Isobavachalcone induces hepatotoxicity in zebrafish embryos and HepG2 cells via the System Xc--GSH-GPX4 signaling pathway in ferroptosis response

Isobavachalcone (IBC) is a flavonoid component of the traditional Chinese medicine Psoraleae Fructus, with a range of pharmacological properties. However, IBC causes some hepatotoxicity, and the mechanism of toxicity is unclear. The purpose of this paper was to investigate the possible mechanism of toxicity of IBC on HepG2 cells and zebrafish embryos. The results showed that exposure to IBC increased zebrafish embryo mortality and decreased hatchability. Meanwhile, IBC induced liver injury and increased expression of ALT and AST activity. Further studies showed that IBC caused the increase of ROS and MDA the decrease of CAT, GSH, and GSH-Px; the increase of Fe2+ content; and the changes of ferroptosis related genes (acsl4, gpx4, and xct) and iron storage related genes (tf, fth, and fpn) in zebrafish embryos. Through in vitro verification, it was found that IBC also caused oxidative stress and increased Fe2+ content in HepG2 cells. IBC caused depolarization of mitochondrial membrane potential (MMP) and reduction of mitochondrial ATP, as well as altered expression of ACSl4, SLC7A11, GPX4, and FTH1 proteins. Treatment of HepG2 cells with ferrostatin-1 could reverse the effect of IBC. Targeting the System Xc--GSH-GPX4 pathway of ferroptosis and preventing oxidative stress damage might offer a theoretical foundation for practical therapy and prevention of IBC-induced hepatotoxicity.

Isobavachalcone, a natural sirtuin 2 inhibitor, exhibits anti-triple-negative breast cancer efficacy in vitro and in vivo

Triple-negative breast cancer (TNBC) is the most aggressive and lethal clinical subtype and lacks effective targeted therapies at present. Isobavachalcone (IBC), the main active component of Psoralea corylifolia L., has potential anticancer effects. Herein, we identified IBC as a natural sirtuin 2 (SIRT2) inhibitor and characterized the potential mechanisms underlying the inhibition of TNBC. Molecular dynamics analysis, enzyme activity assay, and cellular thermal shift assay were performed to evaluate the combination of IBC and SIRT2. The therapeutic effects, mechanism, and safety of IBC were analyzed in vitro and in vivo using cellular and xenograft models. IBC effectively inhibited SIRT2 enzyme activity with an IC50 value of 0.84 ± 0.22 μM by forming hydrogen bonds with VAL233 and ALA135 within its catalytic domain. In the cellular environment, IBC bound to and stabilized SIRT2, consequently inhibiting cellular proliferation and migration, and inducing apoptosis and cell cycle arrest by disrupting the SIRT2/α-tubulin interaction and inhibiting the downstream Snail/MMP and STAT3/c-Myc pathways. In the in vivo model, 30 mg/kg IBC markedly inhibited tumor growth by targeting the SIRT2/α-tubulin interaction. Furthermore, IBC exerted its effects by inducing apoptosis in tumor tissues and was well-tolerated. IBC alleviated TNBC by targeting SIRT2 and triggering the reactive oxygen species ROS/β-catenin/CDK2 axis. It is a promising natural lead compound for future development of SIRT2-targeting drugs.

The enhanced hepatotoxicity of isobavachalcone in depigmented zebrafish due to calcium signaling dysregulation and lipid metabolism disorder

Isobavachalcone (IBC) is a flavonoid component derived from Psoraleae Fructus that can increase skin pigmentation and treat vitiligo. However, IBC has been reported to be hepatotoxic. Current studies on IBC hepatotoxicity are mostly on normal organisms but lack studies on hepatotoxicity in patients. This study established the depigmented zebrafish model by using phenylthiourea (PTU) and investigated the difference in hepatotoxicity between normal and depigmented zebrafish caused by IBC and the underlying mechanism. Morphological, histological, and ultrastructural examination and RT-qPCR verification were used to evaluate the effects of IBC on the livers of zebrafish larvae. IBC significantly decreased liver volume, altered lipid metabolism, and induced pathological and ultrastructural changes in the livers of zebrafish with depigmentation compared with normal zebrafish. The RNA-sequencing and RT-qPCR results showed that the difference in hepatotoxicity between normal and depigmented zebrafish caused by IBC was closely related to the calcium signaling pathway, lipid decomposition and metabolism, and oxidative stress. This work delved into the mechanism of the enhanced IBC-induced hepatotoxicity in depigmented zebrafish and provided a new insight into the hepatotoxicity of IBC.

