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Osteomyelitis is difficult to cure, and the rapidly rising morbidity is a thorny problem accompanied by a large number of joint replacement applications. Staphylococcus aureus is the main pathogen of osteomyelitis. Circular RNAs (circRNAs), as emerging noncoding RNAs, play important roles in multiple physiopathological processes which could provide novel insights into osteomyelitis.

Background: The potential functions of circular RNAs (circRNAs) and micro RNAs (miRNAs) in osteosarcoma (OS) have not been fully elucidated. Especially, the behavior and mechanism of immune responses in OS development and progression have not been fully demonstrated. It was reported that circRNAs and miRNAs can serve as biomarkers for the diagnosis, prognosis, and therapy of many cancers. This study aimed to identify novel key serum biomarkers to diagnose and predict metastasis of OS based on the analysis of immune cell infiltration characteristics.Methods: The differentially-expressed circRNAs (DEcircRNAs), differentially-expressed miRNAs (DEmiRNAs),and differentially-expressed mRNAs (DEmRNAs) of human OS were investigated based on the microarray data downloaded from Gene Expression Omnibus (GEO) datasets. Then, we analyzed immune characteristics pattern of tumor-infiltrating immune cells in OS. On this basis, we identified statistically-significant transcription factors and performed pathway enrichment analysis. Subsequently, we constructed protein-protein interaction (PPI) and competitive endogenous RNA (ceRNA) networks. Moreover, the biological characteristic of targets in ceRNA networks was proposed. Finally, the expression and diagnostic capability of these potential biomarkers from ceRNA network were confirmed by RT-qPCR in patients’ serum.Results: Seven differentially-expressed circRNAs (DEcircRNAs), 166 differentially-expressed miRNAs (DEmiRNAs) and 175 differentially-expressed mRNAs (DEmRNAs) were identified in total. The highest level of infiltration in OS patients were M0 macrophages, M2 macrophages and CD8+ T cells. Further, M0 macrophages and CD8+ T cells were showed the largest negative correlation coefficients. These significant immune characteristics pattern of tumor-infiltrating immune cells were revealed by the principal component analysis in OS. Moreover, we found 185 statistically-significant transcription factors in which the main significant molecules show the potential in immunotherapy of OS. Hsa-circ-0010220, hsa-miR-326, hsa-miR-338-3p, and FAM98A from ceRNA networks associated with immune cell infiltration were confirmed as the potential novel biomarkers for OS diagnosis, of which FAM98A could distinguish and predict metastasis. Most importantly, a novel diagnostic model consisting of the four promising biomarkers (hsa-circ-0010220, hsa-miR-326, hsa-miR-338-3p, and FAM98A) was highlighted with 0.928 AUC value.Conclusions: In summary, the potenial serum biomarkers to diagnose and predict metastasis of OS based on the analysis of immune cell infiltration characteristics were found, and a novel diagnostic model consisting of four promising serum biomarkers was proposed firstly. These results provided a new perspective for the immunotherapy of OS.

Background The role of circular RNAs (circRNAs) and microRNAs (miRNAs) in osteosarcoma (OS) development has not been fully elucidated. Further, the contribution of the immune response to OS progression is not well defined. However, it is known that circRNAs and miRNAs can serve as biomarkers for the diagnosis, prognosis, and therapy of many cancers. Thus, the aim of this study was to identify novel key serum biomarkers for the diagnosis and metastatic prediction of OS by analysis of immune cell infiltration and associated RNA molecules. Methods Human OS differentially expressed circRNAs (DEcircRNAs), differentially expressed miRNAs (DEmiRNAs), and differentially expressed mRNAs (DEmRNAs) were identified by analysis of microarray data downloaded from Gene Expression Omnibus (GEO) datasets. Further, characteristic patterns of OS-infiltrating immune cells were analyzed. On this basis, we identified statistically significant transcription factors. Moreover we performed pathway enrichment analysis, constructed protein–protein interaction networks, and devised competitive endogenous RNA (ceRNA) networks. Biological targets of the ceRNA networks were evaluated and potential OS biomarkers confirmed by RT-qPCR analysis of the patients’ serum. Results Seven differentially expressed circRNAs, 166 differentially expressed miRNAs, and 175 differentially expressed mRNAs were identified. An evaluation of cellular OS infiltration identified the highest level of infiltration by M0 macrophages, M2 macrophages, and CD8+ T cells, with M0 macrophages and CD8+ T cells as the most prominent. Significant patterns of tumor-infiltrating immune cells were identified by principal component analysis. Moreover, 185 statistically significant transcription factors were associated with OS. Further, in association with immune cell infiltration, hsa-circ-0010220, hsa-miR-326, hsa-miR-338-3p, and FAM98A were identified as potential novel biomarkers for OS diagnosis. Of these, FAM98A had the most promise as a diagnostic marker for OS and OS metastasis. Most importantly, a novel diagnostic model consisting of these four biomarkers (hsa-circ-0010220, hsa-miR-326, hsa-miR-338-3p, and FAM98A) was established with a 0.928 AUC value. Conclusions In summary, potential serum biomarkers for OS diagnosis and metastatic prediction were identified based on an analysis of immune cell infiltration. A novel diagnostic model consisting of these four promising serum biomarkers was established. Taken together, the results of this study provide a new perspective by which to understand immunotherapy of OS.

