Antibacterial and Cytotoxic Phenolic Polyketides from Two Marine-Derived Fungal Strains of Aspergillus unguis

A chemical investigation on the EtOAc extracts from two marine-derived fungal strains of Aspergillus unguis resulted in the isolation of three previously undescribed phenolic polyketides including unguidepside C (1), aspersidone B (3), and agonodepside C (12), and their 14 known congeners. The structures of the new compounds were determined based on detailed analysis and comparison of their spectroscopic data with literature values, as well as Snatzke’s method. The new compounds (1, 3, and 12) displayed a significant anti-Gram-positive bacterial activity, with MIC values ranging from 5.3 to 22.1 µM. Additionally, the isolated compounds (1–11 and 13–16) were evaluated for their cytotoxicity against a panel of tumor cell lines. Most of them (except for 9) displayed cytotoxicity against all the tested cell lines, with IC50 values ranging from 2.5 to 46.9 µM.

Protective Effect of Rifampicin Loaded by HPMA-PLA Nanopolymer on Macrophages Infected with Mycobacterium Tuberculosis

Purpose. This research was designed to investigate the protective effect of rifampicin (RIF) loaded by N-(2-hydroxypropyl) methylacrylamide- (HPMA-) polylactic acid (PLA) nanopolymer on macrophages infected with Mycobacterium tuberculosis (MTB). Methods. We first induced H37Rv to infect macrophages to build a cell model. Then, the HPMA-PLA nanopolymer loaded with RIF was prepared to treat MTB-infected macrophages. The macrophage activity was tested by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, the nitric oxide (NO) in cells was measured through Griess reagent, and the bacterial activity of MTB was observed via the colony-forming unit (CFU) assay. The inflammation-related factors in cells were detected via the enzyme-linked immunosorbent assay (ELISA), the apoptosis of macrophages was examined via flow cytometry, and the expression of apoptosis-related proteins was determined by western blot (WB). Results. HPMA-PLA had no obvious toxicity to macrophages. The expression of NO and inflammatory factors in macrophages infected with MTB increased significantly, but the apoptosis rate was not significantly different from that of uninfected cells. However, after treatment with HPMA-PLA-RIF or free RIF, the inflammatory reaction of infected cells was inhibited, the expression of NO was decreased, the apoptosis rate was increased, and the bacterial activity in cells was decreased, with statistically significant differences; moreover, HPMA-PLA-RIF was more effective than free RIF. Conclusions. HPMA-PLA-RIF has a high protective effect on macrophages infected with MTB, with high safety. Its protective mechanism is at least partly through inhibiting the production of NO and inflammatory response, which can inhibit bacterial activity and induce cell apoptosis.

Metal-Organic Framework Reinforced Acrylic Polymer Marine Coatings

Metal-organic frameworks (MOFs), a class of crystalline, porous, 3D materials synthesized by the linking of metal nodes and organic linkers are rapidly emerging as attractive materials in gas storage, electrodes in batteries, super-capacitors, sensors, water treatment, and medicine etc. However the utility of MOFs in coatings, especially in marine coatings, has not been thoroughly investigated. In this manuscript we report the first study on silver MOF (Ag-MOF) functionalized acrylic polymers for marine coatings. A simple and rapid microwave technique was used to synthesize a two-dimensional platelet structured Ag-MOF. Field tests on the MOF reinforced marine coatings exhibited an antifouling performance, which can be attributed to the inhibition of marine organisms to settle as evidenced by the anti-bacterial activity of Ag-MOFs. Our results indicate that MOF based coatings are highly promising candidates for marine coatings.

