Unusual Secondary Metabolites of the Aerial Parts of <i>Dionysia diapensifolia</i> Bioss. (Primulaceae) and Their Anti-Inflammatory Activity

• Main Authors: Mostafa Alilou, Stefania Marzocco, Hossein Batooli, Jakob Troppmair, Stefan Schwaiger, Hermann Stuppner
• Format: Article
• Language: English
• Published: MDPI AG 2020-03-01
• Series: Biomolecules
• Subjects: <i>dionysia diapensifolia</i> bioss; anti-inflammatory; macrophages; phenolic compounds; flavone
• Online Access: https://www.mdpi.com/2218-273X/10/3/438

The genus <i>Dionysia</i>, belonging to the Primulaceae family, encompasses more than 50 species worldwide with a center of diversity located in the arid Irano-Turanian mountains. In this study, a phytochemical investigation of the aerial parts of <i>D. diapensifolia</i> Bioss. led to the isolation of 24 phenolic compounds <b>1</b>&#8722;<b>7</b> and <b>9</b>&#8722;<b>25</b>, and one sesquiterpenoid <b>8</b>. Compound <b>1</b> was identified as new natural product, while isolation of <b>2</b> and <b>3</b>, already known as synthetic products, from a natural source is reported for the first time in the present study. Isolation of compound <b>8</b> from a <i>Dionysia</i> species and indeed the whole Primulaceae family is reported for the first time too. Structure elucidation was performed by extensive spectroscopic analyses (1D-, 2D-NMR, and MS), and by comparison with reported literature data. Furthermore, DP4+ chemical shift probability calculations were performed to establish the relative configuration of compound <b>1</b>. Additionally, subfractions obtained by liquid-liquid extraction of the methanolic extract of the plant, and subsequently the isolated new and selected known compounds <b>1</b>&#8722;<b>4</b>, <b>6</b>, <b>8</b>&#8722;<b>11</b> obtained from the diethyl ether subfraction were investigated for their inhibitory effect on NO release and iNOS and COX-2 expression in J774A.1 murine macrophages. The results showed a potential anti-inflammatory activity of the obtained subfractions, of which the diethyl ether subfraction was the most active one in inhibiting NO release and COX-2 expression (<i>p</i> &lt; 0.001). Among the investigated isolated compounds, compound <b>4</b> significantly (<i>p</i> &lt; 0.001) inhibited NO release and iNOS and COX-2 expression in a comparable manner like the used positive controls (L-NAME and indomethacin, respectively). Moreover, other isolated substances displayed moderate to high inhibitory activities, illustrating the potential anti-inflammatory activity of <i>Dionysia diapensifolia</i>.