A comparative study of the dynamic accumulation of polyphenol components and the changes in their antioxidant activities in diploid and tetraploid Lonicera japonica.

Polyploidization is an effective method to achieve a higher yield of secondary metabolism active ingredients in medicinal plants. Polyphenols are the main active substances that contribute to the antioxidant activity of Lonicera japonica. For studying on the effect of chromosome doubling and harvest time on the dynamic accumulation of the main active substances and antioxidant capabilities of L. japonica, the polyphenol composition contents (7 phenolic acids and 3 flavonoids) and the antioxidant capacity in buds and flowers of diploid and tetraploid L. japonica at six different growth stages were determined by HPLC-DAD and three common antioxidant assays (FRAP, OH RSC and DPPH ARP), and the correlation between the dynamic accumulation of the polyphenol components and antioxidant capacity was also analyzed in current research. The results indicated that the content of the most determined phenolic acids and flavonoids and the antioxidant capacity in most of the growth stages from tetraploid plants were significantly higher than those in the diploid plants. Furthermore, the changes in the antioxidant activity presented a significant positive correlation with the variations in the chlorogenic acid, rutin, hyperoside, luteoloside in the two ploidy levels of L. japonica plants. The higher yields of chlorogenic acid (158.97, 164.00, 199.85 mg), luteoloside (5.44, 4.03, 6.31 mg), hyperoside (1.15, 1.06, 1.30 mg) and total flavonoids (9.87, 8.67, 11.10 mg) from 100 buds or flowers in tetraploid plants occurred during the S3-S5 stages, and these stages also exhibited higher antioxidant activities. Therefore, the stages of S3-S5 are recommended as the best time for harvesting high-yield, high-quality tetraploid Flos Lonicerae Japonicae.

Stereoselective syntheses of the bioactive polypropionates aureothin, N-acetylaureothamine, and aureonitrile.

[reaction: see text] Concise total syntheses of the bioactive polypropionates aureothin, N-acetylaureothamine, and aureonitrile are described.

Stereoselective synthesis of cyercene A and the placidenes.

Members of a family of alpha-methoxy-gamma-pyrone-containing polypropionate natural products have been stereoselectively synthesized. Two key iodovinyl pyrone building blocks were coupled to appropriately selected vinyl stannanes to assemble the highly substituted polyene side chains of the natural products. [structure: see text]