Unveiling Gambogenic Acid as a Promising Antitumor Compound: A Review.

Gambogenic acid is a derivative of gambogic acid, a polyprenylated xanthone isolated from Garcinia hanburyi. Compared with the more widely studied gambogic acid, gambogenic acid has demonstrated advantages such as a more potent antitumor effect and less systemic toxicity than gambogic acid according to early investigations. Therefore, the present review summarizes the effectiveness and mechanisms of gambogenic acid in different cancers and highlights the mechanisms of action. In addition, drug delivery systems to improve the bioavailability of gambogenic acid and its pharmacokinetic profile are included. Gambogenic acid has been applied to treat a wide range of cancers, such as lung, liver, colorectal, breast, gastric, bladder, and prostate cancers. Gambogenic acid exerts its antitumor effects as a novel class of enhancer of zeste homolog 2 inhibitors. It prevents cancer cell proliferation by inducing apoptosis, ferroptosis, and necroptosis and controlling the cell cycle as well as autophagy. Gambogenic acid also hinders tumor cell invasion and metastasis by downregulating metastasis-related proteins. Moreover, gambogenic acid increases the sensitivity of cancer cells to chemotherapy and has shown effects on multidrug resistance in malignancy. This review adds insights for the prevention and treatment of cancers using gambogenic acid.

Austalide K from the Fungus Penicillium rudallense Prevents LPS-Induced Bone Loss in Mice by Inhibiting Osteoclast Differentiation and Promoting Osteoblast Differentiation.

Osteoporosis is a chronic disease that has become a serious public health problem due to the associated reduction in quality of life and its increasing financial burden. It is known that inhibiting osteoclast differentiation and promoting osteoblast formation prevents osteoporosis. As there is no drug with this dual activity without clinical side effects, new alternatives are needed. Here, we demonstrate that austalide K, isolated from the marine fungus Penicillium rudallenes, has dual activities in bone remodeling. Austalide K inhibits the receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation and improves bone morphogenetic protein (BMP)-2-mediated osteoblast differentiation in vitro without cytotoxicity. The nuclear factor of activated T cells c1 (NFATc1), tartrate-resistant acid phosphatase (TRAP), dendritic cell-specific transmembrane protein (DC-STAMP), and cathepsin K (CTSK) osteoclast-formation-related genes were reduced and alkaline phosphatase (ALP), runt-related transcription factor 2 (Runx2), osteocalcin (OCN), and osteopontin (OPN) (osteoblast activation-related genes) were simultaneously upregulated by treatment with austalide K. Furthermore, austalide K showed good efficacy in an LPS-induced bone loss in vivo model. Bone volume, trabecular separation, trabecular thickness, and bone mineral density were recovered by austalide K. On the basis of these results, austalide K may lead to new drug treatments for bone diseases such as osteoporosis.

Gambogenic acid induces ferroptosis in melanoma cells undergoing epithelial-to-mesenchymal transition.

Melanoma is characterized by high malignancy and early onset of metastasis. Epithelial-to-mesenchymal transition (EMT) is an early event during tumor metastasis. Tumor cells that develop EMT can escape apoptosis, but they are vulnerable to ferroptosis inducers. Gambogenic acid (GNA), a xanthone found in Gamboge, has cytotoxic effects in highly invasive melanoma cells. This study investigated the anti-melanoma effect and mechanism of action of GNA in TGF-ß1-induced EMT melanoma cells. We found that GNA significantly inhibited the invasion, migration and EMT in melanoma cells, and these cells exhibited small mitochondrial wrinkling (an important feature of ferroptosis). An iron chelator, but not an apoptosis inhibitor or a necrosis inhibitor, abolished the inhibitory effects of GNA on proliferation, invasion and migration of TGF-ß1-stimulated melanoma cells. GNA upregulated the expression of p53, solute carrier family 7 member 11 (SLC7A11) and glutathione peroxidase 4 (GPX4) in the model cells, contributing to the mechanisms underlying GNA-induced ferroptosis. Collectively, our findings suggest that GNA induces ferroptosis in TGF-ß1-stimulated melanoma cells via the p53/SLC7A11/GPX4 signaling pathway.

