Saikosaponin a activates tet1/dll3/notch1 signalling and promotes hippocampal neurogenesis to improve depression-like behavior in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Radix Bupleuri, also named "Chaihu" in Chinese, is a substance derived from the dry roots of Bupleurum chinense DC. [Apiaceae] and Bupleurum scorzonerifolium Willd. [Apiaceae]. Radix Bupleuri was initially recorded as a medicinal herb in Shen Nong Ben Cao Jing, the earliest monograph concerning traditional Chinese medicine (TCM). Ever since, Radix Bupleuri has been broadly used to alleviate exterior syndrome, disperse heat, modulate the liver-qi, and elevate yang-qi in TCM. Radix Bupleuri has also been utilized as an important component in Xiaoyaosan, a classical formula for relieving depression, which was originated from the famous Chinese medical book called "Tai Ping Hui Min He Ji Ju Fang" in Song Dynasty. Currently, many valuable pharmacological effects of Radix Bupleuri have been explored, such as antidepressant, neuroprotective activities, antiinflammation, anticancer, immunoregulation, etc. Former studies have illustrated that Saikosaponin A (SSa), one of the primary active components of Radix Bupleuri, possesses potential antidepressant properties. However, the underlying mechanisms still remain unknown.

AIM OF THE STUDY

We used a chronic social defeat stress (CSDS) mouse model to explore the ameliorative effects and potential mechanisms of SSa in depressive disorder in vivo.

MATERIALS AND METHODS

The CSDS mouse model was established and mice underwent behavioral studies using assays such as the social interaction test (SIT), sucrose preference test (SPT), forced-swim test (FST), tail suspension test (TST), and open field test (OFT). Western blotting, immunofluorescence, and Golgi staining were performed to investigate signaling pathway activity, and alterations in synaptic spines in the hippocampus. To model the anticipated interaction between SSa and Tet1, molecular docking and microscale thermophoresis (MST) techniques were employed. Finally, sh-RNA Tet1 was employed for validation via lentiviral transfection in CSDS mice to confirm the requirement of Tet1 for SSA efficacy.

RESULTS

SSa dramatically reduced depressed symptoms, boosted the expression of Tet1, Notch, DLL3, and BDNF, encouraged hippocampus development, and enhanced the dendritic spine density of hippocampal neurons. In contrast, Tet1 knockdown in CSDS mice dampened the beneficial effects of SSa on depressive symptoms.

CONCLUSIONS

Therefore, our results suggest that SSa significantly activates the Tet1/Notch/DLL3 signaling pathways and promotes hippocampal neurogenesis to exert antidepressant effects in the CSDS mouse model in vivo. The present results also provide new insight into the importance of the Tet1/DLL3/Notch pathways as potential targets for novel antidepressant development.

Assessment of Genetic Diversity in Bupleurum spp. Basing Agronomic Traits, Medicinal Components and ISSR Markers

Radix bupleuri is one of the bulk medicinal materials in China and it is widely adopted in clinical applications and drug discovery. The investigation of agronomic traits, active component content and genetic diversity in diverse Radix bupleuri germplasms may provide evidence to promote the selection of better strains. In this research, 13 germplasms from various sources were used to investigate the variations between different Radix bupleuri germplasms. Nine biological characteristics were noted in the field, and the levels of the two primary active ingredients were determined using high performance liquid chromatography (HPLC). Moreover, the molecular marker technique of inter-simple sequence repeat (ISSR) and the unweighted pair group method with arithmetic means (UPGMA) were employed to evaluate the molecular genetic diversity. The findings showed that there was a wide range of variation among the many varieties of Radix bupleuri, with coefficients of variation for agronomic traits and active component content ranging from 7.62% to 41.54% and 36.47% to 53.70%, respectively. Moreover, there are different degrees of relationship between the two. Since there was a significant correlation between root weight and saikosaponin content, it was possible to classify a plant based on its weight and anticipate its saikosaponin content. The 13 species were divided into four groups based on their germplasm by genetic markers-based cluster analysis. This indicated the possibility that the component content would not necessarily be related to germplasm and might easily be influenced by environmental factors. The use of ISSR marker technology made it possible to precisely identify the various Radix bupleuri provenances and its counterfeit products. There may be a way to prevent the misunderstandings caused by the appearance and composition of Chinese medicinal substances. In our study, the germplasm of Radix bupleuri that was widely circulated in the market was comprehensively evaluated in terms of agronomic traits, active components and molecular level, and identified by simple means, to provide a theoretical basis for the evaluation and screening of fine germplasms of Radix bupleuri.

