Piper longum L., known as long pepper, is an edible and medicinal plant used as spice and for the treatment of stomach disease and analgesia in traditional Chinese medicine. N-Alkylamides are the major secondary metabolites in this plant.Sixteen known N-alkylamides were isolated from P. longum. Their structures were established on the basis of spectroscopic data and comparison to reported literatures. Among them, five compounds were isolated from this plant for the first time. Ethanol extract, compounds 1, 2, 3, 7 and 11 exhibited potent ability to increase the melanin content and weak stimulative effect on the tyrosinase activity in a concentrationdependent manner. Moreover, compound 2 also presented strong capacity to increase the tyrosinase activity in a concentration-dependent manner. These results indicated that P. longum might be a good natural source of lead compound for skin disorder diseases.
Shawurenine C (1a) and D (1b), a new pair of regioisomeric C 19 -diterpenoid alkaloids, and five known C 19diterpenoid alkaloids (2 -6) were isolated from the aerial part of Delphinium shawurense W. T. Wang. The chemical structures of new compounds were established based on spectroscopic analyses: HR-ESI-MS, and 1D, 2D NMR spectroscopic data. The anti-inflammatory and cytotoxic activities of these diterpenoid alkaloids were also evaluated.
Piper longum is a well‐known spice and traditional medicine. It was revealed to possess anti‐diabetic activity, but few information about its active component and underlying mechanism could be available. In this study, retrofractamides A (1) and C (2) isolated from P. longum showed potent inhibitory activity against PTP1B. Therefore, the potential mechanism was predicted by network pharmacology and molecular docking. PI3K/AKT was obtained as the most remarkable pathway against type 2 diabetes mellitus (T2DM), and AKT1 and GSK3β were yielded as the top two core targets of retrofractamides A (1) and C (2). Molecular docking of compounds with AKT1 and GSK3β showed strong binding affinity between them. Additionally, cellular experiments with a L6 cell model was conducted to further verify the above predictions. Results indicated that retrofractamides A (1) and C (2) exerted anti‐diabetic effect via activating PI3K/AKT pathway, and they promoted glucose consumption, glucose uptake, glycogen synthesis and glycolysis.
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