Di-indenopyridines as topoisomerase II-selective anticancer agents: Design, synthesis, and structure-activity relationships.

Topoisomerases are key molecular enzymes responsible for altering DNA topology, thus they have long been considered as attractive targets for novel chemotherapeutic agents. Topoisomerase type II (Topo II) catalytic inhibitors embrace a fresh perspective meant to get beyond drawbacks caused by topo II poisons, such as cardiotoxicity and secondary malignancies. Based on previously reported 5H-indeno[1,2-b]pyridines, here we presented new twenty-three hybrid di-indenopyridines along with their topo I/IIα inhibitory and antiproliferative activity. Most of the prepared 11-phenyl-diindenopyridines showed negligible topo I inhibitory activity, showing selectivity over topo II. Among the series, we finally selected compound 17, which displayed 100 % topo IIα inhibition at 20 µM concentration and comparable antiproliferative activity against the tested cell lines. Through competitive EtBr displacement assay, cleavable complex assay, and comet assay, compound 17 was finally determined as a non-intercalative catalytic topo IIα inhibitor. The findings in this study highlight the significance of phenolic, halophenyl, thienyl, and furyl groups at the 4-position of the indane ring in the design and synthesis of di-indenopyridines as potent catalytic topo IIα inhibitors with remarkable anticancer effects.

Chemical inhibition of TRAF6-TAK1 axis as therapeutic strategy of endotoxin-induced liver disease.

The liver is exposed to gut-derived bacterial endotoxin via portal circulation, and recognizes it through toll-like receptor 4 (TLR4). Endotoxin lipopolysaccharide (LPS) stimulates the self-ubiquitination of ubiquitin ligase TRAF6, which is linked to scaffold with protein kinase TAK1 for auto-phosphorylation and subsequent activation. TAK1 activity is a signal transducer in the activating pathways of transcription factors NF-κB and AP-1 for production of various cytokines. Here, we hypothesized that TRAF6-TAK1 axis would be implicated in endotoxin-induced liver disease. Following exposure to endotoxin LPS, TLR4-mediated phosphorylation of TAK1 and transcription of cell-death cytokine TNF-α were triggered in Kupffer cells but not in hepatocytes as well as TNF receptor-mediated and caspase-3-executed apoptosis was occurred in D-galactosamine (GalN)-sensitized hepatocytes under co-culture with Kupffer cells. Treatment with pyridinylmethylene benzothiophene (PMBT) improved endotoxin LPS-induced hepatocyte apoptosis in GalN-sensitized C57BL/6 mice via suppressing NF-κB- and AP-1-regulated expression of TNF-α in Kupffer cells, and rescued the mice from hepatic damage-associated bleeding and death. As a mechanism, PMBT directly inhibited Lys 63-linked ubiquitination of TRAF6, and mitigated scaffold assembly between TRAF6 and the TAK1-activator adaptors TAB1 and TAB2 complex in Kupffer cells. Thereby, PMBT interrupted TRAF6 ubiquitination-induced activation of TAK1 activity in the TLR4-mediated signal cascade leading to TNF-α production. However, PMBT did not directly affect the apoptotic activity of TNF-α on GalN-sensitized hepatocytes. Finally, we propose chemical inhibition of TRAF6-TAK1 axis in Kupffer cells as a strategy for treating liver disease due to gut-derived endotoxin or Gram-negative bacterial infection.

Potent inhibitory activity of hydroxylated 2-benzylidene-3,4-dihydronaphthalen-1(2H)-ones on LPS-stimulated reactive oxygen species production in RAW 264.7 macrophages.

This study attempted to discover tetralone-derived potent ROS inhibitors by synthesizing sixty-six hydroxylated and halogenated 2-benzylidene-3,4-dihydronaphthalen-1(2H)-ones via Claisen-Schmidt condensation reaction. The majority of the synthesized and investigated compounds significantly inhibited ROS in LPS-stimulated RAW 264.7 macrophages. When compared to malvidin (IC50 = 9.00 µM), compound 28 (IC50 = 0.18 µM) possessing 6­hydroxyl and 2­trifluoromethylphenyl moiety showed the most potent ROS inhibition. In addition, the compounds 20, 31, 39, 45, 47-48, 52, 55-56, 58-60, and 62 also displayed ten folds greater ROS inhibitory activity relative to the reference compound. Based on the structure-activity relationship study, incorporating hydroxyl groups at the 6- and 7-positions of tetralone scaffold along with different halogen functionalities in phenyl ring B is crucial for potent ROS suppression. This study contributes to a better understanding of the effect of halogen and phenolic groups in ROS suppression, and further investigations on 2-benzylidene-3,4-dihydronaphthalen-1(2H)-ones will potentially lead to the discovery of effective anti-inflammatory agents.

