Protective effects of Labisia pumila var. alata on biochemical and histopathological alterations of cardiac muscle cells in isoproterenol-induced myocardial infarction rats

Abstract

The study was designed to evaluate the cardioprotective effects of the standardized aqueous and 80% ethanol extracts of Labisia pumila var. alata (LPva) in isoproterenol (ISO)-induced myocardial infarction (MI) in rats. The extracts were administered to Wistar rats orally for 28 days with three doses (100, 200 and 400 mg/kg of body weight) prior to ISO (85 mg/kg)-induced MI in two doses on day 29 and 30. The sera and hearts were collected for biochemical and histopathological analysis after the rats were sacrificed 48 h after the first induction. The main components of the extracts, gallic acid, alkylresorcinols and flavonoids were identified and quantitatively analyzed in the extracts by using a validated reversed phase HPLC method. The extracts showed significant protective effects as pretreated rats showed a significant dose-dependent decrease (p < 0.05) in cardiac enzyme activities, i.e., cardiac troponin I (cTnI), creatine kinase MB isoenzyme (CK-MB), lactate dehydrogenase (LDH), alanine transaminase (ALT) and aspartate transaminase (AST), when compared with ISO-control rats. There were significant rises (p < 0.05) in the activity of oxidase enzymes, i.e., glutathione peroxide (GPx), catalase (CAT) and superoxide dismutase (SOD) of the pretreated rats, when compared with ISO-control group. Histopathological examination showed an improvement in membrane cell integrity in pre-treated rats compared to untreated rats. The major components of LPva extracts can be used as their biomarkers and contributed to the cardioprotective effects against ISO-induced MI rats.

Figure 1

Chemical structures of 5-(Z-nonadec-14-enyl)resorcinol (1) and demethylbelamcandaquinone B (2).

Figure 2

RP-HPLC chromatogram of the 80% ethanol extract of Labisia pumila var. alata at 280 nm (A) and 350 nm (B), for identification and quantification of 5-(Z-nonadec-14-enyl)resorcinol (compound 1) and demethylbelamcandaquinone B (compound 2), gallic acid, rutin and myricetin. RP-HPLC chromatogram of the aqueous extract (C) of Labisia pumila var. alata at 280 nm for identification and quantification of gallic acid.

Figure 2

RP-HPLC chromatogram of the 80% ethanol extract of Labisia pumila var. alata at 280 nm (A) and 350 nm (B), for identification and quantification of 5-(Z-nonadec-14-enyl)resorcinol (compound 1) and demethylbelamcandaquinone B (compound 2), gallic acid, rutin and myricetin. RP-HPLC chromatogram of the aqueous extract (C) of Labisia pumila var. alata at 280 nm for identification and quantification of gallic acid.

Figure 3

Effect of the aqueous and 80% ethanol extracts of Labisia pumila var. alata at different concentrations on serum troponin I (cTnI) and CK-MB isoenzyme in normal control and experimental myocardial infarction rats. ISO = isoproterenol, Pro = propranolol. ^a Significantly different to isoproterenol-induced (negative control) group at p < 0.05; ^b Significantly different to normal group at p < 0.05; ^c Significantly different to propranolol (positive control) group at p < 0.05.

Figure 4

Effect of the aqueous (AqELP) and 80% ethanol (EtELP) extracts of Labisia pumila var. alata on histopathological changes, (A) control (normal), (B) ISO (negative control), (C) propranolol 10 mg/kg (positive control), (D): AqELP 100 mg/kg, (E) AqELP 200 mg/kg, (F) AqELP 400 mg/kg, (G): EtELP 100 mg/kg, (H): EtELP 200 mg/kg and (I): EtELP 400 mg/kg. Heart tissues (4 µm thickness) were stained with hematoxylin and eosin and visualized under light microscope at ×10 magnification.