# Plant Iridoids Affect Intraocular Pressure and Vascular Flow in the Rabbit Eye
## 4 Discussion
This compound, derived from the roots of _Rehmannia glutinosa_, displays antioxidant and anti-inflammatory effects, reduces apoptotic protein expression, improves mitochondrial membrane potential, increases ATP and glutathione content, and inhibits lipid peroxidation [36]. The administration of iridoid glycosides from _Morinda citrifolia_ fruit extract improves blood flow and has a fibrinolytic effect, which is attributed to the iridoid glycoside asperulosic acid [37; 38]. In a mouse model of hindlimb ischemia, there was a significant acceleration in perfusion recovery and a reduction in muscle tissue damage in the group receiving auxubine (Au). Au was found to promote angiogenesis in peripheral ischemia through the vascular endothelial cell growth factor (VEGF)/Akt/endothelial nitric oxide synthase (eNOS) signaling pathway. The authors qualify Au as a potent new compound with potential use in the treatment of peripheral vascular disease [39]. Aucubin can protect RGC retinal ganglion cells in diabetic rats, inhibit RGC apoptosis, and reduce oxidative stress and inflammatory response, and 10 mg/kg of aucubin showed optimal efficacy. This mechanism may be related to inhibition of the p38 MAPK signaling pathway [40]. Topical administration of aucubin eye drops has shown beneficial effects on abnormal ocular changes caused by urban particular matter (UPM), such as excessive tear secretion and lacimal gland damage. The results of the study demonstrate the beneficial effects of aucubin in dry eye disease [41]. Picroside II protects the blood-brain barrier by inhibiting the oxidative signaling pathway in cerebral ischemia-reperfusion injury [42]. It also inhibits neuronal apoptosis and improves the morphology and structure after cerebral ischemia in rats [43]. Ginsenoside, a non-peptide angiogenic agent, administered in a rat model of myocardial infarction effectively improved myocardial perfusion and preserved left ventricular function during infarction [44]. Combination therapies have been used for more than 2500 years in traditional Chinese medicine. A preparation of three components, ginseng, berberine, and jasminoide, acting synergistically, was employed in the treatment of rats affected by obstruction of the middle cerebral artery caused by focal cerebral ischemia. The respective proportions of the substances displayed a good pharmacological effect on acute ischemic stroke and allowed the strongest synergistic effect. The researchers pointed out that in addition to restoring blood supply and protecting easily damaged cells in the ischemic area as early as possible, attention should be also paid to the removal of toxic metabolites [45]. Other iridoids also have effects on microcirculation. Oleuropein and pinorezinol were able to protect rats from pial microcirculation in reperfusion injury, increase nitric oxide release, and reduce oxidative stress, maintaining the distribution of pial blood flow. Control rats showed reduced arteriolar diameter, microvascular leakage, leukocyte adhesion in the venules, and reduced capillary perfusion. Pretreatment with oleuropein or pinorezinol determined dilatation in all rows of arterioles, decreasing microvascular leakage and leukocyte adhesion via protection of capillary perfusion. Test substances, administered together, prevented microvascular damage to a greater extent [46]. In a study of the effects of gentiopicoside on diabetic peripheral neuropathy in rats, gentiopicoside was found to exert a protective effect on nerves and attenuated experimental neuropathy by improving nerve blood flow through regulation of the PPAR-\(\gamma\)/AMPK/ACC signaling pathway. Motor and sensory nerve conduction velocity was also improved [47]. A neuroprotective role for morroniside was observed in spinal cord injury in rats, and treatment improved functional recovery.