Planta Med 2008; 74 - SL93
DOI: 10.1055/s-0028-1083973

Inhibition of the L-type calcium channel by a standardised Olea europaea leaf extract: A phytochemical and electrophysiological examination

HW Rauwald 1, A Scheffler 2, B Kampa 1, U Mann 1, S Dhein 2
  • 1Department of Pharmaceutical Biology, Leipzig University, Johannisallee 21–23, 04103 Leipzig, Germany
  • 2Clinic for Cardiac Surgery, Leipzig University, Strümpellstraße 39, 04289 Leipzig, Germany

Cardiovascular diseases are still the leading causes of morbidity and mortality in industrialized countries with hypertension being one of the main risk factors [1]. In Southern Europe Olea europaea leaves are known as a folk remedy for this ailment [2, 3]. The quality of the used leaf raw material and dry extract were analysed according to PhEur 5 monograph. In addition a gradient elution HPLC method was developed showing a fingerprint chromatogram with six characteristic phenolic compounds: oleuropein, hydroxytyrosol, tyrosol, verbascoside, apigenin-7-O-glucoside, and luteolin-7-O-glucoside [4]. For pharmacological testing, we investigated the effects of a commercial Olea europaea leaf extract (OLE) on cultured cardiomyocytes and isolated rabbit hearts, which were perfused according to the Langendorff technique and connected to a 256 channel epicardial mapping system. Voltage clamp experiments were performed in cultured neonatal rat cardiomyocytes using a perforated-patch technique. OLE caused a concentration-dependent decrease in systolic left ventricular pressure and heart rate as well as an increase in relative coronary flow and a slight, but no significant prolongation of PQ-time. There were no significant changes between the groups in the activation-recovery-interval and its dispersion, total-activation-time, peak-to-peak amplitude, percentage of identical breakthrough-points and similar vectors of local activation. Voltage clamp experiments in cultured neonatal rat cardiomyocytes showed a significant decrease in maximum ICa,L by OLE which was reversible upon wash-out. Our findings demonstrate that OLE suppresses the L-type-calcium-channel directly and reversibly and thus help to understand the traditional use of OLE in the treatment of cardiovascular disease.

References: 1. Dhein, S. et al. (1993) Circulation 87: 617–630.

2. Rauwald, H. W. et al. (1991) Pharm Pharmacol Lett 1: 78–81.

3. Rauwald, H. W. et al. (1994) Phytother Res 8: 135–140.

4. Kampa, B. (2007) Diploma Thesis, Leipzig University