Simultaneous Determination of Seven Components in Gamboge and Its Processed Products Using a Single Reference Standard

Objective To establish a quality control method for simultaneous determination of multiple components in gamboge. Methods A single reference standard for the determination of multiple components （SSDMC） with HPLC was proposed. Seven major components of gamboge including gambogenic acid （S）, β-morellic acid （C1）, 2R-30-hydroxygambogic acid （C2）, isogambogenic acid （C3）, gambogellic acid （C4）, 2R-gambogic acid （C5）, and 2S-gambogic acid （C6） were simultaneously analyzed using gambogenic acid as reference standard. The credibility and feasibility of SSDMC method were validated with respect to linearity, limits of detection and quantification, precision, stability, repeatability, accuracy, ruggedness, and robustness. The relative conversion factors （RCFs） of S and C1-6 were calculated. Twelve batches of gamboge including crude and processed products were successfully analyzed by applying the SSDMC and traditional external standard （ES） methods. Results The SSDMC method was credible and feasible. The RCFs of S and C1-6 were 1.000, 0.913, 0.864, 1.064, 0.777, 0.921, and 0.919, respectively. No significant difference was observed in the contents of the seven components between SSDMC and ES methods. The heat-processing technique caused a reduction in the seven components. Conclusion SSDMC is a simple, reliable, and effective method for the analysis of the complex multiple components in gamboge, and it is also a practical and economical approach.

N-gamboyl Gemcitabine Inhibits Tumor Cells Proliferation and Migration

Gambogic acid(GA) is a natural substance with a good antitumor effect, but it is too lipophilic to be metabolized and excreted, thus accumulating in the body. Gemcitabine(GEM), one of the first-line antitumor drugs, has high hydrophilicity, which greatly shortens its half-life in vivo. We previously reported a compound named N-gamboyl gemcitabine(GAG), derived from the condensation of GEM and GA, whose hydrophilicity is better than GA and stability is better than GEM. Here, the antitumor performance of GAG was investigated for the first time by using several common tumor cell lines as tumor models. The results of in vitro study showed that GAG significantly inhibited the proliferation and migration of the tumor cells. The IC50 values of GAG for the tumor cells were lower than those of GEM and GA. The present study suggests that GAG has a promising potential to be developed into a broad-spectrum antitumor drug.

Gambogic Acid通过影响NF-κB信号通路诱导A549细胞凋亡

目的:研究Gambogic Acid(GA)对人非小细胞肺癌A549细胞系中NF-κB信号通路的影响及其对细胞凋亡的促进作用。方法:Western blot法和共聚焦显微镜成像技术检测GA对NF-κB的信号通路的影响,MTT及流式细胞(FCM)术检测GA对A549细胞的促凋亡作用。结果:Western blot发现GA能显著抵抗TNF-α诱导导致的IκB磷酸化水平上升及IκB的降解;共聚焦显微镜成像进一步发现GA有效阻止了NF-κB入核;MTT结果显示GA能显著抑制A549细胞的增殖,当药物浓度为5.0μmol/L时抑制率可达到(93.5±6.5)%(P<0.05),IC50值为1.2±0.4μmol/L;凋亡检测结果显示A549细胞在0.0、0.5、1.0、2.0、3.0及5.0μmol/L药物处理下细胞凋亡率分别是(6.0±0.7)%、(15.5±2.3)%、(35.0±3.6)%、(43.5±2.7)%、(43.0±3.8)%及(53.7±2.6)%(P<0.05);结论:实验表明,GA能有效地抑制A549细胞增殖和诱导其凋亡,其机制可能是通过影响NF-κB信号通路而发生作用。

Anticancer effect and apoptosis induction of gambogic acid in human gastric cancer line BGC-823

