PhD Scientific Days 2024

Poster Session R - Pharmaceutical Sciences and Health Technologies 2.

Bioassay-guided Isolation of Antibacterial Clerodane Diterpenes from the Roots of Giant Goldenrod (Solidago gigantea Ait.)

Text of the abstract

Introduction: Plants are widely recognized as a rich source of secondary metabolites exhibiting a vast array of valuable biological activities and diverse chemical structures. Solidago gigantea Ait., commonly known as giant goldenrod, is a plant native to North America that has become an invasive species in certain regions of Europe. Despite its potential, the bioactive compounds abundant in this plant have not been extensively investigated.
Aims: The main objective of this work was to detect, isolate, and characterize the bioactive components present in the ethanol extract obtained from S. gigantea roots. The in vitro antibacterial activity of these isolates was evaluated against Gram-positive Bacillus subtilis bacterium. Additionally, future studies will focus on exploring their antimicrobial effects against phytopathogenic bacteria (e.g. Rhodococcus fascians) and fungi (e.g. Fusarium avenaceum), as well as their enzyme (e.g. lipase, acetylcholinesterase, -glucosidase) inhibitory activity.
Method: High-performance thin-layer chromatography coupled with direct bioautography (HPTLC–DB) was utilized for non-targeted, effect-directed screening of antibacterial components. Successive preparative flash column chromatography and semipreparative high-performance liquid chromatography (RP-HPLC) were employed for fractionation and isolation. The structures of the molecules were elucidated using one- and two-dimensional nuclear magnetic resonance spectroscopy (NMR) and high-resolution tandem mass spectrometry (HRMS/MS).
Results: Seven new cis- and trans-clerodane diterpenes were isolated from the roots of S. gigantea possessing a wide range of structural motifs, such as furan, butenolide (lactone), five-membered cyclic hemiacetal, and isobutyrate. The epimers of a rare, highly oxygenated, tetrasubstituted tetrahydrofuran ring along with angelate moieties in unusual positions were revealed. Their antibacterial activity against Gram-positive B. subtilis bacteria was proved by direct bioautography. The corresponding IC50 values will be determined by in vitro microdilution assays.
Conclusion: After optimizing the antibacterial activity of the isolated compounds they can potentially serve as promising antibacterial agents.
Funding: This study was supported by the National Research, Development and Innovation Office of Hungary (K128921 and SNN139496).