Tumour-suppressive effects of curcumin analogs CCA-1.1 and Pentagamavunone-1 in colon cancer: In vivo and in vitro studies.

This study aimed to evaluate the efficacy of Chemoprevention Curcumin Analog-1.1 (CCA-1.1) and Pentagamavunone-1 (PGV-1) in vivo and in vitro in colorectal cancer model. CCA-1.1 or PGV-1 was administered orally to 1,2-dimethylhydrazine (DMH)-induced rats for 16 weeks. The cytotoxicity of both compounds was tested on Caco-2, CT26, and NIH/3T3 cells using the MTT method. The cell cycle, apoptosis, and reactive oxygen species (ROS) levels were analyzed through flow cytometry. X-gal staining was used to examine the compound's effect on senescence. Oral co-administration of CCA-1.1 or PGV-1 significantly suppressed the carcinogenic characteristics and symptoms of premalignant colon cancer relative to DMH-only and untreated groups. CCA-1.1 and PGV-1 administration did not affect the blood profile. CCA-1.1 and PGV-1 demonstrated great cytotoxicity on Caco-2 and CT26 cells, with 50% inhibition concentration (IC50) values of 4.3 ± 0.2 and 3.1 ± 0.1 µM for CCA-1.1 and 11.2 ± 1.1 and 4.8 ± 0.1 µM for PGV-1, respectively, while not toxic against fibroblast cells. Both compounds instigated G2/M arrest and efficiently induced cell senescence and apoptosis. Moreover, these analogs selectively elevated oxidative stress in colon cancer cells without inducing noticeable changes in fibroblasts. In conclusion, PGV-1 and CCA-1.1 suppressed colorectal tumor formation and induced mitotic arrest.

Transcriptomics analyses reveal the effects of Pentagamaboronon-0-ol on PI3K/Akt and cell cycle of HER2+ breast cancer cells.

Introduction: Monoclonal antibodies and targeted therapies against HER2+ breast cancer has improved overall and disease-free survival in patients; however, encountering drug resistance causes recurrence, necessitating the development of newer HER2-targeted medications. A curcumin analog PGB-0-ol showed most cytotoxicity against HCC1954 HER2+ breast cancer cells than against other subtypes of breast cancer cells. Objective: Here, we employed next-generation sequencing technology to elucidate the molecular mechanism underlying the effect of PGB-0-ol on HCC1954 HER2+ breast cancer cells. Methods: The molecular mechanism underlying the action of PGB-0-ol on HCC1954 HER2+ breast cancer cells was determined using next-generation sequencing technologies. Additional bioinformatics studies were performed, including gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, disease-gene, and drug-gene associations, network topology analysis (NTA), and gene set enrichment analysis (GSEA). Results: We detected 2,263 differentially expressed genes (DEGs) (1,459 upregulated and 804 downregulated) in the PGB-0-ol- and DMSO-treated HCC1954 cells. KEGG enrichment data revealed the control of phosphatidylinositol signaling system, and ErbB signaling following PGB-0-ol treatment. Gene ontology (GO) enrichment analysis demonstrated that these DEGs governed cell cycle, participated in the mitotic spindle and nuclear membrane, and controlled kinase activity at the molecular level. According to the NTA data for GO enrichment, GSEA data for KEGG, drug-gene and disease-gene, PGB-0-ol regulated PI3K/Akt signaling and cell cycle in breast cancer. Overall, our investigation revealed the transcriptomic profile of PGB-0-ol-treated HCC1954 breast cancer cells following PGB-0-ol therapy. Bioinformatics analyses showed that PI3K/Akt signaling and cell cycle was modulated. However, further studies are required to validate the findings of this study.

Multi-Targeted Neutron Capture Therapy Combined with an 18 kDa Translocator Protein-Targeted Boron Compound Is an Effective Strategy in a Rat Brain Tumor Model.