Circular RNAs (circRNAs) play important roles in a variety of pathological functions. However, the potential functions and detailed mechanisms of circRNAs in osteosarcoma (OS) have not been fully elucidated. In this study, the circRNA, micro RNA (miRNA), and messenger RNA (mRNA) expression profile of human OS was investigated based on the raw microarray data GSE140256, GSE65071 and GSE16088 in Gene Expression Omnibus (GEO) datasets, and seven differentially-expressed circRNAs (DEcircRNAs), 166 differentially-expressed miRNAs (DEmiRNAs), and 175 differentially-expressed mRNAs (DEmRNAs) were identified in total. FunRich was employed to analyze the differentially-expressed transcription factors on the basis of identified DEmiRNAs. In addition, the Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were used to further study biological functions of the DEmRNAs. Interestingly, post-translational protein modification, collagen-containing extracellular matrix, and single-stranded DNA binding were the most significant pathways enriched for DEmRNAs in GO annotation analysis. Meanwhile, in KEGG pathway enrichment analysis, complement and coagulation cascades, RNA transport and drug metabolism − other enzymes were the most significantly enriched pathways of DEmRNAs in OS. We constructed circRNA-miRNA-mRNA and protein–protein interaction (PPI) networks that may be associated with pathological processes of OS. Finally, we also revealed the pattern of tumor-infiltrating immune cells in OS and further explored the ceRNA networks we constructed in which we found that COL1A1 and RAN were significantly correlated with overall survival in patients with osteosarcoma (p in vivo and reveals a novel idea for understanding the pathogenesis of OS.

Intracellular Staphylococcus aureus (S. aureus) infection is generally persistent, recurrent and difficult to treat due to the poor availability of antibiotics within macrophages cells and the lack of ideal diagnostic markers. Circular RNAs (circRNAs), with covalently closed circular structures, exists in the serum stably and is not easily degraded by nucleases. Besides, circRNAs play a pivotal in the eukaryotic regulation of genes expression and served as biomarkers in variety disease including microbial infections. However, the function of host circRNAs in intracellular S. aureus infection remains largely unclear.In this study, the circRNAs expression profile was investigated by RNA sequencing technology in both S. aureus-infected THP-1 derived macrophages and mock control cells. The differentially expressed circRNAs (DE circRNAs) with a fold-change1.5 (p 0.05) are analyzed using functional pathway clustering prediction. Then, RT-qPCR was performed to verify the top 2 up-regulated circRNAs in the THP-1 cell and human serum samples so as to evaluate the value of circRNAs for S. aureus diagnosis.An intracellular survival THP-1 derived macrophages model of S. aureus infection was established. A total of 5,299 circRNAs were identified in human THP-1 derived macrophages infected with intracellular S. aureus. There were 61 DE circRNAs with a fold-change1.5 (p 0.05) after S. aureus infection. Among them, 22 circRNAs were up-regulated while 39 circRNAs down-regulated. GO and KEGG pathway analysis demonstrated that DE circRNAs were enriched in the processes such as Neurotrophin, Pyruvate metabolism and Notch signaling pathway. Moreover, hsa_circ_0000311 and chr13:43500472-43544806-(novel) were verified to be significantly upregulated in THP-1 derived macrophages and human serum samples between two groups. Finally, the networks of circRNA-miRNA-mRNA based on these two circRNAs were constructed respectively.Our study provides the first profile analysis of host circRNAs involved in intracellular S. aureus infection, which may serve as biomarkers for S. aureus diagnosis and contribute to the understanding of S. aureus evasion mechanisms.

