Anti-inflammatory properties of uvaol on DSS-induced colitis and LPS-stimulated macrophages.

BACKGROUND: Apocynum venetum leaves are used as a kind of phytomedicine and the main ingredient in some traditional Chinese medicine products for the relief of colitis. To understand the bioactive constituents of A. venetum L., we did a phytochemistry study and investigated anti-Inflammatory effects of compounds and explored the underlying mechanisms. METHODS: We isolated compounds from ethanol extract of A. venetum L. leaf and detected the most effective compound by NO inhibition assay. We investigated anti-Inflammatory effects on dextran sulfate sodium (DSS)-induced colitis mice and lipopolysaccharide (LPS)-stimulated RAW264.7 cells. The disease activity index was determined by scores of body weight loss, diarrhea and rectal bleeding; histological damage was analyzed by H&E staining; macrophages change in the colon were analyzed by immunohistochemistry (IHC); myeloperoxidase activity was measured by myeloperoxidase assay kits; levels of proinflammatory cytokines were determined by qPCR and ELISA; protein production such as COX-2, iNOS, STAT3 and ERK1/2 were determined by western blotting. RESULTS: We isolated uvaol from ethanol extract of A. venetum L. leaf and found uvaol has excellent potential of inhibiting NO production. We further found uvaol could attenuate disease activity index (DAI), colon shortening, colon injury, and colonic myeloperoxidase activity in DSS-induced colitis mice. Moreover, uvaol significantly reduces mRNA expression and production of pro-inflammatory cytokines (TNF-α, IL-6, IL-1ß, and MCP-1) and infiltration of macrophages in colonic tissues of colitis mice. Studies on LPS challenged murine macrophage RAW246.7 cells also revealed that uvaol reduces mRNA expression and production of pro-inflammatory cytokines and mediators. Mechanically, uvaol inhibits the pro-inflammatory ERK/STAT3 axis in both inflamed colonic tissues and macrophages. CONCLUSIONS: A. venetum leaf contains uvaol and uvaol has potent anti-inflammatory effects on DSS-induced experimental colitis and LPS-stimulated RAW264.7 macrophage cells. These results suggest uvaol is a prospective anti-inflammatory agent for colonic inflammation.

Anti HSV-1 flavonoid derivatives tethered with houttuynin from Houttuynia cordata.

This paper reports the phytochemical investigation of the 50% aq. EtOH extract of Houttuynia cordata, an effective TCM and functional food in China, which led to the isolation of 17 flavonoids including four new ones. The four new compounds were flavonoid derivatives tethered with houttuynin (3-oxododecanal). Each of the new compounds was obtained as a pair of inseparable diasteriomeric epimers due to the chiral carbon of hemiketal at C-3″. This phenomenon is rooted in the ring-chain tautomerism of the hemiketal functional group in solution, which was proved by dynamic NMR experiments. The new compounds 1-4 displayed inhibitory activities against herpes simplex virus 1, with respective IC50 values of 38.46, 14.10, 62.00 and 70.76 µM, which was associated with the medicinal functions of H. cordata.

Houttuynoids A-E, anti-herpes simplex virus active flavonoids with novel skeletons from Houttuynia cordata.

Houttuynoids A-E (1-5), a new type of flavonoid with houttuynin tethered to hyperoside, and their presumed biosynthetic precursor hyperoside (6) were isolated from the whole plant of Houttuynia cordata. Their structures were elucidated by analysis of 1D and 2D NMR. A hypothetical biogenetic pathway for houttuynoids A-E was proposed. Compounds 1-5 exhibited potent anti-HSV (herpes simplex viruses) activity.

Inhibition of enterovirus 71 replication by chrysosplenetin and penduletin.

In recent years, enterovirus 71 (EV71) infections have caused an increasing epidemic in young children, accompanying with more severe nervous system disease and more deaths. Unfortunately, there is no specific medication for it so far. Here we investigated the anti-EV71 activity of chrysosplenetin and penduletin, two o-methylated flavonols isolated from the leaves of Laggera pterodonta. These two compounds were found to have strong activity in vitro against EV71 with low cytotoxicity. In the cytopathic effect (CPE) inhibition assays, both plaque reduction assay and virus yield inhibition assay, the compounds showed a similar 50% inhibitory concentration (IC(50)) value of about 0.20 µM. The selectivity indices (SI) of chrysosplenetin and penduletin were 107.5 and 655.6 in African green monkey kidney (Vero) cells, and 69.5 and 200.5 in human rhabdomyosarcoma (RD) cells, accordingly. The preliminary mechanism analysis indicates that they function not through blocking virus entry or inactivating virus directly but inhibiting viral RNA replication. In the time-of-addition assay, both compounds inhibited progeny virus production and RNA replication by nearly 100% when introduced within 4h post infection. In addition to EV71, both compounds inhibited several other human enteroviruses with similar efficacy. These findings provide a significant lead for the discovery of anti-EV71 drug.

Herpes simplex virus (HSV) immediate-early (IE) promoter-directed reporter system for the screening of antiherpetics targeting the early stage of HSV infection.

Most of the current antiherpetics target viral DNA polymerase, but with the emergence of drug-resistant viruses, antiherpetics with different targets have become necessary. Inhibition of herpes simplex virus (HSV) replication at the early stages of infection minimizes cytotoxicity and immune suppression induced by HSV infection. In this report, quantitative reporter systems that use recombinant HSV and a stably transfected cell line were developed for the screening of agents targeting the early stages of HSV infection. The reporter genes in both systems were directed by HSV immediate-early (IE) promoters, so considerably less time was required for the quantification of HSV infection than the traditional plaque reduction assay. The results show that both reporter assays were sensitive to antiherpetic screening. Both assays were quantitative, rapid, easy to perform, and highly adaptable for automatic high-throughput screening. Exploiting the flexibility of these 2 assays, modified assays were also proposed for the detailed analysis of antiherpetic mechanisms.

[Silencing HSV1 gD expression in cultured cells by RNA interference].

To explore the anti-HSV-1 effect of silencing gD gene expression by RNA interference, five 21-nucleotide duplex small interfering RNAs(siRNAs) targeting the HSV1 gD sequence were designed and the gD-EGFP fusion gene expression vector was constructed, then co-transfected into Vero cell, and screened the effective siRNA through analyzing the intensity of the EGFP fluorescence. Finally, the anti-HSV1 effect was confirmed by plaque reduction assay, real-time PCR and daughter virus titration of HSV1 infected Vero cells transfected with siRNAs. The study demonstrated that siRNAs could effectively and specifically inhibit gD gene expression in HSV1-infected cells, but only had a little effect on HSV1 infection, so taking gD as the target of siRNA against HSV1 needs further study.