Isobavachalcone inhibits RANKL-induced osteoclastogenesis via miR-193-3p/NF-κB/NFATc1 signaling pathway in BMMs cells

Inhibition of extensive osteoclastogenesis and bone resorption is considered a potential therapeutic target for the treatment of osteoporosis. Isobavachalcone (IBC) is derived from the traditional Chinese herb Psoralea corylifolia Linn. We showed that IBC dose-dependently suppressed receptor activator of nuclear factor kappa B ligand (RANKL)-induced osteoclastogenesis in bone marrow monocyte/macrophage (BMMs) and osteoclastic bone-resorption function without cytotoxicity at a dose of no more than 8 µmin vitro. Mechanistically, the results of western blot and quantitative real-time polymerase chain reaction (qRT-PCR) indicated that IBC inhibited the RANKL-induced degradation of IκBα and phosphorylation of nuclear factor kappa B (NF-κB) in BMMs, and subsequently downregulated the expression of osteoclastic-specific genes and osteoclastogenesis-related proteins. TRAP staining and qRT-PCR showed that IBC can inhibit osteoclast differentiation by down-regulating the expression of miR-193-3p on osteoclast differentiation. Overall, our findings suggest that IBC may serve as a promising compound for the treatment of osteoporosis and other metabolic bone diseases.

Field Control Effect and Initial Mechanism: A Study of Isobavachalcone against Blister Blight Disease

Blister blight (BB) disease is caused by the obligate biotrophic fungal pathogen Exobasidium vexans Massee and seriously affects the yield and quality of Camellia sinensis. The use of chemical pesticides on tea leaves substantially increases the toxic risks of tea consumption. Botanic fungicide isobavachalcone (IBC) has the potential to control fungal diseases on many crops but has not been used on tea plants. In this study, the field control effects of IBC were evaluated by comparison and in combination with natural elicitor chitosan oligosaccharides (COSs) and the chemical pesticide pyraclostrobin (Py), and the preliminary action mode of IBC was also investigated. The bioassay results for IBC or its combination with COSs showed a remarkable control effect against BB (61.72% and 70.46%). IBC, like COSs, could improve the disease resistance of tea plants by enhancing the activity of tea-plant-related defense enzymes, including polyphenol oxidase (PPO), catalase (CAT), phenylalanine aminolase (PAL), peroxidase (POD), superoxide dismutase (SOD), β-1,3-glucanase (Glu), and chitinase enzymes. The fungal community structure and diversity of the diseased tea leaves were examined using Illumina MiSeq sequencing of the internal transcribed spacer (ITS) region of the ribosomal rDNA genes. It was obvious that IBC could significantly alter the species' richness and the diversity of the fungal community in affected plant sites. This study broadens the application range of IBC and provides an important strategy for the control of BB disease.

Isobavachalcone Induces Multiple Cell Death in Human Triple-Negative Breast Cancer MDA-MB-231 Cells

Standardized treatment guidelines and effective drugs are not available for human triple-negative breast cancer (TNBC). Many efforts have recently been exerted to investigate the efficacy of natural compounds as anticancer agents owing to their low toxicity. However, no study has examined the effects of isobavachalcone (IBC) on the programmed cell death (PCD) of human triple-negative breast MDA-MB-231 cancer cells. In this study, IBC substantially inhibited the proliferation of MDA-MB-231 cells in concentration- and time-dependent manners. In addition, we found that IBC induced multiple cell death processes, such as apoptosis, necroptosis, and autophagy in MDA-MB-231 cells. The initial mechanism of IBC-mediated cell death in MDA-MB-231 cells involves the downregulation of Akt and p-Akt-473, an increase in the Bax/Bcl-2 ratio, and cleaved caspases-3 induced apoptosis; the upregulation of RIP3, p-RIP3 and MLKL induced necroptosis; as well as a simultaneous increase in LC3-II/I ratio induced autophagy. In addition, we observed that IBC induced mitochondrial dysfunction, thereby decreasing cellular ATP levels and increasing reactive oxygen species accumulation to induce PCD. These results suggest that IBC is a promising lead compound with anti-TNBC activity.

