Rehmannioside A inhibits the activity of CYP3A4, 2C9 and 2D6 in vitro

To assess the effect of Rehmannioside A on CYP450s activity and to estimate its inhibitory properties.The effect of Rehmannioside A on the activity of major CYP450s in human liver microsomes (HLMs) was assessed with the corresponding substrates and marker reactions, and compared with a blank control and the respective inhibitors. Suppression of CYP3A4, 2C9 and 2D6 was assessed by the dose-dependent assay and fitted with non-competitive or competitive inhibition models. The inhibition of CYP3A4 was determined in a time-dependent manner.Rehmannioside A suppressed the activity of CYP3A4, 2C9, and 2D6 with IC50 values of 10.08, 12.62, and 16.43 μM, respectively. Suppression of CYP3A4 was fitted to a non-competitive model with Ki value of 5.08 μM, whereas CYP2C9 and 2D6 were fitted to a competitive model with Ki values of 6.25 and 8.14 μM. Additionally, the inhibitory effect on CYP3A4 was time-dependent with KI value of 8.47 μM-1 and a Kinact of 0.048 min-1.In vitro suppression of CYP3A, 2C9 and 2D6 by Rehmannioside A indicated that Rehmannioside A or its source herbs may interact with drugs metabolised by these CYP450s, which could guide the clinical application.

Antidepressant-like effects of Rehmannioside A on rats induced by chronic unpredictable mild stress through inhibition of endoplasmic reticulum stress and apoptosis of hippocampus

Depression is one of the most prevalent psychiatric mood diseases worldwide, whose therapy is in urgent need of development. Although the neuroprotective effects of Rehmannioside A (Rea) have been demonstrated, its anti-depressive effect remains unclear. Here, a depression model was induced with chronic unpredictable mild stress (CUMS) in rats. The behavioral trails, including sucrose preference test, forced swim test and open field test were used to determine the success of the CUMS-induced model. The effect of Rea on the neuronal protection, apoptosis and endoplasmic reticulum stress (ERS) was evaluated by HE, NISSL, IF and TUNEL staining, and western blot assays. Mechanically, the MAPK signaling pathway-related proteins expressions were examined by western blot. The results showed that CUMS stimulation evoked a prominent reduction of rat body weight, sucrose preference, and numbers of crossing, rearing and grooming with the enhanced immobility times. Besides, CUMS exposure induced the nuclear shrinkage and damage, as well as the decreased ISSL⁺ numbers. Moreover, CUMS stimulation increased the relative protein expressions of Bax and Cleaved caspase-3 and the percent of TUNEL positive cells, and decreased the relative protein expressions of Bcl-2. Furthermore, CUMS exposure also increased the relative protein expression of GRP-78, XBP-1, ATF-6, ATF-4 and CHOP. However, the CUMS-induced changes of all these indicators were reversed with Rea introduction in a dose-dependent fashion. Mechanically, Rea supply observably antagonized the CUMS-induced the relative protein levels of p-p38/p-38, p-ERK1/2/ERK1/2 and p-JNK/JNK. Therefore, Rea attenuated depression through suppressing ERS and apoptosis in hippocampus of CUMS-induced rats involved in MAPK signaling.

Rehmannioside A improves cognitive impairment and alleviates ferroptosis via activating PI3K/AKT/Nrf2 and SLC7A11/GPX4 signaling pathway after ischemia

ETHNOPHARMACOLOGICAL RELEVANCE

Rehmannioside A is derived from Rehmannia glutinosa Libosch, which is widely used as an important ingredient in diverse traditional Chinese medicines to treat diseases caused by "kidney deficiency" such as cerebral arteriosclerosis, aging-related stroke and dementia in China. Recent studies have proved that Rehmannia glutinosa Libosch and Rehmannioside A can improve memory capability and recover nerve damage.

AIM OF THE STUDY

To investigate the effect of Rehmannioside A on cognitive impairment after ischemia in rats and SH-SY5Y cells, and further evaluate the anti-oxidative and anti-ferroptosis mechanisms.

