Steroid glycosides from the starfish <i>Pentaceraster gracilis</i>

<p>Using combined chromatographic separations, two new steroid glycosides namely pentacerosides A (<b>1</b>) and B (<b>2</b>), and four known compounds were isolated from the methanol extract of the starfish <i>Pentaceraster gracilis</i>. Their structures were determined on the basis of spectroscopic data (¹H and ¹³C NMR, HSQC, HMBC, ¹H-¹H COSY, ROESY, and FT-ICR-MS) and by comparing obtained results to the literature values. Among the isolated compounds, only maculatoside (<b>5</b>) showed significant cytotoxic effect against Hep-G2 (IC₅₀ = 16.75 ± 0.69 μM) and SK-Mel2 (IC₅₀ = 19.44 ± 1.45 μM) cell lines and moderate effect on KB (IC₅₀ = 36.53 ± 0.78 μM), LNCaP (IC₅₀ = 39.75 ± 3.34 μM), and MCF7 (IC₅₀ = 47.34 ± 7.01 μM) cell lines.</p

Polar steroid derivatives from the Vietnamese starfish <i>Astropecten polyacanthus</i>

<p>Five polar steroid derivatives, including one new glycosylated polyhydroxysteroid namely polyacanthoside A (<b>1</b>), were isolated from the water-soluble materials from the MeOH extract of the Vietnamese starfish <i>Astropecten polyacanthus</i> using various chromatographic separations. The structure elucidation was confirmed by spectroscopic experiments such as HR-ESI-MS, 1D and 2D NMR. Among the isolated compounds, (20<i>R</i>,24<i>S</i>)-3<i>β</i>,6<i>α</i>,8,15<i>β</i>,24-pentahydroxy-5<i>α</i>-cholestane (<b>3</b>) showed significant cytotoxic effect against five human cancer cell lines as HepG2, KB, LNCaP, MCF7 and SK-Mel2 with the IC₅₀ values from 18.03 ± 2.63 to 21.59 ± 3.23 μM.</p

A new rearranged abietane diterpene from <i>Clerodendrum inerme</i> with antioxidant and cytotoxic activities

<p>Eight compounds were isolated from the leaves of <i>Clerodendrum inerme</i>, including one new rearranged abietane diterpene, crolerodendrum B (<b>1</b>). Their structures were determined by means of spectroscopic methods including one-dimensional and two-dimensional nuclear magnetic resonance (1-D and 2-DNMR), high-resolution electrospray ionisation mass spectrometry (HR-ESI-MS) and circular dichroism (CD). The DPPH radical scavenging and cytotoxic activities of isolated compounds against MCF7 (breast), HCT116 (colon) and B16F10 (melanoma) cancer cell lines were evaluated. Compounds <b>1</b>, <b>3</b> and <b>4</b> exhibited strong DPPH radical-scavenging effects (ED₅₀ values of 17.6 ± 2.1, 10.1 ± 0.8 and 11.3 ± 0.3 μM, respectively) and <b>4</b> showed strong cytotoxicity against the HCT116 cell line (IC₅₀ = 3.46 ± 0.01 μM).</p

Asterosaponins and glycosylated polyhydroxysteroids from the starfish <i>Culcita novaeguineae</i> and their cytotoxic activities

<div><p>Using combined chromatographic methods, two asterosaponins (compounds <b>1</b> and <b>2</b>), including a new compound novaeguinoside E (compound <b>1</b>), and six glycosylated polyhydroxysteroids (compounds <b>3</b>–<b>8</b>) were isolated from a methanol extract of the starfish <i>Culcita novaeguineae</i>. Their structures were determined on the basis of spectroscopic data (¹H and ¹³C NMR, HSQC, HMBC, ¹H–¹H COSY, ROESY, and HRESI-MS) and by comparison with the literature values. The new compound <b>1</b> represents the third example of asterosaponins containing the 5α-cholesta-9(1l)-en-3β,6α,20,22-tetraol aglycone. Among isolated compounds, <b>4</b>–<b>7</b> exhibited moderate to weak cytotoxic activities against five human cancer cell lines such as Hep-G2 (hepatoma), KB (epidermoid carcinoma), LNCaP (prostate cancer), MCF7 (breast cancer), and SK-Mel2 (melanoma).</p></div

Two new simple iridoids from the ant-plant <i>Myrmecodia tuberosa</i> and their antimicrobial effects

<p>Six iridoid derivatives (<b>1–6</b>), including two new compounds myrmecodoides A and B (<b>1</b> and <b>2</b>), were isolated from the ant-plant <i>Myrmecodia tuberosa</i>. Their structures were determined on the basis of spectroscopic data (¹H and ¹³C NMR, HSQC, HMBC, ¹H-¹H COSY, NOESY and HR-ESI-MS) and by comparison with the literature values. Among isolates, <b>3</b> and <b>4</b> exhibit weak antibacterial effect against <i>Staphylococcus aureus</i> subsp. <i>aureus</i> with MIC value of 100.0 μg/mL.</p