Labdane-type Diterpenes fromPinus eldaricaNeedles and Their Anti-Helicobacter pyloriActivity

Abstract

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.

N-Hydroxy-Phe-Phe, a new dipeptide, and cytotoxic macrocyclic trichothecenes from the lethal toxic mushroom Podostroma cornu-damae

“…These conformers were subjected to geometry optimization using TmoleX 4.3.2 software, with density functional theory (DFT) settings of B3-LYP/6-31+G(d,p). 23…”

“…This function utilizes parameters such as σ , which represents the bandwidth at a height of 1/ e , and Δ E i and R i , corresponding to the excitation energy and rotatory strength for transition i , respectively. 23 For this particular study, the value of σ was set to 0.2 eV. By considering the Boltzmann populations of conformers, the excitation energies and rotational strengths of the ECD spectra were calculated.…”

“…These conformers were subjected to geometry optimization using TmoleX 4.3.2 software, with density functional theory (DFT) settings of B3-LYP/6-31+G(d,p). 23 Chemical shifts for 1a/1b were determined by calculating the magnetic shielding tensors and applying the following equation:…”

Determination of the Absolute Configuration of Secondary Alcohols in a Compound Mixture via the Application of Competing Enantioselective Acylation Coupled with LC/MS Analysis

“…For further analysis in this study, the chosen conformers were limited to those falling within a 2 kJ mol −1 range in the MMFF force field. Subsequently, these conformers underwent geometry optimization using TmoleX 4.3.2 software, employing density functional theory (DFT) settings of B3-LYP/6-31+G(d,p) [ 29 ].…”

Identification of Obscurolide-Type Metabolites and Antifungal Metabolites from the Termite-Associated Streptomyces neopeptinius BYF101

“…ECD Calculations and DP4+ Analysis. The experimental procedures and methods used were previously reported, 19,39 and the detailed experimental procedures used are described in the Supporting Information.…”