Tumor ablation using low-intensity ultrasound and sound excitable drug.

The cell membrane is a semi-fluid container that defines the boundary of cells, and provides an enclosed environment for vital biological processes. A sound excitable drug (SED) that is non-cytotoxic to cells is developed to disrupt the plasma membrane under gentle ultrasound insonation, 1MHz, 1W/cm2. The frequency and power density of insonation are within the physical therapy and medical imaging windows; thus the applied ultrasound is safe and not harmful to tissues. The insertion of SEDs into the plasma membrane is not toxic to cells; however, the intruding SEDs weaken the membrane's integrity. Under insonation, the ultrasound energy destabilized the SED disrupted membranes, resulting in membrane rupture and eventual cell death. In a xenograft breast tumor model, the SED alone or the ultrasound alone caused little adverse effects to tumor tissue, while the combined treatment triggered necrosis with a brief local insonation of 3min. The described sono-membrane rupture therapy could be a safe alternative to the currently used high-energy tissue ablation technology, which uses X-rays, gamma rays, electron beams, protons, or high-intensity focused ultrasound.

Dendrofalconerol A sensitizes anoikis and inhibits migration in lung cancer cells.

Resistance to anoikis, enhanced cell motility, and growth in anchorage-independent conditions are hallmarks of highly metastatic cancer cells. The present study demonstrates the anoikis-sensitizing and anti-migration activities of dendrofalconerol A (DF-A), a pure bis(bibenzyl) isolated from the stem of Dendrobium falconeri (Orchidaceae), and its underlying mechanisms in human lung cancer H460 cells. DF-A at non-toxic concentrations significantly increased the anoikis response of the cancer cells, but caused no toxic effect on normal keratinocytes. In addition, DF-A significantly inhibited the growth of lung cancer cells in anchorage-independent conditions. Western blot analysis revealed that the anoikis-sensitizing effect of such a compound involves its ability to suppress survival signals as well as anti-apoptotic proteins, namely, activated protein kinase B (Akt) and Bcl-2. Furthermore, DF-A decreased caveolin-1 (Cav-1), a protein responsible for aggressiveness, while having no effect on Bax, Mcl-1, and activated Erk (p42/44) proteins. In the case of cell motility, DF-A exhibited strong anti-migration activity with the mechanism involving suppression of pFAK and Rho-GTP, but had no effect on Rac-GTP in lung cancer cells. Taken together, DF-A possesses anoikis-sensitizing activity along with anti-migration effects, and may be developed as a novel active compound for cancer treatment.

Blumeaxanthene II, a novel xanthene from Blumea riparia DC.

A novel xanthene (1), blumeaxanthene II, was isolated from the aerial parts of Blumea riparia (Bl.) DC., a Chinese medicinal plant with hemostatic properties, and its structure was determined by extensive spectroscopic analyses. This compound is the first example of a halogenated xanthene from a natural plant, and a biosynthetic pathway was proposed. Blumeaxanthene II was also tested against Bel-7404 cells in vitro but was found to be only weakly cytotoxic.

Demethylbellidifolin preserves endothelial function by reduction of the endogenous nitric oxide synthase inhibitor level.

The present study examined the anti-oxidation and protective effects of demethylbellidifolin (DMB), a xanthone compound extracted from swertia davidi Franch, on endothelium. The relationship between the protective effects of DMB on endothelium and the level of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase, was also determined in the present study. DMB significantly inhibited Cu(2+)-induced low-density lipoprotein (LDL) oxidation and scavenged DPPH radicals. DMB significantly attenuated the inhibition of endothelium-dependent vasodilator responses, induced by lysophosphatidycholine (LPC) in vitro and LDL in vivo, and increased release of lactate dehydrogenase induced by LDL in cultured endothelial cells. DMB significantly attenuated the increased concentration of malondialdehyde and ADMA, and the decreased level of nitric oxide induced by LDL in vivo and in cultured endothelial cells. DMB also significantly reduced the decreased activity of dimethylarginine dimethylaminohydrolase (DDAH) induced by LDL in cultured endothelial cells. In summary, the present results suggest that DMB protects endothelial damage induced by LPC in vitro and LDL in vivo or in endothelial cells, and the protective effect of DMB on the endothelium is related to reduction of ADMA concentration via an increase of DDAH activity by inhibition of lipid peroxidation.

