Effects of diphyllin as a novel V-ATPase inhibitor on TE-1 and ECA-109 cells

Synthesis and Preliminary Anticancer Evaluation of 4-C Derivatives of Diphyllin

The natural lignan diphyllin has shown promising antitumor activity, although its clinical advancement has been impeded by challenges such as low solubility, poor metabolic stability, and limited potency. In response, we developed and synthesized two sets of diphyllin 4-C derivatives, comprising six ester derivatives and eight 1, 2, 3-triazole derivatives. Notably, among these derivatives, 1, 2, 3-triazole derivatives 7c and 7e demonstrated the most potent cytotoxic effects, with IC50 values ranging from 0.003 to 0.01 μM. Treatment with 0.2 μM of 7c and 7e resulted in a reduction of V-ATPase activity in HGC-27 cells to 23% and 29%, respectively.

Bioactivities and Mechanisms of Action of Diphyllin and Its Derivatives: A Comprehensive Systematic Review

Natural products are treasure houses for modern drug discovery. Diphyllin is a natural arylnaphthalene lignan lactone isolated from the leaf of Astilboides tabularis. Studies have found that it possesses plenty of bioactivity characteristics. In this paper, we reviewed the structure, bioactivity, and mechanism of action of diphyllin and its derivatives. The references were obtained from PubMed, Web of Science, and Science Direct databases up to August 2023. Papers without a bio-evaluation were excluded. Diphyllin and its derivatives have demonstrated V-ATPase inhibition, anti-tumor, anti-virus, anti-biofilm, anti-inflammatory, and anti-oxidant activities. The most studied activities of diphyllin and its derivatives are V-ATPase inhibition, anti-tumor activities, and anti-virus activities. Furthermore, V-ATPase inhibition activity is the mechanism of many bioactivities, including anti-tumor, anti-virus, and anti-inflammatory activities. We also found that the galactosylated modification of diphyllin is a common phenomenon in plants, and therefore, galactosylated modification is applied by researchers in the laboratory to obtain more excellent diphyllin derivatives. This review will provide useful information for the development of diphyllin-based anti-tumor and anti-virus compounds.

Arylnaphthalene Lignans with Anti-SARS-CoV-2 and Antiproliferative Activities from the Underground Organs of Linum austriacum and Linum perenne

Diphyllin (1) and justicidin B (2) are arylnaphthalene lignans with antiviral and antiproliferative effects. Compound 1 is also known as an effective inhibitor of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). To evaluate the in vitro antiviral and cytotoxic potency of both lignans in SARS-CoV-2 -infected cells and various cancer cell lines, respectively, 1 and 2 were isolated from the underground organs of Linum austriacum and Linum perenne. Two previously undescribed arylnaphthalene lignans, denominated linadiacin A and B (3 and 4), were also isolated and identified. In acidic media, 3 was converted by a two-step reaction into 2 via the intermediate 4. Optimum acid treatment conditions were determined to isolate lignans by one-step preparative high-performance liquid chromatography (HPLC). The results of the conversion, HPLC-tandem mass spectrometry, nuclear magnetic resonance spectroscopy, and molecular modeling studies allowed complete structure analysis. Compounds 1 and 2 were the most effective against SARS-CoV-2 with a 3-log reduction in the viral copy number at a 12.5 μM concentration. Ten human cancer cell lines showed sensitivity to at least one of the isolated lignans.

Dandelion Seed Extract Affects Tumor Progression and Enhances the Sensitivity of Cisplatin in Esophageal Squamous Cell Carcinoma

Like dandelion, dandelion seed also have anti-inflammatory activity. Therefore, in this article, we intend to explore the anti-cancer availability of aqueous dandelion seed extract (DSE) in esophageal squamous cell carcinoma (ESCC). Firstly, the effects of DSE on cell proliferation, apoptosis, migration, invasion and angiogenesis were investigated. Then to explore the mechanism of DSE against ESCC, the levels of proliferation-associated proteins (PI3K, Akt and pAkt), apoptosis-associated proteins (survivin, Bcl-2, Bax, caspase3 and caspase9), metastasis-associated proteins (MMP2, MMP9, VEGF) and EMT progression-associated proteins (Snail, E-cadherin and Vimentin) were analyzed. Next, we further explored the effect of DSE on the sensitivity of cisplatin (DDP) in ESCC cells and investigated the effect of DSE combined with DDP on DNA damage repair-associated proteins (MSH2, MLH1 and ERCC1) and drug resistant target protein STAT3. The results indicated that DSE selectively inhibited cell growth, proliferation, migration, invasion, angiogenesis and induced cell apoptosis in ESCC cells. It was observed the decreased PI3K, Akt and pAkt proteins levels in KYSE450 and Eca109 cells administrated with DSE. The data also showed that the application of DSE decreased the level of survivin and the ratio of Bcl-2/Bax, while increased the levels of caspase3 and caspase9. We also observed that DSE significantly decreased the levels of MMP2, MMP9 and VEGF proteins and inhibited the EMT progression in KYSE450 and Eca109 cells. In addition, survivin plays a critical role in DSE against ESCC followed with the application of survivin inhibitor YM155 impairing the inhibitory abilities of DSE in ESCC cells. Meanwhile, it was observed that DSE enhances the sensitivity of DDP to human ESCC cells via promoting DNA damage and inhibiting phosphorylation of STAT3. Therefore, DSE may affect ESCC progression and enhance the sensitivity of cisplatin, and consequently become an effective anti-cancer option for human ESCC treatment.