As of April 1, 2021, more than 2.8 million people have died of SARS-CoV-2 infection. In addition, the mutation of virus strains that have accompanied the pandemic has brought more severe challenges to pandemic control. Host microRNAs (miRNAs) are widely involved in a variety of biological processes of coronavirus infection, including autophagy in SARS-CoV-2 infection. However, the mechanisms underlying miRNAs involved in autophagy in SARS-CoV-2 infection have not been fully elucidated. In this study, the miRNA and messenger RNA (mRNA) expression profiles of patients with SARS-CoV-2 infection were investigated based on raw data from Gene Expression Omnibus (GEO) datasets, and potential novel biomarkers of autophagy were revealed by bioinformatics analyses. We identified 32 differentially expressed miRNAs and 332 differentially expressed mRNAs in patients with SARS-CoV-2 infection. Cytokine receptor related pathways were the most enriched pathways for differentially expressed miRNAs identified by pathway analysis. Most importantly, an autophagy interaction network, which was associated with the pathological processes of SARS-CoV-2 infection, especially with the cytokine storm, was constructed. In this network, hsa-miR-340-3p, hsa-miR-652-3p, hsa-miR-4772-5p, hsa-miR-192-5p, TP53INP2, and CCR2 may be biomarkers that predict changes in mild SARS-CoV-2 infection. Some molecules, including hsa-miR-1291 and CXCR4, were considered potential targets to predict the emergence of severe symptoms in SARS-CoV-2 infection. To our knowledge, this study provided the first profile analysis of an autophagy interaction network in SARS-CoV-2 infection and revealed several novel autophagy-related biomarkers for understanding the pathogenesis of SARS-CoV-2 infection in vivo.

To determine reasonable treatment of intertrochanteric fractures with proximal femoral nail anti-rotation (PFNA) or hemi-arthroplasty (HA) in elderly patients. Between January 2009 and June 2013, a total of 367 patients were admitted to the Orthopedics Department of The Second Affiliated Hospital of Soochow University. Patient data were retrospectively analyzed and included 160 males and 207 females. The ages of the patients were between 60 and 97 years and the average age was 72 +/- 3.9 years. According to the Evans-Jensen classification scheme, the fracture types were type IA (n = 18), type IB (n =3 1), type II (n=154), and type III (n = 164). A comparison between the two surgical methods (PFNA and HA) included the duration of surgery, intra-operative blood loss, post-operative weight-bearing time, implant complications, and the Harris hip score. The data were analyzed after 14-50 months (average 24 months) of follow-up. The gender and age of the patients did not differ significantly between the two methods of treatment; however, the duration of surgery between the PFNA hemi-arthroplasty groups did differ (hemi-arthroplasty required less time), the intra-operative blood loss in the PFNA group was significantly less than the hemi-arthroplasty group, and the post-operative weight-bearing time was significantly shorter in the hemi-arthroplasty group than the PFNA group. A retrospective study was conducted in 367 patients during the 42-month study period (January 2009-June 2013) to observe the efficacy of PFNA and hemi-arthroplasty. Complete data were available for analysis. There are significant advantages and disadvantages with respect to the two surgical treatment modalities. For elderly patients with unstable fractures, severe osteoporosis, and pre-operative mobility, hemi-arthroplasty is preferred because hemi-arthroplasty has fewer disadvantages compared to PFNA, which is not suitable for full weight bearing and bone union. PFNA for the treatment of intertrochanteric fractures has been increasingly accepted and widely used; however the use of arthroplasty remains controversial (3). Conservative treatment for intertrochanteric fractures in elderly patients has become a main trend and often takes longer, gives rise to more complications, and has mortality rates higher than surgical treatment.

