (HRESIMS, 1D and 2D NMR, and ECD), as well as single-crystal X-ray crystallography of 1, (-)-7, and 9. The anti-inflammatory activities of all isolates were evaluated by measuring their inhibitory effects on NO production in LPS-stimulated RAW 264.7 macrophages, and the structure-activity relationships of 1-11 are also discussed. Compound 8 exhibited anti-inflammatory activity with an IC value of 0.36 μM, which might be related to the regulation of the NF-κB signaling pathway via the suppression of p65 nuclear translocation and the consequent decrease of IL-6 and TNF-α.

Frutescone A-G [(1-6), (+)-7, (-)-7], a new group of naturally occurring tasmanone-based meroterpenoids, were isolated from the aerial parts of Baeckea frutescens L. Compounds 1 and 4 featured a rare carbon skeleton with an unprecedented oxa-spiro[5.8] tetradecadiene ring system, existing as two favored equilibrating conformers in CDCl solution, identified by variable-temperature NMR. The regioselective syntheses of 4-7 were achieved in a concise manner by a biomimetically inspired key hetero-Diels-Alder reaction "on water". Compounds 1, 4, and 5 exhibited moderate cytotoxicities in vitro.

Celastrol, a friedelane-type triterpenoid isolated from the genus Triperygium, possesses antitumor, anti-inflammatory, and immunosuppressive activities. A total of 42 celastrol derivatives (1a–1t, 2a–2l, and 3a–3j) were synthesized and evaluated for their immunosuppressive activities. Compounds 2a–2e showed immunosuppressive effects, with IC50 values ranging from 25 to 83 nM, and weak cytotoxicity (CC50 > 1 μM). Compound 2a, with a selectivity index value 31 times higher than that of celastrol, was selected as a lead compound. Further research showed that 2a exerted its immunosuppressive effects by inducing apoptosis and inhibiting cytokine secretion via Lck- and ZAP-70-mediated signaling pathways.

Compounds 1–4 represent the first examples of natural atropisomeric meroterpenoids with a rare triketone-phloroglucinol-terpene skeleton.

A new phenolic glycoside, 6'-[(E)-2''-hydroxymethyl, 2''-butenoyl] arbutin (1), and two known phenolic glycosides, 6'-[(E)-4''-hydroxycinnamoyl] arbutin (2) and 6'-[(E)-3'',4''-dihydroxycinnamoyl] arbutin (3), were isolated from the leaves of Heliciopsis lobata (Merr.) Sleum. Their structures were elucidated by various spectroscopic methods including 2D NMR spectroscopy.