Diphyllin Shows a Broad-Spectrum Antiviral Activity against Multiple Medically Important Enveloped RNA and DNA Viruses

Diphyllin is a natural arylnaphtalide lignan extracted from tropical plants of particular importance in traditional Chinese medicine. This compound has been described as a potent inhibitor of vacuolar (H⁺)ATPases and hence of the endosomal acidification process that is required by numerous enveloped viruses to trigger their respective viral infection cascades after entering host cells by receptor-mediated endocytosis. Accordingly, we report here a revised, updated, and improved synthesis of diphyllin, and demonstrate its antiviral activities against a panel of enveloped viruses from Flaviviridae, Phenuiviridae, Rhabdoviridae, and Herpesviridae families. Diphyllin is not cytotoxic for Vero and BHK-21 cells up to 100 µM and exerts a sub-micromolar or low-micromolar antiviral activity against tick-borne encephalitis virus, West Nile virus, Zika virus, Rift Valley fever virus, rabies virus, and herpes-simplex virus type 1. Our study shows that diphyllin is a broad-spectrum host cell-targeting antiviral agent that blocks the replication of multiple phylogenetically unrelated enveloped RNA and DNA viruses. In support of this, we also demonstrate that diphyllin is more than just a vacuolar (H⁺)ATPase inhibitor but may employ other antiviral mechanisms of action to inhibit the replication cycles of those viruses that do not enter host cells by endocytosis followed by low pH-dependent membrane fusion.

PHY34 inhibits autophagy through V-ATPase V0A2 subunit inhibition and CAS/CSE1L nuclear cargo trafficking in high grade serous ovarian cancer

PHY34 is a synthetic small molecule, inspired by a compound naturally occurring in tropical plants of the Phyllanthus genus. PHY34 was developed to have potent in vitro and in vivo anticancer activity against high grade serous ovarian cancer (HGSOC) cells. Mechanistically, PHY34 induced apoptosis in ovarian cancer cells by late-stage autophagy inhibition. Furthermore, PHY34 significantly reduced tumor burden in a xenograft model of ovarian cancer. In order to identify its molecular target/s, we undertook an unbiased approach utilizing mass spectrometry-based chemoproteomics. Protein targets from the nucleocytoplasmic transport pathway were identified from the pulldown assay with the cellular apoptosis susceptibility (CAS) protein, also known as CSE1L, representing a likely candidate protein. A tumor microarray confirmed data from mRNA expression data in public databases that CAS expression was elevated in HGSOC and correlated with worse clinical outcomes. Overexpression of CAS reduced PHY34 induced apoptosis in ovarian cancer cells based on PARP cleavage and Annexin V staining. Compounds with a diphyllin structure similar to PHY34 have been shown to inhibit the ATP6V0A2 subunit of V(vacuolar)-ATPase. Therefore, ATP6V0A2 wild-type and ATP6V0A2 V823 mutant cell lines were tested with PHY34, and it was able to induce cell death in the wild-type at 246 pM while the mutant cells were resistant up to 55.46 nM. Overall, our data demonstrate that PHY34 is a promising small molecule for cancer therapy that targets the ATP6V0A2 subunit to induce autophagy inhibition while interacting with CAS and altering nuclear localization of proteins.

Targeting the Microenvironment in Esophageal Cancer

Esophageal cancer (EC) is the eighth most common type of cancer and the sixth leading cause of cancer-related deaths worldwide. At present, the clinical treatment for EC is based mainly on radical surgery, chemotherapy, and radiotherapy. However, due to the limited efficacy of conventional treatments and the serious adverse reactions, the outcome is still unsatisfactory (the 5-year survival rate for patients is less than 25%). Thus, it is extremely important and urgent to identify new therapeutic targets. The concept of tumor microenvironment (TME) has attracted increased attention since it was proposed. Recent studies have shown that TME is an important therapeutic target for EC. Microenvironment-targeting therapies such as immunotherapy and antiangiogenic therapy have played an indispensable role in prolonging survival and improving the prognosis of patients with EC. In addition, many new drugs and therapies that have been developed to target microenvironment may become treatment options in the future. We summarize the microenvironment of EC and the latest advances in microenvironment-targeting therapies in this review.

