Ginseng Compound Shows Promise Against Cancer and Superbugs in Virtual Screening

A single molecule extracted from the roots of a traditional Chinese medicinal herb may be able to fight cancer and disarm dangerous bacteria at the same time, according to a new computational study published in Discover Chemistry. The compound, known as notoginsenoside L1, is a dammarane-type triterpenoid saponin isolated from Panax notoginseng, the herb better known as sanqi or three-seven root, which has been used in East Asian medicine for centuries. In the study, researcher SaravanaVadivu Arunachalam of Vinayaka Mission’s Research Foundation in Chennai, India, combined quantum mechanical calculations with molecular docking simulations to build the most detailed picture yet of how this molecule behaves electronically and how it might interact with disease-related proteins.

The first stage of the investigation focused on the molecule’s intrinsic structure. Using the Gaussian 09 software package, the geometry of notoginsenoside L1 was optimized at the B3LYP/6-311G(d,p) level of density functional theory, a standard quantum chemical approach that treats electrons with a hybrid exchange-correlation functional. The calculations were performed with water as a solvent through a polarizable continuum model, and the structure was confirmed as a true energy minimum when no negative vibrational frequencies remained. The resulting bond lengths told a coherent chemical story: O–H bonds clustered near 0.96 angstroms, C–H bonds fell between 1.088 and 1.102 angstroms, and C–C single bonds ranged from about 1.517 to 1.602 angstroms, with the elongated cases pointing to steric crowding in the branched triterpenoid framework.

Particularly revealing were the C–O bond lengths. Typical single C–O bonds of alcohols and ether linkages appeared near 1.44 angstroms, but several bonds shortened to around 1.38 angstroms, hinting at partial double-bond character from resonance or conjugation effects. One bond, C52–O54 at 1.21039 angstroms, matched the signature of a true carbonyl double bond, confirming a ketone group within the structure. Together, these measurements established notoginsenoside L1 as a polyfunctional molecule whose chemical reactivity is concentrated at its oxygen-containing sites, precisely the regions most likely to engage in hydrogen bonding with biological targets.

To map where those interactions would occur, the study employed two complementary charge analyses. The molecular electrostatic potential, computed on a Mulliken charge basis, spanned from −0.436 to +0.436 atomic units, painting electron-rich zones in red around the electronegative oxygen atoms and electron-poor zones in green around hydrogen atoms. A more refined analysis based on natural bond orbital charges widened that range to −0.778 to +0.778 atomic units, sharpening the distinction between sites that could accept hydrogen bonds and those positioned to donate them. Because NBO analysis incorporates localized orbital interactions and electron delocalization, it offers a chemically intuitive guide to where a ligand will make or break contacts inside a protein pocket.

The frontier molecular orbital analysis added a thermodynamic dimension to the picture. The highest occupied molecular orbital sat at −8.915 electron volts, describing the molecule’s capacity to donate electrons, while the lowest unoccupied orbital lay at −4.157 electron volts, describing its capacity to accept them. The gap between the two, 4.759 electron volts, falls in an intermediate range that the study interprets as a balance of good kinetic stability with reasonable chemical reactivity. In practical terms, the molecule is neither so inert that it ignores biological partners nor so reactive that it degrades or reacts indiscriminately, a profile well suited to a drug candidate that must survive long enough to reach its targets.

Vibrational calculations reinforced confidence in the structural model. A broad absorption band near 3400 wavenumbers, matched almost exactly by the theoretical prediction of 3399 wavenumbers, corresponded to O–H stretching from the molecule’s many hydroxyl groups. Aliphatic C–H stretching appeared near 2929 wavenumbers, while bands at 1418 and 1374 wavenumbers confirmed the deformation modes of the CH2 and CH3 groups that make up the saturated triterpenoid skeleton. The fingerprint region between 1245 and 1019 wavenumbers was dominated by C–O and C–O–C stretches from the glycosidic linkages and sugar units, the carbohydrate chains that distinguish saponins from simpler terpenoids. The close agreement between calculated and observed frequencies validated the optimized geometry as an accurate representation of the real molecule.

