Akebia saponin E, as a novel PIKfyve inhibitor, induces lysosome-associated cytoplasmic vacuolation to inhibit proliferation of hepatocellular carcinoma cells

Natural Saponins on Cholesterol-Related Diseases: Treatment and Mechanism

Saponins are compounds composed of lipophilic aglycones linked to hydrophilic sugars. Natural saponins are isolated from plants and some Marine organisms. As important cholesterol-lowering drugs, natural saponins have attracted wide attention for their therapeutic potential in a variety of cholesterol-related metabolic diseases. To review the effects of natural saponins on cholesterol-related metabolic diseases, and to deepen the understanding of the cholesterol-lowering mechanism of saponins. The literature related to saponins and cholesterol-lowering diseases was collected using keywords "saponins" and "cholesterol" from PubMed, Web of Science, and Google Scholar from January 2000 to May 2024. The total number of articles related to saponins and cholesterol-lowering diseases was 240 after excluding irrelevant articles. Natural saponins can regulate cholesterol to prevent and treat a variety of diseases, such as atherosclerosis, diabetes, liver disease, hyperlipidemia, cancer, and obesity. Mechanistically, natural saponins regulate cholesterol synthesis and uptake through the AMPK/SREBP2/3-hydroxy-3-methyl-glutaryl coenzyme A reductase pathway and PCSK9/LDLR pathway, and regulate cholesterol efflux and esterification targeting Liver X receptor/ABC pathway and ACAT family. Natural saponins have broad application prospects in regulating cholesterol metabolism, for the development of more cholesterol-lowering drugs provides a new train of thought. However, it is still necessary to further explore the molecular mechanism and expand clinical trials to provide more evidence.

Research Progress of Chinese Medicine in Treating Chronic Liver Disease by Regulating Autophagy

In recent years, rising living standards and an accelerated lifestyle have led to an increase in the incidence of chronic liver disease. Modern medicine has yet to fully develop effective methods for preventing and treating these conditions due to their complex pathogenesis. Autophagy, a cellular process that maintains homeostasis by removing abnormal proteins, has emerged as a promising therapeutic target for chronic liver diseases. These diseases include liver fibrosis, liver cirrhosis, non-alcoholic steatohepatitis, chronic hepatitis B, and hepatocellular carcinoma. Chinese medicine, with its multi-component, multi-target, and multi-pathway approach, offers unique advantages in treating these conditions, especially given the unclear etiology of chronic liver diseases. Recent research demonstrates that Chinese medicine - comprising single herbs, herbal combinations, and proprietary formulas - can effectively regulate autophagy, thereby providing therapeutic and preventive benefits for chronic liver diseases. This paper reviews recent studies, categorizes various chronic liver diseases, and examines the impact of active ingredients and compound formulas from Chinese medicine on autophagy. These insights are crucial for slowing the progression of chronic liver diseases and pave the way for the future application of Chinese medicine in preventing and managing these conditions through autophagy modulation.

Inhibition of PIKfyve Leads to Lysosomal Disorders via Dysregulation of mTOR Signaling

PIKfyve is an endosomal lipid kinase that synthesizes phosphatidylinositol 3,5-biphosphate from phosphatidylinositol 3-phsphate. Inhibition of PIKfyve activity leads to lysosomal enlargement and cytoplasmic vacuolation, attributed to impaired lysosomal fission processes and homeostasis. However, the precise molecular mechanisms underlying these effects remain a topic of debate. In this study, we present findings from PIKfyve-deficient zebrafish embryos, revealing enlarged macrophages with giant vacuoles reminiscent of lysosomal storage disorders. Treatment with mTOR inhibitors or effective knockout of mTOR partially reverses these abnormalities and extend the lifespan of mutant larvae. Further in vivo and in vitro mechanistic investigations provide evidence that PIKfyve activity is essential for mTOR shutdown during early zebrafish development and in cells cultured under serum-deprived conditions. These findings underscore the critical role of PIKfyve activity in regulating mTOR signaling and suggest potential therapeutic applications of PIKfyve inhibitors for the treatment of lysosomal storage disorders.