Heterologous biosynthesis of isobavachalcone in tobacco based on in planta screening of prenyltransferases

Isobavachalcone (IBC) is a prenylated chalcone mainly distributed in some Fabaceae and Moraceae species. IBC exhibits a wide range of pharmacological properties, including anti-bacterial, anti-viral, anti-inflammatory, and anti-cancer activities. In this study, we attempted to construct the heterologous biosynthesis pathway of IBC in tobacco (Nicotiana tabacum). Four previously reported prenyltransferases, including GuILDT from Glycyrrhiza uralensis, HlPT1 from Humulus lupulus, and SfILDT and SfFPT from Sophora flavescens, were subjected to an in planta screening to verify their activities for the biosynthesis of IBC, by using tobacco transient expression with exogenous isoliquiritigenin as the substrate. Only SfFPT and HlPT1 could convert isoliquiritigenin to IBC, and the activity of SfFPT was higher than that of HlPT1. By co-expression of GmCHS8 and GmCHR5 from Glycine max, endogenous isoliquiritigenin was generated in tobacco leaves (21.0 μg/g dry weight). After transformation with a multigene vector carrying GmCHS8, GmCHR5, and SfFPT, de novo biosynthesis of IBC was achieved in transgenic tobacco T₀ lines, in which the highest amount of IBC was 0.56 μg/g dry weight. The yield of IBC in transgenic plants was nearly equal to that in SfFPT transient expression experiments, in which substrate supplement was sufficient, indicating that low IBC yield was not attributed to the substrate supplement. Our research provided a prospect to produce valuable prenylflavonoids using plant-based metabolic engineering.

[Isobavachalcone induces cell death through multiple pathways in human breast cancer MCF-7 cells]

OBJECTIVE

To explore the effects of isobavachalcone (IBC) on cell death of human breast cancer MCF-7 cells and explore the possible mechanism.

METHODS

MCF-7 cells were treated with different concentrations of IBC, and the changes in cell proliferation were assessed using MTT assay. Apoptosis of MCF-7 cells following treatment with 10, 20, and 40 μmol/L IBC was analyzed using flow cytometry with annexin V-FITC/PI double staining and fluorescence microscopy, and the expressions of apoptosis- and autophagy-related proteins (Bax, Bcl-2, Akt, p-Akt, p62, and LC3) were detected with Western blotting. Electron microscopy was used to observe the changes in submicrostructure of the cells following treatment with 40 μmol/L IBC. JC-1 assay kit, ATP assay kit, and reactive oxygen species (ROS) kit were used to determine the effect of IBC on mitochondrial function of the cells.

RESULTS

MTT assay showed that IBC significantly inhibited the proliferation of MCF-7 cells in a concentration- and time-dependent manner, with IC₅₀ values of 38.46, 31.31, and 28.26 μmol/L at 24, 48, and 72 h, respectively. IBC also concentration-dependently induced apoptosis of MCF-7 cells. IBC-induced cell death was inhibited by z-VAD-fmk, a caspase inhibitor (P < 0.05), but not by the necroptosis inhibitor necrostatin-1 (Nec-1). Western blotting showed that IBC-induced MCF-7 cell apoptosis by increasing Bax expression and down-regulating the expressions of Bcl-2, Akt and p-Akt-473 (all P < 0.05). With the increase of IBC concentration, the expression of autophagy-related protein p62 and the LC3-II/I ratio increased progressively. Electron microscopy revealed the presence of autophagic bodies in IBC-treated MCF-7 cells. IBC treatment also resulted in decreased mitochondrial membrane potential and intracellular ATP level and increased ROS accumulation in MCF-7 cells (P < 0.05).

CONCLUSION

IBC is capable of inducing both apoptosis and autophagy in MCF-7 cells, suggesting the potential value of IBC as a lead compound in the development of anti-breast cancer agents.

Isobavachalcone: A comprehensive review of its plant sources, pharmacokinetics, toxicity, pharmacological activities and related molecular mechanisms

Isobavachalcone (IBC), also known as isobapsoralcone, is a natural flavonoid widely derived from many medicinal plants, including Fabaceae, Moraceae, and so forth. IBC has been paid more and more attention by researchers in recent years due to its pharmacological activity in many diseases. This review aims to describe in detail the plant sources, pharmacokinetics, toxicity, pharmacological activities, and molecular mechanisms of IBC on various diseases. We found that IBC can be obtained not only by extraction but also by chemical synthesis. Pharmacokinetic studies have shown that IBC has low bioavailability, but can penetrate the blood-brain barrier and is widely distributed in the brain. Its pharmacological activities mainly include anticancer, antibacterial, anti-inflammatory, antiviral, neuroprotective, bone protection, and other activities. In particular, IBC shows strong anti-tumor and anti-inflammatory therapeutic potential due to its anti-cancer and anti-inflammatory activities. However, due to its hepatotoxicity, there may be more drug interactions. Therefore, more and more in-depth studies are needed for its clinical application. Mechanically, IBC can induce the production of reactive oxygen species (ROS), inhibit AKT, ERK, and Wnt pathways, and promote apoptosis of cancer cells through mitochondrial or endoplasmic reticulum pathways. IBC can inhibit the NF-κB pathway and the production of multiple inflammatory mediators by activating NRF2/HO-1 pathway, thus producing anti-inflammatory effects. Moreover, we discussed the limitations of current research on IBC and put forward some new perspectives and challenges, which provide a strong basis for clinical application and new drug development of IBC in the future.

