Evaluation of blood and urine based biomarkers for detection of clinically-significant prostate cancer.

BACKGROUND: Recognizing the limitations of prostate-specific antigen (PSA) screening and the morbidity of prostate biopsies, several blood- and urine-based biomarkers have been proposed for pre-biopsy risk stratification. These assays aim to reduce the frequency of unnecessary biopsies (i.e., negative or Grade Group 1 [GG1]) while maintaining highly sensitive detection of clinically significant cancer (GG ≥ 2) prostate cancer. METHODS: We reviewed the literature describing the use of currently available blood- and urine-based biomarkers for detection of GG ≥ 2 cancer, including the Prostate Health Index (PHI), 4Kscore, MyProstateScore (MPS), SelectMDx, ExoDx Prostate Intelliscore (EPI), and IsoPSA. To facilitate clinical application, we focused on the use of biomarkers as a post-PSA secondary test prior to biopsy, as proposed in clinical guidelines. Our outcomes included test performance measures-sensitivity, specificity, negative predictive value (NPV), and positive predictive value (PPV)-as well as clinical outcomes resulting from biomarker use (i.e., unnecessary biopsies avoided, GG ≥ 2 cancers missed). RESULTS: Contemporary validation data (2015-2023) reveal that currently available biomarkers provide ~15-50% specificity at a sensitivity of 90-95% for GG ≥ 2 PCa. Clinically, this indicates that secondary use of biomarker testing in men with elevated PSA could allow for avoidance of up to 15-50% of unnecessary prostate biopsies, while preserving detection of 90-95% of GG ≥ 2 cancers that would be detected under the traditional "biopsy all" approach. CONCLUSIONS: The contemporary literature further supports the proposed role of post-PSA biomarker testing to reduce the use of invasive biopsy while maintaining highly sensitive detection of GG ≥ 2 cancer. Questions remain regarding the optimal application of biomarkers in combination or in sequence with mpMRI.

Robust Magnetized Graphene Oxide Platform for In Situ Peptide Synthesis and FRET-Based Protease Detection.

Graphene oxide (GO)/peptide complexes as a promising disease biomarker analysis platform have been used to detect proteolytic activity by observing the turn-on signal of the quenched fluorescence upon the release of peptide fragments. However, the purification steps are often cumbersome during surface modification of nano-/micro-sized GO. In addition, it is still challenging to incorporate the specific peptides into GO with proper orientation using conventional immobilization methods based on pre-synthesized peptides. Here, we demonstrate a robust magnetic GO (MGO) fluorescence resonance energy transfer (FRET) platform based on in situ sequence-specific peptide synthesis of MGO. The magnetization of GO was achieved by co-precipitation of an iron precursor solution. Magnetic purification/isolation enabled efficient incorporation of amino-polyethylene glycol spacers and subsequent solid-phase peptide synthesis of MGO to ensure the oriented immobilization of the peptide, which was evaluated by mass spectrometry after photocleavage. The FRET peptide MGO responded to proteases such as trypsin, thrombin, and ß-secretase in a concentration-dependent manner. Particularly, ß-secretase, as an important Alzheimer's disease marker, was assayed down to 0.125 ng/mL. Overall, the MGO platform is applicable to the detection of other proteases by using various peptide substrates, with a potential to be used in an automated synthesis system operating in a high throughput configuration.

Gold Nanoparticle-Stabilized, Tyrosine-Rich Peptide Self-Assemblies and Their Catalytic Activities in the Reduction of 4-Nitrophenol.

Peptides are suitable candidates for templates in the fabrication of various metal nanoparticles (NPs) because of their metal-binding ability and templating effect, which impart physicochemical properties to the produced nanoparticles. Peptide-binding gold nanoparticles (AuNPs) show high catalytic activity that permits their application in oxidation or reduction reactions. Herein, we prepared morphology-controllable AuNPs stabilized by self-assembled tyrosine-rich peptides (YC7) by varying the pH and YC7 peptide/Au3+ concentration ratio in 2-( N-morpholino)ethanesulfonic acid (MES) buffer solution. The catalytic activities of the YC7 peptide-stabilized AuNPs (YC7@AuNPs) were tested for 4-nitrophenol (4-NP) reduction, and kinetic analysis was performed to calculate the apparent rate constants and activation energies. The relatively low activation energy of the YC7@AuNPs could be explained by the hypothesis that the tyrosine-moiety of YC7 enriches the electron density of Au metal.