With the electronic portrait complete, the study turned to molecular docking against four carefully chosen proteins. Two were bacterial virulence factors: LuxS from Helicobacter pylori, the enzyme behind AI-2 quorum sensing, the chemical communication system bacteria use to coordinate biofilm formation, and α-hemolysin from Staphylococcus aureus, a pore-forming toxin that punches lethal holes in host cells. The other two were cancer targets: EGFR, the epidermal growth factor receptor whose overactive signaling drives tumor proliferation, and BCL-2, the anti-apoptotic protein that cancer cells rely on to evade programmed cell death. Ligand preparation used PubChem structures processed through Open Babel and AutoDock Tools, while protein structures came from the Protein Data Bank under the identifiers 1J6X, 7AHL, 1M17 and 4LVT.

The docking results revealed a striking asymmetry. Against the bacterial targets, notoginsenoside L1 achieved binding energies of −4.63 kilocalories per mole for LuxS and −5.24 kilocalories per mole for α-hemolysin, with inhibition constants of 405.04 micromolar and 145.21 micromolar respectively. In the LuxS complex, hydrogen bonds formed with residues LYS36, ASN9, ASP24 and ASN4 at distances between 1.596 and 2.929 angstroms, placing the ligand near the enzyme’s active region where it could plausibly disrupt quorum-sensing signaling. In the α-hemolysin complex, hydrogen bonds to ASN188 and ARG200 and a hydrophobic contact with TYR182 suggested the molecule could interfere with toxin activity. Because anti-virulence strategies suppress pathogenicity without killing bacteria outright, they are considered less likely to drive the resistance that plagues conventional antibiotics.

The anticancer results were even more compelling. Against EGFR, the compound recorded a binding energy of −8.31 kilocalories per mole, the strongest of all four targets, with an inhibition constant of 804.06 nanomolar. Hydrogen bonds to GLU738 and THR766, combined with hydrophobic interactions involving LEU834, ARG817 and PHE699, positioned the ligand squarely in the kinase’s ATP-binding pocket, implying it could block phosphorylation and halt the growth signals that fuel tumor expansion. Binding to BCL-2 was more moderate at −4.05 kilocalories per mole, but hydrogen bonds with PHE135, ASP137 and ASN189 along with a hydrophobic contact with TRP185 placed the ligand in the binding groove that regulates apoptosis, suggesting a possible secondary route to cancer cell death. Across all four complexes, stabilization came overwhelmingly from hydrogen bonding and van der Waals forces, with electrostatic contributions minimal.

The physicochemical profile helps explain these results. With a molecular formula of C35H58O13 and a weight of 686.83 grams per mole, notoginsenoside L1 is larger than typical small-molecule drugs, but its 13 hydrogen bond acceptors, 8 donors, moderate flexibility of 7 rotatable bonds and balanced lipophilicity, an iLOGP of 3.37, equip it for rich contact networks inside protein pockets. Its high topological polar surface area of 215.83 square angstroms may limit membrane permeability, a caveat the study implicitly acknowledges by framing the work as a foundation for further development rather than a finished drug. The author emphasizes that these in silico findings, from the DFT-confirmed stability to the multi-target docking scores, position notoginsenoside L1 as a promising multi-target candidate warranting experimental validation, a reminder that one of the oldest remedies in the pharmacopoeia may still hold molecular secrets worth decoding.

Subject of Research: Computational analysis of the molecular structure and protein-binding interactions of the ginseng saponin notoginsenoside L1

Article Title: Deciphering the molecular interactions of notoginsenoside L1 through DFT and multi-target docking

Article References: Deciphering the molecular interactions of notoginsenoside L1 through DFT and multi-target docking. (n.d.). https://doi.org/10.1007/s44371-026-01033-5

Image Credits: AI Generated

DOI: 10.1007/s44371-026-01033-5

Keywords: notoginsenoside L1, Panax notoginseng, density functional theory, molecular docking, EGFR, BCL-2, LuxS, alpha-hemolysin, quorum sensing, anti-virulence, triterpenoid saponins, drug discovery