Isobavachalcone suppresses the TRIF-dependent signaling pathway of Toll-like receptors

Toll-like receptors (TLRs) are integral membrane-bound receptors that are central to innate and adaptive immune responses. They are known to activate a cascade of downstream signals to induce the secretion of inflammatory cytokines, chemokines, and type I interferons. Dysregulated activation of TLR signaling pathways can induce the activation of various transcription factors, such as nuclear factor kappa B (NF-κB) and interferon regulatory factor 3 (IRF3). TLRs act via MyD88- and TRIF-mediated pathways to induce inflammatory responses. To evaluate the therapeutic potential of isobavachalcone (IBC), a natural chalcone component of Angelica keiskei, we examined its effects on signal transduction via TLR signaling pathways. IBC inhibited the activation of NF-κB and IRF3 induced by TLR agonists and their target genes. IBC also inhibited the activation of NF-κB and IRF3 induced by overexpression of downstream signaling components of TLR signaling pathways. These results suggest that IBC can regulate both MyD88- and TRIF-dependent signaling pathways of TLRs, resulting in a dramatic increase of new therapeutic options for various inflammatory diseases involving TLRs.

Therapeutic potential of isobavachalcone, a natural flavonoid, in murine experimental colitis by inhibiting NF-κB p65

The incidence of ulcerative colitis (UC), one of the two types of inflammatory bowel disease, is increasing in many countries. Various natural products have been demonstrated with therapeutic potentials for UC. Herein, the therapeutic effects and mechanisms of isobavachalcone (IBC), a natural chalcone, were evaluated in dextran sulfate sodium (DSS)-induced colitis mice and lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. The results demonstrated that IBC treatment significantly improved the clinical symptoms, assessed by the disease activity index (DAI) scores and the histological changes of the colon. The levels of myeloperoxidase (MPO), TNF-α, IL-6, IL-1β, and prostaglandin E2 (PGE2) in colon tissues were suppressed by IBC. The upregulation of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and NF-κB p65 in colon tissues were reversed by IBC as well. Furthermore, IBC significantly inhibited LPS-triggered secretion of TNF-α, IL-6, and nitrite, and nuclear translocation of NF-κB p65, in RAW264.7 cells. The luciferase reporter assay indicated that IBC significantly inhibited LPS-triggered transcription of toll-like receptor 4 (TLR4). Molecular docking results showed that the binding pocket of IBC was adjacent to Ser276 of p65-p50 heterodimer and IBC could form H-bond with Thr191. Collectively, these results demonstrated that IBC ameliorated colitis in mice possibly through inhibition of NF-κB p65.

Isobavachalcone as an Active Membrane Perturbing Agent and Inhibitor of ABCB1 Multidrug Transporter

Isobavachalcone (IBC) is an active substance from the medicinal plant Psoralea corylifolia. This prenylated chalcone was reported to possess antioxidative, anti-inflammatory, antibacterial, and anticancer activities. Multidrug resistance (MDR) associated with the over-expression of the transporters of vast substrate specificity such as ABCB1 (P-glycoprotein) belongs to the main causes of cancer chemotherapy failure. The cytotoxic, MDR reversing, and ABCB1-inhibiting potency of isobavachalcone was studied in two cellular models: human colorectal adenocarcinoma HT29 cell line and its resistant counterpart HT29/Dx in which doxorubicin resistance was induced by prolonged drug treatment, and the variant of MDCK cells transfected with the human gene encoding ABCB1. Because MDR modulators are frequently membrane-active substances, the interaction of isobavachalcone with model phosphatidylcholine bilayers was studied by means of differential scanning calorimetry. Molecular modeling was employed to characterize the process of membrane permeation by isobavachalcone. IBC interacted with ABCB1 transporter, being a substrate and/or competitive inhibitor of ABCB1. Moreover, IBC intercalated into model membranes, significantly affecting the parameters of their main phospholipid phase transition. It was concluded that isobavachalcone interfered both with the lipid phase of cellular membrane and with ABCB1 transporter, and for this reason, its activity in MDR cancer cells was presumptively beneficial.