Fabrication of Localized Surface Plasmon Resonance Sensor Based on Optical Fiber and Micro Fluidic Channel.

This paper proposes Fiber-Optic Localized Surface Plasmon Resonance (FO LSPR) sensor combined with a micro fluidic channel, which enables continuous supply of fluid for bio-reaction. The proposed method prevents degradation of the sensing performance due to changes in measurement conditions. The feasibility of the FO LSPR sensor with a micro fluidic channel was demonstrated by computational fluid dynamics (CFD) simulation. Also, the proposed method was assessed by measuring the output intensity of the FO LSPR sensor at various refractive index solutions. Finally, a prostate-specific antigen (PSA) immunoassay was performed to evaluate the possibility of the fabricated sensor system as a biosensor.

Activatable iRGD-based peptide monolith: Targeting, internalization, and fluorescence activation for precise tumor imaging.

A disulfide-bridged cyclic RGD peptide, named iRGD (internalizing RGD, c(CRGDK/RGPD/EC)), is known to facilitate tumor targeting as well as tissue penetration. After the RGD motif-induced targeting on αv integrins expressed near tumor tissue, iRGD encounters proteolytic cleavage to expose the CendR motif that promotes penetration into cancer cells via the interaction with neuropilin-1. Based on these proteolytic cleavage and internalization mechanism, we designed an iRGD-based monolithic imaging probe that integrates multiple functions (cancer-specific targeting, internalization and fluorescence activation) within a small peptide framework. To provide the capability of activatable fluorescence signaling, we conjugated a fluorescent dye to the N-terminal of iRGD, which was linked to the internalizing sequence (CendR motif), and a quencher to the opposite C-terminal. It turned out that fluorescence activation of the dye/quencher-conjugated monolithic peptide probe requires dual (reductive and proteolytic) cleavages on both disulfide and amide bond of iRGD peptide. Furthermore, the cleavage of the iRGD peptide leading to fluorescence recovery was indeed operative depending on the tumor-related angiogenic receptors (αvß3 integrin and neuropilin-1) in vitro as well as in vivo. Compared to an 'always fluorescent' iRGD control probe without quencher conjugation, the dye/quencher-conjugated activatable monolithic peptide probe visualized tumor regions more precisely with lower background noise after intravenous injection, owing to the multifunctional responses specific to tumor microenvironment. All these results, along with minimal in vitro and in vivo toxicity profiles, suggest potential of the iRGD-based activatable monolithic peptide probe as a promising imaging agent for precise tumor diagnosis.

Nanomechanical measurement of astrocyte stiffness correlated with cytoskeletal maturation.

Astrocytes are known to serve as scaffolding cells that shape the brain. The physical properties of astrocytes, such as stiffness, are important for their scaffolding function. These properties may be altered in certain pathological conditions, such as in brain cancer. However, actual stiffness of astrocytes is not yet well understood. Here, we report that the astrocyte stiffness is positively correlated with the density of cytoskeletal proteins, such as actin filaments, microtubules, and intermediate filaments. The value of the stiffness of astrocytes as measured by atomic force microscopy (AFM) increases 38-fold in five-week-old rats compared to postnatal-day zero pups. Using multicolor confocal microscopy, we found that the complexity of cytoskeletal proteins, such as actin filaments, microtubules, and intermediate filaments, increase as the animal gets older. Our findings indicate that the change of stiffness positively correlates with the maturation of cytoskeletal proteins, and suggest that AFM can be useful as an analytical and diagnostic tool for neuroscience.

A micro-fabricated force sensor using an all thin film piezoelectric active sensor.

The ability to measure pressure and force is essential in biomedical applications such as minimally invasive surgery (MIS) and palpation for detecting cancer cysts. Here, we report a force sensor for measuring a shear and normal force by combining an arrayed piezoelectric sensors layer with a precut glass top plate connected by four stress concentrating legs. We designed and fabricated a thin film piezoelectric force sensor and proposed an enhanced sensing tool to be used for analyzing gentle touches without the external voltage source used in FET sensors. Both the linear sensor response from 3 kPa to 30 kPa and the exact signal responses from the moving direction illustrate the strong feasibility of the described thin film miniaturized piezoelectric force sensor.

Controllable core-shell-type resin for solid-phase peptide synthesis.