Topoisomerase IIα inhibitory and antiproliferative activity of dihydroxylated 2,6-diphenyl-4-fluorophenylpyridines: Design, synthesis, and structure-activity relationships.

A new series of fifty-four 2-phenol-4-aryl-6-hydroxyphenylpyridines containing fluorophenyl, trifluoromethylphenyl, and trifluoromethoxy phenyl groups were synthesized and tested for topoisomerase IIα inhibitory and antiproliferative activity against different cancer cell lines in an attempt to look into topoisomerase IIα-targeted prospective anticancer agents to counter the limitations of available treatment options. When compared to positive controls, several compounds 11-12, 37, 50, and 51 showed high antiproliferative activity, while several 4-fluorophenyl substituted compounds 13-14 and 18 showed strong topoisomerase IIα inhibition. Surprisingly, most of the compounds had a significant antiproliferative effect on the HCT15 colorectal adenocarcinoma and T47D breast cancer cell lines. Moreover, compound 12 with para-fluorophenyl at the 4-position and meta-phenolic groups at the 2- and 6-positions inhibited proliferating HeLa cervix adenocarcinoma cells with an IC50 value of 1.28 µM. Based on biological results, the structure-activity relationships of the synthesized derivatives emphasized the significance of 4-trifluoromethoxyphenyl groups for strong antiproliferative activity and 4-fluorophenyl groups for strong topo IIα inhibition. Furthermore, meta- and para-phenolic groups at the 2- and 4-positions are favorable for strong topo IIα inhibitory and antiproliferative activity. The research findings provide insight into the effect of different fluorine functionalities in the discovery of novel topoisomerase IIα-targeted anticancer agents.

Identification of new halogen-containing 2,4-diphenyl indenopyridin-5-one derivative as a boosting agent for the anticancer responses of clinically available topoisomerase inhibitors.

Based on previous reports on the significance of halogen moieties and the indenopyridin-5-one skeleton, we designed and synthesized a novel series of halogen (F-, Cl-, Br-, CF3- and OCF3-)-containing 2,4-diphenyl indenopyridin-5-ones and their corresponding -5-ols. Unlike indenopyridin-5-ols, most of the prepared indenopyridin-5-ones with Cl-, Br-, and CF3- groups at the 2-phenyl ring conferred a strong dual topoisomerase I/IIα inhibitory effect. Among the series, para-bromophenyl substituted compound 9 exhibited the most potent topoisomerase inhibition and antiproliferative effects, which showed dependency upon the topoisomerase gene expression level of diverse cancer cells. In particular, as a DNA minor groove-binding non-intercalative topoisomerase I/IIα catalytic inhibitor, compound 9 synergistically promoted the anticancer efficacy of clinically applied topoisomerase I/IIα poisons both in vitro and in vivo, having the great advantage of alleviating poison-related toxicities.

AK-I-190, a New Catalytic Inhibitor of Topoisomerase II with Anti-Proliferative and Pro-Apoptotic Activity on Androgen-Negative Prostate Cancer Cells.

Castration-resistant prostate cancer (CRPC) is a clinical challenge in treatment because of its aggressive nature and resistance to androgen deprivation therapy. Topoisomerase II catalytic inhibitors have been suggested as a strategy to overcome these issues. We previously reported AK-I-190 as a novel topoisomerase II inhibitor. In this study, the mechanism of AK-I-190 was clarified using various types of spectroscopic and biological evaluations. AK-I-190 showed potent topoisomerase II inhibitory activity through intercalating into DNA without stabilizing the DNA-enzyme cleavage complex, resulting in significantly less DNA toxicity than etoposide, a clinically used topoisomerase II poison. AK-I-190 induced G1 arrest and effectively inhibited cell proliferation and colony formation in combination with paclitaxel in an androgen receptor-negative CRPC cell line. Our results confirmed that topoisomerase II catalytic inhibition inhibited proliferation and induced apoptosis of AR-independently growing prostate cancer cells. These findings indicate the clinical relevance of topoisomerase II catalytic inhibitors in androgen receptor-negative prostate cancer.

