Chronotoxicity of Semen Strychni is associated with circadian metabolism and transport in mice

Brucine-Induced Neurotoxicity by Targeting Caspase 3: Involvement of PPARγ/NF-κB/Apoptosis Signaling Pathway

Brucine, a weak alkaline indole alkaloid, is one of the main bioactive and toxic constituents of Strychnos nux-vomica L., which exerts multiple pharmacological activities, such as anti-tumor, anti-inflammatory, and analgesic effect. However, its potential toxic effects limited its clinical application, especially central nervous system toxicity. The present study was designed to investigate the neurotoxicity and mechanism of brucine. Our results showed that brucine significantly induced Neuro-2a cells and primary astrocyte death, as evidenced by MTT assay and LDH release. Moreover, transcriptome analysis indicated that PPAR/NF-κB and apoptosis signaling pathways were involved in the brucine-induced cytotoxicity in Neuro-2a cells. Subsequently, in fact, brucine evidently inhibited PPARγ and promoted phosphorylation of NF-κB. Furthermore, PPARγ inhibitor aggravated the neurotoxicity, while NF-κB inhibitor substantially reversed brucine-induced neurotoxicity. Moreover, brucine also significantly induced neuronal apoptosis and triggered increase in ratio of Bax/Bcl-2 and level of cleaved caspase 3, as well as its activity as evidenced by TUNEL staining and Western blot. Furthermore, molecular docking analysis predicted that brucine directly bound to caspase 3. Intriguingly, a caspase 3 inhibitor (Z-DEVE-FMK) largely abolished the neurotoxicity of brucine. Our results reveal that brucine-induced neurotoxicity via activation of PPARγ/NF-κB/caspase 3-dependent apoptosis pathway. These findings will provide a novel strategy against brucine-induced neurotoxicity.

Recent advances in circadian-regulated pharmacokinetics and its implications for chronotherapy

Dependence of pharmacokinetics and drug effects (efficacy and toxicity) on dosing time has long been recognized. However, significant progress has only recently been made in our understanding of circadian rhythms and their regulation on drug pharmacokinetics, efficacy and toxicity. This review will cover the relevant literature and a series of publications from our work summarizing the effects of circadian rhythms on drug pharmacokinetics, and propose that the influence of circadian rhythms on pharmacokinetics are ultimately translated into therapeutic effects and side effects of drugs. Evidence suggests that daily rhythmicity in expression of drug-metabolizing enzymes and transporters necessary for drug ADME (absorption, distribution, metabolism and excretion) are key factors determining circadian pharmacokinetics. Newly discovered mechanisms for circadian control of the enzymes and transporters are covered. We also discuss how the rhythms of drug-processing proteins are translated into circadian pharmacokinetics and drug chronoefficacy/chronotoxicity, which has direct implications for chronotherapy. More importantly, we will present perspectives on the challenges that are still needed for a breakthrough in translational research. In addition, knowledge of the circadian influence on drug disposition has provided new possibilities for novel pharmacological strategies. Careful application of pharmacokinetics-based chronotherapy strategies can improve efficacy and reduce toxicity. Circadian rhythm-mediated metabolic and transport strategies can also be implemented to design drugs.

CYP3A1 metabolism-based neurotoxicity of strychnine in rat

Strychnine is one of the main bioactive and toxic constituents of Semen Strychni. In the present study, the neurotoxic effects of strychnine, and the role of individual differences in metabolism on susceptibility to neurotoxicity of strychnine were investigated. The acute toxicity was observed by a single dose of strychnine (2.92 mg/kg, i.g.) in rats, the epileptic stages of rats were scored according to Racine's scale. The neurotoxicity of strychnine was evaluated by the levels of ROS, MDA, SOD and GSH in hippocampus, striatum, and cortex tissues measurements and histopathological analysis. The concentrations of strychnine in the plasma, hippocampus, striatum, and cortex tissues were determined using high performance liquid chromatography tandem mass spectrometry (LC-MS/MS). The expressions of the cytochrome P450, which is the most critical protein family involved in drugs metabolism, were detected by proteomics. The mechanism of susceptibility to neurotoxicity of strychnine was elucidated by correlation analysis among above indicators. The results indicated that striatum and cortex were the main toxic targets of strychnine, and the CYP3A1 might be a susceptible biomarker to neurotoxicity of strychnine. These results provide valuable insights into the neurotoxic susceptibility of strychnine that will aid in the rational clinical use of strychnine (possibly including Semen Strychni).

