Schisandra chinensis bee pollen's chemical profiles and protective effect against H ₂ O ₂-induced apoptosis in H9c2 cardiomyocytes

Background: Schisandra chinensis (Turcz.) Baill bee pollen extract (SCBPE) is often used as a functional food in China due to its good antioxidant property. However, its chemical compositions and effects on H9c2 cardiomyocytes against H₂O₂-induced cell injury still lacks of reports thus far. This study aimed to characterize the main components of SCBPE and investigate its protective effects against H₂O₂-induced H9c2 cardiomyocyte injury.

Methods: The main components of SCBPE were analyzed via ultraperformance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (UPLC-QTOF MS/MS). The three main nucleosides in SCBPE were quantitatively analyzed via ultraperformance liquid chromatography-diode array detection. Furthermore, the potential mechanism by which SCBPE exerts protective effects against H₂O₂-induced H9c2 cardiomyocyte injury was explored for the first time via cell survival rate measurements; cell morphological observation; myocardial superoxide dismutase (SOD) activity and malondialdehyde (MDA) and glutathione (GSH) level determination; flow cytometry; and quantitative polymerase chain reaction.

Results: Two carbohydrates, three nucleosides, and nine quinic acid nitrogen-containing derivatives in SCBPE were identified or tentatively characterized via UPLC-QTOF MS/MS. The nine quinic acid nitrogen-containing derivatives were first reported in bee pollen. The contents of uridine, guanosine, and adenosine were 2.4945 ± 0.0185, 0.1896 ± 0.0049, and 1.8418 ± 0.0157 μg/mg, respectively. Results of in vitro experiments showed that cell survival rate, myocardial SOD activity, and GSH level significantly increased and myocardial MDA level significantly decreased in SCBPE groups compared with those in H₂O₂ group. Cell morphology in SCBPE groups also markedly improved compared with that in H₂O₂ group. Results indicated that SCBPE protected H9c2 cardiomyocytes from H₂O₂-induced apoptosis by downregulating the mRNA expressions of Bax, cytochrome C, and caspase-3 and upregulating the Bcl-2 mRNA expression.

Conclusions: This study is the first to report that SCBPE could protect against oxidative stress injury and apoptosis in H₂O₂-injured H9c2 cells. Results indicated that the nucleosides and quinic acid nitrogen-containing derivatives could be the main substances that exert protective effects against H₂O₂-induced H9c2 cardiomyocyte injury.

Keywords: H2O2; H9c2 cardiomyocytes; Nucleosides; Protective effect; Quinic acid nitrogen-containing derivatives; Schisandra chinensis bee pollen extract.