Identification of Pyruvate Dehydrogenase E1 as a Potential Target against Magnaporthe oryzae through Experimental and Theoretical Investigation

Magnaporthe oryzae (M. oryzae) is a typical cause of rice blast in agricultural production. Isobavachalcone (IBC), an active ingredient of Psoralea corylifolia L. extract, is an effective fungicide against rice blast. To determine the mechanism of IBC against M. oryzae, the effect of IBC on the metabolic pathway of M. oryzae was explored by transcriptome profiling. In M. oryzae, the expression of pyruvate dehydrogenase E1 (PDHE1), part of the tricarboxylic acid (TCA cycle), was significantly decreased in response to treatment with IBC, which was verified by qPCR and testing of enzyme activity. To further elucidate the interactions between IBC and PDHE1, the 3D structure model of the PDHE1 from M. oryzae was established based on homology modeling. The model was utilized to analyze the molecular interactions through molecular docking and molecular dynamics simulation, revealing that IBC has π-π stacking interactions with residue TYR139 and undergoes hydrogen bonding with residue ASP217 of PDHE1. Additionally, the nonpolar residues PHE111, MET174, ILE 187, VAL188, and MET250 form strong hydrophobic interactions with IBC. The above results reveal that PDHE1 is a potential target for antifungal agents, which will be of great significance for guiding the design of new fungicides. This research clarified the mechanism of IBC against M. oryzae at the molecular level, which will underpin further studies of the inhibitory mechanism of flavonoids and the discovery of new targets. It also provides theoretical guidance for the field application of IBC.

Isobavachalcone inhibits acute myeloid leukemia: Potential role for ROS-dependent mitochondrial apoptosis and differentiation

Isobavachalcone (IBC) has been shown to induce apoptosis and differentiation of acute myeloid leukemia (AML) cells. However, the underlying molecular mechanisms are not fully understood. Herein, IBC exhibited significant inhibition on the cell viability, proliferation, and the colony formation ability of AML cells. Moreover, IBC induced mitochondrial apoptosis evidenced by reduced mitochondrial membrane potential, increased Bax level, decreased Bcl-2, Bcl-xL, and Mcl-1 levels, elevated cytochrome c level in the cytosol and increased cleavage of caspase-9, caspase-3, and PARP. Furthermore, IBC obviously promoted the differentiation of AML cells, accompanied by the increase of the phosphorylation of MEK and ERK and the C/EBPα expression as well as the C/EBPβ LAP/LIP isoform ratio, which was significantly reversed by U0126, a specific inhibitor of MEK. Notably, IBC enhanced the intracellular ROS level. More importantly, IBC-induced apoptosis and differentiation of HL-60 cells were significantly mitigated by NAC. In addition, IBC also exhibited an obvious anti-AML effect in NOD/SCID mice with the engraftment of HL-60 cells. Together, our study suggests that the ROS-medicated signaling pathway is highly involved in IBC-induced apoptosis and differentiation of AML cells.

Inhibitory Effects of Isobavachalcone on Tau Protein Aggregation, Tau Phosphorylation, and Oligomeric Tau-Induced Apoptosis

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases without any effective medicine treatments. The neurofibrillary tangles containing hyperphosphorylated tau protein are one important pathological characteristic. Thus, one practicable strategy for AD drug design is to discover compounds that could inhibit tau protein aggregation and/or phosphorylation. In this study, isobavachalcone, a natural plant-derived compound, has been shown to inhibit tau protein aggregation and disaggregate tau fibrils in vitro by directly interacting with tau protein at amino acids I278, V309, etc. It is able to reduce tau phosphorylation at four disease-related sites in vivo by regulating the critical kinase and protein phosphatase, GSK3β and PP2A. The compound also exhibits protection against tau oligomers-induced apoptosis through the mitochondria and ER mediated apoptotic pathways. In summary, isobavachalcone is a promising candidate for further evaluation as a potential preventive and therapeutic medicine for AD.