Discovery of a 2,4-diphenyl-5,6-dihydrobenzo(h)quinolin-8-amine derivative as a novel DNA intercalating topoisomerase IIα poison.

Several anticancer agents have been developed and innovative approaches have been made toward cancer type-specific medicines for cancer treatment. As a continuous effort to develop potential chemotherapeutic agents, a novel series of 2,4-diphenyl-5,6-dihydrobenzo(h)quinolin-8-amines containing amino groups, hydroxyphenyl and fluorine functionalities were designed and synthesized. The compounds were evaluated for topo IIα inhibitory and cytotoxicity against HCT15, and HeLa human cancer cell lines. Among synthesized thirty compounds, the majority exhibited strong topo IIα inhibition and anti-proliferation against HCT15 colorectal adenocarcinoma cell line. The structure-activity relationship study revealed that compounds with -CF3 and -OCF3 substituents at 4- position and 3' or 4'-hydroxyphenyl at 2-position attached to the central pyridine ring displayed potent topo IIα and anti-proliferative activity in colorectal and cervix cancer cell line. In vitro studies provided the evidence that compounds 16, 19, 22, and 28 possess excellent topo IIα inhibition and antiproliferative activity. For a better understanding, topo IIα cleavage complex, EtBr displacement, KI quenching assays and molecular docking of compound 19 was performed and the results revealed the mode of action as a DNA intercalative topo IIα poison inhibitor. The results obtained from this study provide insight into the DNA binding mechanism of 2,4-diphenyl-5,6-dihydrobenzo(h)quinolin-8-amines and alteration in topo IIα inhibitory and antiproliferative activity with modifications in the rigid structure.

4-Flourophenyl-substituted 5H-indeno[1,2-b]pyridinols with enhanced topoisomerase IIα inhibitory activity: Synthesis, biological evaluation, and structure-activity relationships.

A series of fluorinated and hydroxylated 2,4-diphenyl indenopyridinols were designed and synthesized using l-proline-catalyzed and microwave-assisted synthetic methods for the development of new anticancer agents. Adriamycin and etoposide were used as reference compounds for the evaluation of topo IIα inhibitory and anti-proliferative activity of the synthesized compounds. Exploring the structure-activity relationships of 36 prepared compounds and biological results, most of the compounds with ortho- and para-fluorophenyl at 4-position of indenopyridinol ring displayed strong topo IIα inhibition. In addition, the majority of the ortho- and meta-fluorophenyl substituted compounds 1-24 displayed strong anti-proliferative activity against DU145 prostate cancer cell line compared to the positive controls. Interestingly, compound 4 possessing ortho-phenolic and ortho-fluorophenyl group at 2- and 4-position, respectively of the central pyridine ring showed high anti-proliferative activity (IC50 = 0.82 µM) against T47D human breast cancer cell line, while para-phenolic and para-fluorophenyl substituted compound 36 exhibited potent topo IIα inhibitory activity with 94.7% and 88.6% inhibition at 100 µM and 20 µM concentration, respectively. A systematic comparison between the results of this study and the previous study indicated that minor changes in the position of functional groups in the structure affect the topo IIα inhibitory activity and anti-proliferative activity of the compounds. The findings from this study will provide valuable information to the researchers working on the medicinal chemistry of topoisomerase IIα-targeted anticancer agents.

Anticancer Activity of Indeno[1,2-b]-Pyridinol Derivative as a New DNA Minor Groove Binding Catalytic Inhibitor of Topoisomerase IIα.

Topoisomerase IIα has been a representative anti-cancer target for decades thanks to its functional necessity in highly proliferative cancer cells. As type of topoisomerase IIα targeting drugs, topoisomerase II poisons are frequently in clinical usage. However, topoisomerase II poisons result in crucial consequences resulted from mechanistically induced DNA toxicity. For this reason, it is needed to develop catalytic inhibitors of topoisomerase IIα through the alternative mechanism of enzymatic regulation. As a catalytic inhibitor of topoisomerase IIα, AK-I-191 was previously reported for its enzyme inhibitory activity. In this study, we clarified the mechanism of AK-I-191 and conducted various types of spectroscopic and biological evaluations for deeper understanding of its mechanism of action. Conclusively, AK-I-191 represented potent topoisomerase IIα inhibitory activity through binding to minor groove of DNA double helix and showed synergistic effects with tamoxifen in antiproliferative activity.

