Astragaloside IV
Astragaloside IV (AS IV) is a saponin purified from a traditional Chinese herbal medicine component Astragalus membraneaceus (Fisch.) Bunge 1) 2).
Astrageloside IV has broad application prospects, especially in cardiovascular diseases, digestive diseases, cancer and other modern high incidence, high-risk diseases, and could be developed as a medicine 3).
Delayed cerebral ischemia is an important cause of morbidity and mortality in patients with subarachnoid hemorrhage (SAH).
H9c2 cells were treated with various doses of AS-IV for 24 h upon hypoxia. CCK-8 assay, flow cytometry/Western blot, and qRT-PCR were respectively conducted to measure the changes in cell viability, apoptosis, and the expression of miR-23a and miR-92a. Sprague-Dawley rats were received coronary ligation, and were administrated by various doses of AS-IV for 14 days. The infarct volume and outcome of rats followed by ligation were tested by ultrasound, arteriopuncture and nitrotetrazolium blue chloride (NBT) staining.
They found that 10 μg/ml of AS-IV exerted myocardioprotective effects against hypoxia-induced cell damage, as AS-IV significantly increased H9c2 cells viability and decreased apoptosis. Interestingly, the myocardioprotective effects of AS-IV were alleviated by miR-23a and/or miR-92a overexpression. Knockdown of miR-23a and miR-92a activated PI3K/AKT and MAPK/ ERK signaling pathways. Bcl-2 was a target gene for miR-23a, and BCL2L2 was a target gene for miR-92a. In the animal model of myocardial infarction (MI), AS-IV significantly reduced the infarct volume, ejection fraction (EF), shortening fraction (FS) and LV systolic pressure (LVSP), and significantly increased left ventricular end-diastolic internal diameter (LVEDd). And also, the elevated expression of miR-23a and miR-92a in MI rat was reduced by AS-IV.
AS-IV protected cardiomyocytes against hypoxia-induced injury possibly via down-regulation of miR-23a and miR-92a, and via activation of PI3K/AKT and MAPK/ERK signaling pathways 4).
A rat model of SAH was established by puncturing one side of the internal carotid artery. Then, rats received daily intraperitoneal injections of Astragaloside IV (AS-IV) (20 mg/kg; SAH-AS-IV group), 0.1% DMSO (SAH-DMSO group) or saline (SAH group) for 5 days; an additional control group consisted of rats receiving sham surgery and saline injections. Morphological characteristics of the basilar artery (BA) were measured from histological sections stained with hematoxylin-eosin, and used as indicators of cerebral vasospasm. Immunohistochemistry was used to detect toll-like receptor-4 (TLR4) and nuclear factor kappa B (NF-κB) p65 protein levels in the BA. Enzyme-linked immunosorbent assay was used to measure the plasma concentrations of tumor necrosis factor-alpha (TNF-α) and interleukin 6 (IL-6).
Compared with controls, the SAH-DMSO and SAH groups showed increased wall thickness and reduced luminal cross-sectional area (indicative of vasospasm), and increased TLR4 expression and enhanced NF-κB activation in the BA, as well as elevated plasma levels of TNF-α and IL-6. Administration of AS-IV was associated with significant attenuation of all the above changes induced by SAH (P<0.05).
AS-IV may attenuate delayed cerebral vasospasm after SAH through inhibition of TLR4/NF-κB-mediated inflammatory signaling pathways 5).
Li et al., found that astragaloside IV (10 and 20mg/kg) significantly attenuated the cerebral water content (P<0.05) and improved neurological outcomes (P<0.05) in comparison with vehicle group. Moreover, we investigate the effect of astragaloside IV on the (blood-brain barrier) BBB since cerebral edema was closely related to the permeability of the BBB. We found that the permeability of BBB was improved significantly in astragaloside IV groups compared with vehicle group via Evans blue leakage (P<0.05). This was further confirmed under the electron microscope, using lanthanum as a tracer of blood vessel permeability. Lanthanum was usually found within the blood vessel in sham group, rather than in perivascular tissues as shown in vehicle group. In drug groups, lanthanum stain was mainly restricted within the cerebral capillary, indicating the potential BBB-protective effect of astragaloside IV. Furthermore, we found that expressions of Matrix metalloproteinase-9 (MMP-9) and aquaporin 4 (AQP4) were increased in vehicle group, which were related to cerebral vasogenic edema or cytotoxic edema. The up-regulations of MMP-9 and AQP4 were inhibited significantly by astragaloside IV administration. We propose that the anti-edema potential of astragaloside IV was correlated with its regulation of MMP-9 and AQP4 6).