Isobavachalcone ameliorates diabetic nephropathy in rats by inhibiting the NF-κB pathway

Isobavachalcone (ISO) exhibits good anti-inflammatory activity. We evaluated the renoprotective effects of ISO against diabetic nephropathy (DN). Diabetic rats established by the single injection of streptozotocin (STZ) were orally treated with ISO. The levels of serum creatinine (Scr), blood urea nitrogen (BUN), and 24 hr urinary protein were measured. In this study, ISO effectively ameliorated renal damage by reducing BUN, Scr, and 24 hr urinary protein and also improved kidney pathological appearances. ISO prevented STZ-caused apoptosis in the glomerular tissue in vivo and blocked the high glucose (HG)-induced growth inhibitory effect in human renal glomerular endothelial cells in vitro. Moreover, ISO reduced pro-inflammatory mediator production and blocked the NF-κB pathway in the damaged renal tissues and HG-treated HRGEC cells. Taken together, the results of this study indicate that ISO consumption might have significant beneficial effects on the DN and this action might be correlated with the modulation of the NF-κB pathway. PRACTICAL APPLICATIONS: ISO is an active compound from the dried ripe fruit of Psoralea corylifolia L. seed, which is traditionally served as a food ingredient in Asia. In this investigation, we observed the beneficial effects of ISO on a murine model with DN. Further research revealed that the protective action of ISO might be connected with its weak hypoglycaemic and notable anti-inflammatory effects. Our research data suggest that ISO-enriched food might be a good choice for people suffering from DN.

Isobavachalcone isolated from Psoralea corylifolia inhibits cell proliferation and induces apoptosis via inhibiting the AKT/GSK-3β/β-catenin pathway in colorectal cancer cells

Background: Colorectal cancer (CRC) is a common form of cancer associated with a high mortality rate and poor prognosis. Given the limited efficacy of current therapies for CRC, interest in novel therapeutic agents isolated from natural sources has increased. We studied the anticancer properties of isobavachalcone (IBC), a flavonoid isolated from the herb Psoralea corylifolia, which is used in traditional Chinese medicine, in an in vitro model of CRC.

Materials and methods: Cell viability and growth of CRC cells were determined by Cell Counting Kit-8 and colony formation assays following treatment with varying concentrations of IBC, respectively. Apoptosis was examined by 4′,6-diamidino-2-phenylindole staining and flow cytometry with Annexin V/propidium iodide double staining. Western blot analysis was used to analyze expression of apoptosis-associated protein pathway and the AKT/GSK-3β/β-catenin signaling pathway.

Results: Initial experiments showed that IBC inhibited proliferation and colony formation of human CRC cell lines in dose- and time-dependent manners. The antiproliferative effect of IBC resulted from induction of apoptosis, as evidenced by morphological changes in the nucleus, flow cytometry analysis, upregulation of cleaved caspase-3 and cleaved PARP, changes in the ratio of the anti-apoptotic protein Bcl-2 and the pro-apoptotic protein Bax, translocation of Bax from the cytosol to the mitochondria, and decreased expression of two inhibitors of apoptosis family proteins, XIAP, and survivin. Western blot analysis of signaling pathway proteins demonstrated that IBC downregulated Wnt/β-catenin signaling, which has previously been associated with CRC, by inhibiting the AKT/GSK-3β signaling pathway.

Conclusion: This study demonstrated that IBC inhibited cell proliferation and induced apoptosis through inhibition of the AKT/GSK-3β/β-catenin pathway in CRC. These results suggest the potential of IBC as a novel therapeutic agent for the treatment of CRC.

Identification of isobavachalcone as a potential drug for rice blast disease caused by the fungus Magnaporthe grisea

The rice blast disease caused by the fungus Magnaporthe grisea is one of the most devastating rice diseases, but there is no effective fungicide toward chitinase which is a key enzyme of M. grisea. In this study, we observed that distortion and cell-wall damage of M. grisea hyphae were significantly under the scanning electron micrograph after a 24-h treatment with 10 mg/L isobavachalcone (IBC) extracted from Psoralea corylifolia L. To further explore the effect of IBC on the cell wall of M. grisea, we examined changes in enzymes associated with cell wall degradation by enzyme activity experiments, treated liquid culture mycelia with 10 mg/L IBC for 1 h. Results displayed that chitinase was obviously more active than control group. To illustrate the interactions between IBC and chitinase, the studies of homology modeling and molecular docking were carried out successively. The results revealed that IBC had hydrogen bonds with residues ASP267 and ARG276 of chitinase. Besides, these nonpolar residues TYR270, PRO271, VAL272, LEU310, PRO311, TYR316, and LEU317 were able to form strong hydrophobic interactions. Binding energies of the chitinase-IBC complexes were calculated by MM-GBSA showed that the ΔG_bind score of molecular dynamics had lower binding energy and more stable than docking complexes. All above, IBC owns significant agonistic activity in chitinase and would be a potent fungicide to inhibit the growth of M. grisea. We hope the above information provides an important insight for understanding the interactions between IBC and chitinase, which may be useful in the discovery of a novel potent agonist. Communicated by Ramaswamy H. Sarma.