Synthesis and structure-activity relationships of hydroxylated and halogenated 2,4-diaryl benzofuro[3,2-b]pyridin-7-ols as selective topoisomerase IIα inhibitors.

The objective of this study was to discover potential topoisomerase (topo) targeting anticancer agents. Novel series of hydroxylated and halogenated(-F, -Cl, and -CF3) 2,4-diaryl benzofuro[3,2-b]pyridin-7-ols were systematically designed and synthesized by faster, economic, and environmentally friendly l-proline catalyzed and microwave-assisted one pot reaction method. The synthesized compounds were assessed for topo I and IIα inhibitory and anti-proliferative activities. The in vitroevaluation displayed that most of the compounds have selective topo IIα inhibitoryactivity as well as selectivity towards T47D human cancer cell line. Structure-activity relationship study suggested that the introduction of additional hydroxyl functionality at 7-positon of benzofuro[3,2-b]pyridine skeleton is crucial for selective topo IIα inhibitory activity. Placement of phenolic moiety on the 4-position of the tricyclic system imparts better topo IIα inhibitory and anti-proliferative activity.

Kikuchi Disease Manifesting as Multifocal Lymphadenopathy and Splenomegaly: Ultrasonography, CT, and 18F-FDG PET/CT Findings Mimicking Lymphoma.

Kikuchi disease is a type of benign, self-limiting necrotizing lymphadenitis that occurs most commonly in young women and usually manifests as palpable cervical lymph nodes and fever. Patients with an unusual location of lymph node involvement can be misdiagnosed with malignant disease. Here, we report a case of Kikuchi disease in a 15-year-old girl presenting with persistent fever for 2 weeks. Imaging studies, including ultrasonography, CT, and 18F-fluorodeoxyglucose PET/CT, revealed splenomegaly and enlarged lymph nodes in the neck, axilla, abdomen, retroperitoneum, and inguinal region. Laparoscopic excision of the celiac lymph nodes confirmed histiocytic necrotizing lymphadenitis, also known as Kikuchi disease. Conservative treatment with corticosteroids improved the patient's condition.

Assessing Drug Interaction and Pharmacokinetics of Loxoprofen in Mice Treated with CYP3A Modulators.

Loxoprofen (LOX) is a non-selective cyclooxygenase inhibitor that is widely used for the treatment of pain and inflammation caused by chronic and transitory conditions. Its alcoholic metabolites are formed by carbonyl reductase (CR) and they consist of trans-LOX, which is active, and cis-LOX, which is inactive. In addition, LOX can also be converted into an inactive hydroxylated metabolite (OH-LOXs) by cytochrome P450 (CYP). In a previous study, we reported that CYP3A4 is primarily responsible for the formation of OH-LOX in human liver microsomes. Although metabolism by CYP3A4 does not produce active metabolites, it can affect the conversion of LOX into trans-/cis-LOX, since CYP3A4 activity modulates the substrate LOX concentration. Although the pharmacokinetics (PK) and metabolism of LOX have been well defined, its CYP-related interactions have not been fully characterized. Therefore, we investigated the metabolism of LOX after pretreatment with dexamethasone (DEX) and ketoconazole (KTC), which induce and inhibit the activities of CYP3A, respectively. We monitored their effects on the PK parameters of LOX, cis-LOX, and trans-LOX in mice, and demonstrated that their PK parameters significantly changed in the presence of DEX or KTC pretreatment. Specifically, DEX significantly decreased the concentration of the LOX active metabolite formed by CR, which corresponded to an increased concentration of OH-LOX formed by CYP3A4. The opposite result occurred with KTC (a CYP3A inhibitor) pretreatment. Thus, we conclude that concomitant use of LOX with CYP3A modulators may lead to drug-drug interactions and result in minor to severe toxicity even though there is no direct change in the metabolic pathway that forms the LOX active metabolite.

Discovery and Biological Evaluations of Halogenated 2,4-Diphenyl Indeno[1,2-b]pyridinol Derivatives as Potent Topoisomerase IIα-Targeted Chemotherapeutic Agents for Breast Cancer.

