A syringic acid derivative and two iridoid glycosides from the roots of <i>Stachys geobombycis</i> and their antioxidant properties

<p>A new derivative of syringic acid, stageobester A (<b>1</b>) and two iridoid glycosides which including a new one, stageoboside A (<b>2</b>), were isolated from the roots of <i>Stachys geobombycis</i>. Their structures were elucidated on the basis of spectroscopic methods, including extensive NMR and MS spectra. In addition, all the isolates were tested for their antioxidant capacity. Compounds <b>1</b> and <b>2</b> showed moderate antioxidant activities against DPPH radical, with IC₅₀ values of 113.33 ± 1.53 and 40.33 ± 2.08 mg/L, respectively.</p

Eremophilane sesquiterpenes from the endophytic fungus <i>Xylaria</i> sp. GDG-102

<p>A new eremophilane sesquiterpene, xylareremophil (<b>1</b>), together with five known eremophilanes, 1α,10α-epoxy-3α-hydroxyeremophil-7(11)-en-12,8β-olide (<b>2</b>), 1,10α,13-trihydroxyeremophil-7(11)-en-12,8-olide (<b>3</b>), 1α,10α-epoxy-13-hydroxyeremophil-7(11)-en-12,8β-olide (<b>4</b>), mairetolides B (<b>5</b>) and G (<b>6</b>) were isolated from the endophytic fungus <i>Xylaria</i> sp. GDG-102 cultured from <i>Sophora tonkinensis.</i> Their structures were elucidated on the basis of spectroscopic data analysis. The absolute configurations of <b>1</b> was determined by comparing computed electronic circular dichroism (ECD) and optical rotation (OR) with experimental results. Compounds <b>1</b>, <b>5</b> and <b>6</b> showed antibacterial activities against <i>Proteus vulgaris</i>, <i>Micrococcus luteus</i>, <i>Micrococcus lysodeikticus</i> and <i>Bacillus subtilis</i> with MIC values of 25–100 μg/mL.</p