Combined treatment with Prunella vulgaris and Radix bupleuri activated the Bax/Bcl-2 and Caspase-3 signal pathways in papillary thyroid carcinoma cells

To explore the effect of Prunella vulgaris (PV) combined with Radix bupleuri (RB) on apoptosis of papillary thyroid carcinoma cells. Our study was divided into four groups: the control group, the PV group, the RB group, and the PV combined with the RB group. The viability of cells from different treatment groups was assessed by the CCK-8 assay. Cell migration and invasion were assessed by healing wounding and the transwell assay, respectively. Cell apoptosis rate and cell cycle arrest were detected by a flow cytometry assay. The protein expression of Bcl-2, Bax, Caspase-3, CyclinA1, CyclinB1, and CDK1 was detected using a western blot assay. Our results indicated that, compared with the control group, PV combined with RB group could significantly alter the cell morphology, inhibit cell migration and invasion, decrease the number of cells in the G0/G1 phase and increase the number of cells in the G2/M phase, and promote the cell apoptosis. Moreover, PV combined with RB treatment also obviously increased the expression of Bax/Bcl2 and caspase-3 proteins and decreased the expression of Cyclin A1, Cyclin B1, and CDK1 proteins. Overall, our results indicated that PV combined with RB could activate the Bax/Bcl-2 and Caspase-3 signal pathways to induce cell apoptosis in papillary thyroid carcinoma cells; this also provides a new way to treat thyroid cancer.

Chemotherapeutic Potential of Saikosaponin D: Experimental Evidence

Saikosaponin D (SSD), an active compound derived from the traditional plant Radix bupleuri, showcases potential in disease management owing to its antioxidant, antipyretic, and anti-inflammatory properties. The toxicological effects of SSD mainly include hepatotoxicity, neurotoxicity, hemolysis, and cardiotoxicity. SSD exhibits antitumor effects on multiple targets and has been witnessed in diverse cancer types by articulating various cell signaling pathways. As a result, carcinogenic processes such as proliferation, invasion, metastasis, and angiogenesis are inhibited, whereas apoptosis, autophagy, and differentiation are induced in several cancer cells. Since it reduces side effects and strengthens anti-cancerous benefits, SSD has been shown to have an additive or synergistic impact with chemo-preventive medicines. Regardless of its efficacy and benefits, the considerations of SSD in cancer prevention are absolutely under-researched due to its penurious bioavailability. Diverse studies have overcome the impediments of inadequate bioavailability using nanotechnology-based methods such as nanoparticle encapsulation, liposomes, and several other formulations. In this review, we emphasize the association of SSD in cancer therapeutics and the discussion of the mechanisms of action with the significance of experimental evidence.