BACKGROUND: Boron neutron capture therapy (BNCT) has been adapted to high-grade gliomas (HG); however, some gliomas are refractory to BNCT using boronophenylalanine (BPA). In this study, the feasibility of BNCT targeting the 18 kDa translocator protein (TSPO) expressed in glioblastoma and surrounding environmental cells was investigated. METHODS: Three rat glioma cell lines, an F98 rat glioma bearing brain tumor model, DPA-BSTPG which is a boron-10 compound targeting TSPO, BPA, and sodium borocaptate (BSH) were used. TSPO expression was evaluated in the F98 rat glioma model. Boron uptake was assessed in three rat glioma cell lines and in the F98 rat glioma model. In vitro and in vivo neutron irradiation experiments were performed. RESULTS: DPA-BSTPG was efficiently taken up in vitro. The brain tumor has 16-fold higher TSPO expressions than its brain tissue. The compound biological effectiveness value of DPA-BSTPG was 8.43 to F98 rat glioma cells. The boron concentration in the tumor using DPA-BSTPG convection-enhanced delivery (CED) administration was approximately twice as high as using BPA intravenous administration. BNCT using DPA-BSTPG has significant efficacy over the untreated group. BNCT using a combination of BPA and DPA-BSTPG gained significantly longer survival times than using BPA alone. CONCLUSION: DPA-BSTPG in combination with BPA may provide the multi-targeted neutron capture therapy against HG.

The impact of TP53 status of tumor cells including the type and the concentration of administered 10B delivery agents on compound biological effectiveness in boron neutron capture therapy.

Human head and neck squamous cell carcinoma cells transfected with mutant TP53 (SAS/mp53) or neo vector (SAS/neo) were inoculated subcutaneously into left hind legs of nude mice. After the subcutaneous administration of a 10B-carrier, boronophenylalanine-10B (BPA) or sodium mercaptododecaborate-10B (BSH), at two separate concentrations, the 10B concentrations in tumors were measured using γ-ray spectrometry. The tumor-bearing mice received 5-bromo-2'-deoxyuridine (BrdU) continuously to label all intratumor proliferating (P) tumor cells, then were administered with BPA or BSH. Subsequently, the tumors were irradiated with reactor neutron beams during the time of which 10B concentrations were kept at levels similar to each other. Following irradiation, cells from some tumors were isolated and incubated with a cytokinesis blocker. The responses of BrdU-unlabeled quiescent (Q) and total (= P + Q) tumor cells were assessed based on the frequencies of micronucleation using immunofluorescence staining for BrdU. In both SAS/neo and SAS/mp53 tumors, the compound biological effectiveness (CBE) values were higher in Q cells and in the use of BPA than total cells and BSH, respectively. The higher the administered concentrations were, the smaller the CBE values became, with a clearer tendency in SAS/neo tumors and the use of BPA than in SAS/mp53 tumors and BSH, respectively. The values for BPA that delivers into solid tumors more dependently on uptake capacity of tumor cells than BSH became more alterable. Tumor micro-environmental heterogeneity might partially influence on the CBE value. The CBE value can be regarded as one of the indices showing the level of intratumor heterogeneity.

Dodecaborate-Encapsulated Extracellular Vesicles with Modification of Cell-Penetrating Peptides for Enhancing Macropinocytotic Cellular Uptake and Biological Activity in Boron Neutron Capture Therapy.

Boron neutron capture therapy (BNCT) is a radiation therapy for cancer. In BNCT, the internalization of boron-10 atoms by cancer cells induces cell death through the generation of α particles and recoiling lithium-7 nuclei when irradiated with low-energy thermal neutrons. In this study, we aimed to construct exosomes [extracellular vesicles (EVs)]-based drug delivery technology in BNCT. Because of their pharmaceutical advantages, such as controlled immune responses and effective usage of cell-to-cell communication, EVs are potential next-generation drug delivery carriers. In this study, we successfully developed polyhedral borane anion-encapsulated EVs with modification of hexadeca oligoarginine, which is a cell-penetrating peptide, on the EV membrane to induce the actin-dependent endocytosis pathway, macropinocytosis, which leads to efficient cellular uptake and remarkable cancer cell-killing BNCT activity. The simple and innovative technology of the EV-based delivery system with "cassette" modification of functional peptides will be applicable not only for BNCT but also for a wide variety of therapeutic methodologies.