AIM: To investigate the anticancer effect of a traditional Chinese medicine gambogic acid (GA) in human gastric cancer line BGC-823 and further study the mechanism of apoptosis induction of GA.METHODS: Low differential human gastric cancer line BGC-823 were treated with GA at different doses and different times, the inhibitory rates were detected by MTT assay. Apoptosis induced by GA in BGC-823 cells was observed by Annexin-V/PI doubling staining flow cytometry assay. And T/C (%) was chosen to detect the inhibition of GA on human gastric adenocarcinoma BGC-823 nude mice xenografts. Apoptosis on nude mice xenografts was observed by Annexin-V/PI doubling staining flow cytometry assay and DNA fragmentation assay. To further determine the molecular mechanism of apoptosis induced by GA, the changes on the expression of bcl-2 and bax genes were detected by RT-PCR.RESULTS: After incubation with GA, low differential human gastric cancer line BGC-823 was dramatically inhibited in a dose-dependent manner. After these cells were exposedto GA for 24, 48 and 72 h, the IC50 value was 1.02±0.05, 1.41±0.20 and 1.14±0.19 μmol/L, respectively. Apoptosis in BGC-823 cells induced by GA was observed by AnnexinV/PI doubling staining flow cytometry assay. The apoptotic population of BGC-823 cells was about 12.96% and 24.58%, respectively, when cells were incubated with 1.2 μmol/L GA for 48 and 72 h. T/C (%) of human gastric carcinoma adenocarcinoma BGC-823 nude mice xenografts was 44.3, when the nude mice were treated with GA (8 mg/kg). Meanwhile, apoptosis induced by GA was observed in human gastric carcinoma adenocarcinoma BGC-823 nude mice xenografts. The increase of bax gene and the decrease of bc1-2 gene expressions were found by RT-PCR.CONCLUSION: The inhibition of GA on human gastric cancer line BGC-823 was confirmed. This effect connects with the inducing apoptosis in BGC-823 cells and the molecular mechanism might be related to the reduction of expression of apoptosis-regulated gene bcl-2, and the improvement of the expression of apoptosis-regulated gene bax. The result was also confirmed in vivo.

Gambogic acid induces mitochondria-dependent apoptosis by modulation of Bcl-2 and Bax in mantle cell lymphoma JeKo-1 cells

Objective： To study the mechanisms in gambogic acid （GA） -induced JeKo-1 human Mantle Cell Lymphoma cell apoptosis in vitro. Methods： The proliferation of GA-treated JeKo-1 cells was measured by CCK-8 assay and Ki-67 immunocytochemical detection. Apopt0sis, cell cycle and mitochondrial membrane potential were measured by flow cytometric analysis. Caspase-3, -8 and -9 were detected by colorimetric assay. Bcl-2 and Bax were analyzed by Western blotting. Results： GA inhibited cell growth in a time- and dose- dependent manner. GA induces apoptosis in JeKo- 1 cells but not in normal bone marrow cells, which was involved in reducing the membrane potential of mitochondria, activating caspases-3, -8 and -9 and decreasing the ratio of Bd-2 and Bax without cell cycle arresting. Conclusions： GA induced apoptosis in human MCL JeKo-1 cells by regulating Bcl-2/Bax and activating caspase-3, -8 and -9 via mitochondrial pathway without affecting cell cycle.

Effects of Gambogic Acid on the Regulation of Nucleoporin Nup88 in U937 Cells

In order to investigate the anti-leukemia effects of gambogic acid （GA） and its relation to the regulation of nucleoporin Nup88 in U937 cells in vitro, the inhibitory effect of GA on the growth of U937 cells was examined by using MTT assay. Apoptosis was detected by Annexin-V FITC/PI double-labeled cytometry. Cell cycle regulation was studied by propidium iodide method. Both flow cytometry （FCM） and RT-PCR were employed to assess the expression of Nup88, and the localization of Nup88 was determined by confocal microscopy. The results indicated that GA had strong inhibitory effect on cell proliferation and apoptosis induction activity in U937 cells in vitro in a time-and dose-dependent manner. The 24-h IC50 value was （1.019±0.134） mg/L. Moreover, GA induced arrest of U937 cells in G0/G1 phase. Over-expression of Nup88 was found in U937 cells, whereas GA could significantly down-regulate both the protein and mRNA levels of Nup88. Nup88 was diffusely distributed between nucleus and cytoplasm and was located at the cytoplasmic side of nuclear rim, and occasionally in cytoplasm. It is suggested that GA exerts its anti-leukemia effects by regulating the expression and distribution of nucleoporin Nup88. It promises to be new agent for the treatment of acute leukemia.