With the aim of developing new effective topoisomerase IIα-targeted anticancer agents, we synthesized a series of hydroxy- and halogenated 2,4-diphenyl indeno[1,2-b]pyridinols using a microwave-assisted single step synthetic method and investigated structure-activity relationships. The majority of compounds with chlorophenyl group at 2-position and phenol group at the 4-position of indeno[1,2-b]pyridinols exhibited potent antiproliferative activity and topoisomerase IIα-selective inhibition. Of the 172 compounds tested, 89 showed highly potent and selective topoisomerase IIα inhibition and antiproliferative activity in the nanomolar range against human T47D breast (2.6 nM) cancer cell lines. In addition, mechanistic studies revealed compound 89 is a nonintercalative topoisomerase II poison, and in vitro studies showed it had promising cytotoxic effects in diverse breast cancer cell lines and was particularly effective at inducing apoptosis in T47D cells. Furthermore, in vivo administration of compound 89 had significant antitumor effects in orthotopic mouse model of breast cancer.

Identification of sulfonyl-loxoprofen as novel phase 2 conjugate in rat.

Loxoprofen is a prodrug that exerts strong analgesic and anti-inflammatory effects through its active trans-alcohol metabolite, which is produced in the liver by carbonyl reductase. Previous metabolic studies have evaluated loxoprofen, but its sulfate and taurine conjugates have not yet been studied. We characterized the metabolomic profile of loxoprofen in rat plasma, urine, and feces using high-resolution mass spectrometry. We identified 17 metabolites of loxoprofen in the three different biological matrices, 13 of which were detected in plasma and feces and 16 in urine. Amongst these metabolites, two novel taurine conjugates (M12 and M13) and two novel acyl glucuronides (M14, M15) were identified for the first time in rats. In addition, we detected three novel sulfate conjugates (M9, M10, and M11) of loxoprofen. Further study of these metabolites of loxoprofen is essential in order to assess their potency and toxicity.

Introduction of amino moiety enhances the inhibitory potency of 1-tetralone chalcone derivatives against LPS-stimulated reactive oxygen species production in RAW 264.7 macrophages.

The design and synthesis of a series of thirty-two halogenated 1-tetralone or 6-amino-1-tetralone chalcone derivatives was achieved by the Claisen-Schmidt condensation reaction and were evaluated for their inhibitory effects against ROS production in LPS-stimulated RAW 264.7 macrophages. It was observed that the introduction of amino moiety into 1-tetralone skeleton greatly increased the inhibitory potency compared to corresponding 1-tetralone chalcones. Among the synthesized compounds, compound 18 which consists of 6-amino-1-tetralone skeleton together with o-fluorobenzylidene showed the most potent ROS inhibitory effect with IC50 value of 0.25 ±â€¯0.13 µM. SAR analysis revealed that amino moiety at the 6th position of 1-tetralone chalcones have an important role for exerting the greater ROS inhibitory potency in LPS-stimulated RAW 264.7 macrophages than those exhibited by 1-tetralone chalcones alone.

A new phenolic series of indenopyridinone as topoisomerase inhibitors: Design, synthesis, and structure-activity relationships.

DNA Topoisomerase IIα (topo IIα) is one of the most effective therapeutic targets to control cancer. In an effort to develop novel and effective topo IIα targeting anti-proliferative agent, a phenolic series of indenopyridinone and indenopyridinol were designed and prepared using efficient multi-component one pot synthetic method. Total twenty-two synthesized compounds were assessed for topo I and IIα inhibition, and anti-proliferation in three different human cancer cell lines. Overall structure-activity relationship study explored the significance of meta-phenolic group at 4-position and para-phenolic group at 2- and/or 4-position of indenopyridinone skeleton for strong topo IIα-selective inhibition and anti-proliferative activity against human cervix (HeLa) and colorectal (HCT15) cell lines. Compound 12 with excellent topo IIα inhibition (93.7%) was confirmed as a DNA intercalator that could be a new promising lead to develop effective topo IIα-targeted anticancer agents.

Optimizing the cutoff for the identification of skin sensitizers by the HaCaSens assay: Introducing an ROC-analysis-based cutoff approach.

