Identification of haemanthamine as a phytotoxic alkaloid in Narcissus pseudonarcissus L. (Daffodil) emerging buds.

Emerging buds of Narcissus pseudonarcissus were found to accumulate the alkaloid haemanthamine (1) at high concentrations, exceeding that of narciclasine (2), the most abundant constituent in bulbs of the plant. A phytoactivity screening assay demonstrated the novel phytotoxicity of haemanthamine against Raphanus sativus (radish), Lactuca sativus (lettuce), Triticum aestivum (red wheat), Solanum lycopersicum (tomato), Cucumis sativus (cucumber), Ipomoea (Morning glory), and Lens culinaris (lentil). Haemanthamine (1) phytotoxicity was found to exceed that of the commercial herbicide glyphosate and less toxic than narciclasine (2).

The synthesis of densely functionalised α-acyloxy enaminals and enaminones via a novel homogeneous silver(i) catalysed rearrangement.

A synthesis of densely functionalised α-acyloxy enaminals and enaminones via a novel homogeneous silver(i) catalyzed rearrangement of 1-acyloxy-3-azido ketones is reported. This silver catalyzed reaction involves an internal redox process comprised of four net transformations: loss of nitrogen, reductive cleavage of the azide, 1,2-acyl migration and oxidation of the acyloxy position to an aldehyde (enaminal) or ketone (enaminone). These mild reaction conditions have been applied to acyclic, cyclic, and chiral substrates yielding the rearranged enaminals or enaminones in up to 91% yield, all of which prove to be stable, isolatable products.

R430: A potent inhibitor of DNA and RNA viruses.

Acyclovir (ACV) is an effective antiviral agent for treating lytic Herpes Simplex virus, type 1 (HSV-1) infections, and it has dramatically reduced the mortality rate of herpes simplex encephalitis. However, HSV-1 resistance to ACV and its derivatives is being increasingly documented, particularly among immunocompromised individuals. The burgeoning drug resistance compels the search for a new generation of more efficacious anti-herpetic drugs. We have previously shown that trans-dihydrolycoricidine (R430), a lycorane-type alkaloid derivative, effectively inhibits HSV-1 infections in cultured cells. We now report that R430 also inhibits ACV-resistant HSV-1 strains, accompanied by global inhibition of viral gene transcription and enrichment of H3K27me3 methylation on viral gene promoters. Furthermore, we demonstrate that R430 prevents HSV-1 reactivation from latency in an ex vivo rodent model. Finally, among a panel of DNA viruses and RNA viruses, R430 inhibited Zika virus with high therapeutic index. Its therapeutic index is comparable to standard antiviral drugs, though it has greater toxicity in non-neuronal cells than in neuronal cells. Synthesis of additional derivatives could enable more efficacious antivirals and the identification of active pharmacophores.

Comparison of three cell-based drug screening platforms for HSV-1 infection.

Acyclovir (ACV) and its derivatives have been highly effective for treating recurrent, lytic infections with Herpes Simplex Virus, type 1 (HSV-1), but searches for additional antiviral drugs are motivated by recent reports of resistance to ACV, particularly among immunocompromised patients. In addition, the relative neurotoxicity of ACV and its inability to prevent neurological sequelae among HSV-1 encephalitis survivors compel searches for new drugs to treat HSV-1 infections of the central nervous system (CNS). Primary drug screens for neurotropic viruses like HSV-1 typically utilize non-neuronal cell lines, but they may miss drugs that have neuron specific antiviral effects. Therefore, we compared the effects of a panel of conventional and novel anti-herpetic compounds in monkey epithelial (Vero) cells, human induced pluripotent stem cells (hiPSCs)-derived neural progenitor cells (NPCs) and hiPSC-derived neurons (N = 73 drugs). While the profiles of activity for the majority of the drugs were similar in all three tissues, Vero cells were less likely than NPCs to identify drugs with substantial inhibitory activity in hiPSC-derived neurons. We discuss the relative merits of each cell type for antiviral drug screens against neuronal infections with HSV-1.

Direct Synthesis of Thioethers from Carboxylates and Thiols Catalyzed by FeCl3.

A new and efficient method has been developed for the synthesis of thioethers from carboxylates and thiols. The reaction proceeds via a Fe(III)-catalyzed direct displacement of carboxylates from benzylic or allylic esters by heterocyclic thiols. Short reaction times, good to excellent yields of products, and few side reactions are the significant features of the new protocol.