Cytotoxic triterpenes from <i>Salvia buchananii</i> roots

<p>A pentacyclic triterpene, named salvibuchanic acid (<b>1</b>), together with five known compounds, were isolated from the roots of <i>Salvia buchananii</i> Hedge (Lamiaceae). The structural characterisation of all compounds was performed by spectroscopic analyses, including 1D and 2D NMR and HRESIMS experiments. The lupane triterpene (<b>1</b>) and hyptadienic acid (<b>2</b>) were investigated for their potential cytotoxic activity on Jurkat, HeLa and MCF7 cell lines. Both compounds showed an interesting antiproliferative activity with similar potency in all cell lines. By means of flow cytometric studies, hyptadienic acid (<b>2</b>) induced in HeLa cells a S cell cycle block, while <b>1</b> elicited both cytostatic and cytotoxic responses.</p

A Chemical–Biological Study Reveals C₉‑type Iridoids as Novel Heat Shock Protein 90 (Hsp90) Inhibitors

The potential of heat shock protein 90 (Hsp90) as a therapeutic target for numerous diseases has made the identification and optimization of novel Hsp90 inhibitors an emerging therapeutic strategy. A surface plasmon resonance (SPR) approach was adopted to screen some iridoids for their Hsp90 α binding capability. Twenty-four iridoid derivatives, including 13 new natural compounds, were isolated from the leaves of <i>Tabebuia argentea</i> and petioles of <i>Catalpa bignonioides</i>. Their structures were elucidated by NMR, electrospray ionization mass spectrometry, and chemical methods. By means of a panel of chemical and biological approaches, four iridoids were demonstrated to bind Hsp90 α. In particular, the dimeric iridoid argenteoside A was shown to efficiently inhibit the chaperone in biochemical and cellular assays. Our results disclose C₉-type iridoids as a novel class of Hsp90 inhibitors