MATERIALS AND METHODS

Differentially expressed proteins (DEPs) in patients after cerebral ischemic stroke were revealed by a RayBio protein array. Cognitive impairment model was established by middle cerebral artery occlusion and reperfusion (MCAO) 14 days in rats. Rehmannioside A was administered intraperitoneally injection at dose of 80 mg/kg. The SH-SY5Y cells were exposed to H2O2 for 24 h and treated with Rehmannioside A (80 μM) for 24 h. The neuroprotecion of Rehmannioside A were evaluated by infarct volume (TTC), neurological defects (Garcia score) and learning memory (Morris water maze test) in vivo, and cell viability (CCK-8 or LDH) in vitro. Superoxide dismutase (SOD), malondialdehyde (MDA) and myeloperoxidase (MPO) activity of rats, glutathione (GSH), oxidized glutathione (GSSG) and nicotinamide adenine dinucleotide phosphate (NADPH) of cells were detected by biochemical assay. Intracellular reactive oxygen species (ROS) were measured by DCFH-DA assay. Myeloperoxidase (MPO), PI3 kinase (PI3K), p-PI3K, Akt, p-Akt, heme oxygenase-1 (HO-1), nuclear factor-E2-related factor 2 (Nrf2), SLC7A11, glutathione peroxidase 4 (GPX4) of the cerebral cortex in rats or SH-SY5Y cells were examined by western blotting.

RESULTS

Compared with model group, the cognitive impairment and neurological deficits of Rehmannioside A group were significantly improved, and the cerebral infarction was reduced in MCAO rats. Moreover, the cell viability obviously increased and the H2O2-induced toxicity was reduced in Rehmannioside A group. Further research indicated that the expression of p-PI3K, p-Akt, nuclear Nrf2, HO-1 and SLC7A11 in Rehmannioside A group was significantly higher than model group.

CONCLUSION

Rehmannioside A has neuroprotection effect and improves cognitive impairment after cerebral ischemia by inhibiting ferroptosis and activating PI3K/AKT/Nrf2 and SLC7A11/GPX4 signaling pathway. These findings provide valuable insight into the pathogenesis and therapeutic target of ischemic stroke.

Rea regulates microglial polarization and attenuates neuronal apoptosis via inhibition of the NF-κB and MAPK signalings for spinal cord injury repair

Inflammation and neuronal apoptosis aggravate the secondary damage after spinal cord injury (SCI). Rehmannioside A (Rea) is a bioactive herbal extract isolated from Rehmanniae radix with low toxicity and neuroprotection effects. Rea treatment inhibited the release of pro-inflammatory mediators from microglial cells, and promoted M2 polarization in vitro, which in turn protected the co-cultured neurons from apoptosis via suppression of the NF-κB and MAPK signalling pathways. Furthermore, daily intraperitoneal injections of 80 mg/kg Rea into a rat model of SCI significantly improved the behavioural and histological indices, promoted M2 microglial polarization, alleviated neuronal apoptosis, and increased motor function recovery. Therefore, Rea is a promising therapeutic option for SCI and should be clinically explored.

Rehmannioside A attenuates cognitive deficits in rats with vascular dementia (VD) through suppressing oxidative stress, inflammation and apoptosis

Vascular dementia (VD) is a degenerative cerebrovascular disorder, leading to progressive decline of cognitive abilities and memory. Rehmannioside A (ReA) is isolated from Rehmanniae Radix, which exhibits protective role against various diseases. The present study was performed to calculate the possible neuroprotective effects of ReA on VD. Here, the morris water maze (MWM) test and electrophysiological recordings indicated that ReA reduced cognitive deficits. Additionally, through hematoxylin and eosin (H&E) and Nissl staining, ReA attenuated the histological alterations of hippocampus in rats with VD. ReA group significantly reduced oxidative stress, inflammatory response and apoptosis in the hippocampus of rats with VD, which was linked to the activation of nuclear erythroid related factor-2 (Nrf2), while the inactivation of nuclear factor-κB (NF-κB) and Caspase-3. Further, the anti-oxidative, anti-inflammatory and anti-apoptosis abilities of ReA were confirmed in cells stimulated by hydrogen peroxide. Overall, the results above demonstrated the protective effects of ReA against cognitive deficits and indicated the potential value of ReA in the therapy of VD in future.