Osteosarcoma (OS) is the most common type of bone cancer. Even with early diagnosis and aggressive treatment, the prognosis for OS is poor. In the present study, we investigated the proliferation and invasion inhibitory effect of apigenin on human OS cells and the possible molecular mechanisms involved. The cell viability of U2OS and MG63 human OS cell lines was detected by MTT assay. Cell cycle progression and invasion were assessed by flow cytometry and the Matrigel Boyden chamber assay, respectively, and the involvement of molecular mechanisms was examined by western blot analysis. We demonstrated that apigenin inhibited proliferation and reduced invasion in human OS cells, and downregulated the expression of β-catenin in OS cells. Furthermore, the inhibitory effect of apigenin on OS cells was reversed by overexpression of β-catenin, but enhanced by knockdown of β-catenin. Collectively, our results showed that apigenin inhibits the tumor growth of OS cells by inactivating Wnt/β-catenin signaling. Therefore, apigenin is a promising chemotherapeutic agent that may be used in the treatment of human OS.

In this paper, an improved grey model by using Fourier series of error residuals to predict the tendency of ultraviolet protection performance of aging B.mori silk fabric is proposed. The ultraviolet protection factor of B.mori silk fabric under natural weathering was used as the test data set. In addition, the relative percentage error (RPE), the average relative percentage error (ARPE) and the root mean square error (RMSE) were used to compare the performance of the forecast models. The results showed that the improved EFGVM(1,1) model is more accurate and performs better than the traditional GM(1,1) model and grey Verhulst model.

A novel physical blend method was developed to accelerate the self-assembly process of silk fibroin (SF) solution into porous and nanofibrous hydrogel by temperature-sensitive copolymer. Silk-based hydrogel was firstly achieved through blending SF solution with copolymer aqueous solution and then removed the copolymer from blend solution by heat treatment (50°C) after 24 h hydrogelation. Copolymer molecules would interact with SF molecules resulting in reduction of copolymer micelles, which further affect the hydrogelation of SF solutions. Copolymers could be separated from blend solution by heat treatment under an acceptable temperature (50°C), especially the copolymer2. Fourier transform infrared (FTIR) and X-ray diffraction showed the blending of copolymer significantly accelerated the self-assembly of SF into physically crosslinked β-sheet crystals at room temperature which led to the sol-gel transition. Results from DTA and X-ray diffraction showed that the effect of copolymer on crystalline structure of SF in silk-based hydrogel was very weak. SF molecules transformed from distributed globular nanoparticles to nanofilaments clustered during hydrogelation, resulting in the porous and nanofibrous structure of silk-based hydrogel. Furthermore, silk-based hydrogel was prepared in aqueous solution avoiding organic solvents and harsh processing conditions, suggesting that this silk-based hydrogel could be a potential candidate scaffold for biomedical applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Silk fibroin (SF) nanofibers, formed through electrospinning, have attractive utility in regenerative medicine due to the biocompatibility, mechanical properties and tailorable degradability. The mechanism of SF electrospun nanofiber formation was studied to gain new insight into the formation and control of nanofibers. SF electrospinning solutions with different nanostructures (nanospheres or nanofilaments) were prepared by controlling the drying process during the preparation of regenerated SF films. Compared to SF nanospheres in solution, SF nanofilaments had better spinnability with lower viscosity when the concentration of silk protein was below 10%, indicating a critical role for SF morphology, and in particular, nanostructures for the formation of electrospun fibers. More interesting, the diameter of electrospun fibers gradually increased from 50 nm to 300 nm as the increase in concentration of SF nanofilaments in the solution from 6% to 12%, implying size control by simply adjusting SF nanostructure and concentration. Aside from process parameters investigated in previous studies, such as SF concentration, viscosity and electrical potential, the present mechanism emphasizes significant influence of SF nanostructure on spinnability and diameter control of SF electrospun fibers, providing a controllable option for the preparation of silk-based electrospun scaffolds for biomaterials, drug delivery and tissue engineering needs.

