Gamma-mangostin Protects S16Y Schwann Cells Against tert-Butyl Hydroperoxide-induced Apoptotic Cell Death.

BACKGROUND: Peripheral neuropathy is a common complication that affects individuals with diabetes. Its development involves an excessive presence of oxidative stress, which leads to cellular damage in various tissues. Schwann cells, which are vital for peripheral nerve conduction, are particularly susceptible to oxidative damage, resulting in cell death. MATERIALS AND METHODS: Gamma-mangostin (γ-mangostin), a xanthone derived from Garcinia mangostana, possesses cytoprotective properties in various pathological conditions. In this study, we employed S16Y cells as a representative Schwann cell model to investigate the protective effects of γ-mangostin against the toxicity induced by tert-Butyl hydroperoxide (tBHP). Different concentrations of γ-mangostin and tBHP were used to determine non-toxic doses of γ-mangostin and toxic doses of tBHP for subsequent experiments. MTT cell viability assays, cell flow cytometry, and western blot analysis were used for evaluating the protective effects of γ-mangostin. RESULTS: The results indicated that tBHP (50 µM) significantly reduced S16Y cell viability and induced apoptotic cell death by upregulating cleaved caspase-3 and cleaved PARP protein levels and reducing the Bcl- XL/Bax ratio. Notably, pretreatment with γ-mangostin (2.5 µM) significantly mitigated the decrease in cell viability caused by tBHP treatment. Furthermore, γ-mangostin effectively reduced cellular apoptosis induced by tBHP. Lastly, γ-mangostin significantly reverted tBHP-mediated caspase-3 and PARP cleavage and increased the Bcl-XL/Bax ratio. CONCLUSION: Collectively, these findings highlight the ability of γ-mangostin to protect Schwann cells from apoptotic cell death induced by oxidative stress.

Stem Extract from Momordica cochinchinensis Induces Apoptosis in Chemoresistant Human Prostate Cancer Cells (PC-3).

Natural compounds have been recognized as valuable sources for anticancer drug development. In this work, different parts from Momordica cochinchinensis Spreng were selected to perform cytotoxic screening against human prostate cancer (PC-3) cells. Chromatographic separation and purification were performed for the main constituents of the most effective extract. The content of the fatty acids was determined by Gas Chromatography-Flame Ionization Detector (GC-FID). Chemical structural elucidation was performed by spectroscopic means. For the mechanism of the apoptotic induction of the most effective extract, the characteristics were evaluated by Hoechst 33342 staining, sub-G1 peak analysis, JC-1 staining, and Western blotting. As a result, extracts from different parts of M. cochinchinensis significantly inhibited cancer cell viability. The most effective stem extract induced apoptosis in PC-3 cells by causing nuclear fragmentation, increasing the sub-G1 peak, and changing the mitochondrial membrane potential. Additionally, the stem extract increased the pro-apoptotic (caspase-3 and Noxa) mediators while decreasing the anti-apoptotic (Bcl-xL and Mcl-1) mediators. The main constituents of the stem extract are α-spinasterol and ligballinol, as well as some fatty acids. Our results demonstrated that the stem extract of M. cochinchinensis has cytotoxic and apoptotic effects in PC-3 cells. These results provide basic knowledge for developing antiproliferative agents for prostate cancer in the future.

HDAC inhibitor cowanin extracted from G. fusca induces apoptosis and autophagy via inhibition of the PI3K/Akt/mTOR pathways in Jurkat cells.