Effect of Gambogic Acid on the Regulation of hERG Channel in K562 Cells in vitro

Overexpression of human ether-h-go-go （eag） related gene （bERG） has been found in a broad range of human leukemia cell lines and primary human leukemia. The block of hERG protein might be a potential therapeutic strategy for leukemia. Gambogic acid （GA） has recently exhibited marked anti-tumor potency on solid tumors of various derivations. Here, we investigated the anti-leukemia effects of GA and its relation to the regulation of hERG in K562 leukemia cells in vitro. K562 cells were treated with various concentrations of GA （0.125-8.0 μmol/L） for 0-72 h. MTT assay was used to evaluate the inhibition effect of GA on the growth of K562 cells. Cell apoptosis was measured through both Annexin-V FITC/PI double-labeled cytometry and transmission electron microscopy. Cell cycle regulation was studied by a propidium iodide method. RT-PCR and Western blot were applied to detect the expression level of hERG in K562 cells. GA presented striking growth inhibition and apoptosis induction potency on K562 ceils in vitro in a time- and dose-dependent manner. The IC50 value of GA for 24 h was 2.637±0.208 μmol/L. Moreover, GA induced K562 cells arrested in G0/G1 phase, accordingly, cells in S phase decreased gradually, and no obvious changes were found in G2/M phase cells. Under the transmission electron microscopy, apoptotic bodies containing nuclear fragments were found in GA-treated K562 cells. After treatment with GA of 2.0 μmol/L for 24 h, the percentage of apoptotic cells was increased from 4.09% to 18.47% （P〈0.01）. Overexpression of hERG channel was found in K562 cells, while GA could down-regulate it at both protein and mRNA levels （P〈0.01）. It was concluded that GA exhibited its anti-leukemia effects partially through down-regulating the expression level of hERG channel in K562 cells, suggesting that GA may be a potential agent against leukemia with a mechanism of blocking hERG channel.

Gambogic acid induces apoptosis and inhibits colorectal tumor growth via mitochondrial pathways

