Eun-Seok Park1, Jun Chul Kang1, Yong Chang Jang1, Jong Seok Park2, Shin Yi Jang3, Dae-Eun Kim4, Bokyung Kim5, Hwa-Sup Shin6. 1. Department of Biomedical Chemistry, College of Biomedical and Health science, Konkuk University, 322 Danwol-Dong, Chungju 380-701, Chungbuk, Republic of Korea. 2. Department of Biomedical Laboratory Science, Taegu Health College, Taegu 702-722, Republic of Korea. 3. Cardiovascular Imaging Center, Samsung Medical Center, Seoul 135-710, Republic of Korea. 4. Department of Biomedical Laboratory Science, Kyungbok University, Pochen 487-717, Republic of Korea. 5. Department of Physiology, Institute of Functional Genomics, Konkuk University School of Medicine, Chungju 380-701, Chungbuk, Republic of Korea. 6. Department of Biomedical Chemistry, College of Biomedical and Health science, Konkuk University, 322 Danwol-Dong, Chungju 380-701, Chungbuk, Republic of Korea. Electronic address: hsshin@kku.ac.kr.
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE: Many studies have emphasized that flavonoids, found in various fruits, vegetables, and seeds, as well as tea and red wine, have potential health-promoting and disease-preventing effects. Rhamnetin is a flavonoid that exhibits antioxidant capabilities. However, little is known about its effect on cardiac myocytes under oxidative stress and the underlying mechanisms. MATERIALS AND METHODS: H9c2 cardiomyoblast cells were subjected to H2O2, to study the protective effect of rhamnetin on cell viability, apoptosis, and ROS production. Signaling proteins related to apoptosis, survival, and redox were analyzed by Western blot. Furthermore, the mRNA expressions of SIRTs were tested by real time-polymerase chain reaction (PCR). RESULTS: We investigated the protective effects of rhamnetin against H₂O₂-induced apoptosis in H9c2 cardiomyoblasts. Rhamnetin protected cells against H₂O₂-induced cell death without any cytotoxicity, as determined by the XTT assay, LDH assay, TUNEL assay, Hoechst 33342 assay, and Western blot analysis of apoptosis-related proteins. Rhamnetin also enhanced the expression of catalase and Mn-SOD, thereby inhibiting production of intracellular ROS. Furthermore, rhamnetin recovered the H₂O₂-induced decrease in phosphorylation of Akt/GSK-3β and MAPKs (ERK1/2, p38 MAPK, and JNK) and pretreatment with their inhibitors, attenuating the rhamnetin-induced cytoprotective effect. Further studies with real time-PCR and a sirtuin inhibitor showed that cardioprotection by rhamnetin occurred through induction of SIRT3 and SIRT4. CONCLUSIONS: Taken together, these results suggest that rhamnetin may have novel therapeutic potential to protect the heart from ischemia-related injury.
ETHNOPHARMACOLOGICAL RELEVANCE: Many studies have emphasized that flavonoids, found in various fruits, vegetables, and seeds, as well as tea and red wine, have potential health-promoting and disease-preventing effects. Rhamnetin is a flavonoid that exhibits antioxidant capabilities. However, little is known about its effect on cardiac myocytes under oxidative stress and the underlying mechanisms. MATERIALS AND METHODS: H9c2 cardiomyoblast cells were subjected to H2O2, to study the protective effect of rhamnetin on cell viability, apoptosis, and ROS production. Signaling proteins related to apoptosis, survival, and redox were analyzed by Western blot. Furthermore, the mRNA expressions of SIRTs were tested by real time-polymerase chain reaction (PCR). RESULTS: We investigated the protective effects of rhamnetin against H₂O₂-induced apoptosis in H9c2 cardiomyoblasts. Rhamnetin protected cells against H₂O₂-induced cell death without any cytotoxicity, as determined by the XTT assay, LDH assay, TUNEL assay, Hoechst 33342 assay, and Western blot analysis of apoptosis-related proteins. Rhamnetin also enhanced the expression of catalase and Mn-SOD, thereby inhibiting production of intracellular ROS. Furthermore, rhamnetin recovered the H₂O₂-induced decrease in phosphorylation of Akt/GSK-3β and MAPKs (ERK1/2, p38MAPK, and JNK) and pretreatment with their inhibitors, attenuating the rhamnetin-induced cytoprotective effect. Further studies with real time-PCR and a sirtuin inhibitor showed that cardioprotection by rhamnetin occurred through induction of SIRT3 and SIRT4. CONCLUSIONS: Taken together, these results suggest that rhamnetin may have novel therapeutic potential to protect the heart from ischemia-related injury.