Cowanin, a xanthone derivative extracted from the Garcinia fusca plant, has been recognized for various biological activities including, antimicrobial, anti-inflammatory, and anticancer activities. However, the mechanism to induce cancer cell death in cancer cells remains to be fully elucidated. Our previous report showed that other xanthones from these plants could act as histone deacetylase inhibitors (HDACi), so we deeply analyzed the role of cowanin, a major compound of G.fusca, and investigated through the mode of cell death both apoptosis and autophagy that have never been reported. As a result, it was demonstrated that cowanin indicated the role of HDACi as other xanthones. The molecular docking analysis showed that cowanin could interact within the catalytic pocket region of HDAC class I (HDAC2, 8) and II (HDAC4, 7) proteins and inhibit their activity. Also, the level of protein expression of HDAC2, 4, 7, and 8 was distinctly decreased, and the level of histone H3 and H4 acetylation increased in cowanin treated cells. For the mode of cell death, cowanin demonstrated both apoptosis and autophagy activation in Jurkat cells. Besides, cowanin significantly suppressed phosphorylation of PI3K, Akt, and mTOR signaling. Therefore, these findings revealed that cowanin represents a new promising candidate for development as an anticancer agent by inducing apoptosis and autophagy via PI3K/AKT/mTOR pathway and effectively inhibiting HDAC activity.

Sonicated Extract from the Aril of Momordica Cochinchinensis Inhibits Cell Proliferation and Migration in Aggressive Prostate Cancer Cells.

Momordica cochinchinensis or gac fruit has been reported to have several biological activities, including antioxidation, anti-inflammatory, and anticancer activities. However, the effect on cancer cell metastasis has not been extensively studied. With this aim, the extract from the aril part was selected and investigated for prostate cancer cell migration. The aril extracts were prepared as boiled extract, sonicated extract, ethanol extract, and HAE (hexane:acetone:ethanol; 2 : 1 : 1) extract, while the prostate cancer cell models were PC-3 and LNCaP cells. An MTT assay was performed to compare the antiproliferative effect between prostate cancer cells and normal Vero cells. As a result, the sonicated extract had the highest efficiency in PC-3 cells, with IC50 values of 2 mg/mL and 0.59 mg/mL for 48 and 72 h, respectively, while it had less of an effect in LNCaP cells and was not toxic to normal cells. Cell damage was further confirmed using LDH and cell cycle analysis. As a result, the sonicated extract did not cause cell damage or death and only inhibited cell proliferation. The effect on cancer metastasis was further examined by wound healing, transwell migration assays, and western blotting. The results demonstrated that the sonicated extract inhibited PC-3 cell migration and decreased MMP-9 but increased TIMP-1 expression. All these results support that gac fruit is a valuable source for further development as an anticancer agent for prostate cancer patients.

Highly potent cholinesterase inhibition of geranylated xanthones from Garcinia fusca and molecular docking studies.

Three new oxygenated xanthones, fuscaxanthones L-N (1-3), and 14 known xanthones 4-17, together with the other known metabolites 18-20 were isolated from the stem barks of Garcinia fusca Pierre. Their chemical structures were determined based on NMR and MS spectroscopic data analysis, as well as single X-ray crystallography. The geranylated compounds, cowanin (13), cowagarcinone E (15), norcowanin (16) and cowanol (17) exhibited potent inhibitions against acetylcholinesterase (AChE) (IC50 0.33-1.09 µM) and butyrylcholinesterase (BChE) (IC50 0.048-1.84 µM), which were more active than the reference drug, galanthamine. Compound 15 was highly potent BChE inhibitor (IC50 0.048 µM) and was 76-fold more potent than the drug. Structure-activity relationship studies indicated that the C-2 prenyl and C-8 geranyl substituents in the tetraoxygenated scaffold are important for high activity. Molecular docking studies revealed that the leads 13 and 15-17 showed similar binding orientations on both enzymes and very well-fitted at the double binding active sites of PAS and CAS with strong hydrophobic interactions from both isoprenyl side chains.

Protective effects of γ-mangostin on 6-OHDA-induced toxicity in SH-SY5Y cells.