S670, an amide derivative of 3-O-acetyl-11-keto-β-boswellic acid, induces ferroptosis in human glioblastoma cells by generating ROS and inhibiting STX17-mediated fusion of autophagosome and lysosome

Glioblastoma (GBM) is the most common malignant tumor in the brain with temozolomide (TMZ) as the only approved chemotherapy agent. GBM is characterized by susceptibility to radiation and chemotherapy resistance and recurrence as well as low immunological response. There is an urgent need for new therapy to improve the outcome of GBM patients. We previously reported that 3-O-acetyl-11-keto-β-boswellic acid (AKBA) inhibited the growth of GBM. In this study we characterized the anti-GBM effect of S670, a synthesized amide derivative of AKBA, and investigated the underlying mechanisms. We showed that S670 dose-dependently inhibited the proliferation of human GBM cell lines U87 and U251 with IC50 values of around 6 μM. Furthermore, we found that S670 (6 μM) markedly stimulated mitochondrial ROS generation and induced ferroptosis in the GBM cells. Moreover, S670 treatment induced ROS-mediated Nrf2 activation and TFEB nuclear translocation, promoting protective autophagosome and lysosome biogenesis in the GBM cells. On the other hand, S670 treatment significantly inhibited the expression of SXT17, thus impairing autophagosome-lysosome fusion and blocking autophagy flux, which exacerbated ROS accumulation and enhanced ferroptosis in the GBM cells. Administration of S670 (50 mg·kg-1·d-1, i.g.) for 12 days in a U87 mouse xenograft model significantly inhibited tumor growth with reduced Ki67 expression and increased LC3 and LAMP2 expression in the tumor tissues. Taken together, S670 induces ferroptosis by generating ROS and inhibiting STX17-mediated fusion of autophagosome and lysosome in GBM cells. S670 could serve as a drug candidate for the treatment of GBM.

Germplasm resources and genetic improvement of Akebia: A new fruit crop in China

Akebia species, belonging to Lardizabalaceae, are widespread from subtropical to temperate environments of China, Japan, and Korea. All known Akebia species have medicinal and dietary value and have been widely cultivated as a new fruit crop in many areas of China. However, compared with other crop species, the breeding improvement and commercial cultivation of Akebia remain in their infancy. This review systematically introduces the present germplasm resources, geographical distribution, biological characteristics, interspecific and intraspecific cross compatibility, molecular biology, and breeding progress in Akebia species. Akebia plants are widely distributed in Shanxi, Henan, Sichuan, Chongqing, Hunan, Hubei, Jiangxi, Zhejiang, and Fujian provinces of China, and wild Akebia plants exhibit abundant phenotypic and genetic diversity due to their wide range of geographical distribution and high adaptability in different habitats. Interspecific artificial hybridization experiments have been conducted in our Akebia germplasm resources nursery. The results showed that there was no reproductive isolation between Akebia species, and fertile progeny could be produced. The synthesis of knowledge on these species provides insights for the rational development and utilization of these germplasm resources, and can facilitate the development of new breeding lines or varieties for commercial cultivation or production. Finally, perspectives on Akebia breeding research are discussed and conclusions are provided. This review provided breeders with new insights into Akebia domestication and breeding, and we also proposed five basic steps in the domestication of new fruit crops.

Intermittent inhibition of FYVE finger-containing phosphoinositide kinase induces melanosome degradation in B16F10 melanoma cells

BACKGROUND

Melanosomes are lysosome-related organelles that contain melanogenic factors and synthesize melanin as they mature. FYVE finger-containing phosphoinositide kinase (PIKfyve) regulates late endosome and lysosome morphology, vesicle trafficking, and autophagy. In melanocytes, PIKfyve inhibition has been reported to induce hypopigmentation due to impairments in the metabolism of early-stage melanosomes.

METHODS AND RESULTS

Here, we report a new type of melanosome metabolism: post-PIKfyve inhibition, which was found during the characterization of the endosome/lysosome fluoroprobe GIF-2250. In B16F10 mouse melanoma cells, GIF-2250 highlighted vesicles positive for lysosomal-associated membrane protein 1 (lysosome marker) and other endosome/lysosome markers (CD63 and Rab7/9). When cells were continuously treated with PIKfyve inhibitors, intracellular vacuoles formed, while GIF-2250 fluorescence signals diminished and were diffusely distributed in the vacuoles. After removal of the PIKfyve inhibitors, the GIF-2250 signal intensity was restored, and some GIF-2250-positive vesicles wrapped the melanosomes, which spun at high speed. In addition, intermittent PIKfyve inhibition caused melanin diffusion in the vacuoles and possible leakage into the cytoplasmic compartments, and melanosome degradation was detected by a transmission electron microscope. Melanosome degradation was accompanied by decreased levels of melanin synthesis enzymes and increased levels of the autophagosome maker LC3BII, which is also associated with early melanosomes. However, the protein levels of p62, which is degraded during autophagy, were increased, suggesting an impairment in autophagy flux during intermittent PIKfyve inhibition. Moreover, the autophagy inhibitor 3-methyladenine does not affect these protein levels, suggesting that the melanosome degradation by the intermittent inhibition of PIKfyve is not mediated by canonical autophagy.

