Eight new matrine-type alkaloids, flavesines G−J (1−4), alopecurine B (5), 7,11-dehydro-oxymatrine (6), 10-oxy-5,6-dehydromatrine ( 7), and 10-oxysophoridine (8), along with nine known analogues (9−17) were isolated from the roots of Sophora f lavescens. Compounds 1−3 are the first natural matrine-type alkaloids with an open-loop ring D, while compound 4 represents an unprecedented dimerization pattern constructed from matrine and piperidine, and 5 is the first example of a matrine-type alkaloid with cleavage of the C-5−C-6 bond. The new structures were elucidated by means of spectroscopic data analysis (including NMR, MS, IR, and UV), and the absolute configurations were determined using single-crystal X-ray diffraction and ECD data. The isolated alkaloids were evaluated for their antiviral activity against hepatitis B virus, and compounds 1, 4, 5, 10, and 14 exhibited comparable antiviral potencies to matrine.
The capabilities to tune the conduction properties of materials by doping or electric fields are essential for the design of electronic devices. However, in two-dimensional materials substitutional doping has been achieved in only a few systems, such as Nb substitutional doping in MoS. Surface charge transfer is still one of the popular ways to control whether the conduction is dominated by holes or electrons. Here, we demonstrate that a capping layer of cross-linked poly(methyl methacrylate) modifies the potential in a black phosphorus (BP) layer so that conduction in the absence of an external electric field is dominated by electrons, rather than holes. Using this technique to form adjoining regions dominated by hole and electron conduction, a family of novel planar devices, such as BP-gated diodes, BP bidirectional rectifier, and BP logic inverters, can be fabricated. The devices are potentially useful for electronic applications, including rectification and switching.
The present study found that the supercritical fluid extract of "Guangchenpi" possessed in vitro antiviral activity against respiratory syncytial virus (RSV). Bioassay-guided isolation and identification of this extract led to obtain five active polymethoxylated flavones (1-5). Cytopathic effect (CPE) reduction assay exhibited that tangeretin (2) and nobiletin (3), two major polymethoxylated flavones in the extract, possessed better anti-RSV effect comparable to the positive control ribavirin. Plaque reduction assay revealed that tangeretin dose-dependently inhibited RSV-induced plaque formation on the HEp-2 cells. This polymethoxylated flavone mainly affected the intracellular replication of RSV, and it also could inhibit RSV entry into the HEp-2 cells. Further investigations with quantitative real-time PCR and confocal and Western blot assays indicated that tangeretin downregulated the expression of RSV phosphoprotein (P protein). Results suggest the potential application of the supercritical fluid extract of "Guangchenpi" and tangeretin in the treatment and the prevention of RSV infection.
Seven new clerodane diterpenoids (1-7) were isolated from roots of Croton crassifolius, along with six known compounds. The structures were elucidated by extensive spectroscopic methods (IR, UV, HRESIMS, 1D NMR, and 2D NMR), and the structures of 1, 3, 4, and 7 were confirmed by single-crystal X-ray diffraction analyses. Compounds 1-13 were evaluated for in vitro antiviral activity against herpes simplex virus type 1 using the cytopathic effect reduction assay.
Six new Securinega alkaloids (1, 3, 5, 7, 9, 10) together with four known ones were isolated from the twigs and leaves of Flueggea leucopyra. The structures of new compounds were established on the basis of the spectroscopic methods including UV, IR, HR-electrospray ionization (ESI)-MS, 1D and 2D NMR, and the absolute configurations of these new alkaloids were assigned by the modified Mosher's method and the circular dichroism (CD) spectra.
Six unusual matrine-type alkaloid dimers, flavesines A-F (1-6, respectively), together with three proposed biosynthetic intermediates (7-9) were isolated from the roots of Sophora flavescens. Compounds 1-5 were the first natural matrine-type alkaloid dimers, and compound 6 represented an unprecedented dimerization pattern constructed by matrine and (-)-cytisine. Their structures were elucidated by NMR, MS, single-crystal X-ray diffraction, and a chemical method. The hypothetical biogenetic pathways of 1-6 were also proposed. Compounds 1-9 exhibited inhibitory activities against hepatitis B virus.
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