γ-Mangostin is a xanthone with hydroxyl groups that confer the substance-free radical scavenging effects. As opposed to the other more extensively studied mangostins, scarce research has been conducted on neuroprotective effects of γ-mangostin on models of Parkinson's disease (PD). Therefore, this investigation aimed to elucidate its antioxidant and neuroprotective effects on 6-OHDA-induced toxicity in SH-SY5Y cells. 6-OHDA treatment, an inducer of PD pathology in vitro studies, decreased cell viability and increased the level of intracellular ROS production. Furthermore, the substance-induced the expression of phosphorylated p38 MAPK, negatively affected the Bax/Bcl-2 ratio and increased caspase-3 activity; all of which were factors that are associated with apoptosis. Pretreatment of cells with γ-mangostin at concentrations of 0.5, 1, and 2.5µM markedly increased cell survival and reduced the level of intracellular ROS formation as shown by DPPH radical scavenging activity of the compound. Furthermore, a significant suppression of p-p38, improved Bax/Bcl-2 ratio expression, and reduced caspase-3 activity was exhibited in the cells after γ-mangostin pretreatment. The reduction of apoptosis was further supported by the reduction of pyknotic nuclei indicated by Hoescht 33342 staining. These findings indicate that γ-mangostin could attenuate 6-OHDA-induced neuronal cell death and that the protective effect of γ-mangostin is associated with its antioxidative potential and through the modulation of the apoptotic signalling pathway. Therefore, γ-mangostin may be an effective xanthone among other mangostins for preventing neurodegeneration in PD caused by oxidative stress.

2-Arylbenzofurans from Artocarpus lakoocha and methyl ether analogs with potent cholinesterase inhibitory activity.

In vitro screening for acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities of the Artocarpus lakoocha root-bark extracts revealed interesting results. Bioassay-guided fractionation resulted in the isolation of two new (1 and 2) and six known 2-arylbenzofurans 3-8, along with one stilbenoid 9 and one flavonoid 10. The structures of the isolated compounds were elucidated by UV, IR, 1D- and 2D-NMR and MS spectroscopic data analysis. Compounds 4, 6 and 7 exhibited more potent AChE inhibitory activity (IC50 = 0.87-1.10 µM) than the reference drug, galantamine. Compounds 4, 8 and 9 displayed greater BChE inhibition than the standard drug. The preferential inhibition of BChE over AChE indicated that 4 also showed a promising dual AChE and BChE inhibitor. The synthetic mono-methylated analogs 4a-c and 6a-b were found to be good BChE inhibitors with IC50 values ranging between 0.31 and 1.11 µM. Based on the docking studies, compounds 4 and 6 are well-fitted in the catalytic triad of AChE. Compounds 4 and 6 showed different binding orientations on BChE, and the most potent BChE inhibitor 4 occupied dual binding to both CAS and PAS more efficiently.

New bioactive cyclopeptide alkaloids with rare terminal unit from the root bark of Ziziphus cambodiana.

Six new 14-membered ring cyclopeptide alkaloids, cambodines A-F (1-6), and two known compounds, frangufoline (7) and lotusanine B (8), were isolated from the root bark extract of Ziziphus cambodiana Pierre. Their structures and configurations were established based on 1D and 2D NMR, HRMS, ECD, and X-ray crystallographic data. Compounds 1 and 3 are rare 5(14)-type cyclopeptide alkaloids that possess an imidazolidin-4-one ring in the terminal unit. The cyclopeptides were tested for their in vitro antiplasmodial, antitubercular, and cytotoxic effects against three cancer cell lines. Compound 3 showed significant antiplasmodial activity against the malarial parasite Plasmodium falciparum, with an IC50 value of 6.09 µM.

Acute inhibitory effect of alpha-mangostin on sarcoplasmic reticulum calcium-ATPase and myocardial relaxation.

The benefits of α-mangostin for various tissues have been reported, but its effect on the heart has not been clarified. This study aimed to evaluate the effects of α-mangostin on cardiac function. Using a cardiac sarcoplasmic reticulum (SR) membrane preparation, α-mangostin inhibited SR Ca2+ -ATPase activity in a dose-dependent manner (IC50 of 6.47 ± 0.7 µM). Its suppressive effect was specific to SR Ca2+ -ATPase but not to myofibrillar Ca2+ -ATPase. Using isolated cardiomyocytes, 50 µM of α-mangostin significantly increased the duration of cell relengthening and increased the duration of Ca2+ transient decay, suggesting altered myocyte relaxation. The relaxation effect of α-mangostin was also supported in vivo after intravenous infusion. A significant suppression of both peak pressure and rate of ventricular relaxation (-dP/dt) relative to DMSO infusion was observed. The results from the present study demonstrated that α-mangostin exerts specific inhibitory action on SR Ca2+ -ATPase activity, leading to myocardial relaxation dysfunction.

