Gossypol Acetic Acid Attenuates Cardiac Ischemia/Reperfusion Injury in Rats via an Antiferroptotic Mechanism

Myocardial ischemia/reperfusion (I/R) injury has been associated with ferroptosis, which is characterized by an iron-dependent accumulation of lipid peroxide to lethal levels. Gossypol acetic acid (GAA), a natural product taken from the seeds of cotton plants, prevents oxidative stress. However, the effects of GAA on myocardial I/R-induced ferroptosis remain unclear. This study investigated the ability of GAA to attenuate I/R-induced ferroptosis in cardiomyocytes along with the underlying mechanisms in a well-established rat model of myocardial I/R and isolated neonatal rat cardiomyocytes. H9c2 cells and cardiomyocytes were treated with the ferroptosis inducers erastin, RSL3, and Fe-SP. GAA could protect H9c2 cells against ferroptotic cell death caused by these ferroptosis inducers by decreasing the production of malondialdehyde and reactive oxygen species, chelating iron content, and downregulating mRNA levels of Ptgs2. GAA could prevent oxygen-glucose deprivation/reperfusion-induced cell death and lipid peroxidation in the cardiomyocytes. Moreover, GAA significantly attenuated myocardial infarct size, reduced lipid peroxidation, decreased the mRNA levels of the ferroptosis markers Ptgs2 and Acsl4, decreased the protein levels of ACSL4 and NRF2, and increased the protein levels of GPX4 in I/R-induced ex vivo rat hearts. Thus, GAA may play a cytoprotectant role in ferroptosis-induced cardiomyocyte death and myocardial I/R-induced ferroptotic cell death.

Identification of natural products and their derivatives as promising inhibitors of protein glycation with non-toxic nature against mouse fibroblast 3T3 cells

<p>This study was performed to identify new inhibitors of protein glycation <em>in vitro</em>. Protein glycation is one of the major causes of late diabetic complications. In this study, terpenoids and alkaloids, isolated from different medicinal plants, along with their derivatives, were evaluated for their antiglycation activity <em>in vitro,</em> while MTT assay on mouse fibroblast 3T3 cells was used to assess their potential cytotoxicity. Among the tested compounds, gossypol (2,2′-<em>bis</em>-(formyl-1,6,7-trihydroxy-5-isopropyl-3-methylnaphthalene) (<strong>1</strong>), isolated from<em> Gossypium herbaceum, </em>and its derivatives,<em> </em>gossypol acetic acid (<strong>2</strong>), gossypolidene- 4-aminoantipyrine (<strong>4</strong>), and gazolidone (<strong>6</strong>), showed a potent antiglycation activity (IC₅₀ &lt; 16 <em>µ</em>M), while gossypolidene-4-aminoantipyrine (<strong>5</strong>) showed a significant antiglycation activity with IC₅₀value 82.934±2.924<em> µ</em>M, in BSA-fluorescence assay. Alkaloid, noscapine (3S)-6,7-Dimethoxy-3-[(5R)-4-methoxy-6-methyl-5,6,7,8-tetrahy-dro-1,3-dioxolo[4,5-g]isoquinolin-5-yl] isobenzofuran-1(3<em>H</em>)-one (<strong>7</strong>), isolated from <em>Papaver somniferum, N</em>-nitrosoaphyllinic acid (<strong>9</strong>), a derivative of alkaloid aphylline<em>, </em>and 2<em>H</em>-quinolizine, octahydro salt (<strong>11</strong>), a salt of alkaloid lupinine, exhibited significant inhibition activity with<em> </em>IC₅₀values 152.662±5.432, 393.758 ±4.001 µM and 110.203±4.816µM, respectively. Similarly, compounds<strong> </strong>gossypolidene thiocarbamide (<strong>3</strong>), deoxypeganine hydrochloride (<strong>8</strong>)<strong>, </strong>lupinine (<strong>10</strong>) and cytisine (<strong>12</strong>) showed moderate inhibition with IC₅₀ values of 401.865 ±18.450, 863.322 ±6.415, 712.176±7.745, and 728.462±2.331<em> </em>µM, respectively. The results were compared with the standard antiglycation agent, rutin (<strong>13</strong>) (IC₅₀=98.012±2.030 µM).</p>Cellular cytotoxicity assay showed only gossypol acetic acid (<strong>2</strong>) and gossypolidene thiocarbamide (<strong>3</strong>) as somewhat toxic to 3T3 (mouse fibroblast) cells with IC₅₀values<em> </em>2.07 ±0.61 and 5.00 ±1.89 µM, respectively. Cycloheximide was used as a standard in this assay with IC₅₀ value 0.3 ± 0.089 μM

Gossypol Acetic Acid Prevents Oxidative Stress-Induced Retinal Pigment Epithelial Necrosis by Regulating the FoxO3/Sestrin2 Pathway

The late stage of dry age-related macular degeneration (AMD), or geographic atrophy (GA), is characterized by extensive retinal pigment epithelial (RPE) cell death, and a cure is not available currently. We have recently demonstrated that RPE cells die from necrosis in response to oxidative stress, providing a potential novel mechanism for RPE death in AMD. In this study, we screened U.S. Food and Drug Administration-approved natural compounds and identified gossypol acetic acid (GAA) as a potent inhibitor of oxidative stress-induced RPE cell death. GAA induces antioxidative response and inhibits accumulation of excessive reactive oxygen species in cells, through which it prevents the activation of intrinsic necrotic pathway in response to oxidative stress. Sestrin2 (SESN2) is found to mediate GAA function in antioxidative response and RPE survival upon oxidative stress. Moreover, Forkhead box O3 transcription factor (FoxO3) is further found to be required for GAA-mediated SESN2 expression and RPE survival. Mechanistically, GAA promotes FoxO3 nuclear translocation and binding to theSESN2enhancer, which in turn increases its transcriptional activity. Taken together, we have identified GAA as a potent inhibitor of oxidative stress-induced RPE necrosis by regulating the FoxO3/SESN2 pathway. This study may have significant implications in the therapeutics of age-related diseases, especially GA.