Combination of vascular targeting agents with thermal or radiation therapy.

PURPOSE: The most likely clinical application of vascular targeting agents (VTAs) is in combination with more conventional therapies. In this study, we report on preclinical studies in which VTAs were combined with hyperthermia and/or radiation. METHODS AND MATERIALS: A C3H mammary carcinoma grown in the right rear foot of female CDF1 mice was treated when at 200 mm3 in size. The VTAs were combretastatin A-4 disodium phosphate (CA4DP, 25 mg/kg), flavone acetic acid (FAA, 150 mg/kg), and 5,6-dimethylxanthenone-4-acetic acid (DMXAA, 20 mg/kg), and were all injected i.p. Hyperthermia and radiation were locally administered to tumors of restrained, nonanesthetized mice, and response was assessed using either a tumor growth or tumor control assay. RESULTS: Heating tumors at 41.5 degrees C gave rise to a linear relationship between the heating time and tumor growth with a slope of 0.02. This slope was increased to 0.06, 0.09, and 0.08, respectively, by injecting the VTAs either 30 min (CA4DP), 3 h (FAA), or 6 h (DMXAA) before heating. The radiation dose (+/-95% confidence interval) that controls 50% of treated tumors (the TCD(50) value) was estimated to be 53 Gy (51-55 Gy) for radiation alone. This was decreased to 48 Gy (46-51 Gy), 45 Gy (41-49 Gy), and 42 Gy (39-45 Gy), respectively, by injecting CA4DP, DMXAA, or FAA 30-60 min after irradiating. These values were further decreased to around 28-33 Gy if the tumors of VTA-treated mice were also heated to 41.5 degrees C for 1 h, starting 4 h after irradiation, and this effect was much larger than the enhancement seen with either 41.5 degrees C or even 43 degrees C alone. CONCLUSIONS: Our preclinical studies and those of others clearly demonstrate that VTAs can enhance tumor response to hyperthermia and/or radiation and support the concept that such combination studies should be undertaken clinically for the full potential of VTAs to be realized.

Garcinone E, a xanthone derivative, has potent cytotoxic effect against hepatocellular carcinoma cell lines.

Treatment of hepatocellular carcinomas (HCCs) with chemotherapy has generally been disappointing and it is most desirable to have more effective new drugs. We extracted and purified 6 xanthone compounds from the rinds (peel) of the fruits of Garcinia mangostana L., using partitioned chromatography and then tested the cytotoxic effects of these compounds on a panel of 14 different human cancer cell lines including 6 hepatoma cell lines, based on the MTT method. Several commonly used chemotherapeutic agents were included in the assay to determine the relative potency of the potential new drugs. Our results have shown that one of the xanthone derivatives which could be identified as garcinone E has potent cytotoxic effect on all HCC cell lines as well as on the other gastric and lung cancer cell lines included in the screen. We suggest that garcinone E may be potentially useful for the treatment of certain types of cancer.

Protective effects of demethylbellidifolin on myocardial ischemia-reperfusion injury in rats.

The effect of demethylbellidifolin (DMB), a major compound of Swertia davidi Franch, on ischemia-reperfusion injury was studied in rats. Ischemia-reperfusion injury in vivo and in vitro was induced by 20 min of global ischemia followed 40 min of reperfusion and 60 min of coronary artery occlusion followed 180 min of reperfusion, respectively. DMB (100 or 300 microg/L) significantly improved the recovery of cardiac function during reperfusion in isolated rat hearts, as shown by enhancement of coronary flow, left ventricular pressure and its first derivatives (+/-dp/dt(max)). DMB decreased the release of creatine kinase in coronary effluent as well as the level of malondialdehyde in myocardial tissues. In vivo, DMB (0.5 or 1.0 mg/kg) markedly decreased infarct size and the release of creatine kinase. These results suggest that DMB protects the myocardium against damage due to ischemia-reperfusion in rats. The present study also suggests that the effect of DMB may be related to inhibition of lipid peroxidation.

