Cytotoxic Lignans from Fruits of <i>Cleistanthus indochinensis</i>: Synthesis of Cleistantoxin Derivatives

Two new aryl-tetralin lignans, <b>1</b> and <b>2</b>, were isolated from the fruits of <i>Cleistanthus indochinensis</i> by bioassay-guided purification. Their structures were determined by spectroscopic analysis including MS and 2D NMR. The absolute configurations of <b>1</b> and <b>2</b> were established from examination of their CD spectra. Compound <b>1</b> was cytotoxic against KB cells with an IC₅₀ value of 0.022 μM, while compound <b>2</b> had weaker cytotoxicity, with an IC₅₀ value of 1.4 μM. When tested against other cancer cell lines (MCF-7, MCF-7R, and HT29), <b>1</b> showed an IC₅₀ of 0.014 against MCF-7R cells and an IC₅₀ of 0.036 μM against MCF-7 cells. A series of amide derivatives of a new lactone, homoderivatives of <b>1</b>, were prepared. Of these derivatives, only compound <b>3</b> had weak cytotoxicity against KB cells

Cytotoxic Lignans from Fruits of <i>Cleistanthus indochinensis</i>: Synthesis of Cleistantoxin Derivatives

Two new aryl-tetralin lignans, <b>1</b> and <b>2</b>, were isolated from the fruits of <i>Cleistanthus indochinensis</i> by bioassay-guided purification. Their structures were determined by spectroscopic analysis including MS and 2D NMR. The absolute configurations of <b>1</b> and <b>2</b> were established from examination of their CD spectra. Compound <b>1</b> was cytotoxic against KB cells with an IC₅₀ value of 0.022 μM, while compound <b>2</b> had weaker cytotoxicity, with an IC₅₀ value of 1.4 μM. When tested against other cancer cell lines (MCF-7, MCF-7R, and HT29), <b>1</b> showed an IC₅₀ of 0.014 against MCF-7R cells and an IC₅₀ of 0.036 μM against MCF-7 cells. A series of amide derivatives of a new lactone, homoderivatives of <b>1</b>, were prepared. Of these derivatives, only compound <b>3</b> had weak cytotoxicity against KB cells

Antimicrobial metabolites from a marine-derived Actinomycete <i>Streptomyces</i> sp. G278

<p>Analysis of an antimicrobial extract prepared from culture broth of the marine-derived actinomycete <i>Streptomyces</i> sp. G278 led to the isolation of ten compounds, <b>1</b>-<b>10</b>. Two compounds, 2,5-Bis(5-<i>tert</i>-butyl-2-benzoxazolyl)thiophene (<b>1</b>), and 3-hydroxyl-2-methylpyridine (<b>2</b>) were isolated from a natural source for the first time. The structures of the isolated compounds were established by their spectral data analysis, including mass spectrometry, 1D-NMR, 2D-NMR, and X-ray crystallographic analysis in case of compound <b>3</b>. All isolated compounds were evaluated for their antimicrobial activity against a panel of clinically significant microorganisms. Compounds <b>1</b> and <b>3</b> selectively inhibited <i>Enterococcus faecalis</i> (MIC: 256 μg/mL). Compound <b>2</b> was found to have antibacterial and antifungal activity against <i>Escherichia coli</i> (MIC: 64 μg/mL), <i>Salmonella enterica</i> (MIC: 256 μg/mL), <i>Staphylococcus aureus</i> (MIC: 256 μg/mL), <i>Enterococcus faecalis</i> (MIC: 256 μg/mL), and <i>Candida albicans</i> (MIC: 64 μg/mL). Except for compounds <b>9</b> and <b>10</b>, the other known metabolites (<b>4</b>-<b>8</b>) also exhibited antimicrobial activity.</p

Acetylcholinesterase Inhibitors from the Leaves of <i>Macaranga kurzii</i>

Bioassay-guided fractionation of an extract of leaves of <i>Macaranga kurzii</i> yielded four new compounds, a stilbene (furanokurzin, <b>1</b>) and three flavonoids (macakurzin A–C, <b>2</b>–<b>4</b>). Nine known compounds were also isolated (<b>5</b>–<b>13</b>). Their structures were determined by spectroscopic analyses including MS and 2D NMR. The isolates were all evaluated for acetylcholinesterase inhibitory activity. Compound <b>6</b> (<i>trans</i>-3,5-dimethoxystilbene) exhibited the greatest activity (IC₅₀ 9 μM). Cytotoxic evaluation against KB cells showed that compound <b>7</b> had an IC₅₀ of 4 μM, followed by <b>11</b> (IC₅₀ 10 μM) and <b>3</b> (IC₅₀ 13 μM)

Two new sesquiterpenes from the fruits of <i>Fissistigma villosissimum</i>

<p>Two new sesquiterpenes, namely fissistinone (<b>1</b>) and fissistinol (<b>2</b>), along with ten known compounds (<b>3–12</b>), were isolated from the fruits of <i>Fissistigma villosissimum</i>. Their structures were elucidated on the basis of spectral data analysis, including one-dimensional (1D), two-dimensional (2D)-nuclear magnetic resonance (NMR), and high-resolution–electrospray ionization–mass spectrometry (HR–ESI–MS). Compounds <b>1</b>–<b>8</b> were evaluated for their cytotoxic activities against KB cell line; however, all these compounds did not show cytotoxic activity.</p

