MeJA-induced hairy roots in Plumbago auriculata L. by RNA-seq profiling and key synthase provided new insights into the sustainable production of plumbagin and saponins.

Naturally synthesized secondary metabolites in plants are considered an important source of drugs, food additives, etc. Among them, research on natural plant medicinal components and their synthesis mechanisms has always been of high concern. We identified a novel medicinal floral crop, Plumbago auriculata L., that can be treated with methyl jasmonate (MeJA) for the rapid or sustainable production of natural bioactives from hairy roots. In the study, we globally analyzed the changes in the accumulation of plumbagin and others in the hairy roots of Plumbago auriculata L. hairy roots (PAHR) 15834 in P. auriculata L. based on 100 µmol/L of MeJA treatment by RNA-seq profiling, and we found that there was a significant increase in the accumulation of plumbagin and saponin before 24 h. To explain the principle of co-accumulation, it showed that MeJA induced JA signaling and the shikimic acid pathway, and the methylvaleric acid (MVA) pathway was activated downstream subsequently by the Mfuzz and weighted gene co-expression analysis. Under the shared metabolic pathway, the high expression of PAL3 and HMGR promoted the activity of the "gateway enzymes" phenylalanine ammonia lyase (PAL) and 3-hydroxy-3-methylglutaryl CoA reductase (HMGR), which respectively induced the high expression of key reaction enzyme genes, including chalcone synthase (CHS), isopentenyl diphosphate (IPP), and farnesyl pyrophosphate synthase (FPS), that led to the synthesis of plumbagin and saponin. We speculated that large amounts of ketones and/or aldehydes were formed under the action of these characteristic enzymes, ultimately achieving their co-accumulation through polyketone and high-level sugar and amino acid metabolism. The study results provided a theoretical basis for carrying out the factory refinement and biosynthesis of plumbagin and saponins and also provided new ideas for fully exploiting multifunctional agricultural crops and plants and developing new agricultural by-products.

In-vitro Studies of Extracts of Plumbago Zeylanica in Cancer Cell Lines.

Despite increased use of early detection methods and more aggressive treatment strategies, the worldwide incidence of colorectal cancer is still on the rise. Consequently, it remains urgent to identify novel agents with enhanced efficacy in prevention and/or therapeutic protocols. Our studies focused on the use of Plumbagin, a natural phytochemical that showed promising results against other tumor types, to determine its effectiveness in blocking the proliferation and survival of colon cancer cells in experimental protocols mimicking the environment in primary tumors (attached culture conditions) and in circulating tumor cells (unattached conditions). Under both experimental settings, exposure of HCT116 cells to Plumbagin concentrations in the low micromolar range resulted in cell cycle arrest at the G1 phase, apoptosis via the mitochondrial cell death pathway, and increased production of reactive oxygen species. The cell cycle effects were more noticeable in attached cells, whereas the induction of cell death was more evident in unattached cells. These effects were consistent with the nature and the magnitude of the alterations induced by Plumbagin on the expression levels of a set of proteins known to play key roles in the regulation of cell cycle dynamics, apoptosis mechanisms and cell proliferation. In light of its previously reported lack of toxicity on normal colon cells and the striking anti-survival effect on colon cancer cells observed in our study, Plumbagin should be considered a promising drug for the treatment of colon cancer.

Plumbagin ameliorates LPS-induced acute lung injury by regulating PI3K/AKT/mTOR and Keap1-Nrf2/HO-1 signalling pathways.