Synthesis and cytotoxicity of the boron carrier pentagamaboronon-0-ol for boron neutron capture therapy against breast cancer.

Boronic acid-containing curcumin analog, pentagamaboronon-0 (PGB-0), acts as a potential boron-carrier agent but has limited water solubility. Thus, a new compound (PGB-0-ol) with better chemical and pharmacological properties than PGB-0 has been synthesized. Molecular docking was performed using a molecular operating environment. Prediction of PGB-0-ol absorption, distribution, metabolism, and excretion (ADME) was performed using pkCSM software. PGB-0-ol was synthesized by adding NaBH4 to PGB-0 and stirring for 1 h. The crude PGB-0-ol was purified using preparative layer chromatography. Cell viability was evaluated using the trypan blue exclusion assay. In comparison to PGB-0 based on molecular docking study, PGB-0-ol could interact in with several cancer biomarkers, such as human epidermal growth factor2 epidermal growth factor receptor, IκB kinase, folate receptor-α, and integrin αvß3. PGB-0-ol also showed an improved ADME profile because of its higher water solubility than PGB-0. PGB-0-ol was synthesized by selective ketone reduction of PGB-0 into primary alcohol by sodium borohydrate producing 30% yield. The cytotoxicity of PGB-0-ol against several breast cancer cells was lower than that of PGB-0. The novel compound PGB-0-ol was synthesized using simple steps. PGB-0-ol has low cytotoxicity against breast cancer cells and could be applied in boron neutron capture therapy as a boron carrier.

Dodecaborate Conjugates Targeting Tumor Cell Overexpressing Translocator Protein for Boron Neutron Capture Therapy.

We developed novel closo-dodecaborate ([B12H11]2-) anion-containing translocator protein (TSPO) ligand as a boron carrier for boron neutron capture therapy. This compound shows high water solubility and can deliver boron to TSPO highly expressed in breast cancer cells. We describe the synthesis and in vitro evaluation of a dodecaborate-based pyrazolopyrimidine.

The Evaluation of Cytotoxic Properties from CCB-2 Sugar Complexes Against TNBC and Non-TNBC Cells.

OBJECTIVE: The progress from Boron Neutron Capture Therapy (BNCT) development urged us to explore new targeted and selective boron carriers. Firstly, we reported the successful synthesis of CCB-2 which exerts a cytotoxic effect against triple negative breast cancer (TNBC) cells. We introduced the new modification of CCB-2 with sugar and alcohol sugars to enhance its solubility in hoping to increase cellular uptake. METHODS: CCB-2 fructose complex (CCB-2-F), CCB-2 sorbitol complex (CCB-2-Sor), and CCB-2 xylitol complex (CCB-2-Xy) were obtained with small size within nano-specific particle. All the compounds were then determined for their cytotoxic activities through MTT assay. RESULTS: All compounds were performed cytotoxic activities against TNBC 4T1 and HER-2 positive MCF-7/HER2 cells with good selectivity when tested in immortalized fibroblast cells. CONCLUSION: Overall, we provided a new modification of CCB-2 through complexation with sugars. Still, further evaluations are needed to develop more efficient CCB-2 as the new candidate of anticancer agent, notably in breast cancer.

The Therapeutic Effects of Dodecaborate Containing Boronophenylalanine for Boron Neutron Capture Therapy in a Rat Brain Tumor Model.

