A new proline-containing flavonol glycoside from <i>Caragana leucophloea</i> Pojark

<div><p>One new proline-containing flavonol glycoside, namely kaempferol-3-<i>O</i>-methyl-7-<i>O</i>-β-d-glucopyranosyl-8-(1-methyleneproline)-4′-<i>O</i>-β-d-glucopyranoside (<b>1</b>), together with 15 known flavonoids, 3-<i>O</i>-methylkaempferol (<b>2</b>), 3-<i>O</i>-methylquercetin (<b>3</b>), quercetin (<b>4</b>), kaempferol (<b>5</b>), apigenin (<b>6</b>), rhamnazin (<b>7</b>), astragalin (<b>8</b>), alquds (<b>9</b>), quercitrin (<b>10</b>), rutin (<b>11</b>), isoquercitrin (<b>12</b>), apigetrin (<b>13</b>), myricitrin (<b>14</b>), hesperidin (<b>15</b>) and calycosin-7-<i>O</i>-β-d-glucopyranoside (<b>16</b>) were isolated from the aerial parts of <i>Caragana leucophloea</i> Pojark. (Leguminosae). Their structures were determined on the basis of spectroscopic analyses and by comparison with literature data. Compounds <b>2</b>–<b>4</b> revealed a strong antimicrobial activity with minimum inhibitory concentration values of 12.5–150 μg/mL and median inhibitory concentration (IC₅₀) values of 7.42–76.61 μg/mL. Compounds <b>3</b>, <b>4</b>, <b>6</b>–<b>8</b>, <b>10</b>–<b>12</b> and <b>14</b> showed strong antioxidant activity. Compounds <b>2</b>–<b>7</b> exhibited moderate antinematodal activity on <i>Caenorhabditis elegans</i> with IC₅₀ values of 40.51–68.05 μg/mL.</p></div

Monascustin, an Unusual γ‑Lactam from Red Yeast Rice

Monascustin (<b>1</b>), an unusual γ-lactam, was isolated from an ethanol extract of the <i>Monascus purpureus</i> fermented rice. Its structure including the absolute configuration was determined by spectroscopic data analysis and confirmed by X-ray crystallography. A plausible biosynthetic pathway is discussed on the basis of amino acid derivatization. Compound <b>1</b> showed inhibitory activity against histone deacetylase 1

New Ustilaginoidins from Rice False Smut Balls Caused by Villosiclava virens and Their Phytotoxic and Cytotoxic Activities

Ustilaginoidins are a class of bis-naphtho-γ-pyrones, typically produced by Villosiclava virens, the pathogen of the rice false smut (RFS), which has been one of the most destructive rice fungal diseases. Previously, we found that ustilaginoidins identified from the culture of V. virens on rice medium were less polar than those reported from the RFS balls in general. In this study, we reinvestigated the high-performance liquid chromatography with diode array detection and high-resolution mass spectrometry (HPLC–DAD–HRMS) profile of the ethyl acetate (EtOAc) extract of the RFS balls and found several interesting peaks that correspond to new ustilaginoidins. As a result, eight new and polar congeners, named ustilaginoidins Q–T (<b>1</b>–<b>4</b>), 2,3-dihydroustilaginoidin T (<b>5</b>), and ustilaginoidins U–W (<b>6</b>–<b>8</b>), were isolated. In addition, 17 known ustilaginoidins, including ustilaginoidins K–N (<b>9</b>–<b>12</b>), ustilaginoidin P (<b>13</b>), ustilaginoidin E₁ (<b>14</b>), isochaetochromin B₂ (<b>15</b>), and ustilaginoidins A–J (<b>16</b>–<b>25</b>), were re-isolated. The structures of the new compounds were elucidated by comprehensive analysis of the spectroscopic data. Ustilaginoidins Q (<b>1</b>) and R (<b>2</b>) feature an uncommon 2-hydroxypropyl-substituted skeleton and biogenetically incorporate one more acetate unit than common ustilaginoidins. Ustilaginoidin W (<b>8</b>) is a rare formate-containing bis-naphtho-γ-pyrone. Ustilaginoidins R (<b>2</b>), U (<b>6</b>), B (<b>17</b>), and I (<b>24</b>) showed moderate inhibitory activities toward the radicle or germ elongation of rice seeds. Ustilaginoidins R (<b>2</b>), S (<b>3</b>), V (<b>7</b>), W (<b>8</b>), B (<b>17</b>), C (<b>18</b>), and H–J (<b>23</b>–<b>25</b>) were cytotoxic to the tested human cancer cell lines (HCT116, NCI-H1650, BGC823, Daoy, and HepG2), with IC₅₀ values in the range of 4.06–44.1 μM