Medicinal Plants, Phytochemicals, and Herbs to Combat Viral Pathogens Including SARS-CoV-2

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome corona virus-2 (SARS-CoV-2), is the most important health issue, internationally. With no specific and effective antiviral therapy for COVID-19, new or repurposed antiviral are urgently needed. Phytochemicals pose a ray of hope for human health during this pandemic, and a great deal of research is concentrated on it. Phytochemicals have been used as antiviral agents against several viruses since they could inhibit several viruses via different mechanisms of direct inhibition either at the viral entry point or the replication stages and via immunomodulation potentials. Recent evidence also suggests that some plants and its components have shown promising antiviral properties against SARS-CoV-2. This review summarizes certain phytochemical agents along with their mode of actions and potential antiviral activities against important viral pathogens. A special focus has been given on medicinal plants and their extracts as well as herbs which have shown promising results to combat SARS-CoV-2 infection and can be useful in treating patients with COVID-19 as alternatives for treatment under phytotherapy approaches during this devastating pandemic situation.

Diphyllin Improves High-Fat Diet-Induced Obesity in Mice Through Brown and Beige Adipocytes

Brown adipose tissue (BAT) and beige adipose tissue dissipate metabolic energy and mediate nonshivering thermogenesis, thereby boosting energy expenditure. Increasing the browning of BAT and beige adipose tissue is expected to be a promising strategy for combatting obesity. Through phenotype screening of C3H10-T1/2 mesenchymal stem cells, diphyllin was identified as a promising molecule in promoting brown adipocyte differentiation. In vitro studies revealed that diphyllin promoted C3H10-T1/2 cell and primary brown/beige preadipocyte differentiation and thermogenesis, which resulted increased energy consumption. We synthesized the compound and evaluated its effect on metabolism in vivo. Chronic experiments revealed that mice fed a high-fat diet (HFD) with 100 mg/kg diphyllin had ameliorated oral glucose tolerance and insulin sensitivity and decreased body weight and fat content ratio. Adaptive thermogenesis in HFD-fed mice under cold stimulation and whole-body energy expenditure were augmented after chronic diphyllin treatment. Diphyllin may be involved in regulating the development of brown and beige adipocytes by inhibiting V-ATPase and reducing intracellular autophagy. This study provides new clues for the discovery of anti-obesity molecules from natural products.

Lignans and Their Derivatives from Plants as Antivirals

Lignans are widely produced by various plant species; they are a class of natural products that share structural similarity. They usually contain a core scaffold that is formed by two or more phenylpropanoid units. Lignans possess diverse pharmacological properties, including their antiviral activities that have been reported in recent years. This review discusses the distribution of lignans in nature according to their structural classification, and it provides a comprehensive summary of their antiviral activities. Among them, two types of antiviral lignans—podophyllotoxin and bicyclol, which are used to treat venereal warts and chronic hepatitis B (CHB) in clinical, serve as examples of using lignans for antivirals—are discussed in some detail. Prospects of lignans in antiviral drug discovery are also discussed.

Modulation of Multiple Signaling Pathways of the Plant-Derived Natural Products in Cancer

Natural compounds are highly effective anticancer chemotherapeutic agents, and the targets of plant-derived anticancer agents have been widely reported. In this review, we focus on the main signaling pathways of apoptosis, proliferation, invasion, and metastasis that are regulated by polyphenols, alkaloids, saponins, and polysaccharides. Alkaloids primarily affect apoptosis-related pathways, while polysaccharides primarily target pathways related to proliferation, invasion, and metastasis. Other compounds, such as flavonoids and saponins, affect all of these aspects. The association between compound structures and signaling pathways may play a critical role in drug discovery.

Glycosylated diphyllin as a broad-spectrum antiviral agent against Zika virus

Background

Flaviviruses such as Zika cause sporadic pandemic outbreaks worldwide. There is an urgent need for anti-Zika virus (ZIKV) drugs to prevent mother-to-child transmission of ZIKV, new infections in high-risk populations, and the infection of medical personnel in ZIKV-affected areas.