CONCLUSIONS

In conclusion, disturbance of PIKfyve activity induces melanosome degradation in a canonical autophagy-independent manner.

Novel hybrid virtual screening protocol based on pharmacophore and molecular docking for discovery of GSK-3β inhibitors

GSK-3β is a member of the GSKs subfamily and plays a major role in the regulation of transcriptional elongation, which has attracted widespread attention as a therapeutic target for AD. In this study, by combining pharmacophore-based virtual screening and kinase inhibition assays, we have successfully identified four small molecules that inhibit GSK-3β activity at micromolar potency. These hit compounds showed drug-like properties according to Lipinski's rule of five and ADMET. An inter-complex interaction study showed that all hit compounds adapted well to the ATP pocket of the GSK-3β protein. Among them, hits 2 and 4 displayed considerable inhibitory activities with IC₅₀ value of 0.74 ± 0.04 μM and 2.32 ± 0.84 μM respectively. Overall, the discovered GSK-3β inhibitors act as new chemical leads to develop improved inhibitors that block the interaction of GSK-3β, and the hybrid virtual screening strategy designed in this study provides an important reference for design and synthesis novel selective GSK-3β inhibitors.

Mining Therapeutic Efficacy from Treasure Chest of Biodiversity and Chemodiversity: Pharmacophylogeny of Ranunculales Medicinal Plants

Ranunculales, comprising of 7 families that are rich in medicinal species frequently utilized by traditional medicine and ethnomedicine, represents a treasure chest of biodiversity and chemodiversity. The phylogenetically related species often have similar chemical profile, which makes them often possess similar therapeutic spectrum. This has been validated by both ethnomedicinal experiences and pharmacological investigations. This paper summarizes molecular phylogeny, chemical constituents, and therapeutic applications of Ranunculales, i.e., a pharmacophylogeny study of this representative medicinal order. The phytochemistry/metabolome, ethnomedicine and bioactivity/pharmacology data are incorporated within the phylogenetic framework of Ranunculales. The most studied compounds of this order include benzylisoquinoline alkaloid, flavonoid, terpenoid, saponin and lignan, etc. Bisbenzylisoquinoline alkaloids are especially abundant in Berberidaceae and Menispermaceae. The most frequent ethnomedicinal uses are arthritis, heat-clearing and detoxification, carbuncle-abscess and sore-toxin. The most studied bioactivities are anticancer/cytotoxic, antimicrobial, and anti-inflammatory activities, etc. The pharmacophylogeny analysis, integrated with both traditional and modern medicinal uses, agrees with the molecular phylogeny based on chloroplast and nuclear DNA sequences, in which Ranunculales is divided into Ranunculaceae, Berberidaceae, Menispermaceae, Lardizabalaceae, Circaeasteraceae, Papaveraceae, and Eupteleaceae families. Chemical constituents and therapeutic efficacy of each taxonomic group are reviewed and the underlying connection between phylogeny, chemodiversity and clinical uses is revealed, which facilitate the conservation and sustainable utilization of Ranunculales pharmaceutical resources, as well as developing novel plant-based pharmacotherapy.

Current perspectives on naturally occurring saponins as anticancer agents

Saponins, a heterogeneous group of sterol and triterpene glycosides, are distributed widely in nature. Naturally occurring saponins could act on diverse targets in cancer cells and consequently exert potential antiproliferative effects in various cancers, including drug-resistant forms. Therefore, naturally occurring saponins are useful templates for the discovery of novel anticancer candidates. Covering articles published between January 2020 and October 2021, this review aims to outline the recent development of naturally occurring steroidal and triterpenoidal saponins with anticancer potential to provide novel anticancer lead hits/candidates.