Bioactive Bis-naphtho-γ-pyrones from Rice False Smut Pathogen Ustilaginoidea virens

Ustilaginoidins were bis-naphtho-γ-pyrones mycotoxins possessing an a<i>R</i> configuration of the chiral axis previously reported from the false smut balls of rice infected by the fungal pathogen Ustilaginoidea virens. To investigate the chemical diversity of these metabolites and their bioactivities, we fermented this fungus on solid rice media, which afforded the isolation of 13 ustilaginoidins, including seven new compounds, namely ustilaginoidins K–P, <b>1</b>–<b>6</b>, and E₁, <b>7</b>, together with the known ustilaginoidins A, <b>8</b>, D, <b>9</b>, E, <b>10</b>, F, <b>11</b>, and G, <b>12</b>, and isochaetochromin B₂, <b>13</b>. The structures of the new compounds were elucidated by using (1D, 2D) NMR, high-resolution mass spectrometry, UV, and circular dichroism, as well as by comparison with the literature data. A plausible biosynthesis pathway was proposed for these dimeric polyketides. The isolated compounds were evaluated for their antibacterial, cytotoxic, and radicle elongation inhibitory activities. Ustilaginoidins K, <b>1</b> and L, <b>2</b> showed cytotoxic activities on the A2780 human ovarian cancer cell line with IC₅₀ values of 4.18 and 7.26 μM, respectively. Ustilaginoidins N, <b>4</b>, D, <b>9</b>, E, <b>10</b>, and G, <b>12</b> were active against the tested pathogenic bacteria with MIC values in the range of 16–64 μg/mL. Ustilaginoidins O, <b>5</b>, E, <b>10</b>, and F, <b>11</b>, and isochaetochromin B_2, <b>13</b> displayed moderate inhibitory activity on the radicle elongation of rice seeds

Four new taraxastane-type triterpenoic acids from <i>Cirsium setosum</i>

<p>Four new taraxastane-type triterpenoids acids 3<i>β</i>,22<i>α</i>-dihydroxy-20-taraxasten-30-oic acid (<b>1</b>), 3<i>β</i>-hydroxy-22-oxo-20-taraxasten-30-oic acid (<b>2</b>), 3-oxo-22<i>α</i>-hydroxy-20- taraxasten-30-oic acid (<b>3</b>), and 3β,19β-dihydroxy-20-taraxasten-30-oic acid (<b>4</b>) were isolated and characterized from <i>Cirsium setosum</i> (Willd.) MB. Their structures were determined by the combination of 1D and 2D NMR experiments (¹H-¹HCOSY, HSQC, HMBC and ROESY) and mass spectrometry. Compound <b>2</b> exhibited potent selective cytotoxicity against human ovarian cancer cell line A2780 with an IC₅₀ value of 3.9 μM.</p

Bioactive Dibenzo-α-pyrone Derivatives from the Endophytic Fungus <i>Rhizopycnis vagum</i> Nitaf22

