Inducing new secondary metabolites through co-cultivation of the fungus Pestalotiopsis sp. with the bacterium Bacillus subtilis

Two new lactones, pestalotiolactones A (1) and B (2), together with three known compounds (3–5) were isolated from the axenic culture of the endophytic fungus Pestalotiopsis sp., obtained from fruits of Drepanocarpus lunatus (Fabaceae). Co-culture of this fungus with Bacillus subtilis afforded two new sesquiterpenoids pestabacillins A (6) and B (7) as well as eight known compounds (8–15). Their structures were elucidated by extensive analysis of the NMR and MS data as well as by comparison with literature data. All isolated compounds were evaluated for their cytotoxic and antimicrobial activities but proved to be inactive.     

Ag@SiO2纳米颗粒的制备及其在H2O2检测上的应用

利用柠檬酸三钠还原硝酸银制备了银纳米颗粒(AgNPs),然后通过氨水水解正硅酸乙酯(TEOS)的方法,在AgNPs上沉积SiO2,制备出以Ag为核,SiO2为壳的复合纳米颗粒(Ag@SiO2).调节TEOS用量,可以控制SiO2层的厚度.根据AgNPs的局域表面等离激元共振(LSPR)效应,将制得的Ag@SiO2颗粒用于H2O2的检测,检测下限为1μmol/L,并可以通过控制SiO2层的厚度方便地调节Ag@SiO2颗粒与H2O2反应的速率.与传统方法相比,具有简单、快速、成本低的优点.分别运用TEM、紫外-可见分光光度计对反应前后Ag@SiO2颗粒形貌及反应过程中其LSPR吸收的变化进行了表征.     

Antioxidant activity of papaya seed extracts

The antioxidant activities of the ethanol, petroleum ether, ethyl acetate, n-butanol and water extract fractions from the seeds of papaya were evaluated in this study. The ethyl acetate fraction showed the strongest DPPH and hydroxyl free radical-scavenging activities, and its activities were stronger than those of ascorbic acid and sodium benzoate, respectively. The n-butanol fraction demonstrated the greatest ABTS? radicals scavenging activity. The ethyl acetate fraction and the n-butanol fraction not only showed higher antioxidant activities than the petroleum ether fraction, water fraction and ethanol fraction, but also showed higher superoxide anion and hydrogen peroxide radicals scavenging activities than those of the other extract fractions. The high amount of total phenolics and total flavonoids in the ethyl acetate and n-butanol fractions contributed to their antioxidant activities. The ethyl acetate fraction was subjected to column chromatography, to yield two phenolic compounds, p-hydroxybenzoic acid and vanillic acid, which possessed significant antioxidant activities. Therefore, the seeds of papaya and these compounds might be used as natural antioxidants.     

Antibacterial activity of the flavonoids from Dalbergia odorifera on Ralstonia solanacearum

Phytohemical investigation on the heartwood of Dalbergia odorifera resulted in the isolation of nine flavonoids. Their structures were elucidated as sativanone (1), (3R)-vestitone (2), (3R)-2',3',7-trihydroxy-4'-methoxyisoflavanone (3), (3R)-4'-methoxy-2',3,7-trihydroxyisoflavanone (4), carthamidin (5), liquiritigenin (6), isoliquiritigenin (7), (3R)-vestitol (8), and sulfuretin (9) based on their spectral data. All compounds were evaluated for their inhibitory activity against Ralstonia solanacearum. This is the first report about anti-R. solanacearum activity of the compounds from D. odorifera.     

Lanostane Triterpenoids and Ergostane Steroids from Ganoderma luteomarginatum and Their Cytotoxicity