BACKGROUND: The development of effective boron compounds is a major area of research in the study of boron neutron capture therapy (BNCT). We created a novel boron compound, boronophenylalanine-amide alkyl dodecaborate (BADB), for application in BNCT and focused on elucidating how it affected a rat brain tumor model. METHODS: The boron concentration of F98 rat glioma cells following exposure to boronophenylalanine (BPA) (which is currently being utilized clinically) and BADB was evaluated, and the biodistributions in F98 glioma-bearing rats were assessed. In neutron irradiation studies, the in vitro cytotoxicity of each boron compound and the in vivo corresponding therapeutic effect were evaluated in terms of survival time. RESULTS: The survival fractions of the groups irradiated with BPA and BADB were not significantly different. BADB administered for 6 h after the termination of convection-enhanced delivery ensured the highest boron concentration in the tumor (45.8 µg B/g). The median survival time in the BADB in combination with BPA group showed a more significant prolongation of survival than that of the BPA group. CONCLUSION: BADB is a novel boron compound for BNCT that triggers a prolonged survival effect in patients receiving BNCT.

Antibody-Based Receptor Targeting Using an Fc-Binding Peptide-Dodecaborate Conjugate and Macropinocytosis Induction for Boron Neutron Capture Therapy.

Boron neutron capture therapy (BNCT) is a radiation method used for cancer therapy. Cellular uptake of boron-10 (10B) atoms induces cancer cell death by the generation of alpha particles and recoiling lithium-7 (7Li) nuclei when the cells are irradiated with low-energy thermal neutrons. Current BNCT technology shows effective therapeutic benefits in refractory cancers such as brain tumors and head and neck cancers. However, improvements to cancer targeting and the cellular uptake efficacy of the boron compounds and the expansion of the diseases treatable by BNCT are highly desirable. In this research, we aimed to develop an antibody-based drug delivery method for BNCT through the use of the Z33 peptide, which shows specific recognition of and interaction with the Fc domain of human IgG, for on-demand receptor targeting. In addition, we determined with an in vitro assay that macropinocytosis induction during antibody-based drug delivery is crucial for the biological activity of BNCT.

Synthesis and Evaluation of Dodecaboranethiol Containing Kojic Acid (KA-BSH) as a Novel Agent for Boron Neutron Capture Therapy.

Boron neutron capture therapy (BNCT) is a form of tumor-cell selective particle irradiation using low-energy neutron irradiation of boron-10 (10B) to produce high-linear energy transfer (LET) alpha particles and recoiling 7Li nuclei (10B [n, alpha] 7Li) in tumor cells. Therefore, it is important to achieve the selective delivery of large amounts of 10B to tumor cells, with only small amounts of 10B to normal tissues. To develop practical materials utilizing 10B carriers, we designed and synthesized novel dodecaboranethiol (BSH)-containing kojic acid (KA-BSH). In the present study, we evaluated the effects of this novel 10B carrier on cytotoxicity, 10B concentrations in F98 rat glioma cells, and micro-distribution of KA-BSH in vitro. Furthermore, biodistribution studies were performed in a rat brain tumor model. The tumor boron concentrations showed the highest concentrations at 1 h after the termination of administration. Based on these results, neutron irradiation was evaluated at the Kyoto University Research Reactor Institute (KURRI) with KA-BSH. Median survival times (MSTs) of untreated and irradiated control rats were 29.5 and 30.5 days, respectively, while animals that received KA-BSH, followed by neutron irradiation, had an MST of 36.0 days (p = 0.0027, 0.0053). Based on these findings, further studies are warranted in using KA-BSH as a new B compound for malignant glioma.

Chemical structure of hydrolysates of cereulide and their time course profile.

Hydrolysates of an emetic toxin cereulide were found in the broth of Bacillus cereus. The ester cleaved depsipeptides of cereulide were synthesized using liquid phase fragment condensation method starting from commercially available amino acids. The chemical structure of hydrolysates was verified tetradepsipeptide l-O-Val-l-Val-D-O-Leu-d-Ala and dodecadepsipeptide (D-O-Leu-d-Ala-l-O-Val-l-Val)3 using LC-TOFMS. Quantitative analysis of cereulide in the broth revealed production of cereulide in the stationary phase and decomposition in the death phase. The increase in tetradepsipeptide continued after the stationary phase until decomposition occurred.