Two new linear acetogenins from the fruits of <i>Goniothalamus gracilipes</i>

<p>Two new linear acetogenins, gracilipin A (<b>1</b>) and methylsaccopetrin A (<b>2</b>) along with seven known compounds, saccopetrin A (<b>3</b>), 7,3′,4′-trimethylquercetin (<b>4</b>), rhamnazin (<b>5</b>), casticin (<b>6</b>), isokanugin (<b>7</b>), melisimplexin (<b>8</b>) and 5-hydroxy-3,7-dimethoxy-3′,4′-methylenedioxyflavone (<b>9</b>) were isolated from the fruits of <i>Goniothalamus gracilipes</i> Bân. Their structures were established by spectral analysis, such as mass spectrometry, 1D-NMR, 2D-NMR and circular dichroism (CD). Compounds <b>1</b> and <b>3</b> showed cytotoxic activity against KB cell line with IC₅₀ values of 14.6 and 15.3 μM, respectively.</p

Endiandric Acid Analogues from Beilschmiedia ferruginea as Dual Inhibitors of Bcl-xL/Bak and Mcl-1/Bid Interactions

A rapid screening by ¹H and ¹H–¹³C HSQC NMR spectroscopy of EtOAc extracts of Endiandra and Beilschmiedia species allowed the selection of Beilschmiedia ferruginea leaves and flowers extract for a chemical investigation, leading to the isolation of 11 new tetracyclic endiandric acid analogues, named ferrugineic acids A–K (<b>1</b>–<b>11</b>). Their structures were determined by 1D and 2D NMR spectroscopic analysis in combination with HRMS data. These compounds were assayed for Bcl-xL and Mcl-1 binding affinities. Ferrugineic acids B, C, and J (<b>2</b>, <b>3</b>, and <b>10)</b> exhibited significant binding affinity for both antiapoptotic proteins Bcl-xL (<i>K</i>_i = 19.2, 12.6, and 19.4 μM, respectively) and Mcl-1 (<i>K</i>_i = 14.0, 13.0, and 5.2 μM, respectively), and ferrugineic acid D (<b>4</b>) showed only significant inhibiting activity for Mcl-1 (<i>K</i>_i = 5.9 μM)

A new anti-inflammatory β-carboline alkaloid from the hairy-root cultures of <i>Eurycoma longifolia</i>

<p>One new β-carboline alkaloid 7-methoxy-(9H-β-carbolin-1-il)-(<i>E</i>)-1-propenoic acid (<b>1</b>) together with 9-methoxycanthin-6-one (<b>2</b>) and 9-hydroxycanthin-6-one (<b>3</b>) were isolated from the hairy-root cultures of <i>Eurycoma longifolia</i>. The effects of these compounds on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW264.7 cells were investigated. Compound <b>1</b> strongly inhibited the production of NO while <b>2</b> and <b>3</b> having weak or inactive effect. Consistently, compound <b>1</b> decreased the expression of cyclooxygenase-2 and inducible nitric oxide synthase.</p

Antifouling 26,27-Cyclosterols from the Vietnamese Marine Sponge <i>Xestospongia testudinaria</i>

Three new C₂₉ sterols with a cyclopropane ring cyclized between C-26 and C-27 of the side chain, aragusterol I (<b>1</b>), 21-<i>O</i>-octadecanoyl-xestokerol A (<b>4</b>), and 7β-hydroxypetrosterol (<b>5b</b>), were isolated from the Vietnamese marine sponge <i>Xestospongia testudinaria</i>, along with the known compounds, aragusterol B (<b>2</b>), xestokerol A (<b>3</b>), 7α-hydroxypetrosterol (<b>5a</b>), 7-oxopetrosterol (<b>6</b>), and petrosterol (<b>7</b>). The structures of the new compounds were established by analysis of spectroscopic data including 1D and 2D NMR, and high-resolution electrospray ionization mass spectrometry (HRESIMS). Their capacity to inhibit the adhesion of isolated bacteria from marine biofilms was evaluated against the bacterial strains <i>Pseudoalteromonas</i> sp. D41, <i>Pseudoalteromonas</i> sp. TC8, and <i>Polaribacter</i> sp. TC5. Aragusterol B (<b>2</b>) and 21-<i>O</i>-octadecanoyl-xestokerol A (<b>4</b>) exhibited the most potent antifouling activity with EC₅₀ values close to these reported in the literature for tributyltin oxide, a marine anti-biofouling agent now considered to be a severe marine pollutant. Due to its comparable activity to tributyltin oxide and its absence of toxicity, the new 26,27-cyclosterol, 21-<i>O</i>-octadecanoyl-xestokerol A (<b>4</b>) constitutes a promising scaffold for further investigations

Antimicrobial Lavandulylated Flavonoids from a Sponge-Derived Streptomyces sp. G248 in East Vietnam Sea

Three new lavandulylated flavonoids, (2S,2''S)-6-lavandulyl-7,4'-dimethoxy-5,2'-dihydroxylflavanone (1), (2S,2''S)-6-lavandulyl-5,7,2',4'-tetrahydroxylflavanone (2), and (2''S)-5'-lavandulyl-2'-methoxy-2,4,4',6'-tetrahydroxylchalcone (3), along with seven known compounds 4-10 were isolated from culture broth of Streptomyces sp. G248. Their structures were established by spectroscopic data analysis, including 1D and 2D nuclear magnetic resonance (NMR), and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS). The absolute configurations of 1-3 were resolved by comparison of their experimental and calculated electronic circular dichroism spectra. Compounds 1-3 exhibited remarkable antimicrobial activity. Whereas, two known compounds 4 and 5 exhibited inhibitory activity against Mycobacterium tuberculosis H37Rv with minimum inhibitory concentration (MIC) values of 6.0 µg/mL and 11.1 µg/mL, respectively