•Isomerization of piperlonguminine.•Scutifoliamide A was less toxic on HepG2 liver cell than piperlonguminine.•Scutifoliamide A might be a promising antihyperlipidemic agent.Light induced isomerization of piperlonguminine (1) to scutifoliamide A (2), isopiperlonguminine (3) and hoffmannseggiamide A (4) is reported in this work. In vivo antihyperlipidemic study showed that a mixture of 1 and 2 (1:1) had significantly decreased serum total cholesterol (TC) and triglyceride (TG) in rats, which were similar to those of the pure 1 and simvastatin. Additionally, 2 was less toxic on HepG2 liver cell than the 1 and simvastatin.

The natural product piperlonguminine (GBN) which is extracted from Piper longum Linn., has high antihyperlipidaemic activity and low toxicity. However, the content of natural GBN in P. longum (0.20–0.25%) is low, and it is not easy to prepare enough sample of natural GBN for further studies, such as large-scale animal experiments. Therefore, in the present study, we tested and confirmed the antihyperlipidaemic activity of chemically synthesised GBN in rats for the first time. The results of the antihyperlipidaemic assay in vivo showed that synthetic GBN had significant lipid-lowering activities. Synthetic GBN not only inhibited body weight gain (66.3 ± 22.50 g vs. 83.9 ± 19.95 g) but also significantly decreased total cholesterol (TC, 9.67 ± 3.32 mmol/L vs. 22.26 ± 5.84 mmol/L), total glycerol (TG, 1.47 ± 0.08 mmol/L vs. 2.86 ± 0.75 mmol/L), and low-density lipoprotein cholesterol (LDL-C, 3.57 ± 1.15 mmol/L vs. 5.44 ± 1.42 mmol/L) while increasing high-density lipoprotein cholesterol (HDL-C, 1.31 ± 0.56 mmol/L vs. 0.68 ± 0.20 mmol/L) in the serum of rats fed a high-fat diet.Graphical abstractHighlights► Piperlonguminine was synthesised with high yield and purity. ► Synthetic piperlonguminine inhibited body weight gain. ► Synthetic piperlonguminine had significant lipid lowering activities. ► Piperlonguminine is a potential antihyperlipidemic drug candidate. ► Piperlonguminine in Piper longum is too little to be used for pre-clinic and clinic studies.

A novel starch piperinic ester (SPE) with anti-hyperlipidemia activity was synthesized by coupling a carboxylic group of piperic acid and a hydroxyl group on the backbone of starch. The synthetic process includes three steps. Firstly, piperic acid was obtained by hydrolyzing Piperine that was extracted from seeds of Piper longum L. (traditional medicine of Mongolian). Then, piperic acid was reacted with Carbonyldiimidazole (CDI) in DMSO under N2 at 70 °C for 4 h. Finally, starch piperinic ester was obtained by the reaction of activated piperic acid with water soluble starch at 80 °C under N2 for 24 h. The structure of the novel copolymer was characterized by FTIR, 13C NMR and 1H NMR. Anti-hyperlipidemic activity of SPE was assayed by pharmacological testes and the results indicated that the SPE had high anti-hyperlipidemic activity and would be one kind of new potential candidate of anti-hyperlipidemia pro-drug.