Content decline of SERCA inhibitors saikosaponin a and d attenuates cardiotoxicity and hepatotoxicity of vinegar-baked Radix bupleuri

Improper usage of unprocessed Radix bupleuri root (chaihu) may cause cardiotoxicity and liver injury. Baking herb with vinegar is believed to attenuate the adverse responses. However, the chemical and molecular basis involved remained unclear. To this end, we investigated the in vitro toxicity of saikosaponin a, c, d, and their hydrolysates saikosaponin b1 and b2. Results showed that SSa and SSd possessed higher affinity with sarcoplasmic/endoplasmic reticulum calcium ATPase (SERCA) by molecular docking, and exhibited stronger toxic responses on cardiomyocytes and hepatocytes than the other three saikosaponins in equivalent concentrations. Further, SSa and SSd induced LC3 puncta formation in U2OS-mCherry-EGFP-LC3 cells. Blockage of autophagy by 3-methyladenine did not abrogate the cytotoxicities induced by SSa and SSd. In parallel, none of SSc, SSb1, or SSb2 caused cell injury. Our study reveals how changes in chemical ingredients are connected to the toxicity of Chaihu during vinegar baking process and also provides a guidance for structure optimization to reduce drug induced toxicity.

Saikosaponin a functions as anti-epileptic effect in pentylenetetrazol induced rats through inhibiting mTOR signaling pathway

OBJECTIVE

Saikosaponin a (SSa), which is one major bioactive compound isolated from radix bupleuri, has been demonstrated to exhibit the properties of anticonvulsant and antiepileptic in few reports. This study aims to clarify the molecular mechanism by which SSa protects against pentylenetetrazol (PTZ) induced epileptic seizure.

METHODS

PTZ induced rat and hippocampal neuron were established. Treated rats or hippocampal neuron with SSa, and mTOR, P70S6K, IL-1β and TNF-α were then determined.

RESULTS

In PTZ induced rat, SSa significantly reduced seizure severity and duration while markedly elevated seizure latency, and it also down-regulated hippocampal p-mTOR, p-70S6K, L-1β and TNF-α expression. In hippocampal neurons exposed to PTZ, p-mTOR and p-70S6K expression levels were also decreased by SSa. Pre-incubated hippocampal neurons with leucine, an mTOR agonist, reversed the effects of SSa on decreasing cytokines expression and inhibiting cell apoptosis. The treatment of mTOR inhibitor rapamycin prevented against the increase of cytokines expression and hippocampal neuron apoptosis induced by PTZ. Leucine also canceled the alleviation of seizures and induction of hippocampal caspase-3 activity in PTZ induced rat with the treatment of SSa.

CONCLUSION

SSa protects against PTZ induced epileptic seizure and hippocampal neuron apoptosis through inhibiting mTOR signaling pathway.

Binding between Saikosaponin C and Human Serum Albumin by Fluorescence Spectroscopy and Molecular Docking

Saikosaponin C (SSC) is one of the major active constituents of dried Radix bupleuri root (Chaihu in Chinese) that has been widely used in China to treat a variety of conditions, such as liver disease, for many centuries. The binding of SSC to human serum albumin (HSA) was explored by fluorescence, circular dichroism (CD), UV-vis spectrophotometry, and molecular docking to understand both the pharmacology and the basis of the clinical use of SSC/Chaihu. SSC produced a concentration-dependent quenching effect on the intrinsic fluorescence of HSA, accompanied by a blue shift in the fluorescence spectra. The Stern-Volmer equation showed that this quenching was dominated by static quenching. The binding constant of SSC with HSA was 3.72 × 10³ and 2.99 × 10³ L·mol(-1) at 26 °C and 36 °C, respectively, with a single binding site on each SSC and HSA molecule. Site competitive experiments demonstrated that SSC bound to site I (subdomain IIA) and site II (subdomain IIIA) in HSA. Analysis of thermodynamic parameters indicated that hydrogen bonding and van der Waals forces were mostly responsible for SSC-HSA association. The energy transfer efficiency and binding distance between SSC and HSA was calculated to be 0.23 J and 2.61 nm at 26 °C, respectively. Synchronous fluorescence and CD measurements indicated that SSC affected HSA conformation in the SSC-HSA complex. Molecular docking supported the experimental findings in conformational changes, binding sites and binding forces, and revealed binding of SSC at the interface between subdomains IIA-IIB.