Essential Oils of the Leaves of Epaltes australis Less. and Lindera myrrha (Lour.) Merr.: Chemical Composition, Antimicrobial, Anti-inflammatory, Tyrosinase Inhibitory, and Molecular Docking Studies.

Epaltes australis Less. has been traditionally used to treat fever and snake bites, whereas Lindera myrrha (Lour.) Merr. is well-known for addressing colds, chest pain, indigestion, and worm infestations. This study marks the first report on the chemical compositions and biological potentials of essential oils extracted from the leaves of Epaltes australis and Lindera myrrha. Essential oils obtained by hydro-distillation were analysed using the GC/MS (gas chromatography-mass spectrometry). E. australis exhibited a predominant presence of non-terpenic compounds (46.3 %), with thymohydroquinone dimethyl ether as the major compound, constituting 44.2 % of the oil. L. myrrha leaf oil contained a good proportion of sesquiterpene hydrocarbons (56.8 %), with principal compounds including (E)-caryophyllene (22.2 %), ledene (9.7 %), selina-1,3,7(11)-trien-8-one (9.6 %), and α-pinene (7.0 %). Both essential oils exhibited antimicrobial activity against the bacteria Bacillus subtilis and Clostridium sporogenes, and Escherichia coli, and the fungus Aspergillus brasiliensis. L. myrrha leaf essential oil exhibited potent control over the yeast Saccharomyces cerevisiae with a MIC of 32 µg/mL. Additionally, L. myrrha leaf oil showed strong anti-inflammatory activity with an IC50 value of 15.20 µg/mL by inhibiting NO (nitric oxide) production in LPS (lipopolysaccharide)-stimulated RAW2647 murine macrophage cells. Regarding anti-tyrosinase activity, E. australis leaf oil showed the best monophenolase inhibition with the IC50 of 245.59 µg/mL, while L. myrrha leaf oil successfully inhibited diphenolase with the IC50 of 152.88 µg/mL. From molecular docking study, selina-1,3,7(11)-trien-8-one showed the highest affinity for both COX-2 (cyclooxygenase-2) and TNF-α (tumor necrosis factor-α) receptors. Hydrophobic interactions play a great role in the bindings of ligand-receptor complexes.

Multiplexed analysis of silver(I) and mercury(II) ions using oligonucletide-metal nanoparticle conjugates.

A colorimetric assay has been developed for the simultaneous selective detection of silver(I) and mercury(II) ions utilizing metal nanoparticles (NPs) as sensing element based on their unique surface plasmon resonance properties. In this method, sulfhydryl group modified cytosine-(C)-rich ssDNA (SH-C-ssDNA) was self-assembled on gold nanoparticles (AuNPs) to produce the AuNPs-C-ssDNA complex, and sulfhydryl group modified thymine-(T)-rich ssDNA (SH-T-ssDNA) was self-assembled on silver nanoparticles (AgNPs) to produce the AgNPs-T-ssDNA complex. Oligonucleotides (SH-C-ssDNA or SH-T-ssDNA) could enhance the AuNPs or AgNPs against salt-induced aggregation. However, the presence of silver(I) ions (Ag(+)) in the complex of ssDNA-AuNPs would reduce the stability of AuNPs due to the formation of Ag(+) mediated C-Ag(+)-C base pairs accompanied with the AuNPs color change from red to purple or even to dark blue. Moreover, the presence of mercury(II) ions (Hg(2+)) would also reduce the stability of AgNPs due to the formation of Hg(2+) mediated T-Hg(2+)-T base pairs accompanied with the AgNPs color change from yellow to brown, then to dark purple. The presence of both Ag(+) and Hg(2+) will reduce the stability of both AuNPs and AgNPs and cause the visible color change. As a result, Ag(+) and Hg(2+) could be detected qualitatively and quantitatively by the naked eye or by UV-vis spectral measurement. The lowest detectable concentration of a 5 nM mixture of Ag(+) and Hg(2+) in the river water was gotten by the UV-vis spectral measurement.

A novel separation and enrichment method of 17ß-estradiol using aptamer-anchored microbeads.

The estrogenic compound 17ß-estradiol (E2) is widely studied for its potential endocrine disruption effects. Due to the low level of E2 present in the environment, it is highly desirable to develop a sensitive and efficient separation and enrichment method for E2 analysis. In this paper, we proposed a novel E2 preconcentration method using anti-E2 aptamer-anchored isothiocyanate-modified beads (NCS beads). The glass beads are chemically modified with primary amino group, and then treated with phenylene diisothiocyanate (PDITC) to generate an isothiocyanate group, which is reactive towards the amine group. The amino-modified anti-E2 aptamer can be easily covalently immobilized onto the as-prepared NCS beads. The experimental results demonstrated that the aptamer affinity microbeads could selectively retain and separate E2 compound. The effects of the operation parameters on retention of E2, including washing condition, eluting condition, the number of beads, and the incubation time were investigated. Moreover, high-performance liquid chromatography with preconcentration of E2 on the aptamer affinity microbeads was applied to detect the E2 in the spiked water samples and obtained a good recovery.