Ginsenoside Rg1 mitigates cerebral ischaemia/reperfusion injury in mice by inhibiting autophagy through activation of mTOR signalling.

Reperfusion injury, which is distinct from ischaemic injury, occurs when blood flow is restored in previously ischaemic brain tissue, further compromising neurons and other cells and worsening the injury. There is currently a lack of pharmaceutical agents and therapeutic interventions that specifically mitigate cerebral ischaemia/reperfusion (I/R) injury. Ginsenoside Rg1 (Rg1), a protopanaxatriol-type saponin isolated from Panax ginseng C. A. Meyer, has been found to protect against cerebral I/R injury, but its intricate protective mechanisms remain to be elucidated. Numerous studies have shown that autophagy plays a crucial role in protecting brain tissue during the I/R process and is emerging as a promising therapeutic strategy for effective treatment. In this study, we investigated whether Rg1 protected against I/R damage in vitro and in vivo by regulating autophagy. Both MCAO and OGD/R models were established. SK-N-AS and SH-SY5Y cells were subjected to OGD followed by reperfusion with Rg1 (4-32 µM). MCAO mice were injected with Rg1 (30 mg·kg-1·d-1. i.p.) for 3 days before and on the day of surgery. Rg1 treatment significantly mitigated ischaemia/reperfusion injury both in vitro and in vivo. Furthermore, we demonstrated that the induction of autophagy contributed to I/R injury, which was effectively inhibited by Rg1 in both in vitro and in vivo models of cerebral I/R injury. Rg1 inhibited autophagy through multiple steps, including impeding autophagy initiation, inducing lysosomal dysfunction and inhibiting cathepsin enzyme activities. We revealed that mTOR activation was pivotal in mediating the inhibitory effect of Rg1 on autophagy. Treatment with Torin-1, an autophagy inducer and mTOR-specific inhibitor, significantly reversed the impact of Rg1 on autophagy, decreasing its protective efficacy against I/R injury both in vitro and in vivo. In conclusion, our results suggest that Rg1 may serve as a promising drug candidate against cerebral I/R injury by inhibiting autophagy through activation of mTOR signalling.

Medicinal plants and natural compounds against acyclovir-resistant HSV infections.

Herpes simplex virus (HSV), an alphaherpesvirus, is highly prevalent in the human population and is known to cause oral and genital herpes and various complications. Represented by acyclovir (ACV), nucleoside analogs have been the main clinical treatment against HSV infection thus far. However, due to prolonged and excessive use, HSV has developed ACV-resistant strains. Therefore, effective treatment against ACV-resistant HSV strains is urgently needed. In this review, we summarized the plant extracts and natural compounds that inhibited ACV-resistant HSV infection and their mechanism of action.

Safrana l Prevents Prostate Cancer Recurrence by Blocking the Re-activation of Quiescent Cancer Cells via Downregulation of S-Phase Kinase-Associated Protein 2.

The re-proliferation of quiescent cancer cells is considered to be the primary contributor to prostate cancer (Pca) recurrence and progression. In this study, we investigated the inhibitory effect of safranal, a monoterpene aldehyde isolated from Crocus sativus (saffron), on the re-proliferation of quiescent Pca cells in vitro and in vivo. The results showed that safranal efficiently blocked the re-activation of quiescent Pca cells by downregulating the G0/G1 cell cycle regulatory proteins CDK2, CDK4, CDK6, and phospho-Rb at Ser807/811 and elevating the levels of cyclin-dependent kinase inhibitors, p21 and p27. Further investigation on the underlying mechanisms revealed that safranal suppressed the mRNA and protein expression levels of Skp2, possibly through the deregulation of the transcriptional activity of two major transcriptional factors, E2F1 and NF-κB subunits. Moreover, safranal inhibited AKT phosphorylation at Ser473 and deregulated both canonical and non-canonical NF-κB signaling pathways. Safranal suppressed the tumor growth of quiescent Pca cell xenografts in vivo. Furthermore, safranal-treated tumor tissues exhibited a reduction in Skp2, E2F1, NF-κB p65, p-IκBα (Ser32), c-MYC, p-Rb (Ser807), CDK4, CDK6, and CDK2 and an elevation of p27 and p21 protein levels. Therefore, our findings demonstrate that safranal suppresses cell cycle re-entry of quiescent Pca cells in vitro and in vivo plausibly by repressing the transcriptional activity of two major transcriptional activators of Skp2, namely, E2F1 and NF-κB, through the downregulation of AKT phosphorylation and NF-κB signaling pathways, respectively.

Xanthone derivatives from the leaves of Garcinia oligantha.

Nine new and unique xanthone derivatives, including one novel hybrid monoterpene-tetrahydroxanthone (1), three dihydro-xanthone derivatives (2-4), and five skeleton-rearranged xanthone derivatives (5-9), were obtained from a 95% EtOH extract of Garcinia oligantha leaves by a LC-MS-guided fractionation procedure. The structures of the new compounds were elucidated by analysis of their 1D and 2D NMR and MS data. The relative configurations of 2 and 8 were determined via X-ray crystallographic data analysis, while the absolute configurations of 1-2, 5-9 were assigned based on a comparison of calculated and experimental ECD and/or OR data. In SRB, PI-exclusion and Hoechst staining assays, 6 showed strong cytotoxic activities which could dose-dependently induce Taxol-insensitive quiescent LNCaP cell death. Additionally, a preliminary mechanism investigation using immunoblotting and Caspase-3 activity assay, indicated that 6 induced quiescent LNCaP cell death potentially through caspase-dependent mitochondrial apoptosis pathway.

Heat shock protein 27 mediates the effect of 1,3,5-trihydroxy-13,13-dimethyl-2H-pyran [7,6-b] xanthone on mitochondrial apoptosis in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a global public health problem which causes approximately 500,000 deaths annually. Considering that the limited therapeutic options for HCC, novel therapeutic targets and drugs are urgently needed. In this study, we discovered that 1,3,5-trihydroxy-13,13-dimethyl-2H-pyran [7,6-b] xanthone (TDP), isolated from the traditional Chinese medicinal herb, Garcinia oblongifolia, effectively inhibited cell growth and induced the caspase-dependent mitochondrial apoptosis in HCC. A two-dimensional gel electrophoresis and mass spectrometry-based comparative proteomics were performed to find the molecular targets of TDP in HCC cells. Eighteen proteins were identified as differently expressed, with Hsp27 protein being one of the most significantly down-regulated proteins induced by TDP. In addition, the following gain- and loss-of-function studies indicated that Hsp27 mediates mitochondrial apoptosis induced by TDP. Furthermore, a nude mice model also demonstrated the suppressive effect of TDP on HCC. Our study suggests that TDP plays apoptosis-inducing roles by strongly suppressing the Hsp27 expression that is specifically associated with the mitochondrial death of the caspase-dependent pathway. In conclusion, TDP may be a potential anti-cancer drug candidate, especially to cancers with an abnormally high expression of Hsp27.