Methods

Here, we showed that the small molecule 6-deoxyglucose-diphyllin (DGP) exhibited anti-ZIKV activity both in vitro and in vivo. DGP potently blocked ZIKV infection across all human and monkey cell lines tested. DGP also displayed broad-spectrum antiviral activity against other flaviviruses. Remarkably, DGP prevented ZIKV-induced mortality in mice lacking the type I interferon receptor (Ifnar1^−/−). Cellular and virological experiments showed that DGP blocked ZIKV at a pre-fusion step or during fusion, which prevented the delivery of viral contents into the cytosol of the target cell. Mechanistic studies revealed that DGP prevented the acidification of endosomal/lysosomal compartments in target cells, thus inhibiting ZIKV fusion with cellular membranes and infection.

Findings

These investigations revealed that DGP inhibits ZIKV infection in vitro and in vivo.

Interpretation

The small molecule DGP has great potential for preclinical studies and the ability to inhibit ZIKV infection in humans.

Dual Effects of Chinese Herbal Medicines on Angiogenesis in Cancer and Ischemic Stroke Treatments: Role of HIF-1 Network

Hypoxia-inducible factor-1 (HIF-1)-induced angiogenesis has been involved in numerous pathological conditions, and it may be harmful or beneficial depending on the types of diseases. Exploration on angiogenesis has sparked hopes in providing novel therapeutic approaches on multiple diseases with high mortality rates, such as cancer and ischemic stroke. The HIF-1 pathway is considered to be a major regulator of angiogenesis. HIF-1 seems to be involved in the vascular formation process by synergistic correlations with other proangiogenic factors in cancer and cerebrovascular disease. The regulation of HIF-1-dependent angiogenesis is related to the modulation of HIF-1 bioactivity by regulating HIF-1α transcription or protein translation, HIF-1α DNA binding, HIF-1α and HIF-1α dimerization, and HIF-1 degradation. Traditional Chinese herbal medicines have a long history of clinical use in both cancer and stroke treatments in Asia. Growing evidence has demonstrated potential proangiogenic benefits of Chinese herbal medicines in ischemic stroke, whereas tumor angiogenesis could be inhibited by the active components in Chinese herbal medicines. The objective of this review is to provide comprehensive insight on the effects of Chinese herbal medicines on angiogenesis by regulating HIF-1 pathways in both cancer and ischemic stroke.

A novel potent autophagy inhibitor ECDD-S27 targets vacuolar ATPase and inhibits cancer cell survival

Autophagy is a conserved lysosomal-dependent cellular degradation process and its dysregulation has been linked to numerous diseases including neurodegeneration, infectious diseases, and cancer. Modulation of autophagy is therefore considered as an attractive target for disease intervention. We carried out a high-content image analysis screen of natural product-derived compounds to discover novel autophagy modulating molecules. Our screen identified ECDD-S27 as the most effective compound for increasing the number of autophagic vacuoles inside cells. The structure of ECDD-S27 revealed that it is a derivative of cleistanthin A, a natural arylnaphthalene lignan glycoside found in plants. ECDD-S27 increases the number of autophagic vacuoles by inhibiting the autophagic flux and is able to restrict the survival of different cancer cells at low nanomolar concentrations. Molecular docking and SERS analysis showed that ECDD-S27 may potentially target the V-ATPase. Upon treatment of various cancer cells with ECDD-S27, the V-ATPase activity is potently inhibited thereby resulting in the loss of lysosomal acidification. Taken together, these data indicated that ECDD-S27 retards the autophagy pathway by targeting the V-ATPase and inhibits cancer cell survival. The observed antitumor activity without cytotoxicity to normal cells suggests the therapeutic potential warranting further studies on lead optimization of the compound for cancer treatment.

V-ATPases and osteoclasts: ambiguous future of V-ATPases inhibitors in osteoporosis

Vacuolar ATPases (V-ATPases) play a critical role in regulating extracellular acidification of osteoclasts and bone resorption. The deficiencies of subunit a3 and d2 of V-ATPases result in increased bone density in humans and mice. One of the traditional drug design strategies in treating osteoporosis is the use of subunit a3 inhibitor. Recent findings connect subunits H and G1 with decreased bone density. Given the controversial effects of ATPase subunits on bone density, there is a critical need to review the subunits of V-ATPase in osteoclasts and their functions in regulating osteoclasts and bone remodeling. In this review, we comprehensively address the following areas: information about all V-ATPase subunits and their isoforms; summary of V-ATPase subunits associated with human genetic diseases; V-ATPase subunits and osteopetrosis/osteoporosis; screening of all V-ATPase subunits variants in GEFOS data and in-house data; spectrum of V-ATPase subunits during osteoclastogenesis; direct and indirect roles of subunits of V-ATPases in osteoclasts; V-ATPase-associated signaling pathways in osteoclasts; interactions among V-ATPase subunits in osteoclasts; osteoclast-specific V-ATPase inhibitors; perspective of future inhibitors or activators targeting V-ATPase subunits in the treatment of osteoporosis.