A simple, mild, and inexpensive biphasic functionalization approach is attempted for preparing an ideal core-shell-type resin. The core-shell-type architecture was constructed by coupling Fmoc-OSu to the amino groups on the shell layer of an aminomethyl polystyrene (AM PS) resin. The shell layer thickness of the resin could be easily controlled under mild conditions, which was characterized by confocal laser scanning microscopy (CLSM). The efficiency of core-shell-type resin for solid-phase peptide synthesis (SPPS) was demonstrated by the synthesis of various peptides and compared with commercially available noncore-shell-type resins such as AM PS and poly(ethylene glycol)-based resins. The core-shell-type resin provided effective performance during the synthesis of hydrophobic peptide sequences, a disulfide-bridged cyclic peptide, and a difficult PNA sequence. Furthermore, a highly aggregative peptide fragment, MoPrP 105-125, was synthesized more efficiently on the core-shell-type resin under microwave conditions than AM PS and ChemMatrix resins.

Avulsion fracture of the calcaneal tuberosity: classification and its characteristics.

BACKGROUND: Not much is known regarding avulsion fractures of the calcaneal tuberosity. We propose a modified classification scheme that presents the four types of calcaneal avulsion fracture as described by surgical and magnetic resonance imaging (MRI) findings, and evaluation of their specific features. METHODS: Out of 764 cases of calcaneal fractures, we examined 20 cases (2.6%) that involved the tuberosity of the calcaneus. Each case was classified depending on the avulsed fracture patterns as follows; type I is a 'simple extra-articular avulsion' fracture, type II is the 'beak' fracture, type III is an infrabursal avulsion fracture from the middle third of the posterior tuberosity, and finally in type IV there is the 'beak', but a small triangular fragment is separated from the upper border of the tuberosity. We examined the features of each avulsed type according to several criteria including patient age, gender, anatomical variances of the Achilles tendon, the fibers involved and the mechanism of injury. RESULTS: The type I fracture (8/20 cases) was the most common and likely to occur in elderly women. However, in other types, they were more common in relatively younger male patients. Type I were usually caused due to an accidental trip causing a fall by the patient. However, the dominant cause of type II (5/20 cases) fractures a direct blow or hit directly to the bone. Type III (4/20 cases) and IV (3/20 cases) fractures were likely to occur due to falling. All fibers within the Achilles tendon are involved in both type I and II fractures. However, only the superficial fibers are involved in type III fractures, whereas the deep fibers are involved in type IV fractures. CONCLUSIONS: The avulsion patterns of the calcaneal tuberosity fractures are the result of several factors including the bony density level, the mechanism of injury and the fibers of the Achilles tendon that transmit the force. Accurate diagnosis of type III and IV is dependant on MRI technology to confirm the specific location of the injury and provide proper patient treatment therapeutics.

Combined-modality radioimmunotherapy: synergistic effect of paclitaxel and additive effect of bevacizumab.

INTRODUCTION: This study was undertaken to investigate the effect of paclitaxel and bevacizumab on the therapeutic efficacy of (90)Y-labeled B3 monoclonal antibody, directed against Le(y) antigen, for the treatment of Le(y)-positive A431 tumors implanted subcutaneously in the right hind flank of nude mice. METHODS: When the tumor size reached ~200 mm(3), the mice received a single dose of intravenous (iv) (90)Y-labeled B3 (60 µCi/150 µg or 100 µCi/150 µg B3), intraperitoneal paclitaxel (40 mg/kg) or iv bevacizumab (5 mg/kg) for monotherapy. To investigate the effect of combined therapies on survival, the mice were treated with two or three agents in the following combinations: (90)Y-B3 on day 0 and paclitaxel on day 1; bevacizumab on -1 day and (90)Y-B3 on day 0; bevacizumab on -1 day and paclitaxel on day 1; bevacizumab, (90)Y-B3 and paclitaxel each at 1-day intervals. The mice with no treatment were used as a control. The tumor volume at 1000 mm(3) was used as a surrogate end point of survival. RESULTS: Compared to control animals, paclitaxel delayed tumor growth with a significantly longer median survival time (P<.001), whereas bevacizumab alone showed a less pronounced effect on a median survival time (P=.18). (90)Y-B3 increased the median survival time in a dose-dependent manner (P<.05). The combined therapy of bevacizumab with paclitaxel produced a trend toward an increase of the median survival time compared to paclitaxel alone (P=.06), whereas bevacizumab combined with (90)Y-B3 showed a statistically insignificant increase in the median survival time compared to (90)Y-B3 alone (P=.25). The tumor sizes of all animals in these groups reached the surrogate end point of survival by day 35. In contrast, the combined therapy involving (90)Y-B3 with paclitaxel showed a striking synergistic effect in shrinking tumors and prolonging the survival time (P<.001); on day 120, three of nine mice (33%) and six of six mice (100%) were alive without tumor when treated with 60 µCi (90)Y-B3 and 100 µCi (90)Y-B3, respectively. The addition of bevacizumab treatment 1 day before the combined therapy of 60 µCi (90)Y-B3 with paclitaxel did not produce a statistically significant increase in survival when compared to the (90)Y-B3 with paclitaxel (P>.10). Fluorescence microscopy analysis indicated that paclitaxel increased, whereas bevacizumab decreased, the accumulation and penetration of Alexa Fluor 647-B3 into tumor microenvironment compared to the control (P<.05). CONCLUSION: Our findings on the paclitaxel effect support a hypothesis that the increased tumor accumulation and penetration of (90)Y-B3 as well as the high radiosensitization of tumor cells by paclitaxel may be the major factors responsible for the synergistic effect of the combined therapy involving (90)Y-B3 with paclitaxel.

