Abstract:

In order to investigate the effect of casein hydrolysates containing ACE inhibitory peptides and purple sweet
potato extract containing anthocyanins on the systolic blood pressure (SBP) of spontaneously hypertensive rats (SHR) and
Wistar rats, 12-week-old male SHR and Wistar rats were orally administered with different doses of casein hydrolysates (10,
20, 30, and 40 mg/kg mb) and purple sweet potato extract (5.4, 10.8, 21.6 and 32.4 mg/kg mb) as well as combinations of
casein hydrolysates at two hypotensive doses identified and purple sweet potato extract at three hypotensive doses selected,
respectively. The blood pressure of SHR was tested by non-invasive automated sphygmomanometer. The results showed
that both casein hydrolysates and purple sweet potato extracts had a significant hypotensive effect on SHR rats. Moreover,
their effect was significantly enhanced when they were applied in combination at a single dose (P < 0.05). The SBP of SHR
rats was reduced by (24.67 ± 4.46), (28.47 ± 3.96), and (41.51 ± 4.89) mmHg, respectively, at 4 or 5 h after administration
of 10 mg/kg mb casein hydrolysates in combination with purple sweet potato extract at three doses of 5.4, 10.8 and
21.6 mg/kg mb, while it was reduced by (38.03 ± 3.46), (43.92 ± 2.92), and (47.20 ± 4.31) mmHg, respectively, at 5 or 6 h
post-administration of casein hydrolysates at 20 mg/kg mb in combination with purple sweet potato extract at 5.4, 10.8
and 21.6 mg/kg mb. Nevertheless, no effect on the SBP of Wistar rats was observed when they were used in combination.
Combined administration of casein hydrolysates at 10 and 20 mg/kg mb with purple sweet potato extract at 10.8 mg/kg mb
twice daily at 4 h intervals resulted in a decrease in the SBP of SHR rats of (28.20 ± 3.02) and (43.54 ± 2.55) mmHg as
compared with that before administration, respectively. Furthermore, the lower levels of SBP could be maintained for a
long period. Therefore, casein hydrolysate containing ACE inhibitory peptides and purple sweet potato extract containing
anthocyanins, when orally administered in combination, can significantly reduce the SBP of SHR.

Key words: casein hydrolysate, angiotensin converting enzyme (ACE), purple sweet potato extract, hypertension, spontaneously hypertensive rats (SHR)