NMR-based stability evaluation of (E)-1-(3',4'-dimethoxyphenyl)butadiene (DMPBD) from Zingiber cassumunar Roxb. rhizome.

INTRODUCTION: The active compound (E)-1-(3',4'-dimethoxyphenyl)butadiene (DMPBD) isolated from the rhizomes of Zingiber cassumunar Roxb. has potent anti-inflammatory and anticancer activities. Although DMPBD is one of the promising drug candidates for phytomedicine, its limited stability impedes its widespread use. For the development of new drugs, the assessment of their chemical stability is essential, ensuring they maintain their properties within specified limits throughout the period from production until use. OBJECTIVE: In the present study, we aimed to evaluate the stability of DMPBD under various conditions, including different solvents, temperatures, and lighting conditions, to identify the factors affecting stability and optimize the storage and handling conditions. METHODOLOGY: DMPBD samples subjected to the different conditions tested were monitored by quantitative 1H NMR (qHNMR), using an internal standard for the determination of the absolute quantity of DMPBD as a function of time and the changes thereof within 1 month. RESULTS: Significant decomposition of DMPBD was observed in chloroform-d1, whereas its content remained constant in methanol-d4. The content of DMPBD was maintained upon storage at temperatures below 4°C, both as methanolic solution and in the crude extract. Exposure to light had a slight negative impact on its contents. Some degradation products could be identified as resulting from O2-induced cleavage of the diene moiety. CONCLUSIONS: For pharmacological/therapeutic applications, DMPBD should be stored in the form of the crude extract or as a purified material in methanolic solution. Ideally, the storage temperature should be below 4°C and O2 should be excluded.

Computational Analysis and Biological Activities of Oxyresveratrol Analogues, the Putative Cyclooxygenase-2 Inhibitors.

Polyphenols are a large family of naturally occurring phytochemicals. Herein, oxyresveratrol was isolated from ethanolic crude extracts of Artocarpus lacucha Buch.-Ham., and chemically modified to derive its lipophilic analogues. Biological screening assays showed their inhibitory potency against cyclooxygenase-2 (COX-2) with very low cytotoxicity to the MRC-5 normal cell lines. At the catalytic site of COX-2, docking protocols with ChemPLP, GoldScore and AutoDock scoring functions were carried out to reveal hydrogen bonding interactions with key polar contacts and hydrophobic pi-interactions. For more accurate binding energetics, COX-2/ligand complexes at the binding region were computed in vacuo and implicit aqueous solvation using M06-2X density functional with 6-31G+(d,p) basis set. Our computational results confirmed that dihydrooxyresveratrol (4) is the putative inhibitor of human COX-2 with the highest inhibitory activity (IC50 of 11.50 ± 1.54 µM) among studied non-fluorinated analogues for further lead optimization. Selective substitution of fluorine provides a stronger binding affinity; however, lowering the cytotoxicity of a fluorinated analogue to a normal cell is challenging. The consensus among biological activities, ChemPLP docking score and the binding energies computed at the quantum mechanical level is obviously helpful for identification of oxyresveratrol analogues as a putative anti-inflammatory agent.