[Study on essential oils of medicinal plants in insect repellent].

Mosquitoes are seriously harmful to human health for transmitting some mortal diseases. Among the methods of mosquito control, synthetical insecticides are the most popular. However, as a result of longterm use of these insecticides, high resistant mosquitos and heavy environmental pollution appear. Thus, eco-friendly prevention measures are taken into the agenda. Essential oils extracted from medicinal plants have repellent and smoked killing effects on mosquitoes. With abundant medical plants resources and low toxicity, they have the potential of being developed as a new type of mosquito and insect repellent agent. The recent application advances of essential oils of medicinal plants in insect repellent and its application limitations are overviewed. This review will provide references for the future development and in-depth study of essential oils.

Genomic, transcriptomic, and metabolomic analyses provide insights into the evolution and development of a medicinal plant Saposhnikovia divaricata (Apiaceae).

Saposhnikovia divaricata, 2n = 2x = 16, as a perennial species, is widely distributed in China, Mongolia, Russia, etc. It is a traditional Chinese herb used to treat tetanus, rubella pruritus, rheumatic arthralgia, and other diseases. Here, we assembled a 2.07 Gb and N50 scaffold length of 227.67 Mb high-quality chromosome-level genome of S. divaricata based on the PacBio Sequel II sequencing platform. The total number of genes identified was 42 948, and 42 456 of them were functionally annotated. A total of 85.07% of the genome was composed of repeat sequences, comprised mainly of long terminal repeats (LTRs) which represented 73.7% of the genome sequence. The genome size may have been affected by a recent whole-genome duplication event. Transcriptional and metabolic analyses revealed bolting and non-bolting S. divaricata differed in flavonoids, plant hormones, and some pharmacologically active components. The analysis of its genome, transcriptome, and metabolome helped to provide insights into the evolution of bolting and non-bolting phenotypes in wild and cultivated S. divaricata and lays the basis for genetic improvement of the species.

Efficient synthesis of natural polyphenolic stilbenes: resveratrol, piceatannol and oxyresveratrol.

The practical synthesis of important natural polyphenolic stilbenes, including resveratrol, piceatannol and oxyresveratrol, through Perkin methodology is described. Starting from 3,5-dihydoxyacetophenone (1), the common intermediate 3,5-dimethoxyphenylacetic acid (3) can be obtained via methylation and Willgerodt-Kindler reaction. Perkin condensations between (3) and substituted phenylaldehydes 4 furnished E-2,3-diarylacrylic acids 5, followed by decarboxylation in Cu/quinoline giving stilbene intermediates 6 which bear the Z-configuration. Finally, through a simultaneous demethylation/isomerization process in AlI3/CH3CN system, the target compounds 7a-c can be obtained respectively in good to high overall yields. The synthetic method proved to be more concise, trans-specific, mild, economical and commonly applicable.