Lei-Lei Liu

Phytochemicals and Biological Activities of Pulicaria Species

Ligularia, an important genus of the Compositae family, has captured the interest of natural product chemists for years. Phytochemical investigations on the title genus have led to isolation of hundreds of secondary metabolites with various skeletons. Herein, we summarized the chemical constituents of this genus and their biological activities over the past few decades. Open image in new window

Limonoids and Quinoline Alkaloids from Dictamnus dasycarpus

Phytochemical investigation on Dictamnus dasycarpus (Rutaceae) has led to the isolation of four new secondary metabolites (2, 6, 9, and 10) along with twelve known phytochemicals (1, 3- 5, 7, 8, 11-16). Compound 4 was isolated as a natural product for the first time. The structures of compounds 1-16 were elucidated by extensive spectroscopic analyses and comparison with previously reported spectroscopic data. The structures of 8 and 13 were further confirmed based on X-ray data analyses. The absolute configuration of compounds 8-12 were studied based on the CD spectra analyses.

Sesquiterpenoids from Inula britannica.

Phytochemical investigation of the flowers of Inula britannica led to the isolation of nineteen sesquiterpenoids (1- 19), including britanlins E-J ( 2, 3, 5, 8, 13, and 14, respectively) and known sesquiterpenoids (1, 4, 6, 7, 9- 12, and 15- 19). The structures of these isolates were elucidated by detailed spectroscopic analyses and comparison to the previously reported spectroscopic data. The absolute configurations of compounds 12, 15, 17, and 19 were determined by X-ray single crystal diffraction analyses and chemical transformations.

Sesquiterpenoids and other constituents from the flower buds of Tussilago farfara

One new norsesquiterpenoid, namely tussfarfarin A (1), and four new artifacts resulting from extraction procedure, namely tussfarfarin B (2), 6-(1-ethoxyethyl)-2,2-dimethylchroman-4-ol (3), 5-ethoxymethyl-1H-pyrrole-2-carbaldehyde (4), and 3β-hydroxy-7α-ethoxy-24β-ethylcholest-5-ene (5), along with 18 known compounds, were isolated from the flower buds of Tussilago farfara. Their structures were elucidated by extensive spectroscopic analysis.

Chrysindins A-D, polyacetylenes from the flowers of Chrysanthemum indicum.

Four new polyacetylenes, namely chrysindins A-D, together with 6 known polyacetylenes, were isolated from the flowers of Chrysanthemum indicum. Their structures were established on the basis of comprehensive spectroscopic analyses. Chrysindins A and B bear a novel carbon skeleton.

Phytochemicals and biological activities of Saussurea species

The genus Saussurea has been studied from phytochemical and pharmacological viewpoints for years, which resulted in the discovery of hundreds of secondary metabolites with various kinds of bioactivities. This review summarizes the research progress of the genus of Saussurea in the phytochemical and pharmacological viewpoints, which covered the period of 1990–June 2009.

Sesquiterpenoids with Various Carbocyclic Skeletons from the Flowers of Chrysanthemum indicum

A phytochemical investigation of the flowers of Chrysanthemum indicum yielded sesquiterpenoids 1-25 with various carbocyclic skeletons, including 10 new (1-10) and 15 known (11-25) analogues. The structures were elucidated via their physical data, while the absolute configuration of compounds 6, 8, and 10 was assessed via electronic circular dichroism analysis. The evaluation of the effect of sesquiterpenoids on porcine epidemic diarrhea virus (PEDV) replication showed that compounds 1-5, 12, 14, 16, 17, 19, and 21 increased cell viability against cell death in PEDV-injected cells. Compounds 2, 12, and 17 were selected and investigated for their inhibition of proteins required for PEDV replication. Compounds 2 and 17 significantly reduced PEDV nucleocapsid and spike protein synthesis compared with azauridin as a positive control.