The research team, whose earlier work examined fatty acids and acyl glycerides, focused this time on five model complex lipids that represent the major functional classes of lipids in living organisms. These were β-carotene, a carotenoid antioxidant and precursor of vitamin A; cholesterol, a sterol that stiffens membranes and serves as the scaffold for steroid hormones; sphingosine and ceramide, two sphingolipids central to membrane structure and to signalling pathways that govern cell proliferation and programmed cell death; and phosphatidylcholine, the phospholipid that forms the backbone of most cell membranes and of pulmonary surfactant. Because these molecules co-constitute biological membranes, transport fat-soluble vitamins, activate certain enzymes and underpin steroid biosynthesis, any field-induced change in their structure could, in principle, ripple through an entire organism.

Methodologically, the study is a work of numerical simulation rather than laboratory measurement. The authors computed the behaviour of each lipid under static magnetic fields of 0, 0.1, 1, 10 and 100 arbitrary magnetic field units, where a single unit exceeds 1000 tesla, a flux density far beyond anything generated by conventional magnets and comparable only to the most extreme laboratory fields. The computations were performed in silico, in what the researchers describe as a computer vacuum, using advanced quantum-chemical procedures that follow those established in their former paper. For each molecule and each field strength, the simulations tracked the heat of formation, the dipole moment, the electric charge density on atoms directly participating in biological reactivity, and the lengths of the bonds between those atoms. When a field proved strong enough to generate a radical by stretching a bond to breaking point, the analysis shifted to the atoms carrying unpaired electrons, since such radical species behave very differently from intact molecules.

The headline result concerns molecular stability. Across all five lipids, the heat of formation became steadily less negative as the applied flux density increased, a clear computational signature of destabilization. β-carotene went from a heat of formation of minus 158 kilojoules per mole in zero field to minus 81 at 100 units, while ceramide climbed from minus 1659 to minus 985 and sphingosine from minus 1364 to minus 817. Accompanying this trend, the dipole moment of every molecule rose with field strength, indicating that the bonds were elongating and the molecules were becoming easier to polarize. The authors interpret this growing polarity as the principal mechanism of destabilization, with the effect intensifying in the order β-carotene, cholesterol, phosphatidylcholine, sphingosine, ceramide. Notably, the ordering by dipole moment change was slightly different, suggesting that bond polarization is not the only process at work.

The most striking survivor was β-carotene. It was the sole molecule among the five that endured exposure to fields of 10 and 100 units without suffering radical cleavage of any valence bonds. The remaining four lipids all generated radicals once the field reached 10 units. This resilience likely reflects the architecture of β-carotene, a hydrocarbon whose eleven conjugated double bonds form an extended electron system that can absorb and redistribute field-induced perturbations. Yet even this robust molecule was not untouched. The simulations showed that the lengths of its double bonds increased with flux density, and, curiously, the effect was confined to bonds located in the middle of the conjugated chain, where chemically all bonds should be nearly identical. Some bonds became more polar while others lost their original polarity relative to the field-free molecule.

For β-carotene, these subtle changes matter because its antioxidant function depends on the whole conjugated double bond system trapping triplet oxygen through a radical mechanism, a process stimulated by low polarization of the bonds that accept oxygen. Meanwhile, the enzymatic conversion of β-carotene into vitamin A relies on oxygen addition across specific double bonds following an ionic mechanism, which is stimulated by increased bond polarity. The simulations showed that the polarity of the C25=C26 bond, the site cleaved by β,β-carotene-9′,10′-mono-oxygenase to yield two molecules of vitamin A, increased at 0.1, 1 and 10 units before dropping dramatically at 100. The C31=C32 bond, split by β,β-carotene 15,15′-mono-oxygenase to produce β-apo-10′-carotenal and β-ionone, lost polarity at 0.1, 10 and 100 units but gained polarity at 1 unit. In practical terms, this means that manipulating the applied flux density could either stimulate or inhibit the conversion of dietary carotenoid into vitamin A, and could shift where in the molecule the antioxidant reaction with triplet oxygen takes place.