Synthesis and preliminary evaluation of 5,7-dimethyl-2-aryl-3H-pyrrolizin-3-ones as angiogenesis inhibitors.

Sunitinib (Sutent®) is a receptor tyrosine kinase (RTK) and angiogenesis inhibitor approved for the treatment of renal cell carcinomas, gastrointestinal stromal tumours and pancreatic neuroendocrine tumours. A key structural motif retained throughout medicinal chemistry efforts during sunitinib's development was the indoline-2-one group. In the search for new anti-angiogenic scaffolds, we previously reported that non-indoline-2-one-based derivatives of semaxanib (SU5416, a structurally simpler sunitinib predecessor that underwent Phase III trials) are active as angiogenesis inhibitors, indicating that the group is not essential for activity. This Letter describes the synthesis and structure-activity relationships of another class of non-indoline-2-one angiogenesis inhibitors related to sunitinib/semaxanib; the 5,7-dimethyl-2-aryl-3H-pyrrolizin-3-ones. A focussed library of 19 analogues was prepared using a simple novel process, wherein commercially available substituted arylacetic acids activated with an amide coupling reagent (HBTU) were reacted with the potassium salt of 3,5-dimethyl-1H-pyrrole-2-carbaldehyde in one-pot. Screening of the library using a cell-based endothelial tube formation assay identified 6 compounds with anti-angiogenesis activity. Two of the compounds were advanced to the more physiologically relevant rat aortic ring assay, where they showed similar inhibitory effects to semaxanib at 10µg/mL, confirming that 5,7-dimethyl-2-aryl-3H-pyrrolizin-3-ones represent a new class of angiogenesis inhibitors.

Alpha-mangostin attenuation of hyperglycemia-induced ocular hypoperfusion and blood retinal barrier leakage in the early stage of type 2 diabetes rats.

The present study examined effects of alpha-mangostin (α-MG) supplementation on the retinal microvasculature, including ocular blood flow (OBF) and blood-retinal barrier (BRB) permeability in a type 2 diabetic animal model. Male Sprague-Dawley rats were divided into four groups: normal control and diabetes with or without α-MG supplementation. Alpha-mangostin (200 mg/Kg/day) was administered by gavage feeding for 8 weeks. The effects of α-MG on biochemical and physiological parameters including mean arterial pressure (MAP), OBF, and BRB leakage were investigated. Additionally, levels of retinal malondialdehyde (MDA), advance glycation end products (AGEs), receptor of advance glycation end products (RAGE), tumour necrosis factor alpha (TNF-α), and vascular endothelial growth factor (VEGF) were evaluated. The elevated blood glucose, HbA1c, cholesterol, triglyceride, serum insulin, and HOMA-IR were observed in DM2 rats. Moreover, DM2 rats had significantly decreased OBF but statistically increased MAP and leakage of the BRB. The α-MG-treated DM2 rats showed significantly lower levels of retinal MDA, AGEs, RAGE, TNF-α, and VEGF than the untreated group. Interestingly, α-MG supplementation significantly increased OBF while it decreased MAP and leakage of BRB. In conclusion, α-MG supplementation could restore OBF and improve the BRB integrity, indicating its properties closely associated with antihyperglycemic, antioxidant, anti-inflammatory, and antiglycation activities.

Effects of Long-Term Alpha-mangostin Supplementation on Hyperglycemia and Insulin Resistance in Type 2 Diabetic Rats Induced by High Fat Diet and Low Dose Streptozotocin.

