Isolation of Secondary Metabolites and Preparation of Herbal Formulation for Cardioprotection from Paeonia Emodi and Solanum Xanthocarpum

Abstract

In this study the crude methanolic extract of Paeonia emodi (P. emodi) and Solanum xanthocarpum (S. xanthocarpum), (Pe-CR, Sx-CR) and its subsequent fractions, like n-hexane (Pe-HEX, Sx-HEX), chloroform (Pe-CF, Sx-CF), ethyl acetate (Pe-EA, Sx-EA) and aqueous (Pe-AQ, Sx.AQ) were initially screened for its cardioprotective potentials at a dose of 500 mg/kg in mice. The Isoproterenol hydrochloride (ISO) was used to induce myocardial infarction (MI) in mice. During MI, the enzymes such as Alanine Amino Transferase (ALT), Aspartate Amino Transferase (AST), Lactate Dehydrogenase (LDH) and Creatine Phosphokinase (CPK) leaks from the damaged cardiac cells into blood which are important markers of cardiac injury. The effect of plant extracts on the level of these biomarkers was determined in mice and Pe-EA was found most active by reducing the serum levels of ALT, AST, CPK and LDH to 71.53 ± 1.37, 78.50 ± 1.14, 84.66 ± 1.92 and 243.66 ± 6.17 which are comparable with standard group. The Pe-EA was further tested at lower doses of 75, 150 and 300 mg/kg for its cardioprotective potentials and a dose of 300mg/kg significantly reduced the serum levels of ALT (p < 0.001), AST (p < 0.001), CPK (p< 0.05) and LDH (p < 0.001) as compared to ISO treated group. In order to understand the underlying mechanism, the same fraction was subjected to relevant in-vivo and in-vitro experiments including anti-hyperlipidemic, anti-oxidant, membrane stabilization, thrombolytic, calcium channel blocking and DNA ladder assay. As Total Cholesterol (TC), Triglycerides (TG) and low density lipoprotein cholesterol (LDL) plays major role in hyperlipidemia and results in progression of atherosclerotic plaque which leads to MI. In this study Poloxamer-407 (P-407) was used for induction of hyperlipidemia and Pe-EA fraction was tested at a dose of 75, 150 and 300 mg/kg in hyperlipidemic mice. The Pe-Ea exhibited prominent effect 300mg/kg dose by reducing the serum levels of TC, TG and LDL to 113.33 ± 3.32, 121.50 ± 4.58 and 57.20 ± 3.33 mg/dl respectively, almost similar to the standard drug used. To know the possible antihyperlipidemic mechanism, Pe-EA was tested against pancreatic lipase, cholesterol esterase and HMG-CoA reductase at a concentration of 125, 250 and 500 µg/mL. The HMG-CoA reductase inhibitory activity at concentration of 500 µg/mL demonstrated best potential (67.04 ± 1.12%), which suggests its mechanism is same like statins used in treating hyperlipidemia. Similarly, the Pe-EA was tested for the membrane stabilization activity at different doses which showed good stabilizing potential with an IC50 value of 850 µg/mL. Platelets aggregation and formation of thrombus leads to permanent obstruction of blood flow in MI. In order to know thrombolytic potential of Pe-EA, it was screened for thrombolytic effect and was tested at several concentrations where the highest thrombolytic potential of 53.22% was observed at highest concentration (800µl). Recent studies reported that elevated cytosolic free calcium overload majorly contributes to MI. Calcium channel blocking effect of Pe-EA was investigated at different concentrations on isolated rabbit jejunum which exhibited best activity at a dose of 1 mg/mL. Similarly, DNA damage of cardiac myocytes occurs during MI and DNA fragmentation assay was carried out to check the DNA protection ability of Pe-EA. The Pe-EA fraction protected DNA from damaging effects during MI. Bioguided isolation of compounds was carried out from the same fraction through column chromatography. Different subfractions were obtained which were screened for cardioprotective potential. Among all, subfraction Pe-EA 40 exhibited best cardioprotective potential by reducing serum levels of biomarkers responsible for MI. The Pe-EA 40 was used for the synthesis of gold nanoparticles (Pe-EA40-AuNPs) and was screened for cardioprotective potential. Pe-EA 40 was also used for the preparation of herbal formulation (Tablets) and tested in rabbits for cardioprotective potential at optimized dose (80 mg/kg). It decreased the serum levels of ALT, AST, CPK and LDH to 53.37 ± 1.83, 47.65 ± 1.29, 145.34 ± 1.28 and 248.83 ± 4.13 IU/L as compared to group treated with ISO only. Pure compounds were isolated from Pe-EA 40 on the bases of good cardioprotective potential. The isolated compounds IB-1, IB-2 and IB-3 were screened for cardioprotective potential. The compound IB-1 (10 mg/kg) showed significant cardioprotective potential and lowered the serum levels of ALT, AST, CPK and LDH to 63.42 ± 1.72, 78.59± 1.34, 84.00 ± 2.66 and 229.54 ± 4.76 IU/L. Results of the current research work provides evidence that Pe-EA produced its cardioprotective potential via multiple mechanisms including antihyperlipidemic, antioxidant, membrane stabilizing, thrombolytic, calcium channel blocking and DNA protective effect. The cardioprotective effect of Pe-EA was increased two folds upon its formulation in gold nanoparticles (Pe-EA 40-AuNPs). It can be concluded from this study that P. emodi has the cardioprotective potential and can be used for the management and treatment of MI