Effect of chelator conjugation level and injection dose on tumor and organ uptake of 111In-labeled MORAb-009, an anti-mesothelin antibody.

INTRODUCTION: Radiolabeling of a monoclonal antibody (mAb) with a metallic radionuclide requires the conjugation of a bifunctional chelator to the mAb. The conjugation, however, can alter the physical and immunological properties of the mAb, consequently affecting its tumor-targeting pharmacokinetics. In this study, we investigated the effect of the amount of 2-(p-isothiocyanatobenzyl)-cyclohexyl-diethylenetriamine-pentaacetic acid (CHX-A″) conjugated to MORAb-009, a mAb directed against mesothelin, and the effect of MORAb dose on the biodistribution of (111)In-labeled MORAb-009. METHODS: We used nude mice bearing the A431/K5 tumor as a mesothelin-positive tumor model and the A431 tumor as a mesothelin-negative control. To find the optimal level of CHX-A″ conjugation, CHX-A″-MORAb-009 conjugates with 2.4, 3.5 and 5.5 CHX-A″ molecules were investigated. To investigate the effect of injected MORAb-009 dose on neutralizing the shed mesothelin in the circulation, biodistribution studies were performed after the intravenous co-injection of (111)In-labeled MORAb-009 (2.4 CHX-A″/MORAb-009) with three different doses: 0.2, 2 and 30 µg of MORAb-009. RESULTS: The tumor uptake in A431/K5 tumor was four times higher than that in A431 tumor, indicating that the tumor uptake in A431/K5 was mesothelin mediated. The conjugate with 5.5 CHX-A″ showed a lower isoelectric point (pI) and lower immunoreactivity (IR) than the 2.4 CHX-A″ conjugate. These differences were reflected in the biodistribution of the (111)In label. The (111)In-labeled MORAb-009 conjugated with 2.4 CHX-A″ produced higher tumor uptake and lower liver and spleen uptakes than the 5.5 CHX-A″ conjugate. The biodistribution studies also revealed that the tumor uptake was significantly affected by the injected MORAb-009 dose and tumor size. The 30-µg dose produced higher tumor uptake than the 0.2- and 2-µg doses, whereas the 30-µg dose produced lower liver and spleen uptakes than the 0.2-µg dose. CONCLUSION: This study demonstrates that the number of chelate conjugation and the injected dose are two important parameters to achieve high tumor and low non-target organ uptake of (111)In-labeled MORAb-009. This study also suggests that the injected dose of mAb could be individualized based on the tumor size or the blood level of shed antigen in a patient to achieve the ideal tumor-to-organ radioactivity ratios.

Flavonoids and isoflavonoids from Sophorae Flos improve glucose uptake in vitro.

Glucose uptake assay-guided fractionations on the methanol extract of Sophorae Flos led to the isolation of the flavonoids rutin (1), narcissin (2), quercetin (3), tamarixetin (4), and kaempferol (5) and the isoflavonoids cajanin (6), genistein (7), orobol (8), and pratensein (9). Among them, 1, 4, 5, 6, 8, and 9 significantly improved basal glucose uptake in HepG2 cells. Their improving effects were concentration dependent. Compounds 4, 5, 6, and 9 exhibited effects stronger than that of rosiglitazone, which has been used as an antidiabetic drug. However, 2, 3, and 7 did not show any improving effects. Stimulating glucose uptake into peripheral cells may be responsible for reducing the level of blood glucose in the circulation. Therefore, these findings demonstrate a potential to develop these flavonoids and isoflavonoids as hypoglycemic drugs.