OBJECTIVE: The present study investigated the effects of long-term supplementation of alpha-mangostin (MG; a xanthone isolated from mangosteen fruit) on hyperglycemia, and insulin resistance in type 2 diabetic rats. MATERIAL AND METHOD: Type 2 diabetes (DM2) was induced in male Sprague-Dawley rats by feeding high fat diet for three weeks followed by an IP injection of low dose streptozotocin. The rats were divided into four groups: control and diabetes without or with alpha-MG supplementation (CON, DM2, CON-MG and DM2-MG group, respectively). Alpha-MG was administered by gavage feeding in the amount of 200 mg/kg BW/day for 8 or 40 weeks. Fasting blood glucose, plasma HbA1c, cholesterol, and triglyceride were determined in all groups of rats. Serum insulin, calculated HOMA-IR and Oral glucose tolerance test were also carried out. RESULTS: The results showed that both 8 and 40 weeks DM2 groups had a significant increase in fasting blood glucose, HbA1c, plasma cholesterol and triglyceride compared with their aged-match control groups. Furthermore, the serum insulin and HOMA-IR were significantly elevated in 8 weeks DM2 whereas these two parameters were significantly decreased in 40 weeks DM2 group compared with their aged-match CON groups (p < 0.001). The OGTT showed impaired glucose tolerance in DM2 groups. Interestingly, alpha-MG supplemented DM2-MG group had significantly decreased levels of fasting blood glucose, HbA1c, plasma cholesterol, triglyceride when compared with the untreated DM2 groups. Supplementation of alpha-MG for 40 weeks in DM2-MG group showed significantly increase serum insulin levels compared with that of DM2 group (p < 0.001). Moreover alpha-MG supplemented DM-MG group demonstrated a better glucose tolerance pattern which was different from that of DM2 group at both 8 weeks and 40 weeks experimental periods. CONCLUSION: Long-term alpha-mangostin supplementation has anti-hyperglycemic, anti-hyperlipidemic effects and increase insulin sensitivity by improving beta-cell functions in type 2 diabetes mellitus.

Dietary α-mangostin, a xanthone from mangosteen fruit, exacerbates experimental colitis and promotes dysbiosis in mice.

SCOPE: Ulcerative colitis (UC) is a chronic inflammatory disease of the colon. α-Mangostin (α-MG), the most abundant xanthone in mangosteen fruit, exerts anti-inflammatory and antibacterial activities in vitro. We evaluated the impact of dietary α-MG on murine experimental colitis and on the gut microbiota of healthy mice. METHODS AND RESULTS: Colitis was induced in C57BL/6J mice by administration of dextran sulfate sodium (DSS). Mice were fed control diet or diet with α-MG (0.1%). α-MG exacerbated the pathology of DSS-induced colitis. Mice fed diet with α-MG had greater colonic inflammation and injury, as well as greater infiltration of CD3(+) and F4/80(+) cells, and colonic myeloperoxidase, than controls. Serum levels of granulocyte colony-stimulating factor, IL-6, and serum amyloid A were also greater in α-MG-fed animals than in controls. The colonic and cecal microbiota of healthy mice fed α-MG but no DSS shifted to an increased abundance of Proteobacteria and decreased abundance of Firmicutes and Bacteroidetes, a profile similar to that found in human UC. CONCLUSION: α-MG exacerbated colonic pathology during DSS-induced colitis. These effects may be associated with an induction of intestinal dysbiosis by α-MG. Our results suggest that the use of α-MG-containing supplements by patients with UC may have unintentional risk.

Combating Helicobacter pylori infections with mucoadhesive nanoparticles loaded with Garcinia mangostana extract.

AIM: To combat the resistance of Helicobacter pylori to antibiotics through the use of Garcinia mangostana extract (GME) in the form that can be localized at stomach mucosa. MATERIALS & METHODS: GME and its major active component, α-mangostin, are encapsulated into the moderately acid stable mucoadhesive nanocarriers, and tested for anti-H. pylori and antiadhesion activities in vitro and their ability to eradicate H. pylori in infected mice. RESULTS: The two in vitro activities are observed and are enhanced when the materials are encapsulated into nanocarriers. Preliminary in vivo tests revealed the ability to combat H. pylori in mice following oral administration of the encapsulated GME, but not the unencapsulated GME. CONCLUSION: Nanoencapsulated GME is a potential anti-H. pylori agent.