Acute lung injury (ALI) is a major pathophysiological problem characterized by severe inflammation, resulting in high morbidity and mortality. Plumbagin (PL), a major bioactive constituent extracted from the traditional Chinese herb Plumbago zeylanica, has been shown to possess anti-inflammatory and antioxidant pharmacological activities. However, its protective effect on ALI has not been extensively studied. The objective of this study was to investigate the protective effect of PL against ALI induced by LPS and to elucidate its possible mechanisms both in vivo and in vitro. PL treatment significantly inhibited pathological injury, MPO activity, and the wet/dry ratio in lung tissues, and decreased the levels of inflammatory cells and inflammatory cytokines TNF-α, IL-1ß, IL-6 in BALF induced by LPS. In addition, PL inhibited the activation of the PI3K/AKT/mTOR signalling pathway, increased the activity of antioxidant enzymes CAT, SOD, GSH and activated the Keap1/Nrf2/HO-1 signalling pathway during ALI induced by LPS. To further assess the association between the inhibitory effects of PL on ALI and the PI3K/AKT/mTOR and Keap1/Nrf2/HO-1 signalling, we pretreated RAW264.7 cells with 740Y-P and ML385. The results showed that the activation of PI3K/AKT/mTOR signalling reversed the protective effect of PL on inflammatory response induced by LPS. Moreover, the inhibitory effects of PL on the production of inflammatory cytokines induced by LPS also inhibited by downregulating Keap1/Nrf2/HO-1 signalling. In conclusion, the results indicate that the PL ameliorate LPS-induced ALI by regulating the PI3K/AKT/mTOR and Keap1-Nrf2/HO-1 signalling, which may provide a novel therapeutic perspective for PL in inhibiting ALI.

Insecticidal activity and underlying molecular mechanisms of a phytochemical plumbagin against Spodoptera frugiperda.

Introduction: Plumbagin is an important phytochemical and has been reported to exhibit potent larvicidal activity against several insect pests, However, the insecticidal mechanism of plumbagin against pests is still poorly understood. This study aimed to investigate the insecticidal activities of plumbagin and the underlying molecular mechanisms against a devastating agricultural pest, the fall armyworm Spodoptera frugiperda. Methods: The effects of plumbagin on S. frugiperda larval development and the activities of two detoxification enzymes were initially examined. Next, transcriptomic changes in S. frugiperda after plumbagin treatment were investigated. Furthermore, RNA-seq results were validated by qPCR. Results: Plumbagin exhibited a high larvicidal activity against the second and third instar larvae of S. frugiperda with 72 h LC50 of 0.573 and 2.676 mg/g, respectively. The activities of the two detoxification enzymes carboxylesterase and P450 were significantly increased after 1.5 mg/g plumbagin treatment. Furthermore, RNA-seq analysis provided a comprehensive overview of complex transcriptomic changes in S. frugiperda larvae in response to 1.5 mg/g plumbagin exposure, and revealed that plumbagin treatment led to aberrant expression of a large number of genes related to nutrient and energy metabolism, humoral immune response, insect cuticle protein, chitin-binding proteins, chitin synthesis and degradation, insect hormone, and xenobiotic detoxification. The qPCR results further validated the reproducibility and reliability of the transcriptomic data. Discussion: Our findings provide a valuable insight into understanding the insecticidal mechanism of the phytochemical plumbagin.

Antibacterial, Antifungal, and Cytotoxic Potential of PlumbaginLoaded pH-Responsive Vaginal Nanoformulations.

Plumbagin is a naphthoquinone from the roots of the Plumbago species and exhibits anticancer activity. Translational usage of plumbagin in biomedical sciences is restricted due to its poor solubility and bioavailability. Therefore, pH-responsive plumbagin-loaded vaginal nanoformulations with polylactic acid (PLA)-chitosan polymeric coat were fabricated by inotropic gelation technique. Among the four (F1, F2, F3, F4) nanoformulations prepared, F3 exhibited good interaction of polymers with plumbagin as evidenced by FTIR, XRD, and thermal analysis. The positive zeta potential (48.4 ± 5.57 mV), optimal size (694 ± 65.76 nm), low PDI (0.157), and good encapsulation efficiency (77.8 ± 3.62%) of F3 were significant. The indirect method of drug loading (58.35 ± 5.00%) confirmed the drug content of about 495.44 ± 5.00 µg of plumbagin in 1 mg of F3. The drug loading pattern was confirmed by TEM analysis, and the spherical morphology of the nanocomposite was confirmed by SEM analysis. F3 formulation showed 46% and 25.2% of drug release in 24 h in simulated vaginal fluid at pH 4.5 and 7 respectively with sustained release and hydrolyses of lactic acid from PLA. Among all the nanoformulations evaluated, nanoformulation F3 with promising physicochemical properties showed good antifungal and antibacterial activity against various fungal and bacterial strains. F3 exhibited potent cytotoxicity with an IC50 of 3.6 ± 0.12 µg/ml for HeLa and an IC50 of 0.81 ± 0.01 µg/ml for SiHa cells. Altogether, the nanoformulation F3 exhibited potent antimicrobial activity against vaginal infections and cytotoxicity against cervical cancer cell lines.