Intracellular target delivery of cell-penetrating peptide-conjugated dodecaborate for boron neutron capture therapy (BNCT).

In this study, we designed and synthesized organelle-targeted cell-penetrating peptide (CPP)-conjugated boron compounds to increase their cellular uptake and to control the intracellular locations for the induction of sophisticated anticancer biological activity in boron neutron capture therapy (BNCT), leading to anticancer effects with ATP reduction and apoptosis when irradiated with neutrons in an in vitro BNCT assay.

Preparation of pentagamaboronon-0 and its fructose and sorbitol complexes as boron carrier for boron neutron capture therapy (BNCT) application.

Development of specific and selective boron carriers is indispensable for boron neutron capture therapy (BNCT) application. Pentagamaboronon-0 (PGB-0) is a promising candidate as boron carrier compound due to the low but selective cytotoxicity in breast cancer cells. Formerly we reported synthesis of PGB-0 which was ineffective due to its low aqueous solubility. In the present study, we, therefore, introduced the new PGB-0 preparation complexed with sugars to increase its solubility in water. By synthesizing at room temperature and using flash chromatography for the purification, we produced PGB-0 with a yield of 40%. PGB-0 fructose complex (PGB-0-F) and PGB-0 sorbitol complex (PGB-0-Sor) were obtained with smaller particle size compared to PGB-0 suspension in water. Based on the MTT assay, the cytotoxicity of PGB-0-F and PGB-0-Sor were higher than PGB-0 even though still categorized as low cytotoxic agents. In conclusion, we provided PGB-0 with a new method and improved its solubility in water. Further investigations are still needed to develop more efficient PGB-0 as boron carrier for BNCT in various cancers.

Cellular uptake evaluation of pentagamaboronon-0 (PGB-0) for boron neutron capture therapy (BNCT) against breast cancer cells.

Pentagamaboronon-0 (PGB-0), a curcumin analog compound, has been synthesized as a candidate of boron-carrier pharmaceutical (BCP) for boron neutron capture therapy (BNCT); however, this compound is poorly soluble in water. To improve its solubility, aqueous formulations of PGB-0 with a monosaccharide, fructose or sorbitol, were successfully synthesized, namely PGB-0-F and PGB-0-So, respectively. The cytotoxicity study showed that PGB-0-F and PGB-0-So exerted low cytotoxicity against MCF-7 and MDA-MB 231 breast cancer cells. The cellular uptake study using inductively coupled plasma optical emission spectrometry (ICP-OES) and DAHMI live-cell imaging indicated that these compounds were accumulated and distributed within the cytoplasm and cell nuclei. The cellular uptake mechanism was also evaluated to clarify the contribution of the glucose transporter, and the results demonstrated that these compounds entered through active transport into MCF-7 cells but through passive diffusion into MDA-MB 231 cells. In conclusion, the sugar formulations of PGB-0 only improved PGB-0 solubility but had no role in its cellular uptake.

Synthesis of the reported structure of homocereulide and its vacuolation assay.

Homocereulide, isolated from marine bacterium Bacillus cereus, is an analog of emetic toxin cereulide. There is no report on its structure determination and involvement in B. cereus-associated food poisoning. Homocereulide is a cyclic dodecadepsipeptide composed of l-O-Val-l-Val-d-O-Leu-d-Ala and l-O-allo-Ile-d-Val-d-O-Leu-d-Ala. Here, we synthesized homocereulide using liquid phase fragment condensation. The NMR spectrum of synthesized homocereulide confirmed the intended structure and LC-MS results were consistent with natural products. Morphological evaluation using HEp-2 cells showed higher toxicity with homocereulide (1.39 nM) than cereulide (3.95 nM). Though cereulide is the main component in broth culture, homocereulide is also likely involved in B. cereus-associated food poisoning.