Isobavachalcone attenuates myotube atrophy induced by TNF-α through muscle atrophy F-box signaling and the nuclear factor erythroid 2-related factor 2 cascade

Skeletal muscle atrophy is a condition characterized by damaged muscle fibers and reduced numbers of muscle cells due to various causes. Muscle atrophy is associated with chronic diseases, such as heart failure, diabetes, and aging-related diseases. Isobavachalcone (IBC) is a flavonoid found in various foods and natural products, and studies have investigated its diverse effects, including its neuroprotective and anticancer effects. However, no studies have evaluated the effects of IBC on muscle atrophy. Thus, in this study, we assessed the effects of IBC on prevention of muscle atrophy. To evaluate the preventive effects of IBC on muscle atrophy, we used C2C12 myoblasts and induced muscle atrophy by tumor necrosis factor (TNF)-α. IBC regulated the expression levels of muscle atrophy F-box and muscle RING finger-1 in response to damaged muscle cells, thereby restoring the expression of myosin heavy chain and myogenin. Moreover, IBC regulated the phosphorylation of the nuclear factor-κB and p38 and upregulated the expression of nuclear factor erythroid 2-related factor 2 and heme oxygenase-1, which are involved in regulating oxidative stress. Our results indicated that IBC acted to relieve TNF-α-induced skeletal muscle atrophy by regulating the factors related to inflammation and oxidative stress.

Isobavachalcone sensitizes cells to E2-induced paclitaxel resistance by down-regulating CD44 expression in ER+ breast cancer cells

Oestrogen receptor (ER) is expressed in approximately 60%‐70% of human breast cancer. Clinical trials and retrospective analyses have shown that ER‐positive (ER+) tumours are more tolerant to chemotherapeutic drug resistance than ER‐negative (ER−) tumours. In addition, isobavachalcone (IBC) is known as a kind of phytoestrogen with antitumour effect. However, the underlying mechanism of IBC in ER+ breast cancer needs to be elucidated further. Our in vitro experiments showed that IBC could attenuate 17β‐estradiol (E₂)‐induced paclitaxel resistance and that E₂ could stimulate CD44 expression in ER+ breast cancer cells but not in ER− cells. Meanwhile, E₂ could promote ERα expression to render ER+ breast cancer cells resistant to paclitaxel. Furthermore, we established paclitaxel‐resistant breast cancer cell lines and determined the function of ERα in the enhancement of paclitaxel resistance via the regulation of CD44 transcription. IBC down‐regulated ERα and CD44 expression and thus inhibited tumour growth in paclitaxel‐resistant xenograft models. Overall, our data demonstrated for the first time that IBC could decrease CD44 expression level via the ERα pathway and make ER+ breast cancer cells sensitive to paclitaxel treatment.

Isobavachalcone from Angelica keiskei Inhibits Adipogenesis and Prevents Lipid Accumulation

We isolated isobavachalcone (IBC) from Angelica keiskei (AK) as an anti-obesity component. IBC dose-dependently inhibited 3T3-L1 adipocyte differentiation by down-regulating adipogenic factors. At the mitotic clonal expansion stage (MCE), IBC caused cell cycle arrest in G0/G1 with decreased expression of cell cycle-regulating proteins. IBC also inhibited autophagic flux by inducing intracellular accumulation of LC3B and SQSTM1/p62 proteins while decreasing expression levels of regulating factors for autophagy initiation. In parallel with the inhibition of adipocyte differentiation, IBC decreased intrahepatic fat deposits and rescued the liver steatosis in high fat cholesterol diet-fed zebrafish. In this study, we found that IBC isolated from AK suppresses mitotic clonal expansion and autophagy flux of adipocytes and also shows anti-obesity activity in a high cholesterol-diet zebrafish model by decreasing intrahepatic fat deposits. These results suggest that IBC could be a leading pharmacological compound for the development of anti-obesity drugs.

Multi-Target Anti-Alzheimer Activities of Four Prenylated Compounds from Psoralea Fructus

Alzheimer’s disease (AD) is an age-related neurodegenerative disease that is mediated by multiple signaling pathways. In recent years, the components of Psoralea Fructus (PF) have demonstrated some anti-Alzheimer effects both in vitro and in vivo. To further reveal the active compounds of PF and their mechanisms regulating key targets of AD, in this study, we identified four prenylated compounds from the 70% ethanolic aqueous extract of PF, namely bavachin, bavachinin, bavachalcone, and isobavachalcone. Multi-target bioactivity analysis showed that these compounds could differentially inhibit neuroinflammation, oxidative damage, and key AD-related protein targets, such as amyloid β-peptide 42, β-secretase, glycogen synthase kinase 3β, and acetylcholinesterase. These compounds may generate beneficial effects in AD prevention and treatment.