Inhibition of SARS-CoV-2 Nsp9 ssDNA-Binding Activity and Cytotoxic Effects on H838, H1975, and A549 Human Non-Small Cell Lung Cancer Cells: Exploring the Potential of Nepenthes miranda Leaf Extract for Pulmonary Disease Treatment.

Carnivorous pitcher plants from the genus Nepenthes are renowned for their ethnobotanical uses. This research explores the therapeutic potential of Nepenthes miranda leaf extract against nonstructural protein 9 (Nsp9) of SARS-CoV-2 and in treating human non-small cell lung carcinoma (NSCLC) cell lines. Nsp9, essential for SARS-CoV-2 RNA replication, was expressed and purified, and its interaction with ssDNA was assessed. Initial tests with myricetin and oridonin, known for targeting ssDNA-binding proteins and Nsp9, respectively, did not inhibit the ssDNA-binding activity of Nsp9. Subsequent screenings of various N. miranda extracts identified those using acetone, methanol, and ethanol as particularly effective in disrupting Nsp9's ssDNA-binding activity, as evidenced by electrophoretic mobility shift assays. Molecular docking studies highlighted stigmast-5-en-3-ol and lupenone, major components in the leaf extract of N. miranda, as potential inhibitors. The cytotoxic properties of N. miranda leaf extract were examined across NSCLC lines H1975, A549, and H838, focusing on cell survival, apoptosis, and migration. Results showed a dose-dependent cytotoxic effect in the following order: H1975 > A549 > H838 cells, indicating specificity. Enhanced anticancer effects were observed when the extract was combined with afatinib, suggesting synergistic interactions. Flow cytometry indicated that N. miranda leaf extract could induce G2 cell cycle arrest in H1975 cells, potentially inhibiting cancer cell proliferation. Gas chromatography-mass spectrometry (GC-MS) enabled the tentative identification of the 19 most abundant compounds in the leaf extract of N. miranda. These outcomes underscore the dual utility of N. miranda leaf extract in potentially managing SARS-CoV-2 infection through Nsp9 inhibition and offering anticancer benefits against lung carcinoma. These results significantly broaden the potential medical applications of N. miranda leaf extract, suggesting its use not only in traditional remedies but also as a prospective treatment for pulmonary diseases. Overall, our findings position the leaf extract of N. miranda as a promising source of natural compounds for anticancer therapeutics and antiviral therapies, warranting further investigation into its molecular mechanisms and potential clinical applications.

[Effects of plumbagin on proliferation and apoptosis of human hepatocellular carcinoma cells based on CKB/p53 signaling pathway].

To investigate the effects of plumbagin on the proliferation and apoptosis of human hepatoma Huh-7 cells and its mechanism based on the creatine kinase B(CKB)/p53 signaling pathway. Huh-7 cells were treated with plumbagin from 1 to 12 µmol·L~(-1) for cell counting kit-8(CCK-8) assay, and 1, 3, and 6 µmol·L~(-1) were determined as low, medium, and high concentrations of plumbagin for subsequent experiments. CKB gene was knocked out in Huh-7 cells by clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated proteins(Cas)-9 gene editing technology. CKB overexpression lentivirus was transfected into Huh-7 cells to up-regulate the expression of CKB. Cell proliferation and apoptosis were detected by plate cloning assay and flow cytometry. The mRNA expression of CKB was detected by quantitative real-time PCR(qRT-PCR). CKB, p53, mouse double minute 2 homolog(MDM2), B-cell lymphoma 2(Bcl-2), Bcl-2 associated X protein(Bax), and caspase-3 protein were detected by Western blot(WB). The results showed that plumbagin significantly inhibited the proliferation of Huh-7 cells and induced cell apoptosis. Compared with the control group, the apoptosis level was significantly increased in the plumbagin group, while the apoptosis level was significantly decreased in the plumbagin combined with the apoptosis inhibitor group. Plumbagin significantly down-regulated the protein expression levels of CKB, Bcl-2, and MDM2 and up-regulated the protein expression levels of p53, Bax, and caspase-3. Knockdown of the CKB gene decreased the proliferative ability of Huh-7 cells, increased the apoptotic rate, decreased the expression levels of Bcl-2 and MDM2 proteins, and increased the expression levels of p53, Bax, and caspase-3 proteins. After up-regulation of CKB expression, the proliferation ability of Huh-7 cells was enhanced, and the protein expression levels of Bcl-2 and MDM2 were elevated. The protein expression levels of p53, Bax, and caspase-3 were decreased. In addition, plumbagin reversed the effect of overexpression of CKB on the proliferation and apoptosis of Huh-7 cells. In conclusion, plumbagin significantly inhibited the proliferative ability of Huh-7 cells, and the mechanism may be related to the inhibition of CKB expression, activation of the p53 signaling pathway, and regulation of the expression of mitochondrial-associated apoptotic proteins, ultimately inducing cell apoptosis.