AIM: To investigate the effect of gambogic acid(GA) on apoptosis in the HT-29 human colon cancer cell line. METHODS: H-29 cells were used for in vitro experiments in this study. Relative cell viability was assessed using MTT assays. Cell apoptosis was detected by terminal deoxynucleotidyl transferase d UTP nick end labeling and Hoechst 33342 staining, and quantified by flow cytometry. Cellular ultrastructure was observed by transmission electron microscopy. Real-time PCR and Western blot analyses were used to evaluate gene and protein expression levels. For in vivo experiments, BALB/c nude mice received subcutaneous injections of HT-29 cells in the right armpit. When well-established xenografts were palpable with a tumor size of 75 mm3, mice were randomly assigned to a vehicle(negative) control, positive control or GA treatment group(n = 6 each). The animals in the treatment group received one of three dosages of GA(in saline; 5, 10 or 20 mg/kg) via the caudal vein twice weekly, whereas animals in the negative and positive control groups were given equal volumes of 0.9% saline or 10 mg/kg docetaxel, respectively, via the caudal vein once weekly. RESULTS: The cell viability assay showed that GA inhibited proliferation of HT-29 cells in a dose- and time-dependent manner after treatment with GA(0.00, 0.31, 0.62, 1.25, 2.50, 5.00 or 10.00 μmol/L) for 24, 48 or 72 h. After 48 h, the percentage of apoptotic cells in cells treated with 0.00, 1.25, 2.50 and 5.00 μmol/L GA was 1.4% ± 0.3%, 9.8% ± 1.2%, 25.7% ± 3.3% and 49.3% ± 5.8%, respectively. Ultrastructural analysis of HT-29 cells treated for 48 h with 2.5μmol/L GA revealed apoptotic bodies and condensed and fragmented nuclei. Levels of caspase-8,-9 and-3 m RNAs were significantly increased after treatment with GA(1.25, 2.50 or 5.00 μmol/L) for 48 h(P < 0.05 for all). Protein levels of apoptosis-related factors Fas, Fas L, FADD, cytochrome c, and Apaf-1 were increased in GA-treated cells, whereas levels of pro-caspase-8,-9 and-3 were significantly decreased(P < 0.05 for all). Furthermore, GA significantly and dose-dependently inhibited the growth of HT-29 tumors in a mouse xenograft model(P < 0.05).CONCLUSION: GA inhibits HT-29 proliferation via induction of apoptosis. The anti-cancer effects are likely mediated by death receptor(extrinsic) and mitochondrial(intrinsic) pathways.

Synthesis and antitumor activities of structure-related small molecular compounds of gambogic acid

Through simplifying the complicated skeleton of the natural product gambogic acid, two series derivatives of chromone and xanthone were synthesized and examined for their antitumor activities against several cancer cells in vitro by MTT method. The results showed that appropriate introduction of prenyl group to the small molecular compounds could elevate their antitumor activities. The structure–activities relationship of synthesized compounds certified that the bridgecore in gambogic acid was very important for keeping its antitumor activities.

Effects of Gambogic Acid on Regulation of Steroid Receptor Coactivator-3 in Lung Adenocarcinoma A549 Cells

Objective： To investigate the effects of gambogic acid （GA） on the proliferation and apoptosis of Human lung adenocarcinoma A549 cells in vitro, as well as the regulation of steroid receptor coactivator-3 （SRC-3） to explore the relationship between them. Methods： The effect of GA on the growth of A549 cells was studied by MTT assay. Apoptosis was detected through Hoechst 33258 staining. RT-PCR and Western blot technologies were applied to assess the expression of SRC-3, whereas, the localization of SRC-3 was determined by using confocal microscopy method. Results： GA presented striking proliferation inhibition potency on A549 cells in vitro in a time- and dose-dependent manner, with the IC50 value for 24 h was 3.17±0.13 μmol/L. Hoechst 33258 staining showed that GA could induce apoptosis in A549 cells. Over-expression of SRC-3 was found in A549 cells, whereas the mRNA and protein expression levels of SRC-3 were significantly downregulated in A549 cells induced by GA in a dose-dependent manner. The disposition of SRC-3 was situated mainly at the nuclear. Conclusion： GA may exert its strong anti-leukemia effects through the regulation of the expression of SRC-3. It may be a new target for the therapy of lung cancer.

Gold nanostructures for anticancer drug delivery

OBJECTIVE Nanotechnology provides a novel strategy for the delivery of anticancer drugs.METHODS Titanium dioxide coated gold nanostructures(Au/TiO2)was used as the drug carrier for the natural anticancer drug gambogic acid in order to improve its anticancer effect.Biocompatibility and cellular uptake of Au/TiO2 was studied in human glio⁃blastoma U-87 MG cells.Cell viability was evaluated by ATP assay and calcein AM staining.LysoSensor Green DND-189 and Hoechst 33342 were used to analyze the intracellular location of Au/TiO2.The anticancer effect of gambogic acid loaded nanoparticles was compared with free drug.RESULTS Au/TiO2 was biocompatible,and they were localized at the intracellular acidic compartments of endosomes and lysosomes.The intracellular drug content delivered via Au/TiO2 was 6-fold higher than the free form,thus dramatically enhancing the anticancer effect of gambogic acid.Furthermore,mild photothermal therapy also showed synergistic effect with the drug.CONCLUSION Au/TiO2 is a promising anticancer drug carrier.