Li et al., studied the potential of astragaloside IV, one of the major and active components of the astragalus membranaceous, to protect rat against cerebral inflammation injury elicited by focal cerebral ischemia and reperfusion and related protective mechanisms. The rat model was induced by intraluminal occlusion of the right middle cerebral artery with reperfusion. Animals received astragaloside IV (10 or 20 mg/kg) injections when reperfusion was began to. Neurobehavioral evaluation and infarct assessment were studied. Myeloperoxidase (MPO) and tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were measured by enzyme-linked immunosorbent assay (ELISA). The rates of CD11b/CD18-positive neutrophils were analyzed via flow cytometry. Intercellular adhesion molecule-1 (ICAM-1) and nuclear factor κB (NF-κB) were measured by immunohistochemistry and Western blot. Astragaloside IV improved neurological outcome and reduced infarct volume at 24 h after reperfusion. The protective effect was achieved by preventing neutrophils accumulation in the brain parenchyma demonstrated by significantly reducing the concentration of MPO in brain tissue. Astragaloside IV exerts the protection through remarkably decreasing the percentage of CD11b/CD18-positive neutrophils and down-regulating the expression of intercellular adhesion molecule-1 (ICAM-1), which is partly achieved by strongly attenuating the production of TNF-α and IL-1β and inhibiting level of nuclear factor-κB (NF-κB). We propose an anti-inflammatory mechanism evoked by astragaloside IV by suppression of neutrophils adhesion-related molecules, which exerts neuroprotection against I/R injury 7).
Zhang et al., investigated whether AS-IV protect against 1-methyl-4-phenylpyridnium ion (MPP(+))-induced dopaminergic neurotoxicity in SH-SY5Y cells and determined the mechanism of AS-IV neuroprotection. We found that pretreatment with AS-IV significantly reversed the loss of cell viability, nuclear condensation, the generation of intracellular reactive oxygen species (ROS), and the increase in Bax/Bcl-2 ratio and the activity of caspase-3 induced by MPP(+). Our study suggests that the neuroprotective effect of AS-IV is related to mechanisms including ROS production and the inhibition of Bax-mediated pathway. The present study supports the notion that AS-IV may be a promising neuroprotective agent for the treatment of neurodegenerative disorders such as PD 8).
Qu et al., found that astragaloside IV (10, 20 mg/kg) significantly attenuated the permeability of blood-brain barrier in comparison with vehicle group after ischemia/reperfusion assessed via Evans blue leakage (P<0.05). This was further confirmed by examination of blood-brain barrier permeability under the electron microscope, using lanthanum as a tracer of blood vessel permeability. Lanthanum was usually found within the blood vessel in sham group, rather than in perivascular tissues as shown in vehicle group. In drug groups, lanthanum stain was mainly restricted within the cerebral capillary, indicating the potential protective effect of astragaloside IV on the integrity of blood-brain barrier in ischemia/reperfusion rats. Furthermore, we found that expression of occludin and zonae occludens-1 (ZO-1), the tight junction proteins, was decreased in endothelial cells in vehicle group, which, however, could be reversed by astragaloside IV administration. We propose that regulation of tight junctional proteins in the endothelial cells may be one mechanism astragaloside IV-mediated in attribution to blood-brain barrier protection in the ischemia/reperfusion rats 9).
The aim of this study was to evaluate peripheral nerve regeneration across a 15-mm gap in the sciatic nerve of the rat, using a silicone rubber nerve guide filled with different concentrations of astragaloside (0, 50, 100, and 200 microM). Collagen was also filled in the chambers to prevent the astragaloside from leakage. At the end of 8 weeks, animals from the group treated with astragaloside, especially at the concentration of 50 microM, had a higher rate of successful regeneration across the wide gap, a significantly larger number of myelinated axons, and a greater evoked action potential than the control group. However, the high-dose astragaloside (200 microM) completely reversed this positive effect of growth-promoting capability and inhibited nerve regeneration. Thus, astragaloside plays a dual role in anastomosis, being salutary in aiding the growth of axons in peripheral nerve but also detrimental, terminating the nerve regenerative processes if improperly applied 10).