Development and efficacy assessment of polyherbal phytosomal gel for accelerated wound healing.

Curcuma longa L. and Plumbago zeylanica L. are renowned for their antioxidant, anti-inflammatory, and wound-healing properties, primarily attributed to their polyphenolic compounds. However, the limited water solubility of these compounds poses challenges to their effective utilization. Encapsulation within phytosomes offers a solution by enhancing bioavailability and permeability. This study aimed to formulate a phytosome-based polyherbal gel incorporating methanolic extracts of P. zeylanica and C. longa to explore its potential in wound healing. Methanolic extracts of P. zeylanica roots and C. longa rhizomes were encapsulated in phytosomes using the lipid film hydration technique. Various phytosome formulations were developed and characterized for encapsulation efficiency, particle size, polydispersity index and zeta potential. The optimized phytosomal dispersion (F7) was integrated into a carbopol-based hydrogel matrix. In vitro release studies demonstrated prolonged release compared to conventional forms. Stability testing confirmed the robustness of the phytosomal gel at 4 °C/60 ± 5% RH. Wound healing activity was assessed using an excision wound model. The phytosomal gel exhibited enhanced wound contraction and reduced epithelization time compared to conventional gel and control groups, signifying its potent wound-healing effect. In conclusion, the polyherbal phytosomal gel, incorporating P. zeylanica and C. longa, holds promise in promoting wound healing, presenting a novel and effective approach in the realm of topical formulations for wound care.

Cytotoxicity and Multi-Enzyme Inhibition of Nepenthes miranda Stem Extract on H838 Human Non-Small Cell Lung Cancer Cells and RPA32, Elastase, Tyrosinase, and Hyaluronidase Proteins.

The carnivorous pitcher plants of the genus Nepenthes have long been known for their ethnobotanical applications. In this study, we prepared various extracts from the pitcher, stem, and leaf of Nepenthes miranda using 100% ethanol and assessed their inhibitory effects on key enzymes related to skin aging, including elastase, tyrosinase, and hyaluronidase. The cytotoxicity of the stem extract of N. miranda on H838 human lung carcinoma cells were also characterized by effects on cell survival, migration, proliferation, apoptosis induction, and DNA damage. The cytotoxic efficacy of the extract was enhanced when combined with the chemotherapeutic agent 5-fluorouracil (5-FU), indicating a synergistic effect. Flow cytometry analysis suggested that the stem extract might suppress H838 cell proliferation by inducing G2 cell cycle arrest, thereby inhibiting carcinoma cell proliferation. Gas chromatography-mass spectrometry (GC-MS) enabled the tentative identification of the 15 most abundant compounds in the stem extract of N. miranda. Notably, the extract showed a potent inhibition of the human RPA32 protein (huRPA32), critical for DNA replication, suggesting a novel mechanism for its anticancer action. Molecular docking studies further substantiated the interaction between the extract and huRPA32, highlighting bioactive compounds, especially the two most abundant constituents, stigmast-5-en-3-ol and plumbagin, as potential inhibitors of huRPA32's DNA-binding activity, offering promising avenues for cancer therapy. Overall, our findings position the stem extract of N. miranda as a promising source of natural compounds for anticancer therapeutics and anti-skin-aging treatments, warranting further investigation into its molecular mechanisms and potential clinical applications.

Plumbagin induces ferroptosis in colon cancer cells by regulating p53-related SLC7A11 expression.

