Exploring the HSA/DNA/lung cancer cells binding behavior of p-Synephrine, a naturally occurring phenyl ethanol amine with anti-adipogenic activity: multi spectroscopic, molecular dynamic and cellular approaches

Abstract

As a phenolic amine, p-Synephrine (SN) is known to exhibit lipolytic properties as well as enhancing energy expenditure, which can be an excellent alternative to ephedra as a dietary supplement. This study aimed to explore the subtle yet profound complex qualities and aspects of the interaction between SN, human serum albumin (HSA), and calf thymus DNA (ctDNA). To achieve a full comprehension on these fine-point distinctions, a nuanced and detail-oriented approach was implemented through a combination of different biophysical methods and molecular dynamics simulation techniques. The fluorescence spectroscopy revealed the binding of SN to HSA that led to the inducement of conformational changes. The quenching constants (KSV) of SN-HSA complex at 298, 303, and 308 K and were evaluated to be 2.95 × 104, 2.21 × 104 and 0.85 × 104 M−1, respectively. The thermodynamic parameters indicated the spontaneous formation of SN-HSA complex along with its regulation through H-bonding and van der Waals forces. The distance between SN and Trp residue of HSA was estimated at 3.91 nm by the Forster’s theory of non-radiative resonance energy transfer. According to CD spectroscopy, the binding of SN to HSA results in stabilization and promotes its functionality. Various spectroscopy methods and viscosity measurements proved the propensity of SN for binding to the grooves of ctDNA. Thermodynamic parameters indicate that the SN binds to DNA via a spontaneous and entropy-driven process that is mainly regulated by hydrophobic interactions. In conformity to the molecular modeling of HSA-SN complex, SN can be located in the active site of HSA and make a firm interaction, while the outcomes of ctDNA-SN interaction also indicated its tendency towards binding in DNA groove. In comparison to normal cells, SN caused a more pronounced reduction in lung cancer cell viability by increasing the expression of Bax and p53 at the mRNA and protein levels. Moreover, the incubation of H460 cells with the IC50 concentration of SN induced a notable decease in mRNA levels of PI3K, AKT, and mTOR, as well as protein levels of PI3Kγ-P110, P-AKT, and P-m TOR. These data indicate the potential of SN in binding with HSA, which reduces the proliferation of lung cancer cells mediated by apoptosis through the down regulation of PI3K/AKT/m TOR signaling pathway.