Potentiation of the anti-tumour effect of hyperthermia by combining with the vascular targeting agent 5,6-dimethylxanthenone-4-acetic acid.

The potential of the vascular targeting agent 5,6-dimethylxanthenone-4-acetic acid (DMXAA) to enhance the effect of hyperthermia was investigated in a C3H mouse mammary carcinoma grown in the feet of female CDF1 mice and in normal foot skin. DMXAA, when injected intraperitoneally in restrained non-anaesthetized animals, reduced tumour perfusion, as measured using the RbCl extraction procedure, and increased necrosis in histological section, but these effects were dependent on the drug dose and time interval. At a dose of 20 mg/kg, it significantly enhanced the thermal damage of this tumour, when given 1 h or more before the start of heating, as assessed by a tumour growth assay. This enhancement became larger with increasing interval between the two treatments. No thermo-potentiation was seen at doses of 10 mg/kg or lower. These combined effects seem to be associated with the tumour vascular shut-down by DMXAA. Thermal potentiation by DMXAA was also dependent on the heating temperature, with a greater enhancement relative to hyperthermia alone obtained at the lower temperatures at 40.5 and 41.5 degreesC than at the higher temperature of 42.5 degrees C. DMXAA (20 mg/kg) also enhanced the heat damage of normal skin, and this could not be explained by any DMXAA-induced TNF-alpha production. The heat enhancement-ratio by DMXAA was larger in tumours (1.9) than in normal skin (1.3-1.5), thus giving rise to a therapeutic gain.

Antidiabetic activity of a xanthone compound, mangiferin.

Mangiferin (MF) isolated from Anemarrhena asphodeloides Bunge rhizome, was tested for antidiabetic activity in KK-Ay mice, an animal model of type-2 diabetes. MF lowered the blood glucose level of KK-Ay mice 3 weeks after oral administration (p < 0.01). However, no effect on the blood glucose level in normal mice was seen, indicating that MF could be useful in treating type-2 diabetes. In addition, MF improved hyperinsulinemia and, on insulin tolerance test, reduced blood glucose levels of KK-Ay mice. From these findings, it seems likely that MF exerts its antidiabetic activity by decreasing insulin resistance.

The inhibitory effects of mangiferin, a naturally occurring glucosylxanthone, in bowel carcinogenesis of male F344 rats.

Mangiferin, 1,3,6,7-tetrahydroxyxanthone-C2-beta-D-glucoside, is one of xanthone derivatives and C-glucosylxanthones, is widely distributed in higher plants and is one of constituents of folk medicines. Recent studies showed that mangiferin has a potential as an anti-oxidant and an anti-viral agent. In this study, we examined the effects of mangiferin in rat colon carcinogenesis induced by chemical carcinogen, azoxymethane (AOM). We performed two experiments: a short-term assay to investigate the effects of mangiferin on the development of preneoplastic lesions by AOM, aberrant crypt foci (ACF), and the following long-term assay for the influence of mangiferin on tumorigenesis induced by AOM. In the short-term assay, 0.1% mangiferin in a diet significantly inhibited the ACF development in rats treated with AOM compared to rats treated with AOM alone (64.6+/-22.0 vs. 108.3+/-43.0). In the long-term assay, the group treated with 0.1% mangiferin in initiation phase of the experimental protocol had significantly lower incidence and multiplicity of intestinal neoplasms induced by AOM (47.3 and 41.8% reductions of the group treated with AOM alone for incidence and multiplicity, respectively). In addition, the cell proliferation in colonic mucosa was reduced in rats treated with mangiferin (65-85% reductions of the group treated with AOM alone). These results suggest that mangiferin has potential as a naturally-occurring chemopreventive agent.

Is St. John's wort (Hypericum perforatum) an effective antidepressant?