Objective: This study examined the mechanism through which plumbagin induces ferroptosis of colon cancer cells. Methods: CCK-8 assay was performed to examine the viability of colon cancer cells (SW480 and HCT116 cells) after they were treated with 0-, 5-, 10-, 15- and 20-µmol/L plumbagin. Colony formation assay and Transwell assay were used to examine the effects of 15-µmol/L plumbagin on the proliferation, invasive ability. The ferroptosis of SW480 and HCT116 cells and the expression of p-p53, p53 and SLC7A11 were analysed. The effects of blocking necrosis, apoptosis and ferroptosis on the anti-cancer effects of plumbagin were examined. After p53 was silenced, the effects of plumbagin on proliferation, invasion, ferroptosis and SLC7A11 expression were assessed. A tumour-bearing nude mouse model was used to examine the effects of p53 silencing and/or plumbagin on tumour growth, ferroptosis and SLC7A11 expression. Results: Plumbagin inhibited the proliferation of SW480 and HCT116 cells and their invasive and colony-forming abilities. It increased Fe2+ levels but significantly decreased GSH and GPX4 levels. When ferroptosis was inhibited, the effects of plumbagin on colon cancer cells were significantly alleviated. Plumbagin promoted the expression and phosphorylation of p53 and inhibited the mRNA and protein levels of SLC7A11. Silencing of p53 counteracted the effects of plumbagin on the ferroptosis and biological behaviour of SW480 and HCT116 cells. In mouse models of colon cancer, silencing of p53 attenuated the tumour-suppressing effects of plumbagin as well as its inhibitory effects on the protein level of SLC7A11 and restored the expression of GSH and GPX4. Conclusion: Plumbagin promotes ferroptosis and inhibits cell proliferation and invasion by decreasing the protein expression of SLC7A11 through p53.

Plumbagin inhibits fungal growth, HMGB1/LOX-1 pathway and inflammatory factors in A. fumigatus keratitis.

To investigate the anti-inflammatory and antifungal effects of plumbagin (PL) in Aspergillus fumigatus (A. fumigatus) keratitis, the minimum inhibitory concentration (MIC), time-killing curve, spore adhesion, crystal violet staining, calcium fluoride white staining, and Propidium Iodide (PI) staining were employed to assess the antifungal activity of PL in vitro against A. fumigatus. The cytotoxicity of PL was assessed using the Cell Counting Kit-8 (CCK8). The impact of PL on the expression of HMGB1, LOX-1, TNF-α, IL-1ß, IL-6, IL-10 and ROS in A. fumigatus keratitis was investigated using RT-PCR, ELISA, Western blot, and Reactive oxygen species (ROS) assay. The therapeutic efficacy of PL against A. fumigatus keratitis was assessed through clinical scoring, plate counting, Immunofluorescence and Hematoxylin-Eosin (HE) staining. Finally, we found that PL inhibited the growth, spore adhesion, and biofilm formation of A. fumigatus and disrupted the integrity of its cell membrane and cell wall. PL decreased IL-6, TNF-α, and IL-1ß levels while increasing IL-10 expression in fungi-infected mice corneas and peritoneal macrophages. Additionally, PL significantly attenuated the HMGB1/LOX-1 pathway while reversing the promoting effect of Boxb (an HMGB1 agonist) on HMGB1/LOX-1. Moreover, PL decreased the level of ROS. In vivo, clinical scores, neutrophil recruitment, and fungal burden were all significantly reduced in infected corneas treated with PL. In summary, the inflammatory process can be inhibited by PL through the regulation of the HMGB-1/LOX-1 pathway. Simultaneously, PL can exert antifungal effects by limiting fungal spore adhesion and biofilm formation, as well as causing destruction of cell membranes and walls.

Plumbagin Regulates Snail to Inhibit Hepatocellular Carcinoma Epithelial-Mesenchymal Transition in vivo and in vitro.