Enhanced anti-cancer effect of gambogic acid by gold nanorod-based delivery

OBJECTIVE Nanotechnology provides a novel strategy for the delivery of anticancer drugs.In this study,titanium dioxide coated gold nanorod(GNR/TiO_2) nanostructures were used as the drug carrier for gambogic acid in order to improve its anticancer effect.METHODS Biocompatibility and cellular uptake of GNR/TiO_2 nanostructures were studied in human glioblastoma U-87 MG cells.Cell viability was evaluated by ATP assay and calcein AM staining.Lyso Sensor Green DND-189 and Hoechst 33342 were used to analyze the intracellular location of GNR/TiO_2 nanostructures.The in vitro anti-cancer effect of gambogic acid loaded nanoparticles was compared with free drug.RESULTS The results showed that GNR/TiO_2 nanostructures are biocompatible,and they are localized at the intracellular acidic compartments of endosomes and lysosomes.The intracellular drug content delivered via GNR/TiO_2 nanostructures was 6 fold higher than the free form,thus dramatically enhancing the anticancer effect of gambogic acid.Furthermore,mild photothermal therapy also showed synergistic effect with the drug.CONCLUSION Our study suggested that GNR/TiO_2 nanostructures can be considered as a promising anticancer drug carrier.

Gold nanorods for gambogicacid intracellular delivery

OBJECTIVE To improve the anticancer drug gambogic acid’s effect by using titanium dioxide coated gold nanorods(GNR/Ti O2)as a drug carrier.METHODS Biocompatibility and cellular uptake of GNR/Ti O2was studied in human glioblastoma U-87 MG cells.Cel viability was evaluated by ATP assay and calcein AM staining.Lyso SensorTMGreen DND-189 and Hoechst 33342 were used to analyze the intracellular location of GNR/Ti O2.The in vitro anticancer effect of gambogic acid loaded nanoparticles was compared with free drug.RESULTS The results showed that GNR/Ti O2is biocompatible,andthey are localized at the intracellular acidic compartments of endosomes and lysosomes.The intracellular drug content delivered via GNR/Ti O2was 6 fold higher than the free form,thus dramatically enhancing the anticancer effect of gambogic acid.Furthermore,mild photothermal therapy also showed synergistic effect with the drug.CONCLUSION Our study suggested that GNR/Ti O2is a promising anticancer drug carrier。

Multifunctional nano-herb based on tumor microenvironment for enhanced tumor therapy of gambogic acid

Multifunctional drug delivery systems(DDSs)have shown great prospects in overcoming the heterogeneous barrier of delivery drugs to the complex tumor microenvironment(TME).In this study,multifunctional AS/Ge-pNAB microgels with dual-active targeting,triple environment responsiveness,and fluorescence imaging capability were prepared through a straightforward procedure.This was aimed to improve the antitumor therapeutic application of gambogic acid(GA)based on the biological characteristics of TME.The microgels have a uniform double-layer structure with aptamer in the outer layer which helps in recognizing receptors on the tumor cells.The GA loaded nano-herb exhibited environment-responsive drug release profiles under acidic pH,reductant and high temperature.The nano-herb significantly improved the accumulation of GA in tumor sites through the synergistic combination of the enhanced permeability and retention effect and dual-ligand mediated internalization.Then,it accelerated intracellular drug release and killed tumor cells.Therefore,the nano-herb had specific therapeutic effects on the tumor in vitro and in vivo as they remarkably inhibited tumor growth while depicting optimal biosafety and lower levels of off-target toxicity.Overall,these findings demonstrate the great potential of the multifunctional AS/Ge-pNAB microgels for precisely targeted GA delivery and open a new avenue for the facile preparation of multifunctional DDSs.

