Natural occurring 2-(2-phenylethyl) chromones, structure elucidation and biological activities

<div><p>2-(2-Phenylethyl) chromone (PEC), an uncommon class of chromones, possesses a phenylethyl substituent at the C2 position. They have been isolated from a few plant species. They have promising biological activities such as neuro-protective, cytotoxic, acetylcholinesterase inhibitory, antibacterial and anti-inflammatory. This review focuses on the naturally occurring PEC derivatives, their sources, physical and spectral data, as well as biological activities.</p></div

Alnuheptanoid A: a new diarylheptanoid derivative from <i>Alnus japonica</i>

<div><p>Extensive chromatographic investigation of the ethanolic extract of <i>Alnus japonica</i> Steud stem bark led to the isolation of a new diarylheptanoid named alnuheptanoid A [(5<i>S</i>)-7-(3,4-dihydroxyphenyl)-1-(4-hydroxyphenyl)-5-methoxyheptan-3-one] (<b>8</b>), together with seven known diarylheptanoid derivatives: platyphyllenone (<b>5</b>), (5<i>S</i>)-1,7-bis(4-hydroxyphenyl)-5-methoxyheptan-3-one (<b>6</b>), 1-(3,4-dihydroxyphenyl)-7-(4-hydroxyphenyl)-4-hepten-3-one (<b>7</b>), hirsutenone (<b>9</b>), (5<i>R</i>)-<i>O</i>-methylhirsutanonol (<b>10</b>), hirsutanonol (<b>11</b>) and oregonin (<b>13</b>), three triterpenes: α-amyrin (<b>1</b>), betulinaldehyde (<b>3</b>) and betulinic acid (<b>4</b>), and two sterols: β-sitosterol (<b>2</b>) and daucosterol (<b>12</b>). Compound <b>6</b> was isolated for the first time from natural source. The structures of the isolated compounds were determined on the basis of spectroscopic measurements (UV, IR, HR-ESI-MS, 1D and 2D NMR).</p></div

Urgineaglyceride A: a new monoacylglycerol from the Egyptian <i>Drimia maritima</i> bulbs

<div><p>One new compound, (2<i>S</i>)-1-<i>O</i>-(<i>Z</i>)-tetracos-6-enoate glycerol (<b>1</b>) named urgineaglyceride A, along with six known compounds, 3,5,7,3′,5′-pentahydroxydihydroflavonol (<b>2</b>), stigmasterol (<b>3</b>), (25<i>S</i>)-5β-furostane-3β-22α-26-triol (<b>4</b>), scillaridin A (<b>5</b>), (2<i>S</i>)-(+)-2-hydroxynaringenin-4′-<i>O</i>-β-d-glucopyranoside (<b>6</b>) and quercetin-3′-<i>O</i>-β-d-glucopyranoside (<b>7</b>), were isolated from the EtOAc fraction of <i>Drimia maritima</i> (L.) Stearn bulbs. Their structures were secured based on their IR, UV, 1D and 2D NMR data, in addition to HR-MS data and comparison with the literature data. The isolated compounds were evaluated for their <i>in vitro</i> growth inhibitory activity against A549 non-small cell lung cancer (NSCLC), U373 glioblastoma (GBM) and PC-3 prostate cancer cell lines. Compounds <b>2</b> and <b>3</b> displayed variable activities against the tested cancer cell lines. Compound <b>2</b> was a selective inhibitor of the NSCLC cell line with an IC₅₀ of 2.3 μM, whereas <b>3</b> was selective against GBM with IC₅₀ of 0.5 μM and against PC-3 with 2.0 μM.</p></div

Didemnacerides A and B: two new glycerides from Red Sea ascidian <i>Didemnum</i> species

<div><p>Two new glycerides, didemnacerides A (<b>1</b>) and B (<b>2</b>), together with three known sterols, 24-ethyl-25-hydroxycholesterol (<b>3</b>), cholest-6-en-3,5,8-triol (<b>4</b>) and cholestane-3β,5α,6β-26-tetrol (<b>5</b>), were isolated from the Red Sea ascidian <i>Didemnum</i> sp. Their structures were elucidated by using extensive 1D (¹H, ¹³C) and 2D (¹H–¹H COSY, HSQC and HMBC) NMR studies and mass spectroscopic data (GC-MS and HR-MS) as well as alkaline hydrolysis followed by GC–MS and NMR spectral analyses of the fatty acid methyl esters. This is the first report of compounds <b>3</b>–<b>5</b> from the Red Sea ascidian <i>Didemnum</i> species.</p></div

Klodorone A and klodorol A: new triterpenes from <i>Kleinia odora</i>

<div><p>Re-investigation of the EtOH extract of the aerial parts of <i>Kleinia odora</i> led to the isolation of two new triterpenes; klodorone A (<b>3</b>) and klodorol A (<b>4</b>), together with two known compounds: β-amyrin (<b>1</b>) and germanicol (<b>2</b>), which were reported from this plant for the first time. Their structures were determined by using extensive 1D (¹H, ¹³C and DEPT) and 2D (¹H–¹H COSY, HMQC and HMBC) NMR and mass spectral measurements in addition to comparison of their data with the literature.</p></div

2,3-Seco-2,3-dioxo-lyngbyatoxin A from a Red Sea strain of the marine cyanobacterium <i>Moorea producens</i>

<div><p>Chemical investigation of the organic extract of a Red Sea strain of the cyanobacterium <i>Moorea producens</i> has afforded 2,3-seco-2,3-dioxo-lyngbyatoxin A (<b>1</b>). Five known compounds including lyngbyatoxin A (<b>2</b>), majusculamides A and B (<b>3</b> and <b>4</b>), aplysiatoxin (<b>5</b>) and debromoaplysiatoxin (<b>6</b>) were also isolated. Their structures were elucidated by using HR-FAB-MS, 1D and 2D NMR analyses. The compounds were evaluated for antiproliferative activity against HeLa cancer cells. Lyngbyatoxin A (<b>2</b>) showed potent activity, with an IC₅₀ of 9.2 nM, while <b>5</b> and <b>6</b> displayed modest activity with IC₅₀ values of 13.3 and 3.03 μM, respectively. In contrast, compounds <b>1</b>, <b>3</b> and <b>4</b> were inactive, with IC₅₀ values greater than 50 μM. The lack of cytotoxicity for 2,3-seco-2,3-dioxo-lyngbyatoxin A (<b>1</b>) demonstrates that the indole moiety in lyngbyatoxin (<b>2</b>) is essential for its cytotoxicity, and suggests that detoxification of <b>2</b> may be carried out by biological oxidation of the indole moiety to yield <b>1</b>.</p></div