Neuroprotective Effects of Dried Tubers of Aconitum napellus

Design, synthesis, and biological evaluation of low-toxic lappaconitine derivatives as potential analgesics

The C₁₈-diterpenoid alkaloid lappaconitine (LA) is a non-addictive analgesic used in China. The toxicity (LD₅₀ = 11.7 mg/kg) limits its application. Two series of LA derivatives, including amides and sulfonamides (1-93), were designed and synthesized by modification on their C4 acetamidobenzoate side chains in this work. In vivo analgesic activity and toxicity of all derivatives were evaluated, and the structure-activity relationship was summarized. Six lead compounds (35, 36, 39, 49, 70, and 89) exhibited approximate analgesic activity to LA but with significantly reduced toxicity. The therapeutic index of these compounds is 14-30 times that of LA. In vivo metabolism study of the lead compounds 39, 49, 70, and 89 were conducted by UPLC-MS^E, indicating the reason for the low toxicity of the potential derivatives might be they are difficult to metabolize to toxic metabolite N-deacetyllappaconitine compared to LA. The effects of lead compounds on sodium channels and hERG channels were also studied by ion channel reader (ICR) which further revealed their analgesic and toxicity-attenuating mechanisms. Sodium channel assay revealed that the analgesic mechanism of these lead compounds was inhibiting the Na_v 1.7 channels. Taken together, compound 39 was provided as a new analgesic lead compound with significantly low toxicity and comparable activity to LA.

Correction: Shoaib et al. Neuroprotective Effects of Dried Tubers of Aconitum napellus. Plants 2020, 9, 356

We are sorry to report that some images in Figure 1 reported in our recently published paper [...].

Neuroprotective effect of Bryophyllum pinnatum flavonoids against aluminum chloride-induced neurotoxicity in rats

Toxic metals such as aluminum accumulation in the brain have been associated with the pathophysiology of several neurodegenerative disorders. Bryophyllum pinnatum leaves contain a vast array of polyphenols, particularly flavonoids, that may play a role in the prevention of toxic and degenerative effects in the brain. This study assessed the neuro-restorative potential of leaves of B. pinnatum enriched flavonoid fraction (BPFRF) in aluminum-induced neurotoxicity in rats. Neurotoxicity was induced in male Wistar rats by oral administration of 150 mg/kg body weight of aluminum chloride (AlCl₃) for 21 days. Rats were grouped into five (n = 6); Control (untreated), Rivastigmine group, AlCl₃ group and BPFRF group (50 and 100 mg/kg b.wt.) for 21 days. Neuronal changes in the hippocampus and cortex were biochemically and histologically evaluated. Expression patterns of acetylcholinesterase (AChE) mRNA were assessed using semi-quantitative reverse-transcription-polymerase chain reaction protocols. Molecular interactions of BPFRF compounds were investigated in silico. The results revealed that oral administration of BPFRF ameliorated oxidative imbalance by augmenting antioxidant systems and decreasing lipid peroxidation caused by AlCl₃. BPFRF administration also contributed to the down-regulation of AChE mRNA transcripts and improved histological features in the hippocampus and cortex. Molecular docking studies revealed strong molecular interactions between BPFRF compounds, catalase, superoxide dismutase and glutathione peroxidase Overall, these findings suggest the neuroprotective effect of Bryophyllum pinnatum against aluminum-induced neurotoxicity.

Effect of thymoquinone on high fat diet and STZ-induced experimental type 2 diabetes: A mechanistic insight by in vivo and in silico studies

The aim was to investigate whether thymoquinone (TQ) attenuates hyperglycemia-induced insulin resistance in experimental type 2 diabetes. Type 2 diabetes mellitus (T2DM) was induced by injection of streptozotocin (STZ, 40 mg/kg) in high fat diet (HFD) rats. The levels of glucose, insulin, area under curve (AUC) of glucose, lipid profile parameters, homeostasis model assessment of insulin resistance (HOMA-IR), peroxisome proliferator-activated receptor-γ (PPARγ), and dipeptidyl peptidase peptidase-IV (DPP-IV) were evaluated in HFD + STZ-induced type 2 diabetic rats. TQ treatment significantly reduced elevated levels of glucose, AUC of glucose, insulin, and DPP-IV in diabetic-treated groups. In addition, TQ treatment significantly reduced high levels of triglycerides (TG) and cholesterols (total, low-density and very low-density lipoprotein) accompanied by significant augmentation in high-density lipoprotein (HDL) levels in diabetic-treated groups. However, TQ treatment significantly improved insulin sensitivity in diabetic-treated groups, which was confirmed by increased level of PPARγ and decreased level of HOMA-IR. Molecular docking of TQ exhibited substantial binding affinity with PPARγ and DPP-IV target proteins, which is supported by in vivo results. These results demonstrate that TQ attenuates hyperglycemia-induced insulin resistance by counteracting hyperinsulinemia, improving lipid profile, insulin sensitivity, and inhibiting DPP-IV. PRACTICAL APPLICATIONS: T2DM results in relentless hyperglycemia which eventually progress to a state of insulin resistance. TQ is an active principle compound found in Nigella sative seed, having myriad of traditional medicinal values. Administration of TQ significantly prevented hyperglycemia, hyperinsulinemia, hyperlipidemia, insulin resistance, and inhibited DPP-IV in experimental type 2 diabetes. The in vivo results are also supported by molecular docking study of PPARγ and DPP-IV target proteins. Thus, we hypothesize that TQ can be used as an alternative natural drug in the management of hyperglycemia-induced insulin resistance in T2DM.

Plant-Derived Chemicals: A Source of Inspiration for New Drugs

Plants have a long history of use as traditional remedies to treat a range of diseases and the diverse chemicals that they produce have provided great inspiration for the design of new drugs to date. Many plants have yet to be investigated for the presence of biologically-active products. This Special Issue presents a collection of scientific studies which report on the medicinal potential of plants. It also highlights the importance of preserving ethnobotanical knowledge and plant biodiversity worldwide to sustain future drug discovery from plant sources.