Isobavachalcone inhibits the proliferation and invasion of tongue squamous cell carcinoma cells

Isobavachalcone (2′,4′,4-trihydroxy-3′-[3′-methylbut-3′-ethyl] chalcone or IBC) exhibits anticancer activities in a number of types of cancer cell. However, its role in tongue squamous cell carcinoma (TSCC) cells remains unclear. The aim of the present study was to investigate the biological effect of IBC in TSCC Tca8113 cells. The function of IBC on Tca8113 cell apoptosis and apoptosis-associated signaling pathways was determined using an MTT assay, morphological staining, annexin V-propidium iodide (PI) staining and Western blot analysis. The effects of IBC on Tca8113 cell migration, invasion and relative protein expression were confirmed using wound healing analysis, Transwell invasion analysis and Western blot analysis, respectively. The results of the MTT assay and annexin V-PI staining indicated that IBC is able to significantly inhibit proliferation and induce apoptosis of Tca8113 cells in vitro. IBC treatment resulted in typical apoptotic morphology of nuclear fragmentation and apoptotic bodies in Tca8113 cells. Western blot analysis further demonstrated that IBC caused downregulation of the expression of B-cell lymphoma 2 (Bcl-2) protein, upregulation of the expression of Bcl-2-associated X protein (Bax), activation of caspases, and dephosphorylation of protein kinase B (Akt) and extracellular-signal-regulated kinase (ERK) proteins in a concentration- and time-dependent manner. The results of the present study suggest that IBC induces apoptosis in Tca8113 cells and that the induction may be associated with the activation of Bcl-2, Bax and caspase-3, and the inactivation of Akt and ERK. Furthermore, IBC inhibited migration and invasion of Tca8113 cells in vitro by downregulating matrix metalloproteinase (MMP)-2 and MMP-9 protein expression. The results of the present study indicate that IBC may be a potential anticancer drug for the treatment of TSCC.

Isobavachalcone induces the apoptosis of gastric cancer cells via inhibition of the Akt and Erk pathways

In the present study, the MGC803 gastric cancer cell line was used as an experimental model to evaluate the potential role of isobavachalcone (IBC) in cell apoptosis, migration and invasion. The inhibitory effects of IBC on cell proliferation were determined using a methylthiazolyltetrazolium assay. Cellular morphological changes were assessed using Wright-Giemsa staining, and cell apoptosis was evaluated by flow cytometric analysis. The results of the present study demonstrated that IBC inhibited the proliferation of MGC803 cells in a concentration- and time-dependent manner. Furthermore, the wound healing and Matrigel™ Transwell® invasion assays demonstrated that IBC decreased cell migration and invasion in a concentration-dependent manner. Western blotting was used to determine the protein expression levels of caspase-3, B-cell lymphoma-2 (Bcl-2) and Bcl-2-associated X protein (Bax), as well as the key protein kinases in the Akt and extracellular signal-regulated kinase (Erk) signaling pathways. During the IBC-induced apoptosis of MGC803 cells, transient activation of phosphorylated (p)-Akt and p-Erk inhibited the activation of Akt and Erk, upregulated Bax expression, downregulated Bcl-2 expression and activated caspase-3. These results suggest that IBC inhibited the growth of MGC803 gastric cancer cells by regulating the protein expression of caspase-3, Bcl-2 and Bax. In addition, inhibition of the Akt and Erk signaling pathways may be important mechanisms underlying the IBC-induced apoptosis of gastric cancer cells.

Isobavachalcone and bavachinin from Psoraleae Fructus modulate Aβ42 aggregation process through different mechanisms in vitro

Spontaneous aggregation of Aβ is a key factor in the development of Alzheimer's disease. In searching for Aβ aggregation inhibitors from traditional Chinese herbal medicines, we identified two active compounds from Psoraleae Fructus, namely isobavachalcone and bavachinin. We further demonstrated that the two compounds modulate Aβ42 aggregation process through different mechanisms. Isobavachalcone significantly inhibits both oligomerization and fibrillization of Aβ42, whereas bavachinin inhibits fibrillization and leads to off-pathway aggregation. Both of the compounds attenuated Aβ42-induced toxicity in a SH-SY5Y cell model. These findings may provide valuable information for new drug development and Alzheimer's therapy in the future.