Development and Elucidation of a Novel Fluorescent Boron-Sensor for the Analysis of Boronic Acid-Containing Compounds.

Novel boron-containing drugs have recently been suggested as a new class of pharmaceuticals. However, the majority of current boron-detection techniques require expensive facilities and/or tedious pretreatment methods. Thus, to develop a novel and convenient detection method for boron-based pharmaceuticals, imine-type boron-chelating-ligands were previously synthesized for use in a fluorescent sensor for boronic acid containing compounds. However, the fluorescence quantum yield of the imine-type sensor was particularly low, and the sensor was easily decomposed in aqueous media. Thus, in this paper, we report the development of a novel, convenient, and stable fluorescent boron-sensor based on O- and N-chelation (i.e., 2-(pyridine-2yl)phenol), and a corresponding method for the quantitative and qualitative detection of boronic acid-containing compounds using this commercially available sensor is presented.

Practical calculation method to estimate the absolute boron concentration in tissues using 18F-FBPA PET.

PURPOSE: The purpose of this study was to establish a practical method to estimate the absolute boron concentrations in the tissues based on the standardized uptake values (SUVs) after administration of 4-borono-phenylalanine (BPA) using 4-borono-2-18F-fluoro-phenylalanine (18F-FBPA) PET. METHODS: Rat xenograft models of C6 glioma (n = 7, body weight 241 ± 28.0 g) were used for the study. PET was performed 60 min after intravenous injection of 18F-FBPA (30.5 ± 0.7 MBq). After the PET scanning, BPA-fructose (167.3 ± 18.65 mg/kg) was administered by slow intravenous injection to the same subjects. The rats were killed 60 min after the BPA injection and tissue samples were collected from the major organs and tumors. The absolute boron concentrations (unit: ppm) in the samples were measured by inductively coupled plasma optical emission spectrometry (ICP-OES). The boron concentrations in the tissues/tumors were also estimated from the 18F-FBPA PET images using the following formula: estimated absolute boron concentration (ppm) = 0.0478 × [BPA dose (mg/kg)] × SUV. The measured absolute boron concentrations (mBC) by ICP-OES and the estimated boron concentrations (eBC) from the PET images were compared. RESULTS: The percent difference between the mBC and eBC calculated based on the SUVmax was -5.2 ± 21.1% for the blood, -9.4 ± 22.3% for the brain, 1.6 ± 21.3% for the liver, -14.3 ± 16.8% for the spleen, -9.5 ± 27.5% for the pancreas, and 3.4 ± 43.2% for the tumor. Relatively large underestimation was observed for the lung (-48.4 ± 16.2%), small intestine (-37.8 ± 19.3%) and large intestine (-33.9 ± 11.0%), due to the partial volume effect arising from the air or feces contained in these organs. In contrast, relatively large overestimation was observed for the kidney (34.3 ± 29.3%), due to the influence of the high uptake in urine. CONCLUSIONS: The absolute boron concentrations in tissues/tumors can be estimated from the SUVs on 18F-FBPA PET using a practical formula. Caution must be exercised in interpreting the estimated boron concentrations in the lung, small intestine and large intestine, to prevent the adverse effects of overexposure, which could occur due to underestimation by partial volume effect using PET.

Evaluation of a novel sodium borocaptate-containing unnatural amino acid as a boron delivery agent for neutron capture therapy of the F98 rat glioma.

