Molecular cloning and characterization of three phenylalanine ammonia-lyase genes from Schisandra chinensis / 中国天然药物

Phenylalanine ammonia-lyase (PAL), which catalyzes the conversion from L-phenylalanine to trans-cinnamic acid, is a well-known key enzyme and a connecting step between primary and secondary metabolisms in the phenylpropanoid biosynthetic pathway of plants and microbes. Schisandra chinensis, a woody vine plant belonging to the family of Magnoliaceae, is a rich source of dibenzocyclooctadiene lignans exhibiting potent activity. However, the functional role of PAL in the biosynthesis of lignan is relatively limited, compared with those in lignin and flavonoids biosynthesis. Therefore, it is essential to clone and characterize the PAL genes from this valuable medicinal plant. In this study, molecular cloning and characterization of three PAL genes (ScPAL1-3) from S. chinensis was carried out. ScPALs were cloned using RACE PCR. The sequence analysis of the three ScPALs was carried out to give basic characteristics followed by docking analysis. In order to determine their catalytic activity, recombinant protein was obtained by heterologous expression in pCold-TF vector in Escherichia coli (BL21-DE3), followed by Ni-affinity purification. The catalytic product of the purified recombinant proteins was verified using RP-HPLC through comparing with standard compounds. The optimal temperature, pH value and effects of different metal ions were determined. Vmax, Kcat and Km values were determined under the optimal conditions. The expression of three ScPALs in different tissues was also determined. Our work provided essential information for the function of ScPALs.

A new norsesquiterpenoid from Schisandra chinensis / 中国中药杂志

This study investigated the chemical components from the leaves and stems of Schisandra chinensis. Three norsesquiterpenoids were isolated from S. chinensis by various column chromatographies(silica gel, Sephadex LH-20, and MCI), reversed-phase medium-pressure preparative, and semi-preparative high-performance liquid chromatography(HPLC). Their structures were identified based on physicochemical properties, mass spectrometry(MS), nuclear magnetic resonance(NMR), ultraviolet(UV), and electro-nic circular dichroism(ECD) as(3R,4R,5R,6S,7E)-3,4,5,6-tetrahydroxy-7-megastigmen-9-one(1),(3S,5R,6R,7E)-3,5,6-trihydroxy-7-megastigmen-9-one(2), and(3S,4R,9R)-3,4,9-trihydroxymegastigman-5-ene(3). Compound 1 was a new compound, and its absolute configuration was determined by ECD. Compounds 2 and 3 were isolated from the Schisandra plant for the first time.

Lignan constituents from Balanophora involucrate and their anti-inflammatory activities / 中草药

Objective: To study the chemical constituents in the whole herb of Balanophora involucrate. Methods: The compounds were isolated and purified using polyamide, silica gel colimu, ODS, MCI gel, and semi-preparative HPLC, and their structures were elucidated by means of physicochemical properties and spectroscopic analysis. The anti-inflammatory activities of all the isolated compounds were evaluated using Griess method and ELISA for the determination of LPS-induced NO and IL-6 releases in inflammation cell model induced by LPS. Results: Eleven lignans were isolated from 75% ethyl alcohol extract from the whole herb of B. involucrata and identified as (+)-pinoresinol (1), (+)-5’-hydroxypinoresinol (2), isolariciresinol 4-O-β-D-glucopyranoside (3), (+)-isolariciresinol (4), burselignan (5), (+)-9-acetoxyisolariciresinol (6), yunnanensin A (7), (-)-secoisolariciresinol-4-O-β-D- glucopyranoside (8), (-)-secoisolariciresinol (9), dihydrocubebin (10), and secoisolariciresinol-9’-acetate (11). Conclusion: Among them, compound 11 is a new natural product, and compound 2, 5, 7, 8, and 10 are isolated from the genus of Balanophora for the first time. All compounds showed strong anti-inflammatory activities.