Macrofungus Ganoderma luteomarginatum is one of the main species of Ganoderma fungi distributed in Hainan province of China, the fruiting bodies of which have been widely used in folk as a healthy food to prevent tumors. To explore the potential cytotoxic constituents from G. luteomarginatum, the phytochemical investigation on the ethyl acetate soluble fraction of 95% ethanolic extract from the fruiting bodies of this fungus led to the isolation of twenty-six lanostane triterpenoids (1–26), including three undescribed ones (1–3), together with eight ergostane steroids (27–34). The structures of three new lanostane triterpenoids were elucidated as lanosta-7,9(11)-dien-3β-acetyloxy-24,25-diol (1), lanosta-7,9(11)-dien-3-oxo-24,26-diol-25-methoxy (2), and lanosta-8,20(22)-dien-3,11,23-trioxo-7β,15β-diol-26-oic acid methyl ester (3) by the analysis of 1D, 2D NMR, and HRESIMS spectroscopic data. All isolates were assayed for their cytotoxic activities using three human cancer cell lines (K562, BEL-7402, and SGC-7901) and seven lanostane triterpenoids (1, 2, 7, 13, 18, 22, and 24), and one ergostane steroid (34) showed definite cytotoxicity with IC₅₀ values that ranged from 6.64 to 47.63 μg/mL. Among these cytotoxic lanostane triterpenoids, compounds 2 and 13 showed general cytotoxicity against three human cancer cell lines, while compounds 1 and 18 exhibited significant selective cytotoxicity against K562 cells with IC₅₀ values of 8.59 and 8.82 μg/mL, respectively. Furthermore, the preliminary structure–cytotoxicity relationships was proposed.     

Antioxidant phenolic compounds of Dracaena cambodiana

The antioxidant activities of the petroleum ether, ethyl acetate, n-BuOH and water extract fractions from Dracaena cambodiana Pierre ex Gagnep were evaluated in this study. The ethyl acetate fraction contained the highest amount of total phenolics and total flavonoids, and showed the greatest DPPH˙, ABTS+ and Superoxide anion radical-scavenging capacities. The DPPH˙, ABTS+ and Superoxide anion radical-scavenging capacities of nine compounds isolated from the ethyl acetate fraction were also evaluated. The results indicated that these compounds contributed to the antioxidant activity of D. cambodiana. Therefore, D. cambodiana and these compounds might be used as natural antioxidants.     

Antioxidant phenolic compounds of cassava (Manihot esculenta) from Hainan

An activity-directed fractionation and purification process was used to isolate antioxidant components from cassava stems produced in Hainan. The ethyl acetate and n-butanol fractions showed greater DPPH˙and ABTS?+ scavenging activities than other fractions. The ethyl acetate fraction was subjected to column chromatography, to yield ten phenolic compounds: Coniferaldehyde (1), isovanillin (2), 6-deoxyjacareubin (3), scopoletin (4), syringaldehyde (5), pinoresinol (6), p-coumaric acid (7), ficusol (8), balanophonin (9) and ethamivan (10), which possess significant antioxidant activities. The relative order of DPPH? scavenging capacity for these compounds was ascorbic acid (reference) > 6 > 1 > 8 > 10 > 9 > 3 > 4 > 7 > 5 > 2, and that of ABTS?+ scavenging capacity was 5 > 7 > 1 > 10 > 4 > 6 > 8 > 2 > Trolox (reference compound) > 3 > 9. The results showed that these phenolic compounds contributed to the antioxidant activity of cassava.     

Qualitative and Quantitative Analysis of Flidersiachromones in Three Agarwood Samples by HPLC-MS/MS

HPLC/ESI/MS² was used in the qualitative and quantitative analysis of flidersiachromones(FTPECs) in three agarwood samples of Aquilaria sinensis, including an artificial holing agarwood, a wild agarwood, and a high quality agarwood named "Qi Nan". From these three agarwood samples, totally forty-six FTPECs were identified, and twenty-five of which were tentatively identified by the analysis of MS fragmentation ions, the others were indentified via comparing the retention time and MS fragmentation ions of them with those of the reference compounds. Besides, quantitative determination of five characteristic FTPECs(F14, F16 and F18-F20) in the three agarwoods was carried out, and it was found that the absolute content of each compound of these five FTPECs showed positive correlation with the quality of agarwood samples. Due to the wide distribution of four of these FTPECs(F16 and F18-F20) in the chemical constituents of agarwood, it is suggested that the total absolute content of these four FTPECs may be set as one of basis for agarwood quality evaluation.     

A new cytotoxic isocoumarin from endophytic fungus <Emphasis Type="Italic">Penicillium</Emphasis> SP. 091402 of the mangrove plant <Emphasis Type="Italic">Bruguiera sexangula</Emphasis>

A new isocoumarin, (3R*,4S*)-6,8-dihydroxy-3,4,7-trimethylisocoumarin (1), and five known compounds were isolated from mangrove endophytic fungus Penicillium sp. 091402. The structures of all the compounds were elucidated by analysis of spectrometric data.