The worldwide restricted use of animal testing makes it challenging to identify the skin sensitizing potentials of newly manufactured products. The HaCaSens assay has shown promise as an in vitro skin sensitizing assay comparable to existing assays, and is currently under pre-validation. However, there is little agreement on how to assess the results of the assay to discriminate sensitizers from non-sensitizers as the stimulation index (SI) cutoff value was arbitrarily chosen without appropriate statistical methods. Here, we investigated the SI cutoff values in identifying sensitizers to obtain the optimal value. Sensitivities and specificities were calculated for a set of 30 test substances, and plotted in receiver operator characteristics (ROC) curves. The SI cutoff values with the highest sum of sensitivity and specificity according to LLNA data were 2.2, 1.8 and 3.0 for interleukin 1α (IL-1α), interleukin 6 (IL-6), and the combination of the two cytokines respectively. Also, the same statistical analysis of human data demonstrated optimal SI cutoff values 2.0, 2.0 and 3.2 for the same respective parameters. When considering the predictive capacity of each possible SI cutoff value determined by ROC curves, the optimal value for HaCaSens is 3.0 for the combination of IL-1α and IL-6 as it had the highest sensitivity (90.9%), specificity (75.0%) and accuracy (86.7%) based on LLNA data. Thus, we recommend the wide use of the SI cutoff value of 3.0 to ensure consistent endpoints.

Exploring the Metabolism of Loxoprofen in Liver Microsomes: The Role of Cytochrome P450 and UDP-Glucuronosyltransferase in Its Biotransformation.

Loxoprofen, a propionic acid derivative, non-steroidal anti-inflammatory drug (NSAID) is a prodrug that is reduced to its active metabolite, trans-alcohol form (Trans-OH) by carbonyl reductase enzyme in the liver. Previous studies demonstrated the hydroxylation and glucuronidation of loxoprofen. However, the specific enzymes catalyzing its metabolism have yet to be identified. In the present study, we investigated metabolic enzymes, such as cytochrome P450 (CYP) and UDP-glucuronosyltransferase (UGT), which are involved in the metabolism of loxoprofen. Eight microsomal metabolites of loxoprofen were identified, including two alcohol metabolites (M1 and M2), two mono-hydroxylated metabolites (M3 and M4), and four glucuronide conjugates (M5, M6, M7, and M8). Based on the results for the formation of metabolites when incubated in dexamethasone-induced microsomes, incubation with ketoconazole, and human recombinant cDNA-expressed cytochrome P450s, we identified CYP3A4 and CYP3A5 as the major CYP isoforms involved in the hydroxylation of loxoprofen (M3 and M4). Moreover, we identified that UGT2B7 is the major UGT isoform catalyzing the glucuronidation of loxoprofen and its alcoholic metabolites. Further experimental studies should be carried out to determine the potency and toxicity of these identified metabolites of loxoprofen, in order to fully understand of mechanism of loxoprofen toxicity.

Synthesis and biological evaluation of pyridine-linked indanone derivatives: Potential agents for inflammatory bowel disease.

A series of pyridine-linked indanone derivatives were designed and synthesized to discover new small molecules for the treatment of inflammatory bowel disease (IBD). Compounds 5b and 5d exhibited strongest inhibitory activity against TNF-α-induced monocyte adhesion to colon epithelial cells (an in vitro model of colitis). In TNBS (2,4,6-trinitrobenzenesulfonic acid)-induced rat colitis model, oral administration of the compounds 5b and 5d ameliorated colitis with significant recovery in altered expressions of E-cadherin, TNF-α and IL-1ß expressions, indicating 5b and 5d as potential agents for therapeutics development against IBD.

Fabrication of hollow boron-doped diamond nanostructure via electrochemical corrosion of a tungsten oxide template.

In the study, a hollow boron-doped diamond (BDD) nanostructure electrode is fabricated to increase the reactive surface area for electrochemical applications. Tungsten oxide nanorods are deposited on the silicon substrate as a template by the hot filament chemical vapor deposition (HFCVD) method. The template is coated with a 100 nm BDD layer deposited by HFCVD to form a core-shell nanostructure. The WO x core is finally electrochemically dissolved to form hollow BDD nanostructure. The fabricated hollow BDD nanostructure electrode is investigated via scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. The specific surface areas of the electrodes were analyzed and compared by using Brunauer-Emmett-Teller method. Furthermore, cyclic voltammetry and chronocoulometry are used to investigate the electrochemical characteristics and the reactive surface area of the as-prepared hollow BDD nanostructure electrode. A hollow BDD nanostructure electrode exhibits a reactive area that is 15 times that of a planar BDD thin electrode.