Six new dibenzo-α-pyrones, rhizopycnolides A (<b>1</b>) and B (<b>2</b>) and rhizopycnins A–D (<b>3</b>–<b>6</b>), together with eight known congeners (<b>7</b>–<b>14</b>), were isolated from the endophytic fungus <i>Rhizopycnis vagum</i> Nitaf22 obtained from <i>Nicotiana tabacum</i>. The structures of the new compounds were unambiguously elucidated using NMR, HRESIMS, TDDFT ECD calculation, and X-ray crystallography data. Rhizopycnolides A (<b>1</b>) and B (<b>2</b>) feature an uncommon γ-butyrolactone-fused dibenzo-α-pyrone tetracyclic skeleton (6/6/6/5), while rhizopycnin B (<b>4</b>) was the first amino group containing dibenzo-α-pyrone. Rhizopycnolides A (<b>1</b>) and B (<b>2</b>) are proposed to be biosynthesized from polyketide and tricarboxylic acid cycle pathways. The isolated compounds were tested for their antibacterial, antifungal, and cytotoxic activities. Among them, rhizopycnolide A (<b>1</b>), rhizopycnins C (<b>5</b>) and D (<b>6</b>), TMC-264 (<b>8</b>), penicilliumolide D (<b>11</b>), and alternariol (<b>12</b>) were active against the tested pathogenic bacteria <i>Agrobacterium tumefaciens</i>, <i>Bacillus subtilis</i>, <i>Pseudomonas lachrymans</i>, <i>Ralstonia solanacearum</i>, <i>Staphylococcus hemolyticus</i>, and <i>Xanthomonas vesicatoria</i> with MIC values in the range 25–100 μg/mL. Rhizopycnin D (<b>6</b>) and TMC-264 (<b>8</b>) strongly inhibited the spore germination of <i>Magnaporthe oryzae</i> with IC₅₀ values of 9.9 and 12.0 μg/mL, respectively. TMC-264 (<b>8</b>) showed potent cytotoxicity against five human cancer cell lines (HCT-116, HepG2, BGC-823, NCI-H1650, and A2780) with IC₅₀ values of 3.2–7.8 μM

Bioactive Dibenzo-α-pyrone Derivatives from the Endophytic Fungus <i>Rhizopycnis vagum</i> Nitaf22

Six new dibenzo-α-pyrones, rhizopycnolides A (<b>1</b>) and B (<b>2</b>) and rhizopycnins A–D (<b>3</b>–<b>6</b>), together with eight known congeners (<b>7</b>–<b>14</b>), were isolated from the endophytic fungus <i>Rhizopycnis vagum</i> Nitaf22 obtained from <i>Nicotiana tabacum</i>. The structures of the new compounds were unambiguously elucidated using NMR, HRESIMS, TDDFT ECD calculation, and X-ray crystallography data. Rhizopycnolides A (<b>1</b>) and B (<b>2</b>) feature an uncommon γ-butyrolactone-fused dibenzo-α-pyrone tetracyclic skeleton (6/6/6/5), while rhizopycnin B (<b>4</b>) was the first amino group containing dibenzo-α-pyrone. Rhizopycnolides A (<b>1</b>) and B (<b>2</b>) are proposed to be biosynthesized from polyketide and tricarboxylic acid cycle pathways. The isolated compounds were tested for their antibacterial, antifungal, and cytotoxic activities. Among them, rhizopycnolide A (<b>1</b>), rhizopycnins C (<b>5</b>) and D (<b>6</b>), TMC-264 (<b>8</b>), penicilliumolide D (<b>11</b>), and alternariol (<b>12</b>) were active against the tested pathogenic bacteria <i>Agrobacterium tumefaciens</i>, <i>Bacillus subtilis</i>, <i>Pseudomonas lachrymans</i>, <i>Ralstonia solanacearum</i>, <i>Staphylococcus hemolyticus</i>, and <i>Xanthomonas vesicatoria</i> with MIC values in the range 25–100 μg/mL. Rhizopycnin D (<b>6</b>) and TMC-264 (<b>8</b>) strongly inhibited the spore germination of <i>Magnaporthe oryzae</i> with IC₅₀ values of 9.9 and 12.0 μg/mL, respectively. TMC-264 (<b>8</b>) showed potent cytotoxicity against five human cancer cell lines (HCT-116, HepG2, BGC-823, NCI-H1650, and A2780) with IC₅₀ values of 3.2–7.8 μM