Schekwanglupaside C, a new lupane saponin from Schefflera kwangsiensis, is a potent activator of sarcoplasmic reticulum Ca2+-ATPase

Discovery of pyridazinone analogs as potent transient receptor potential canonical channel 5 inhibitors

A deepening understanding of the relationship between transient receptor potential canonical channel 5 (TRPC5) and chronic kidney disease (CKD), has led to the emergence of several types of TRPC5 inhibitors displaying clear therapeutic effect. Herein, we report the synthesis and biological evaluation of a series of pyrroledione TRPC5 inhibitors, culminating in the discovery of compound 16g with subtype selectivity. Compared with GFB-8438, a potent TRPC5 inhibitor (Goldfinch Bio), compound 16g showed improved inhibition of TRPC5 and enhanced protective effect against protamine sulfates (PS)-induced podocyte injury in vitro. In addition, compound 16g did not induce cell death in primary cultured hepatocytes and immortalized podocytes in a preliminary toxicity assessment, indicating its utility as a potent and safe inhibitor for studying the function of TRPC5.

Sarco/endoplasmic reticulum Ca2+ -ATPase 2b mediates oxidation-induced endoplasmic reticulum stress to regulate neuropathic pain

BACKGROUND AND PURPOSE

Neuropathic pain is a widespread health problem with limited curative treatment. Decreased sarco/endoplasmic reticulum Ca²⁺ -ATPase (SERCA) expression has been reported in dorsal root ganglion (DRG) of animals suffering from neuropathic pain. We aimed to establish the relationship between SERCA expression and the pain responses and to elucidate the underlying molecular mechanism.

EXPERIMENTAL APPROACH

Neuropathic pain was modeled using rat chronic constriction injury (CCI). Ca²⁺ imaging and current clamp patch-clamp were used to determine cytosolic Ca²⁺ levels and action potential firing, respectively. Western blots, immunofluorescence staining and RT-PCR were used to quantitatively assess protein and mRNA expression, respectively. H&E staining and coupled enzyme assay were used to evaluate the nerve injury and SERCA2b activity, respectively.

KEY RESULTS

SERCA2b is the predominant SERCA isoform in rat DRG and its expression is decreased after CCI at mRNA, protein and activity levels. Whereas inhibiting SERCA with thapsigargin causes neuronal hyperexcitation, nerve injury, ER stress, satellite glial cell activation and mechanical allodynia, activating SERCA by CDN1163 or overexpressing SERCA2b in DRG after CCI produces long-term relief of mechanical and thermal allodynia with accompanied morphological and functional restoration through alleviation of ER stress. Furthermore, the downregulation of DRG SERCA2b in CCI rats is caused by increased production of reactive oxygen species (ROS) through Sp1-dependent transcriptional inhibition.

CONCLUSION AND IMPLICATIONS

Our findings reveal a novel pathway centering around SERCA2b as the key molecule underlying the mechanism of development and maintenance of neuropathic pain, and SERCA2b activators have the potential for therapeutic treatment of neuropathic pain.

The genus Schefflera: A review of traditional uses, phytochemistry and pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Schefflera is the largest genus in the family Araliaceae, which contains 602 known species indigenous to Asia, Africa, and the southwest Pacific region, several of which are used in traditional medicine.

AIM OF THE REVIEW

The review discusses current knowledge of the traditional uses, phytochemistry, and biological activities of Schefflera species, to assess the medicinal potential of this genus.

MATERIALS AND METHODS

The literature were explored using the keyword "Schefflera" in SciFinder®, Google Scholar®, and PubMed® databases. The taxonomy of all reported plants was authenticated using "The Plant List". Additional data on traditional uses was obtained from secondary references including books and online resources.

RESULTS

Fourteen species were documented as traditional medicines in China, India, Vietnam, Thailand, and Indonesia, specifically to manage rheumatism, pain, and trauma. Other species are used in the treatment of liver disorders, skin conditions, respiratory infections, cancer, diarrhea, malaria, paralysis, and many other conditions. The main phytochemical constituents identified were triterpenoids and saponins, with sesquiterpenes, phenylpropanoids, and lignans. Pharmacological properties of extracts and pure isolated compounds included analgesic, anti-inflammatory, anticancer, hypoglycemic, antimicrobial, hepatoprotective, neuroprotective, antimalarial, and antiallergic effects.

CONCLUSION

The reported biological activities of Schefflera species support their traditional uses, although the available data, even for medicinal species, was limited. Reports of chemical constituents or biological activities could be found for only about 20 species, but suggest that further investigation of efficacy and safety of the largely unexplored genus Schefflera is necessary.

Endoplasmic Reticulum Calcium Pumps and Tumor Cell Differentiation

Endoplasmic reticulum (ER) calcium homeostasis plays an essential role in cellular calcium signaling, intra-ER protein chaperoning and maturation, as well as in the interaction of the ER with other organelles. Calcium is accumulated in the ER by sarco/endoplasmic reticulum calcium ATPases (SERCA enzymes) that generate by active, ATP-dependent transport, a several thousand-fold calcium ion concentration gradient between the cytosol (low nanomolar) and the ER lumen (high micromolar). SERCA enzymes are coded by three genes that by alternative splicing give rise to several isoforms, which can display isoform-specific calcium transport characteristics. SERCA expression levels and isoenzyme composition vary according to cell type, and this constitutes a mechanism whereby ER calcium homeostasis is adapted to the signaling and metabolic needs of the cell, depending on its phenotype, its state of activation and differentiation. As reviewed here, in several normal epithelial cell types including bronchial, mammary, gastric, colonic and choroid plexus epithelium, as well as in mature cells of hematopoietic origin such as pumps are simultaneously expressed, whereas in corresponding tumors and leukemias SERCA3 expression is selectively down-regulated. SERCA3 expression is restored during the pharmacologically induced differentiation of various cancer and leukemia cell types. SERCA3 is a useful marker for the study of cell differentiation, and the loss of SERCA3 expression constitutes a previously unrecognized example of the remodeling of calcium homeostasis in tumors.