Botanical Drug Extracts Combined With Biomaterial Carriers for Osteoarthritis Cartilage Degeneration Treatment: A Review of 10 Years of Research

Osteoarthritis (OA) is a long-term chronic arthrosis disease which is usually characterized by pain, swelling, joint stiffness, reduced range of motion, and other clinical manifestations and even results in disability in severe cases. The main pathological manifestation of OA is the degeneration of cartilage. However, due to the special physiological structure of the cartilage, once damaged, it is unable to repair itself, which is one of the challenges of treating OA clinically. Abundant studies have reported the application of cartilage tissue engineering in OA cartilage repair. Among them, cell combined with biological carrier implantation has unique advantages. However, cell senescence, death and dedifferentiation are some problems when cultured in vitro. Botanical drug remedies for OA have a long history in many countries in Asia. In fact, botanical drug extracts (BDEs) have great potential in anti-inflammatory, antioxidant, antiaging, and other properties, and many studies have confirmed their effects. BDEs combined with cartilage tissue engineering has attracted increasing attention in recent years. In this review, we will explain in detail how cartilage tissue engineering materials and BDEs play a role in cartilage repair, as well as the current research status.

Pharmacokinetics-based Chronotherapy

Dosing time-dependency of pharmacokinetics (or chronopharmacokinetics) has been long recognized. Studies in recent years have revealed that diurnal rhythmicity in expression of drug-metabolizing enzymes and transporters (DMETs) are key factors determining chronopharmacokinetics. In this article, we briefly summarize current knowledge with respect to circadian mechanisms of DMETs and discuss how rhythmic DMETs are translated to drug chronoeffects. More importantly, we present our perspectives on pharmacokinetics-based chronotherapy.

Pharmacokinetics-Based Chronoefficacy of Semen Strychni and Tripterygium Glycoside Tablet Against Rheumatoid Arthritis

Rheumatoid arthritis is a systemic autoimmune disease characterized by synovial inflammation and bone destruction. Identifying drugs with time-varying efficacy and toxicity, and elucidating the mechanisms would help to improve treatment efficacy and reduce adverse effects. Here, we aimed to determine the chronoefficacy of semen strychni (SS) and tripterygium glycoside tablet (TGT) against rheumatoid arthritis in mice, and to investigate a potential role of circadian pharmacokinetics in generating chronoefficacy. SS extract and TGT suspension were prepared with ultrasonication. Effects of SS and TGT on collagen-induced arthritis (CIA) were evaluated by measuring TNF-α and IL-6 levels. SS dosed at ZT18 was more effective in protecting against CIA than drug dosed at ZT6 (i.e., lower levels of key inflammatory factors at ZT18 than at ZT6). This was accompanied by higher systemic exposure levels of strychnine and brucine (two main putative active ingredients of SS) in ZT18-treated than in ZT6-treated CIA mice. TGT dosing at ZT2 showed a better efficacy against CIA as compared to herb doing at ZT14. Consistently, ZT2 dosing generated a higher exposure of triptolide (a main putative active ingredient of TGT) as compared to ZT14 dosing in CIA mice. Moreover, strychnine, brucine, and triptolide significantly inhibited the proliferation of fibroblast-like synoviocytes, and reduced the production of TNF-α and IL-6 and the mRNAs of TNF-α, IL-6, COX-2, and iNOS, suggesting that they possessed an anti-arthritis activity. In conclusion, SS and TGT display chronoefficacy against rheumatoid arthritis in mice, that is attributed to circadian pharmacokinetics of main active ingredients. Our findings have implications for improving treatment outcomes of SS and TGT via timed delivery.