Anti-Helicobacter pylori xanthones of Garcinia fusca.

A new geranylated xanthone derivative, fuscaxanthone I (1), along with nine xanthones (2-9 and 11), a biphenyl (10) and three biflavonoids (12-14) were isolated from the roots of Garcinia fusca Pierre. Compounds 8, 10 and 11-14 were reported from this plant species for the first time. Their structures were elucidated by spectroscopic analyses, including 1D- and 2D-NMR and MS. The isolated compounds were evaluated for antibacterial activity against Helicobacter pylori. Cowaxanthone (5) and fukugiside (14) exhibited stronger inhibitory activity against H. pylori DMST reference strain at MICs 4.6 and 10.8 µM, respectively, than that of the control metronidazole. Isojacareubin (8) displayed the most potent activity against H. pylori HP40 clinical isolate with MIC 23.9 µM, which was approximately two times greater than that of the standard drug amoxicillin.

Antileptospiral activity of xanthones from Garcinia mangostana and synergy of gamma-mangostin with penicillin G.

BACKGROUND: Leptospirosis, one of the most widespread zoonotic infectious diseases worldwide, is caused by spirochetes bacteria of the genus Leptospira. The present study examined inhibitory activity of purified xanthones and crude extracts from Garcinia mangostana against both non-pathogenic and pathogenic leptospira. Synergy between γ-mangostin and penicillin G against leptospires was also determined. METHODS: Minimal inhibitory concentrations (MIC) of crude extracts and purified xanthones from G. mangostana and penicillin G for a non-pathogenic (L. biflexa serovar Patoc) and pathogenic (L. interrogans serovar Bataviae, Autumnalis, Javanica and Saigon) leptospires were determined by using broth microdilution method and alamar blue. The synergy was evaluated by calculating the fractional inhibitory concentration (FIC) index. RESULTS: The results of broth microdilution test demonstrated that the crude extract and purified xanthones from mangosteen possessed antileptospiral activities. The crude extracts were active against all five serovars of test leptospira with MICs ranging from 200 to ≥ 800 µg/ml. Among the crude extracts and purified xanthones, garcinone C was the most active compound against both of pathogenic (MIC =100 µg/ml) and non-pathogenic leptospira (MIC = 200 µg/ml). However, these MIC values were higher than those of traditional antibiotics. Combinations of γ-mangostin with penicillin G generated synergistic effect against L. interrogans serovars Bataviae, Autumnalis and Javanica (FIC = 0.52, 0.50, and 0.04, respectively) and no interaction against L. biflexa serovar Patoc (FIC =0.75). However, antagonistic activity (FIC = 4.03) was observed in L. interrogans serovar Saigon. CONCLUSIONS: Crude extracts and purified xanthones from fruit pericarp of G. mangostana with significant antibacterial activity may be used to control leptospirosis. The combination of xanthone with antibiotic enhances the antileptospiral efficacy.

α-Mangostin: anti-inflammatory activity and metabolism by human cells.

Information about the anti-inflammatory activity and metabolism of α-mangostin (α-MG), the most abundant xanthone in mangosteen fruit, in human cells is limited. On the basis of available literature, we hypothesized that α-MG will inhibit the secretion of pro-inflammatory mediators by control and activated macrophage-like THP-1, hepatic HepG2, enterocyte-like Caco-2, and colon HT-29 human cell lines, as well as primary human monocyte-derived macrophages (MDM), and that such activity would be influenced by the extent of metabolism of the xanthone. α-MG attenuated TNF-α and IL-8 secretion by the various cell lines but increased TNF-α output by both quiescent and LPS-treated MDM. The relative amounts of free and phase II metabolites of α-MG and other xanthones present in media 24 h after addition of α-MG was shown to vary by cell type and inflammatory insult. Increased transport of xanthones and their metabolites across Caco-2 cell monolayers suggests enhanced absorption during an inflammatory episode. The anti-inflammatory activities of xanthones and their metabolites in different tissues merit consideration.