Background/Aims: Plumbagin (PL) has been shown to effe ctively inhibit autophagy, suppressing invasion and migration of hepatocellular carcinoma (HCC) cells. However, the specific mechanism remains unclear. This study aimed to investigate the effect of PL on tumor growth factor (TGF)-ß-induced epithelial-mesenchymal transition (EMT) in HCC. Methods: Huh-7 cells were cultured, and in vivo models of EMT and HCC-associated lung metastasis were developed through tail vein and in situ injections of tumor cells. In vivo imaging and hematoxylin and eosin staining were used to evaluate HCC modeling and lung metastasis. After PL intervention, the expression levels of Snail, vimentin, E-cadherin, and N-cadherin in the liver were evaluated through immunohistochemistry and Western blot. An in vitro TGF-ß-induced cell EMT model was used to detect Snail, vimentin, E-cadherin, and N-cadherin mRNA levels through a polymerase chain reaction. Their protein levels were detected by immunofluorescence staining and Western blot. Results: In vivo experiments demonstrated that PL significantly reduced the expression of Snail, vimentin, and N-cadherin, while increasing the expression of E-cadherin at the protein levels, effectively inhibiting HCC and lung metastasis. In vitro experiments confirmed that PL up-regulated epithelial cell markers, down-regulated mesenchymal cell markers, and inhibited EMT levels in HCC cells. Conclusion: PL inhibits Snail expression, up-regulates E-cadherin expression, and down-regulates N-cadherin and vimentin expression, preventing EMT in HCC cells and reducing lung metastasis.

Plumbagin as a preferential lead molecule to combat EGFR-driven matrix abundance and migration of cervical carcinoma cells.

The handshake between the complex networks of matrix components in the tumor micro-environment (TME) is considered as a crucial event in the progression of several cancers including cervical carcinoma (CC). A number of studies report a connection between epidermal growth factor (EGF) and matrix component production. Studies demonstrate that the mechano-transduction trigger by collagen, influences the tumor cells to undergo epithelial-mesenchymal transition (EMT) and block the entry of drugs. We hypothesize that the intervention to prevent EGF triggered deposition of matrix components could sensitize several therapies for CC cells. We utilized morphological assessment, MTT assay, mitored tracking, acridine orange (AO)/ ethidium bromide (EtBr) staining and bromodeoxyuridine (BrdU) assay to measure the cell viability, mitochondrial activity, cellular apoptosis, and DNA synthesis. Clonogenic assay and scratch healing assay were executed to address the stemness and migratory potential. Detection of glycosaminoglycan's (GAGs), collagen, matrix metalloproteinase (MMP)-2/9 secretion and calcium (Ca2+) ions were performed to assess the production of matrix components. Finally, the interaction between EGFR and plumbagin was evaluated by employing molecular dynamics (MD) simulation. Pre-treating the cells with plumbagin inhibited the EGF-induced EMT along with reduction in cell proliferation, migration, clonogenesis and depletion of matrix components. The actions of EGF and plumbagin were more pronounced in HPV-positive CC cells than HPV-negative CC cells. This study identified that increased matrix production triggered by EGF-rich milieu is inhibited by plumbagin in human papilloma viral (HPV) 68 positive ME180, HPV 16 positive SiHa and HPV-negative C33A cell lines. Delivery of plumbagin directly to TME would effectively accelerate the clearance of CC cells, reduce metastasis and matrix abundance by employing targeted delivery to minimize the undesired effects of plumbagin.

Distribution of Acetogenic Naphthoquinones in Droseraceae and Their Chemotaxonomic Utility.

Chemotaxonomy is the link between the state of the art in analytical chemistry and the systematic classification and phylogenetic analysis of biota. Although the characteristic secondary metabolites from diverse biotic sources have been used in pharmacology and biological systematics since the dawn of mankind, only comparatively recently established reproducible methods have allowed the precise identification and distinction of structurally similar compounds. Reliable, rapid screening methods like TLC (Thin Layer Chromatography) can be used to investigate sufficiently large numbers of samples for chemotaxonomic purposes. Using distribution patterns of mutually exclusive naphthoquinones, it is demonstrated in this review how a simple set of chemical data from a representative sample of closely related species in the sundew family (Droseraceae, Nepenthales) provides taxonomically and phylogenetically informative signal within the investigated group and beyond.

Synergistic Anticancer Activity of Plumbagin and Xanthohumol Combination on Pancreatic Cancer Models.

