Plantainoside D (Isoplantamajoside) shows potent antioxidative effects as those of ascorbic acid, it shows angiotensin-converting enzyme (ACE) inhibitory inhibitory activity in vitro with the IC(50) value of 2.17 mM, it also shows inhibitory activity against PKCalpha with the IC50 value14.8microM.

ACE:2.17 mM , PKC:14.8microM

Plantago asiatica L. and its major constituents(such as Plantainoside D) have ACE inhibitory activity in vitro. The identified compounds contribute to the angiotensin-converting enzyme-inhibitory activity of the extract[1].In vitro, Adriamycin(ADR) caused dose-dependent toxicity in H9c2 cardiac muscle cells. Pre-treatment of the cardiac muscle cells with Plantainoside D(PD) significantly reduced ADR-induced apoptosis of cardiac muscle cells. PD inhibited the ROS produced by ADR in the cardiac muscle cells. As well, PD increased GSH(glutathione), compared with ADR. In response to ADR, NF-kappaB was activated in H9c2 cells. However the treatment of PD reduced the activation of NF-kappaB.The NF-kappaB inhibitor, PDTC, inhibited the cytotoxic effect on ADR-induced apoptosis in cardiac muscle cells. IkappaBalpha-dominant negative plasmid-overexpression abrogated ADR-induced apoptosis in H9c2 cardiac muscle cells[2].

Ethanolic extract of the seeds of Plantago asiatica L. showed significant inhibitory activity of angiotensin-converting enzyme (ACE) determined by monitoring the transformation from a substrate hippuryl-histidyl-leucine (HHL) to the product hippuric acid (HA) in vitro using an UPLC-MS method. The bioguided fractionation of the extract resulted in the isolation of four ACE inhibitory active phenylpropanoid glycosides acteoside, isoacteoside, Plantainoside D, and plantamajoside with IC(50) values of 2.69 mM, 2.46 mM, 2.17 mM, and 2.47 mM, respectively. Their structures were elucidated through the analysis of NMR, UV, IR and MS data[1].