Erythrocyte membrane encapsulated gambogic acid nanoparticles as a therapeutic for hepatocellular carcinoma

Gambogic acid(GA)is a potential clinical anticancer drug that can exert antitumor effects via various molecular mechanisms.Notwithstanding,GA’s low water solubility,poor stability,short half-life,and unavoidable toxic side effects have significantly hampered its clinical application.Erythrocyte membranecoated nanoparticles(RBCM-NPs)improve drug’s physicochemical properties,biocompatibility,and pharmacokinetic behaviors,allowing for long-term drug circulation and passive targeting.In this study,a novel biomimetic drug delivery system(DDS)against hepatocellular carcinoma was prepared by covering RBCM on GPP-NPs(GA-loaded m PEG-PLA NPs)to develop the RBC@GPP-NPs.In comparison to RBCM-free nanoparticles and free GA,RBC@GPP-NPs improved the drug’s water solubility,stability,safety,and antitumor activity in vivo.We expect that this bionic nanoparticle composite can expand the clinical applicability of GA and provide a feasible solution for the research and development of GA’s nano-formulation.

An open-labeled, randomized, multicenter phase Ⅱa study of gambogic acid injection for advanced malignant tumors

Background Gambogic acid is a pure active compound isolated from the traditional Chinese medicinal plant gamboge （Garcinia morella Desv.）. Based on the preliminary results of a phase I study, this phase Ila study compared the efficacy and safety of different dosage schedules of gambogic acid in patients with advanced malignant tumors. Methods Patients with advanced or metastases cancer who had not received any effective routine conventional treatment or who had failed to respond to the existing conventional treatment were randomly assigned to receive either 45 mg/m2 gambogic acid intravenously from Days 1 to 5 of a 2-week cycle （Group A）, or 45 mg/m2 every other day for a total of five times during a 2-week cycle （Group B）. The primary endpoint was objective response rate （ORR）. Results Twenty-one patients assigned to Group A and 26 to Group B were included in the final analysis. The ORRs were 14.3% in Group A and 0% in Group B. It was not possible to analyze the significant difference because one of the values was zero. The disease control rates （DCRs） were 76.2% in Group A and 61.5% in Group B （P=0.0456）. The observed adverse reactions were mostly Grades I and II, and occurred in most patients after administration of the trial drug. There was no significant difference in the incidence of adverse reactions between the two arms. Conclusions The preliminary results of this phase Ila exploratory study suggest that gambogic acid has a favorable safety profile when administered at 45 mg/m2. The DCR was greater in patients receiving gambogic acid on Days 1-5 of a 2-week cycle, but the incidence of adverse reactions was similar irrespective of the administration schedule.

Proteomic and bioinformatic analyses of possible targetrelated proteins of gambogic acid in human breast carcinoma MDA-MB-231 cells

Gambogic acid （GA） is an anticancer agent in phase IIb clinical trial in China but its mechanism of action has not been fully clarified. The present study was designed to search the possible target-related proteins of GA in cancer cells using proteomic method and establish possible network using bioinformatic analysis. Cytotoxicity and anti-migration effects of GA in MDA-MB-231 cells were checked using MTT assay, flow cytometry, wound migration assay, and chamber migration assay. Possible target-related proteins of GA at early （3 h） and late stage （24 h） of treatment were searched using a proteomic technology, two-dimensional electro- phoresis （2-DE）. The possible network of GA was established using bioinformatic analysis. The intracellular expression levels of vimentin, keratin 18, and calumenin were determined using Western blotting. GA inhibited cell proliferation and induced cell cycle arrest at G2/M phase and apoptosis in MDA-MB-231 cells. Additionally, GA exhibited anti-migration effects at non-toxic doses. In 2-DE analysis, totally 23 possible GA targeted proteins were found, including those with functions in cytoskeleton and transport, regulation of redox state, metabolism, ubiquitin-proteasome system, transcription and translation, protein transport and modification, and cytokine. Network analysis of these proteins suggested that cytoskeleton-related proteins might play important roles in the effects of GA. Results of Western blotting confirmed the cleavage of vimentin, increase in keratin 18, and decrease in calumenin levels in GA-treated cells. In summary, GA is a multi-target compound and its anti-cancer effects may be based on several target-related pro- teins such as cytoskeleton-related proteins.