Sensitivity enhancement of a dynamic mode microcantilever by stress inducer and mass inducer to detect PSA at low picogram levels.

We report two types of signal enhancement strategy derived from the origin of mechanical response, surface stress and mass, of the dynamic mode microcantilever for the detection of PSA at low picogram scales (low femtomolar concentration). The PSA detection at extremely low concentration levels is crucial to the early detection of relapses of prostate cancer after the radical prostatectomy and the detection of breast cancer in patient's serum. There is a clear need for the ultrasensitive detection of PSA via simple and rapid diagnostic tools. From the motives, to increase the sensitivity of the microcantilever, PSA polyclonal antibody (PSA pAb) as an additional surface stress inducer and PSA polyclonal antibody-conjugated silica nanoparticles (pAb-SiNPs) as a mass inducer have been applied to the PSA-captured microcantilevers. From two types of sandwich assay, we could confirm the sensitivity enhancement effects (2 approximately 4 times enhanced at the same concentrations) enough to detect PSA at low picogram levels (LOD of 1 pg/mL or below). Moreover, surface stress due to steric interactions between epitope-specific monoclonal antibodies was assessed to support a signal amplification strategy by stress inducer, and the reduction of signal enhancement due to stiffness increase by the mass inducer was studied to clarify the sensitivity enhancement of the microcantilever by mass inducer.

Multiplex immunoassay using fluorescent-surface enhanced Raman spectroscopic dots for the detection of bronchioalveolar stem cells in murine lung.

Immunoassays using nanomaterials have been rapidly developed for the analysis of multiple biomolecules. Highly sensitive and biocompatible surface enhanced Raman spectroscopy-active nanomaterials have been used for biomolecule analysis by many research groups in order to overcome intrinsic problems of conventional immunoassays. We used fluorescent surface-enhanced Raman spectroscopic dots (F-SERS dots) to detect biomolecules in this study. The F-SERS dots are composed of silver nanoparticle-embedded silica nanospheres, organic Raman tagging materials, and fluorescent dyes. The F-SERS dots demonstrated highly sensitive, selective, and multifunctional characteristics for multiplex targeting, tracking, and imaging of cellular and molecular events in the living organism. We successfully applied F-SERS dots for the detection of three cellular proteins, including CD34, Sca-1, and SP-C. These proteins are simultaneously expressed in bronchioalveolar stem cells (BASCs) in the murine lung. We analyzed the relative expression ratios of each protein in BASCs since external standards were used to evaluate SERS intensity in tissue. Quantitative comparisons of multiple protein expression in tissue were first attempted using SERS-encoded nanoprobes. Our results suggested that immunoassays using F-SERS dots offered significant increases in sensitivity and selectivity. Such immunoassays may serve as the primary next-generation labeling technologies for the simultaneous analysis of multiple biomolecules.

Lipoma arborescens of the glenohumeral joint: a possible cause of osteoarthritis.

Lipoma arborescens is a very rare intra-articular lesion characterized by villous lipomatous proliferation of the synovium, usually involving the knee joint. To date, in the literature, there has been only one reported case of lipoma arborescens in the glenohumeral joint. But, the authors treated the patient conservatively and reported only the magnetic resonance imaging (MRI) findings. We report a case of a patient with lipoma arborescens involving the glenohumeral joint. To our knowledge, this is the first reported case of lipoma arborescens involving the glenohumeral joint managed by arthroscopic synovectomy. We identified reactive bone erosions and arthritic changes in the humeral head in a 22-year-old male patient by arthroscopy.

Multiplex targeting, tracking, and imaging of apoptosis by fluorescent surface enhanced Raman spectroscopic dots.

We have developed multifunctional fluorescent surface enhanced Raman spectroscopic tagging material (F-SERS dots) composed of silver nanoparticle-embedded silica spheres with fluorescent organic dye and specific Raman labels for multiplex targeting, tracking, and imaging of cellular/molecular events in the living organism. In this study, F-SERS dots fabricated with specific target antibodies (BAX and BAD) were employed for the detection of apoptosis. The F-SERS dots did not show any particular toxicity in several cell lines. The F-SERS dots could monitor the apoptosis effectively and simultaneously through fluorescent images as well as Raman signals in both cells and tissues with high selectivity. Our results clearly demonstrate that F-SERS dots can be easily applicable to multiplex analysis of diverse cellular/molecular events important for maintaining cellular homeostasis.