SJW is a remarkably safe antidepressant with an apparently unique mode of action. Although it has demonstrated efficacy in mild and moderate depression when compared with placebo or tricyclic antidepressants, several research areas beg to be explored. Its effects should be compared with serotonin reuptake inhibitors. Studies in severely depressed patients are lacking, as are studies on its utility as a therapeutic adjunct to standard antidepressants.

St. John's wort in mild to moderate depression: the relevance of hyperforin for the clinical efficacy.

In a randomized, double-blind, placebo-controlled, multicenter study, the clinical efficacy and safety of two different extracts of St. John's wort were investigated in 147 male and female outpatients suffering from mild or moderate depression according to DSM-IV criteria. Following a placebo run-in period of three to seven days, the patients were randomized to one of three treatment groups: During the 42-day treatment period, they received 3 x 1 tablets of either placebo, Hypericum extract WS 5573 (300 mg, with a content of 0.5% hyperforin), or Hypericum extract WS 5572 (300 mg, with a content of 5% hyperforin). The manufacturing process for the two Hypericum preparations was identical, so that they differed only in their hyperforin content. Efficacy regarding depressive symptoms was assessed on days 0, 7, 14, 28, and 42, using the Hamilton Rating Scale for Depression (HAMD, 17-item version) and the Depression Self-Rating Scale (D-S) according to von Zerssen. In addition, the severity of illness was also rated by the investigators on days 0 and 42 using the Clinical Global Impression (CGI) scale. The last observation of patients withdrawn from the trial prematurely was carried forward. At the end of the treatment period (day 42), the patients receiving WS 5572 (5% hyperforin) exhibited the largest HAMD reduction versus day 0 (10.3 +/- 4.6 points; mean +/- SD), followed by the WS 5573 group (0.5% hyperforin; HAMD reduction 8.5 +/- 6.1 points) and the placebo group (7.9 +/- 5.2 points). As regards the change in the HAMD total score between day 0 and treatment end and its relationship to the hyperforin dose, a significant monotonic trend was demonstrated in the Jonckheere-Terpstra test (p = 0.017). In pairwise comparisons, WS 5572 (5% hyperforin) was superior to placebo in alleviating depressive symptoms according to HAMD reduction (Mann-Whitney U-test: p = 0.004), whereas the clinical effects of WS 5573 (0.5% hyperforin) and placebo were descriptively comparable. These results show that the therapeutic effect of St. John's Wort in mild to moderate depression depends on its hyperforin content.

Over-the-counter psychotropics: a review of melatonin, St John's wort, valerian, and kava-kava.

Use and availability of alternative healthcare products have revived in the last few years. The prevalence of supplement use in the United States is largely unknown but is thought to be widespread. In this article, four of the common substances used to treat emotional problems are reviewed. The plant or substance description, clinical indications, evidence of therapeutic efficacy, mechanisms of therapeutic actions, dosages and regimens, different commercially available preparations, and adverse effects and toxicities are described for melatonin, St John's wort, valerian, and kava-kava. That a product is "natural" does not mean that it is either safe or effective. Many supplements are potent drugs that lack sufficient data on safety, dose-response relationships, drug interactions, and purity.

St. John's Wort (Hypericum perforatum): clinical effects on depression and other conditions.

St. John's Wort (Hypericum perforatum), a perennial flowering plant, has been used medicinally for thousands of years, and has most recently been identified as an effective treatment for mild to moderate depression. Clinical studies on the use of this plant for depression have utilized liquid tinctures and standardized solid extracts (0.3% hypericin--300 mg three times a day). Severe depression may also respond to this botanical, although it appears a larger dose is needed (600 mg solid extract three times a day). Hypericum has been favorably compared to numerous antidepressant drugs, the studies having revealed equivalent results and a much more favorable incidence of side effects. Studies have also demonstrated its efficacy in treating seasonal affective disorder. In vitro investigations of Hypericum show antiviral activity, although there is evidence these promising results might not occur in vivo. Traditional actions and uses include enhancement of wound healing, as well as anti-inflammatory and analgesic activity.