Gambogic acid induces cell apoptosis through endoplasmic reticulum stress triggered inhibition of Akt signaling pathways in extranodal NK/T-cell lymphoma cells

As the chemotherapeutic resistance of extranodal NK/T-cell lymphoma(ENKTL) rises year by year, searching for novel chemoprevention compounds has become imminent. Gambogic acid(GA) has recently been shown to have anti-tumor effects, but its role and underling mechanism in ENKTL are rather elusive. In the present study, we showed that GA inhibited the cell growth and potently induced the apoptosis of ENKTL cells in vitro in a time-and concentration-dependent manner. Furthermore, GA induced cell death through endoplasmic reticulum stress(ERS) mediated suppression of Akt signaling pathways and finally the release of the caspase-3 proteases. Overall, our data provided evidences supporting GA as a potential therapeutic agent for ENKTL, which may facilitate further preclinical development of anti-tumor drugs.

Nanoscale covalent organic framework for the low-temperature treatment of tumor growth and lung metastasis

Photothermal therapy(PTT)has shown promising applications in tumor therapies.However,due to laserinduced nonspecific heating and heat diffusion,high levels of hyperthermia(>50℃)in tumor tissues often increase the risk of cancer recurrence and metastasis,which causes the patient pain and destroys the surrounding normal cells and tissues.It is therefore important to develop photothermal strategies that have excellent therapeutic efficiencies under low-temperature conditions(≤45℃).In addition,the heterogeneity and complexity of tumors require the development of combinatorial antitumor treatments as the therapeutic efficiency of monomodal PTT is not currently sufficient.Herein,we have adopted a stepwise synthetic approach to develop a highly efficient multimodal therapeutic agent GA@PCOF@PDA by successive bonding defect functionalization(BDF),guest encapsulation,and surface modification steps.The covalently grafted porphyrinic photosensitizers(Por),encapsulated gambogic acid(GA),and surface-modified PDA film are independently responsible for photodynamic therapy(PDT),heat-shock protein 90(HSP90)down-regulation and chemotherapy(CT),and low-temperature PTT.This proof-ofconcept study illustrates an efficient,generalized approach to design high-performance covalent organic framework(COF)-based nanoagents that can be easily tailored to combine different therapeutic modalities for improved cancer theranostics at low temperatures.

Synthesis and Anti-tumor Evaluation of Novel C-37 Modified Derivatives of Gambogic Acid

Gambogic acid （GA, 1）, the most prominent representative of Garcinia natural products, has been reported to be a promising anti-tumor agent. In order to further explore the structure-activity relationship of GA and discover novel GA derivatives as anti-tumor agents, 17 novel C-37 modified derivatives of GA were synthesized and evaluated for their in vitro anti-tumor activities against A549, HCT-116, BGC-823, HepG2 and MCF-7 cancer cell lines. Among them, 11 compounds were found to be more potent than GA against some cancer cell lines. Notably, com- pound 8 was almost 5--10 folds more active than GA against A549 and BGC-823 cell lines with the IC50 values of 0.12 μmol·L^-1 and 0.57 μmol·L^-1, respectively. Chemical modification at C-37 position of GA by introducing of hydrophilic amines could lead to increased activity and improved drug-like properties. These findings will enhance our understanding of the structure-activity relationship （SAR） of GA and lead to the discovery of novel GA derivatives as potential anti-tumor agents.