BACKGROUND: Boron neutron capture therapy (BNCT) is a unique particle radiation therapy based on the nuclear capture reactions in boron-10. We developed a novel boron-10 containing sodium borocaptate (BSH) derivative, 1-amino-3-fluorocyclobutane-1-carboxylic acid (ACBC)-BSH. ACBC is a tumor selective synthetic amino acid. The purpose of this study was to assess the biodistribution of ACBC-BSH and its therapeutic efficacy following Boron Neutron Capture Therapy (BNCT) of the F98 rat glioma. METHODS: We evaluated the biodistribution of three boron-10 compounds, ACBC-BSH, BSH and boronophenylalanine (BPA), in vitro and in vivo, following intravenous (i.v.) administration and intratumoral (i.t.) convection-enhanced delivery (CED) in F98 rat glioma bearing rats. For BNCT studies, rats were stratified into five groups: untreated controls, neutron-irradiation controls, BNCT with BPA/i.v., BNCT with ACBC-BSH/CED, and BNCT concomitantly using BPA/i.v. and ACBC-BSH/CED. RESULTS: In vitro, ACBC-BSH attained higher cellular uptake F98 rat glioma cells compared with BSH. In vivo biodistribution studies following i.v. administration and i.t. CED of ACBC-BSH attained significantly higher boron concentrations than that of BSH, but much lower than that of BPA. However, following convection enhanced delivery (CED), ACBC-BSH attained significantly higher tumor concentrations than BPA. The i.t. boron-10 concentrations were almost equal between the ACBC-BSH/CED group and BPA/i.v. group of rats. The tumor/brain boron-10 concentration ratio was higher with ACBC-BSH/CED than that of BPA/i.v. group. Based on these data, BNCT studies were carried out in F98 glioma bearing rats using BPA/i.v. and ACBC-BSH/CED as the delivery agents. The corresponding mean survival times were 37.4 ± 2.6d and 44.3 ± 8.0d, respectively, and although modest, these differences were statistically significant. CONCLUSIONS: Our findings suggest that further studies are warranted to evaluate ACBC-BSH/CED as a boron delivery agent.

Comparison of the pharmacokinetics between L-BPA and L-FBPA using the same administration dose and protocol: a validation study for the theranostic approach using [18F]-L-FBPA positron emission tomography in boron neutron capture therapy.

BACKGROUND: Boron neutron capture therapy (BNCT) is a cellular-level particle radiation therapy that combines the selective delivery of boron compounds to tumour tissue with neutron irradiation. L-p-Boronophenylalanine (L-BPA) is a boron compound now widely used in clinical situations. Determination of the boron distribution is required for successful BNCT prior to neutron irradiation. Thus, positron emission tomography with [18F]-L-FBPA, an 18F-labelled radiopharmaceutical analogue of L-BPA, was developed. However, several differences between L-BPA and [18F]-L-FBPA have been highlighted, including the different injection doses and administration protocols. The purpose of this study was to clarify the equivalence between L-BPA and [19F]-L-FBPA as alternatives to [18F]-L-FBPA. METHODS: SCC-VII was subcutaneously inoculated into the legs of C3H/He mice. The same dose of L-BPA or [19F]-L-FBPA was subcutaneously injected. The time courses of the boron concentrations in blood, tumour tissue, and normal tissue were compared between the groups. Next, we administered the therapeutic dose of L-BPA or the same dose of [19F]-L-FBPA by continuous infusion and compared the effects of the administration protocol on boron accumulation in tissues. RESULTS: There were no differences between L-BPA and [19F]-L-FBPA in the transition of boron concentrations in blood, tumour tissue, and normal tissue using the same administration protocol. However, the normal tissue to blood ratio of the boron concentrations in the continuous-infusion group was lower than that in the subcutaneous injection group. CONCLUSIONS: No difference was noted in the time course of the boron concentrations in tumour tissue and normal tissues between L-BPA and [19F]-L-FBPA. However, the administration protocol had effects on the normal tissue to blood ratio of the boron concentration. In estimating the BNCT dose in normal tissue by positron emission tomography (PET), we should consider the possible overestimation of the normal tissue to blood ratio of the boron concentrations derived from the values measured by PET on dose calculation.