Among diverse cancers, pancreatic cancer is one of the most aggressive types due to inadequate diagnostic options and treatments available. Therefore, there is a necessity to use combination chemotherapy options to overcome the chemoresistance of pancreatic cancer cells. Plumbagin and xanthohumol, natural compounds isolated from the Plumbaginaceae family and Humulus lupulus, respectively, have been used to treat various cancers. In this study, we investigated the anticancer effects of a combination of plumbagin and xanthohumol on pancreatic cancer models, as well as the underlying mechanism. We have screened in vitro numerous plant-derived extracts and compounds and tested in vivo the most effective combination, plumbagin and xanthohumol, using a transgenic model of pancreatic cancer KPC (KrasLSL.G12D/+; p53R172H/+; PdxCretg/+). A significant synergistic anticancer activity of plumbagin and xanthohumol combinations on different pancreatic cancer cell lines was found. The combination treatment of plumbagin and xanthohumol influences the levels of B-cell lymphoma (BCL2), which are known to be associated with apoptosis in both cell lysates and tissues. More importantly, the survival of a transgenic mouse model of pancreatic cancer KPC treated with a combination of plumbagin and xanthohumol was significantly increased, and the effect on BCL2 levels has been confirmed. These results provide a foundation for a potential new treatment for pancreatic cancer based on plumbagin and xanthohumol combinations.

Plumbagin Induces Reactive Oxygen Species and Endoplasmic Reticulum Stress-related Cell Apoptosis in Human Oral Squamous Cell Carcinoma.

BACKGROUND/AIM: Oral squamous cell carcinoma (OSCC), a major malignancy in Taiwan, is an invasive epithelial neoplasm resulting in a low survival rate. Current treatments do not prevent OSCC progression, and antitumor therapies should be improved. Plumbagin, a natural compound extracted from Plumbago zeylanica L., appears to have antitumor effects in various tumors. The antitumor mechanism of plumbagin in OSCC is still unclear. This study investigated the molecular mechanism through which plumbagin induces apoptosis. MATERIALS AND METHODS: To investigate the antiproliferative and pro-apoptotic effects of Plumbagin on OSCC cells and explore its underlying mechanism, cell counting kit-8, cell cycle analysis, and annexin V/PI assay were conducted. The functions of plumbagin on endoplasmic reticulum (ER) stress, reactive oxygen species (ROS) production, and mitochondrial membrane potential (MMP) deficiency were analyzed using flow cytometric analysis. Plumbagin-induced apoptosis-associated proteins were detected using western blotting. RESULTS: Plumbagin induced apoptosis in OSCC cells by suppressing tumor cell proliferation through ROS production, ER stress, mitochondrial dysfunction, and caspases activation. CONCLUSION: Plumbagin is a promising antitumor candidate targeting human OSCC.

Use of antioxidant nanoliposomes for co-delivery of PTEN plasmids and plumbagin to induce apoptosis in hepatic cancer cells.

Hepatocellular carcinoma remains a challenging contributor to the global cancer and related mortality, and claims approximately 800,000 deaths each year. Dysregulation or loss of function mutations involving the tumor suppressor gene, phosphatase and tensin homolog deleted on chromosome ten (PTEN), has been well-characterized in various cancers to elicit anomalous cell proliferation and oncogenic transformation. However, the delivery and bioavailability of genes/drugs of interest to carcinomas remains a serious bottleneck behind the success of any anti-cancer formulation. In this study, we have engineered nanoliposomes containing PTEN plasmids, plumbagin, and antioxidant cerium oxide nanoparticles (Lipo-PTEN-Plum) to restore the PTEN expression and inhibit the AKT/PI3K pathway. The Lipo-PTEN-Plum was quasi-spherical in shape with ∼110 nm diameter and ∼64% plumbagin loading efficiency. The Lipo-PTEN-Plum was successfully internalized HepG2 cells, restore PTEN expression and inhibit PI3K/AKT pathway to induce death in cells grown in monolayer and in form of spheroids. Mechanistically, the formulation showed G2/M cell cycle arrest, DNA damage and apoptosis in hepatic cancer cells. Other cellular events such as Caspase-7 overexpression and PI3K (phosphoinositide 3-kinase), AKT (a serine/threonine protein kinase), PARP [Poly (ADP-ribose) polymerases], and mTOR (Mammalian target of rapamycin) inhibition led to the apoptosis in hepatic cancer cells. The mRNA expression profile of PTEN, PI3K, AKT3, Caspase-7, PARP and mTOR proteins, primarily controlling the cancer cell proliferation and apoptosis, suggest that exogenous supply of PTEN could regulate the expression of oncogenic proteins and thus cancer progression.