The sphingolipids told a different story. Sphingosine must first be enzymatically phosphorylated at its O1 atom before it can be converted into the signalling lipid sphingosine-1-phosphate and, ultimately, into sphingomyelin. The simulations showed that a field of 0.1 units had no effect on the phosphorylation reaction, which is stimulated by a high negative charge at O1, while exposure to 1 unit slightly inhibited it. At 10 and 100 units, sphingosine was converted into radicals, with the homolytic cleavage sites identified in the charge and bond-length tables. Ceramide, the sphingosine bearing a long fatty acid acylated onto its amino group, proved only slightly modulated by the field. The negative charge on its reacting O8 atom decreased marginally at 0.1 units and increased slightly at 1 unit, but higher flux densities produced radicals by stretching the O8-H9 bond from 0.950 angstroms in zero field to 2.142 at 10 units and 2.508 at 100 units, alongside additional cleavages at 100 units.

Cholesterol, whose cyclopentaphenanthrene moiety is shared by all steroid hormones, showed a flux-density-dependent duality. At 0.1 units the polarity of its C2=C14 double bond subtly decreased, which would stimulate its role as a lipid antioxidant, while at 1 unit the polarity of that bond increased, inhibiting the antioxidant function. Simultaneously, the negative charge density on the O1 hydroxyl oxygen increased at both 0.1 and 1 units, stimulating the reactivity of the primary hydroxyl group that anchors cholesterol into membranes and serves as the enzymatic handle for steroidogenesis. At 10 and 100 units, radical cleavage of certain bonds set in, with the C1-O27 bond stretching from 1.430 angstroms in zero field to 2.162 at 10 units and 3.032 at 100 units.

Phosphatidylcholine proved the most enzymatically responsive of the five. The molecule carries three distinct reaction sites, each targeted by a different phospholipase enzyme, and the hydrolytic action of these enzymes is stimulated by high positive charge density on the phosphorus atom P16 or, in the case of phospholipase B, on the C3 atom. The simulations identified that fields of 0.1 and 1 units stimulated all three enzymatic hydrolyses, raising the positive charge on P16 from 1.731 in zero field to 1.787 at 0.1 units and 1.891 at 1 unit. Regardless of which catalysing enzyme was employed, the static magnetic field enhanced the breakdown of this membrane phospholipid. At 10 and 100 units, radical generation took over, with the C15-H51 bond stretching to 2.597 angstroms at 10 units and 3.965 at 100 units.

The authors conclude that static magnetic fields destabilize complex lipids to an extent that depends on the applied flux density, and that manipulating the field strength offers either inhibition or stimulation of the biological functions of the molecules under study. β-carotene’s antioxidant behaviour is fairly sensitive to the field, whereas sphingosine, ceramide and cholesterol show only slight responses at low flux densities. The researchers caution that the presented results concern only changes in selected substrates, while all bioprocesses also involve enzymes, which are themselves exposed to the field; they plan to address that problem in subsequent works. Beyond its implications for assessing potential risks to living organisms, the team notes that the findings could interest developers of novel biomedical and food-application materials and systems, where controlled application of static magnetic fields of varying densities might offer a way to stimulate or inhibit specific processes or even reroute reaction pathways.

Subject of Research: Potential risk resulting from the influence of static magnetic field upon living organisms. Numerically simulated effects of the static magnetic field upon model complex lipids

Article Title: Potential risk resulting from the influence of static magnetic field upon living organisms. Numerically simulated effects of the static magnetic field upon model complex lipids

Article References: Ciesielski, W., Kołoczek, H., Oszczęda, Z., Oszczęda, W., Soroka, J. A., & Tomasik, P. (2023). Potential risk resulting from the influence of static magnetic field upon living organisms. Numerically simulated effects of the static magnetic field upon model complex lipids. BioRisk, 21, 1-10. https://doi.org/10.3897/biorisk.21.101171

Image Credits: AI Generated

DOI: 10.3897/biorisk.21.101171

Keywords: Potential, risk, resulting, influence, static, magnetic, field, upon, living, organisms, Numerically, simulated