OBJECTIVE To study the effect of curcumin analog H8 on the cardiac injury of db/db mice, as well as investigating the neurotoxicity of H8 in mice.

METHODS Thirty-two 8-week-old db/db mice were randomly divided into model group, curcumin group(5 mg·kg⁻¹) and H8 low and high dose groups(5, 10 mg·kg⁻¹), and another 8 db/m mice were regarded as normal group, continuous garage for once a day, curcumin and H8 were dissolved in 1% CMC-Na. After 8 weeks of administration, fasting blood glucose(FBG), lactate dehydrogenase(LDH), creatine kinase isoenzyme(CKMB), creatine kinase(CK) and α-hydroxybutyrate dehydrogenase(ALPHA-HBDH) levels were detected; HE staining was used to observe the pathological changes of cardiac tissue, Masson staining was used to observe the degree of fibrosis; Real-time PCR method was used to detect the atrial natriuretic peptide(ANP), brain natriuretic peptide(BNP), COL-1, α-SMA, TGF-β mRNA expression level; Western blotting was used to detect the expression of COL-1, α-SMA, and TGF-β protein in heart tissue. Molecular docking was used to calculate the sites of H8 and TGF-β II receptor by Discovery Studio 2019 tool software. The 48 SPF ICR mice were randomly divided into normal group, H8 low and high dose groups(5, 10 mg·kg⁻¹). After 12 weeks of administration, serum ALT, AST, AST/ALT levels were detected; conduct climbing pole experiment, mice tail suspension experiment to observe whether H8 had neurotoxicity to normal mice. Check respiratory rate, heart rate, blood pressure, and observe whether H8 had physiological toxicity to normal mice.

RESULTS Compared with the normal group, the histopathological changes of HE in model group were found, some of the cardiomyocytes became degenerated and necrotic increased. At the same time, Masson staining result showed that the degree of myocardial fibrosis increased in the model group; serum FBG, LDH, CKMB, CK and ALPHA-HBDH levels increased, the difference was statistically significant(P<0.05); the expression levels of ANP and BNP mRNA in myocardial tissue were increased, and the expression levels of COL-1, α-SMA, TGF-β mRNA and protein were increased, the difference was statistically significant(P<0.01). Compared with model group, the expression levels of ANP and BNP mRNA in myocardial tissue of H8 low and high group decreased, and the expression levels of COL-1, α-SMA, TGF-β mRNA and protein in myocardial tissue inhibited significantly, and the difference was statistically significant(P<0.05 or P<0.01). Molecular docking results indicate that H8 can interact with TGF-β receptor with hydrogen bonds. Compared with the normal group, there were no significant differences in serum ALT, AST, AST/ALT levels, rod climbing conditions and tail suspension time in the administration group. Compared with the normal group, the respiratory rate, heart rate and blood pressure of mice in the administration group were not significantly different.

CONCLUSION Curcumin and its analogue H8 can improve the heart injury of db/db mice and have no obvious neurotoxic effect on experimental mice.