Copper(II) complexes with plumbagin and bipyridines target mitochondria for enhanced chemodynamic cancer therapy.

The combination of mitochondrial targeting and chemodynamic therapy is a promising anti-cancer strategy. Three mitochondria targeting copper(II) complexes (Cu1-Cu3) with plumbagin and bipyridine ligands for enhanced chemodynamic therapy were synthesized and characterized. Their anti-proliferative activity to HeLa cells was higher than that of cisplatin, and their toxicity to normal cells was low. Cellular uptake and distribution studies indicated that Cu1 and Cu3 were mainly accumulated in mitochondria. The mechanism studies showed that Cu1 and Cu3 converted intracellular H2O2 into toxic hydroxyl radicals by consuming glutathione, leading to mitochondrial dysfunction. Treatment with the copper complex caused ER stress and cell arrest in the S phase which resulted in apoptosis. In vivo, Cu1 and Cu3 effectively inhibited the growth of HeLa xenograft tumors without obvious toxic and side effects.

Cellular ROS tolerance determines the effect of plumbagin on osteoclast differentiation.

Plumbagin is used in traditional medicine because of its anti-inflammatory and anti-microbial properties. As a naphthoquinone, plumbagin triggers the production of reactive oxygen species (ROS). In vitro cancer studies showed that plumbagin triggers apoptosis in cancer cells through ROS production. As cancer-mediated chronic inflammation can affect bone density, it was hypothesized that plumbagin might directly inhibit the formation of bone-resorbing osteoclasts. We previously showed that the effect of plumbagin on osteoclastogenesis differed between bone marrow-derived macrophages and the macrophage cell line RAW 264.7. Although RAW 264.7 macrophages are able to initiate the gene program required for osteoclastogenesis, only primary macrophages successfully differentiate into osteoclasts. Here, we show that RAW 264.7 cells are more sensitive toward plumbagin-induced apoptosis. In the presence of plumbagin and the cytokine RANKL, which triggers ROS production to drive osteoclastogenesis, RAW 264.7 macrophages produce increased amounts of ROS and die. Addition of the ROS scavenger N-acetyl cysteine prevented cell death, linking the failure to differentiate to increased ROS levels. RAW 264.7 cells show reduced expression of genes protective against oxidative stress, while primary macrophages have a higher tolerance toward ROS. Our data suggest that it is indispensable to consider cell (line)-intrinsic properties when studying phytochemicals.

Plumbagin has an inhibitory effect on the growth of TSCC PDX model and it enhances the anticancer efficacy of cisplatin.

BACKGROUND: Head and neck squamous cell carcinomas are the sixth most common malignant tumors worldwide. Tongue squamous cell carcinoma is a common malignant tumor of this type, and it is associated with poor prognosis, a high rate of recurrence and a low survival rate. Plumbagin is derived from Plumbago zeylanica L, several studies report that plumbagin could inhibit cell, tumor metastasis, induce apoptosis in various cancer cells. Patient-derived xenograft (PDX) model can maintain the heterogeneity and microenvironment of human tumors, is a powerful research tool for developing potentially effective therapies for TSCC. METHODS: Tumor tissues obtained from TSCC patients were implanted into immunodeficient mice to establish TSCC PDX models. Subsequently, the PDX models were used to evaluate the anti-tumor effects of plumbagin on TSCC. Furthermore, we conducted next-generation sequencing (NGS) and explored the mRNA expression profiles between the treatment and control groups. We selected eight mRNAs related to the characteristics and prognosis of TSCC patients for further analysis. RESULTS: Plumbagin could inhibit the growth of TSCC PDX models and inhibit expression of Akt/mTOR pathway. In addition, plumbagin was shown to increase drug sensitivity to cisplatin. The eight mRNAs selected for further analysis, AXL, SCG5, VOPP1, DCBLD2 and DRAM1 are cancer-promoting genes, DUSP1, AQP5 and BLNK are cancer suppressor genes. And they were related to the diagnosis, growth, prognosis, and immune cell infiltration in TSCC patients. CONCLUSION: Plumbagin exhibits an inhibitory effect on the growth of the PDX model of TSCC. Moreover, plumbagin enhances the inhibitory effects of cisplatin.