To evaluate the difference between RetroButton and Interference Screw in Anterior Cruciate Ligament (ACL) Reconstruction.Ninety-seven patients with ACL rupture were treated by arthroscopic reconstruction with RetroButton and Interference Screw from June 2008 to December 2011. There were 54 males and 43 females with an average age of 27.5 years (range, 18-53 years). The preoperative magnetic resonance imaging (MRI) of all injured knees revealed the rupture of ACL. The average time from injury to surgery was 13.1 days (range, 6-20 days). All the patients were randomly divided into RetroButton group and Interference Screw group. And all the operations were performed under arthroscopy. Patients were instructed to walk with crutches and weight-bearing 4 weeks after operation. Walk without crutches was allowed 6 to 8 weeks after reconstruction and normal daily activities were gradually resumed.The average follow-up was 54.6 months (range 48-60 months). No adverse biological reactions or infection ever occurred. There was no spontaneous rupture or laxity of graft. The average Lysholm knee score[(56.1 ± 7.9) vs (93.1 ± 6.1); (55.3 ± 8.5) vs (93.2 ± 5.7)], KT-1000 examination [(9.2 ± 1.8) vs (2.1 ± 1.4); (9.5 ± 1.7) vs (2.1 ± 1.5)], International Knee Documentation Committee (IKDC) subjective and objective score [(49.7 ± 5.9) vs (91.7 ± 5.0); (50.2 ± 6.3) vs (91.0 ± 6.1)] were improved significantly in both two groups (all P0.01), and there was no significant difference between the two groups [(93.1 ± 6.1) vs (93.2 ± 5.7), P0.05].ACL reconstruction using RetroButton and Interference Screw are simple and effective, and can lead to good ligamentous stability and knee function. The two kinds of fixation methods have no significant difference in short and medium term effect. Long-term follow-up should be performed to confirm the durable stability of the knee.

Irisin, a recently identified myokine, is implicated in protecting mice from obesity. This study was designed to examine the relation of irisin levels in serum and synovial fluid (SF) with the radiographic severity of osteoarthritis (OA).Our study included 215 patients with knee OA. Irisin levels in serum and SF were evaluated using an enzyme-linked immunosorbent assay. The progression of OA was assessed using Kellgren-Lawrence grading system.Knee OA patients had lower serum irisin concentrations and increased serum C-reactive protein (CRP) levels compared with healthy controls. There were markedly decreased irisin levels in both the serum and the SF, as well as increased serum CRP levels of knee OA patients with Kellgren and Lawrence (KL) grade 4 compared with patients classified as KL grade 2 and 3. Furthermore, patients with KL grade 3 showed markedly reduced serum and SF levels of irisin, as well as increased serum CRP levels compared with patients classified as KL grade 2. Irisin levels in serum and SF of knee OA patients were negatively correlated with disease severity evaluated by KL grading criteria.Irisin levels in the serum and SF of knee OA patients were negatively correlated with disease severity evaluated by the radiographic KL grading criteria.

Injectable hydrogels are an important class of biomaterials, and they have been widely used for controlled drug release. This study evaluated an injectable hydrogel formed in situ system by the reaction of a polyethylene glycol derivative with α,β-polyaspartylhydrazide for local cancer chemotherapy. This pH-responsive hydrogel was used to realize a sol-gel phase transition, where the gel remained a free-flowing fluid before injection but spontaneously changed into a semisolid hydrogel just after administration. As indicated by scanning electron microscopy images, the hydrogel exhibited a porous three-dimensional microstructure. The prepared hydrogel was biocompatible and biodegradable and could be utilized as a pH-responsive vector for drug delivery. The therapeutic effect of the hydrogel loaded with doxorubicin (DOX) after intratumoral administration in mice with human fibrosarcoma was evaluated. The inhibition of tumor growth was more obvious in the group treated by the DOX-loaded hydrogel, compared to that treated with the free DOX solution. Hence, this hydrogel with good syringeability and high biodegradability, which focuses on local chemotherapy, may enhance the therapeutic effect on human fibrosarcoma.

Vascularization is fundamental for bone formation and bone tissue homeostasis. However, in human subjects, a direct molecular relationship has not been identified between angiogenesis and agents that promote bone disease or factors related to age. Osteopenia is a condition in which bone mineral density is lower than normal, and it represents a sign of normal aging. Here we tested whether the type H vessel, which was recently identified as strongly positive for CD31 and Endomucin (CD31hiEmcnhi) in mice, is an important indicator of aging and osteopenia in human subjects. We found that age-dependent losses of type H vessels in human bone sections conform to the observations in aged mice. The abundance of human type H vessels and osteoprogenitors may be relevant to changes in the skeletal microarchitecture and advanced osteopenia. Furthermore, ovariectomized mice, a widely used model for postmenopausal osteoporosis, exhibited significantly reduced type H vessels accompanied by reduced osteoprogenitors, which is consistent with impaired bone microarchitecture and osteoporosis, suggesting that this feature is an indicator of bone mass independent of aging. More importantly, administration of desferrioxamine led to significantly increased bone mass via enhanced angiogenesis and increased type H vessels in ovariectomized mice. Altogether, these data represent a novel finding that type H vessels are regulated in aged and osteopenia subjects. The abundance of human type H vessels is an early marker of bone loss and represents a potential target for improving bone quality via the induction of type H vessels.