Potent activity against multidrug-resistant Mycobacterium tuberculosis of α-mangostin analogs.

A new series of mangostin analogs of natural α-mangostin from mangosteen was prepared and their antimycobacterial activity was evaluated in vitro against Mycobacterium tuberculosis H(37)Ra. The results showed that the monoalkyl tetrahydro α-mangostin analogs displayed increased antimycobacterial activity as compared with the lead natural xanthone, α-mangostin. Among the tested compounds, 6-methoxytetrahydro α-mangostin (16) exhibited the most potent antimycobacterial activity with minimum inhibitory concentration (MIC) of 0.78 µg/mL. The activity of the monoalkylated and monoacylated tetrahydro α-mangostins decreases as the length of carbon chain increases. The methyl ether analog was also active against the multidrug-resistant (MDR) strains with pronounced MICs of 0.78-1.56 µg/mL.

Hydroxyxanthone as an inhibitor of cAMP-activated apical chloride channel in human intestinal epithelial cell.

AIMS: Previous investigation showed that polyphenols abundantly found in many plants could inhibit Cl(-) secretion. The present study was aimed to investigate the effect of phenol containing xanthone derivatives on cAMP-activated intestinal Cl(-) secretion and evaluate potential benefits of these compounds in the treatment of cholera. MAIN METHODS: Four hydroxy xanthones were synthesized via oxidative coupling reaction of the corresponding ortho-hydroxybenzoic acids and hydroxyphenols. Short-circuit current and apical Cl(-) current measurements across monolayers of human intestinal epithelial (T84) cell and Fisher rat thyroid cells transfected with human CFTR (FRT-hCFTR cell) were performed to determine the effect of hydroxyxanthones on cAMP-activated Cl(-) secretion. Intracellular cAMP was measured by immunoassay methods. Anti-diarrheal efficacy was evaluated using closed loop model of cholera. KEY FINDINGS: Among the tested xanthones, 1,3,6-trihydroxyxanthone (THX-001) was found to be the most potent derivative in the inhibition of cAMP-activated Cl(-) secretion across T84 cell monolayers (IC(50)~100µM). Electrophysiological analysis of T84 cells and FRT-hCFTR cells revealed that THX-001 targeted two distinct cAMP-activated Cl(-) channels in the apical membrane of T84 cells, namely, CFTR and inward rectifying Cl(-) channel (IRC). In contrast, THX-001 had no effect on intracellular cAMP levels in these cells. Importantly, THX-001 completely abolished cholera toxin-induced Cl(-) secretion across T84 cell monolayers and significantly inhibited cholera toxin-induced intestinal fluid secretion in mouse closed loop models. SIGNIFICANCE: This study revealed that hydroxyxanthone represents another chemical class of polyphenolic compounds that may hold promise as anti-secretory therapy for cholera.

Antiproliferative effect of α-mangostin on canine osteosarcoma cells.

Osteosarcoma is the most frequently diagnosed primary bone tumor in dog. Since chemotherapeutics are quite limited due to high cost and severe toxicity, therefore, the ultimate goal is to discover cost-effective therapeutics with less toxicity. We have studied the effect of α-mangostin, a xanthone derivative isolated from pericarp of mangosteen (Garcinia mangostana Linn.) in canine osteosarcoma, D-17 cells. The results showed that α-mangostin induced antiproliferation with IC(50) at 15 µg/ml. Hoechst 33342 nuclear staining and nucleosomal DNA-gel electrophoresis revealed that α-mangostin could induce nuclear condensation and fragmentation, typically seen in apoptosis. Cell cycle analysis demonstrated that α-mangostin induced sub-G1 peak. In addition, α-mangostin also induced membrane flipping of the phosphatidylserine and the loss of mitochondrial membrane potential in D-17 cells. In conclusion, α-mangostin, induced apoptotic cell death against canine osteosarcoma D-17 cells, could be a potential candidate for preventive and therapeutic application for bone cancer treatment in dogs.