Nematicidal Activity of Cassia and Cinnamon Oil Compounds and Related Compounds toward Bursaphelenchus xylophilus (Nematoda: Parasitaphelenchidae).

The nematicidal activity of two cassia, Cinnamomum cassia, oils (Especial and true), four cinnamon, Cinnamomum zey-lanicum, oils (technical, #500, bark and green leaf), and their compounds (e.g., trans-cinnamaldehyde and trans-cinnamic acid) toward adult Bursaphelenchus xylophilus was examined by a direct contact bioassay. Results were compared with those of 34 related compounds. As judged by 24-hour LC(50) values, two cassia oils (0.084-0.085 mg/ml) and four cinnamon oils (0.064-0.113 mg/ml) were toxic toward adult B. xylophilus. Of 45 test compounds, trans-cinnamaldehyde (0.061 mg/ml) was the most active nematicide, followed by ethyl cinnamate, alpha-methyl-trans-cinnamaldehyde, methyl cinnamate and allyl cinnamate (0.114-0.195 mg/ml). Potent nematicidal activity was also observed with 4-methoxycinnamonitrile, trans-4-methoxycinnamaldehyde, trans-2-methoxy-cinnamaldehyde, ethyl alpha-cyanocinnamate, cinnamonitrile and cinnamyl bromide (0.224-0.502 mg/ml). Structure-activity relationships indicate that structural characteristics, such as types of functional groups, saturation and carbon skeleton, appear to play a role in determining the toxicities to adult B. xylophilus. Cassia and cinnamon oils and test compounds described merit further study as potential nematicides or leads for the control of pine wilt disease caused by B. xylophilus.

Intrapelvic migration of a well-fixed femoral stem after removal of an acetabular cup.

Failure of total hip arthroplasty with central migration of prosthetic components is uncommon. Various pelvis and visceral complications have been reported from intrapelvic migration of the acetabular cup or the cement or from the heat generated by methylmethacrylate polymerization. To our knowledge, we are the first to report intrapelvic migration of a femoral stem causing ipsilateral lower-extremity swelling, pressure sores, and severe bowel symptoms after the removal of the acetabular component.

Nanoparticle probes with surface enhanced Raman spectroscopic tags for cellular cancer targeting.

We have developed biocompatible, photostable, and multiplexing-compatible surface-enhanced Raman spectroscopic tagging material (SERS dots) composed of silver nanoparticle-embedded silica spheres and organic Raman labels for cellular cancer targeting in living cells. SERS dots showed linear dependency of Raman signatures on their different amounts, allowing their possibility for the quantification of targets. In addition, the antibody-conjugated SERS dots were successfully applied to the targeting of HER2 and CD10 on cellular membranes and exhibited good specificity. SERS dots demonstrate the potential for high-throughput screening of biomolecules using vibrational information.

Antioxidant activity of two phloroglucinol derivatives from Dryopteris crassirhizoma.

The rhizome of Dryopteris crassirhizoma NAKAI exhibited significant antioxidant activity, as assessed by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity in vitro. Two phloroglucinol derivatives, flavaspidic acids PB (1) and AB (2), were isolated from the rhizome of D. crassirhizoma by a bioassay-guided fractionation. 1H-, 13C-NMR, and UV analysis were used to determine the structures. Furthermore, the two compounds were tested for their antioxidant activities, such as their DPPH radical scavenging, superoxide radical scavenging, and lipid peroxidation (LPO) inhibitory activities. Compounds 1 and 2 exhibited potent antioxidant activity against the LPO inhibitory test with IC(50) values of 12.9 and 13.1 microM, respectively, compared with alpha-tocopherol (IC(50); 15.6 microM) and butylated hydroxy anisole (BHA, IC(50); 10.8 microM), while the two compounds had a moderated effect on the DPPH radical scavenging activity (IC(50); 71.7, 76.3 microM) as well as superoxide radical scavenging activity (IC(50); 58.6, 64.4 microM). The potent activity of the flavaspidic acids (1, 2) on inhibiting LPO might be due to possible stabilization as a result of chelating with iron.