Great controversy exists regarding the biologic responses of osteoblasts to X-ray irradiation, and the mechanisms are poorly understood. In this study, the biological effects of low-dose radiation on stimulating osteoblast proliferation, differentiation and fracture healing were identified using in vitro cell culture and in vivo animal studies. First, low-dose (0.5 Gy) X-ray irradiation induced the cell viability and proliferation of MC3T3-E1 cells. However, high-dose (5 Gy) X-ray irradiation inhibited the viability and proliferation of osteoblasts. In addition, dynamic variations in osteoblast differentiation markers, including type I collagen, alkaline phosphatase, Runx2, Osterix and osteocalcin, were observed after both low-dose and high-dose irradiation by Western blot analysis. Second, fracture healing was evaluated via histology and gene expression after single-dose X-ray irradiation, and low-dose X-ray irradiation accelerates fracture healing of closed femoral fractures in rats. In low-dose X-ray irradiated fractures, an increase in proliferating cell nuclear antigen (PCNA)-positive cells, cartilage formation and fracture calluses was observed. In addition, we observed more rapid completion of endochondral and intramembranous ossification, which was accompanied by altered expression of genes involved in bone remodeling and fracture callus mineralization. Although the expression level of several osteoblast differentiation genes was increased in the fracture calluses of high-dose irradiated rats, the callus formation and fracture union were delayed compared with the control and low-dose irradiated fractures. These results reveal beneficial effects of low-dose irradiation, including the stimulation of osteoblast proliferation, differentiation and fracture healing, and highlight its potential translational application in novel therapies against bone-related diseases.

The purpose of the present study was to investigate the effects of bafilomycin A1 (BafA1) on proliferation, apoptosis and autophagy in MG63 osteosarcoma cells. The growth rate of MG63 cells was determined using a Cell Counting Kit‑8 assay. The mitochondrial membrane potential (Δψ) was measured using a fluorescent probe, JC‑1, and the inhibition of autophagy and apoptosis was monitored by transmission electron microscopy. In addition, the inhibition of autophagy was monitored by western blot analysis of microtubule‑associated protein 1 light chain 3 (LC3), and the ratio of LC3‑II/LC3‑I protein levels was calculated as an indicator of the extent of autophagy. Furthermore, the expression levels of specific proteins associated with autophagy, including p53, Beclin1 and p62, were detected in cultured MG63 cells by western blotting. It was shown that the viability of MG63 cells was inhibited following the use of BafA1, and an induction in the expression levels of the apoptosis‑related protein p53 and the autophagic protein Beclin1 was detected. Furthermore, a collapse in Δψ was observed, together with an induction of apoptotic cell death, following treatment with BafA1. Therefore, following BafA1‑mediated inhibition of autophagy, the inhibition of MG63 cell proliferation and induction of apoptosis were observed.

Osteosarcoma shows resistance to chemotherapy and many side effects. The ethyl acetate fraction of ethanolic extract of Chrysophyllum cainito was taken in the present work. The extract was characterized for its phenolic content, antioxidant capacity (ferric reducing antioxidant power and 2,2-diphenyl-1-picrylhydrazyl assays), ability to form reactive oxygen species and annexin V assay. The extract contained phenolic content of 30.1 ± 0.2 mg GAE/g extract. Ferric reducing antioxidant power assay and DPPH assay showed 213.2 ± 12.4 mM Fe2+ equivalent per gram extract and 85.6 ± 4.9 TE/g respectively. For production of reactive oxygen species in the osteosarcoma cells, extract at 50 µg GAE/mLconcentration was statistically equivalent to 100 µM H2O2. EC50 of extract was calculated to be 133 µg GAE/mL in cell viability studies.