Protective effect of Portulaca water extract on the myocardial mitochondria of aging model mice induced by D-galactose

Qin OU; Xiaodong WEI; Dan WANG; Pengxia ZHANG

ABSTRACT

BACKGROUND:

Mitochondria are not only the important place for consuming oxygen and producing free radical, but also an aggressive target place by endogenous free radical. The changes of structure and function of mitochondria will be take place with aging. Portulaca (Portulaca oleracea L.) is usually called as the macrobiotic vegetable. Portulaca is eutrophic and anti-free radical. It is worth exploring whether the anti-aging action of Portulaca is correlated with its protection on myocardial mitochondria.

OBJECTIVE:

To observe the effects of the Portulaca water extract on the lipid peroxidation myocardial mitochondrial phospholipid and the activity of respiratory chain enzymes in aging model mice, and analyze the pathway of protective effect on myocardial mitochondria.

DESIGN:

A completely randomized design and controlled animal experiments.

SETTING:

Department of Biochemistry, School of Basic Medical Sciences, Jiamusi University.MATERIALS ①The animals were raised and the experiments were completed in the Experimental Animal Center of Jiamusi University from March 2003 to August 2004. The animals were killed, hearts were removed and mitochondria were harvested in the Department of Biochemistry; The indexes were determined in the Department of Biochemistry,experimental center and the College of Chemistry and Pharmacology. ② Thirty healthy adult Kunming mice (either male or female) were divided into 3 groups by random feeling ball

method:

young control group (n =8), aging model group (n =11) and Portulaca treated group (n =11). ③ Portulaca was offered by Jiamusi Institute of Chinese Herbs, and appraisement by the Department of Crude Drug of Jiamusi University. Portulacas were made into water extract (crud drug 1 kg/L). Standard cardiolipin was offered by Sigma Company (USA), kits for malonaldehyde (MDA) and the activity of Ca2+-adenosine triphosphatase (Ca2+-ATPase) were provided by Nanjing Jiancheng Bioengineering Institute.

METHODS:

①The aging model mice were daily given subcutaneous injection of D-galactose on the nape back (100 mg/kg);Besides, mice in the Portulaca treated group were perfused with the Portulaca water extract (13 g/kg per day) for 30 days continuously, and those in the young control group were daily given subcutaneous injection of saline of the same volume for 30 days continuously. All the mice were killed on the next day after the last administration, and then hearts were quickly removed and reserved. ② Mitochondria were prepared according to the method provided by Nanjing Jiancheng Bioengineering Institute. The MDA content and the activities of Ca2+-ATPase were determined following the illustration of the kit. The relative amount of cardiolipin in phospholipid on the mitochondrial membrane was determined with the high-performance liquid chromatography. The activities of Complex Ⅰ and Complex Ⅱ +Ⅲ were measured by Wu's method. ③ The differences of measurement data were compared with the analysis of variance and t test.MAIN OUTCOME

MEASURES:

① Composition of phospholipid on myocardial mitochondrial membrane of mice; MDA content, activities of Complex Ⅰ, Complex Ⅱ +Ⅲ and Ca2+-ATPase in mitochondria.

RESULTS:

All the 30 mice were involved in the final analysis of results. ① MDA contents in myocardial mitochondria It was significantly higher in the aging model group [(8.827±0.873) μ mol/g] than in the young control group and Portulaca treated group [(5.194±0.674), (5.901±0.743) μmol/g, t =7.48, 7.22, P ＜ 0.01]. ② Relative amounts of cardiolipin and the activities of Ca2+-ATPase in myocardial mitochondria Those were obviously lower in the aging model group [cardiolipin(0.156±0.012) mg/g, (1.267±0.167) μkat/g] than in the young control group and Portulaca treated group [(0.190±0.022),(0.184±0.021) mg/g; Ca2+-ATPase (1.870±0.254), (1.780±0.237) μ kat/g, t =3.23,5.61, P ＜ 0.05-0.01]. ③ Activities of Complex Ⅰ and Complex Ⅱ + Ⅲ in myocardial mitochondria Those were significantly lower in the aging model group [(3.517±0.383), (20.217±2.200) μkat/g] than in the young control group and Protulaca treated group [Complex Ⅰ(6.817±0.600), (6.067±0.750) μ kat/g; Complex Ⅱ + Ⅲ (56.400±4.933), (51.800±4.217) μkat/g, t =5.74,9.86, P ＜ 0.01].

CONCLUSION:

The Portulaca water extract has the protective effect on myocardial mitochondria by inhibiting the lipid peroxidation in myocardial mitochondria and enhancing the activities of respiratory chain enzymes.