Pinus eldarica is a medicinal tree used in traditional herbal medicine for the treatment of bronchial asthma and various skin diseases. As part of our ongoing search for bioactive phytochemicals with novel structures in natural products, we performed a phytochemical analysis of the methanol (MeOH) extract from P. eldarica needles collected in Iran. Phytochemical investigation of the MeOH extract, aided by liquid chromatography–mass spectrometry-based analysis, resulted in the isolation and identification of three labdane-type diterpenes ( 1–3 ), including a new and relatively unique norlabdane-type diterpene with a peroxide moiety, eldaricoxide A ( 1 ). The chemical structures of the isolated labdane-type diterpenes were elucidated by analyzing the spectroscopic data from 1D and 2D NMR and high-resolution electrospray ionization-mass spectrometry. The absolute configuration of eldaricoxide A ( 1 ) was established by employing a computational method, including electronic circular dichroism calculation and specific optical rotation. An anti- Helicobacter pylori test was conducted, where compound 3 exhibited the most potent antibacterial activity against H. pylori strain 51, inducing 72.7% inhibition (MIC 50 value of 92 μM), whereas eldaricoxide A ( 1 ) exhibited moderate antibacterial activity against H. pylori strain 51, inducing 54.5% inhibition (MIC 50 value of 95 μM). These findings demonstrated that the identified bioactive labdane-type diterpenes 1 and 3 can be applied in the development of novel antibiotics against H. pylori for the treatment of gastric and duodenal ulcers.

Salix pseudolasiogyne (Salicaceae), the “weeping willow,” has been used in traditional Korean medicine to treat pain and fever due to its high concentrations of salicylic acid and salicin. The present study investigated bioactive compounds from S. pseudolasiogyne twigs to discover bioactive natural products. Phytochemical investigation of the ethanol (EtOH) extract of S. pseudolasiogyne twigs followed by liquid chromatography–mass spectrometry (LC/MS)-based analysis led to the isolation of two salicin derivatives, salicortinol and salicortin, the structures of which were determined by interpretation of their NMR spectra and data from the LC/MS analysis. To the best of our knowledge, this is the first report of salicortinol isolated from S. pseudolasiogyne. The isolated compounds were evaluated for their anti-adipogenic effects in 3T3-L1 cells. Both salicortinol and salicortin were found to significantly inhibit adipocyte differentiation in 3T3-L1 cells. In particular, salicortin exhibited a strong inhibitory effect on lipid accumulation. Furthermore, salicortin inhibited the expression of lipogenic and adipogenic transcription factors, including FASN, FABP4, C/EBPα, C/EBPβ, and PPARγ, without inducing cytotoxicity. These results suggest that salicortin could be a potential therapeutic compound for the prevention or treatment of metabolic disorders such as obesity.