Anti-bacterial activity of Corchorus olitorius L. and Acmella caulirhiza Del. On Streptococcus mutans, a cariogenic bacterium

Background: Dental caries remains a global oral health challenge with the prevalence reported as high as 66.7% in adults. Despite the use of modern medicines, the prevalence of dental caries remains high. This has led to extensive screening of natural products particularly from plants such as Corchorus olitorius L. and Acmella caulirhiza Del. for anti-cariogenic activity. Aim: To assess the anti-bacterial activity of Corchorus olitorius L. and Acmella caulirhiza Del. on Streptococcus mutans, a cariogenic bacteria. Methods: Plant materials of C. olitorius L. and A. caulirhiza Del. were extracted using diethyl ether, methanol, distilled water by cold maceration. Agar well diffusion method was used for sensitivity and susceptibility tests on S. mutans (ATCC 6519). Results: The aqueous plant extract of C. olitorius L. and the ether plant extract of A. caulirhiza Del. had the highest zones of inhibition (16.10mm and 12.03mm respectively) at a concentration of 1000mg/ml. The lowest MIC and MBC were 62.5mg/ml and 250mg/ml respectively. Conclusion: Both C. olitorius L. and A. caulirhiza Del. as used in oral health practices have been found to have antibacterial activity against the cariogenic S. mutans. Further studies should be conducted to isolate bioactive compounds against S. mutans. Keywords: Antibacterial activity;Minimum inhibitory concentration; Plant extracts; Corchorus olitorius L.; Acmella caulirhiza Del.; Streptococcus mutans; Dental caries.

Photocatalytic Inhibition of Gram-positive and Gram-negative Bacteria by Nanoparticulate C-doped TiO2

C-doped TiO2 (C-TiO2) was synthesised using a solvothermal method with ethanol/TBT/LDPE medium. Microstructure and elemental composition of C-TiO2 were analysed with TEM and XPS. An anti-bacterial device was utilized for photocatalytic inhibition of gram-positive and gram-negative bacteria. The device to measure bacteriostatic action was placed in a dark room, and the bacterial culture was placed in a holding cup which contained holding box and nanoparticulate C-TiO2. This approach was convenient for addition and removal of C-TiO2. Photocatalytic bacteriostasis by C-TiO2 under visible-light irradiation was quantitively assessed for bacteriostatic properties. Moreover, the qualitative assessment of anti-bacterial activity with C-TiO2 was less significant for gram-positive bacteria in comparison to gram-negative bacteria.

The Effect of Temperature and Heating Time of Roselle Extract (Hibiscus Sabdariffa L) Powder Solution on Growth Inhibition of Staphylococcus aureus ATCC 25923

The main ingredients of roselle (Hibiscus sabdariffa L.) which have antioxidant and antibacterial effect were anthocyanins, and flavonoids. Flavonoid compounds were unstable at high temperatures. Meanwhile, the processing of roselle extract powder into ready-to drink or food preparations generally requires the thermal processes. The aims of this study were to determine the effect of temperature and heating time of roselle extract powder solution on the inhibition of microbial growth of Staphylococcus aureus ATCC 25923. The method of this study uses a ready-to- process roselle powder extract sample. The roselle extract powder solution in a screw cap tube was heated at a temperature of 40°C, 50°C, 60°C, 70°C, 80°C, and 90°C on a waterbath, with heating times at each temperature were 15 minutes and 30 minutes. Anti bacterial activity of the sample solution was measured based on the ability to inhibit the growth of Staphylococcus aureus ATCC 25923 by the agar-well diffusion method. The inhibition zone of the sample was measured by caliper. The result of this study showed that inhibition zones caused by the sample that had been heated at those temperature for 15 minutes were 9.55±0.70 mm, 9.53 ±0.04 mm, 9.70±0.14 mm, 9.68±0.24 mm, 10.10±0.14 mm, and 10.25±0.21 mm. Meanwhile, after heating for 30 minutes the inhibition zones were 10.08±0.25 mm, 10.20±0.28 mm, 10.43±0.18 mm, 10.08±0.18 mm, 10.78±0.04 mm, 9.70±0.14 mm. Two ways statistical test ANOVA Randomized Control Block Design with 95% confidence level was used to prove that there was a significant difference berween the mean inhibition zones of each sample. The conclution of this research was, the temperature in the range of 40 -90 oC has no effect on the anti-bacterial activity of the sample. However, the heating time of the sample affected the antibacterial activity of the roselle extract powder solution against Staphylococcus aureus ATCC 25923.