Experimental extraction tests are conducted to investigate feasibility of saturated palm kernel oil (PKO) and unsaturated soybean oil (SO) to extract polycyclic aromatic hydrocarbons (PAHs) from contaminated sand. The extraction rates and efficiencies for lowly contaminated (LC) and highly contaminated (HC) sands at temperatures of 30 °C and 70 °C are evaluated using empirical first order kinetic dissolution models. In LC sand, the extraction is dominated by the diffusion of PAHs adsorbed onto particle surfaces and the direct dissolution of PAH phase. In HC sand, a rapid diffusion of PAHs adsorbed onto particle surfaces and a direct dissolution of PAH phase occur followed by a slower diffusion of PAHs entrapped within the pores and micropores. Larger diffusion resistance during HC sand extractions results in an average 10.8% reduction in extraction efficiencies compared to LC sand. Increased temperature generally increases the mass transfer rates and extraction efficiencies. Additionally, the physicochemical properties of both oils and PAHs also determine the extent of PAH extraction into oil.
A new microextraction procedure termed multi-walled carbon nanotube-impregnated agarose film microextraction (MWCNT-AFME) has been developed. The method utilized multi-walled carbon nanotubes (MWCNTs) immobilized in agarose film to serve as adsorbent in solid phase microextraction (SPME). The film was prepared by mixing the MWCNTs in agarose solution and drying the mixture in oven. Extraction of selected polycyclic aromatic hydrocarbons was performed by inserting a needle through circular MWCNT-impregnated agarose films (5 mm diameter) and the assembly was dipped into an agitated sample solution prior to micro high performance liquid chromatography-ultraviolet analysis. Back extraction was then performed using ultrasonication of the films in 100 μL of solvent. The film was discarded after single use, thus avoiding any analyte carry-over effect. Due to the mesoporous nature of the agarose film, the MWCNTs were immobilized easily within the film and thus allowing for close contact between adsorbent and analytes. Under the optimized extraction conditions, the technique achieved trace LODs in the range of 0.1 to 50 ng L(-1) for the targeted analytes, namely fluoranthene, phenanthrene and benzo[a]pyrene. The method was successfully applied to the analysis of spiked green tea beverage samples with good relative recoveries in the range of 91.1 to 107.2%. The results supported the feasibility of agarose to serve as adsorbent holder in SPME which then minimizes the consumption of chemicals and disposal cost of organic wastes.
Six aporphine and one phenanthrenoid alkaloids isolated from Aromadendron elegans Blume were investigated for their ability to inhibit arachidonic acid (AA), collagen and ADP induced platelet aggregation in human whole blood. The antiplatelet activity of the compounds was measured in vitro by the Chrono Log whole blood aggregometer using an electrical impedance method. Of the compounds tested, (-)-N-acetylnornuciferine, (-)-N-acetylanonaine and 1-(N-acetyl-N-methylamino)ethyl-3,4,6-trimethoxy-7-hydroxyphenanthrene showed strong inhibition on platelet aggregation caused by all three inducers. (-)-N-acetylanonaine was the most effective antiplatelet compound as it inhibited both arachidonic acid, collagen and ADP-induced platelet aggregation with IC(50) values of 66.1, 95.1 and 80.6 microm, respectively.
A dichloromethane extract of the stem bark of Cryptocarya nigra showed strong in vitro inhibition of Plasmodium falciparum growth, with an IC50 value of 2.82 μg/mL. The phytochemical study of this extract has led to the isolation and characterization of four known alkaloids: (+)-N-methylisococlaurine (1), atherosperminine (2), 2-hydroxyathersperminine (3), and noratherosperminine (4). Structural elucidation of all alkaloids was accomplished by means of high field 1D- and 2D-NMR, IR, UV and LCMS spectral data. The isolated extract constituents (+)-N-methylisococlaurine (1), atherosperminine (2) and 2-hydroxy-atherosperminine (3) showed strong antiplasmodial activity, with IC50 values of 5.40, 5.80 and 0.75 μM, respectively. In addition, (+)-N-methylisocolaurine (1) and atherosperminine (2) showed high antioxidant activity in a DPPH assay with IC50 values of 29.56 ug/mL and 54.53 ug/mL respectively. Compounds 1 and 2 also both showed high antioxidant activity in the FRAP assay, with percentages of 78.54 and 70.66 respectively and in the metal chelating assay, with IC50 values of 50.08 ug/mL and 42.87 ug/mL, respectively.