Anti-Cancer, Anti-Oxidant and Anti-Inflammatory Effects of Herbacetin and Its Molecular Mechanisms

Rhodiola rosea,a perennial herb of the genus Rhodiola in the Crassulaceae family,is commonly used to treat depression,fatigue,cancer and cardiovascular diseases.Herbacetin is a natural flavonol compound extracted from R.rosea plant,with many pharmacological effects such as anti-cancer effect,anti-oxidant effect and anti-inflammatory effect.In this paper,the pharmacological effects and molecular mechanisms of herbacetin were summarized by consulting domestic and foreign literature,in order to provide a theoretical basis for the development and utilization of herbacetin.

Anti-oxidative stress treatment and current clinical trials

Oxidative stress disturbs the balance between the production of reactive oxygen species(ROS)and the detoxification biological process.It plays an important role in the development and progression of many chronic diseases.Upon exposure to oxidative stress or the inducers of ROS,the cellular nucleus undergoes some biological processes via different signaling pathways,such as stress adaption through the forkhead box O signaling pathway,inflammatory response through the IκB kinase/nuclear factor-κB signaling pathway,hypoxic response via the hypoxia-inducible factor/prolyl hydroxylase domain proteins pathway,DNA repair or apoptosis through the p53 signaling pathway,and antioxidant response through the Kelch-like ECH-associated protein 1/nuclear factor E2-related factor 2 signaling pathway.These processes are involved in many diseases.Therefore,oxidative stress has gained more attraction as a targeting process for disease treatment.Meanwhile,anti-oxidative stress agents have been widely explored in pre-clinical trials.However,only limited clinical trials are performed to evaluate the efficacy of anti-oxidative stress agents or antioxidants in diseases.In this letter,we further discuss the current clinical trials related to anti-oxidative stress treatment in different diseases.More pre-clinical studies and clinical trials are expected to use anti-oxidative stress strategies as disease treatment or dietary supplementation to improve disease treatment outcomes.

Effects of Zn Stress on Zn Accumulation and Anti-Oxidant Enzymes Activity in Four Varieties of Ryegrass

We investigated the influence of different content of Zn^2＋（0, 2, 4, 8, 16 mmol·kg^-1） on plant growth, activities of peroxidase （POD） and superoxide dismutase （SOD）, free proline content and Zn accumulation in four varieties of ryegrass （Loliurn perenne L.） hy pot cuhure experiment. The results showed that plant hiomass increased at the ranges of 0-2 （Tuoya）, 0-4 （Yey- ing）, 0-8 mmol·kg^-1（Airuisi and Taide）, respectively, and then decreased under excess Zn. The activities of POD ,SOD and proline content in shoots decreased firstly, and then increased with the in crease of Zn content. The plaut biomass, activities of POD and SOD in Taide were evidently higher than in the other three varie ties. Root tolerance index （RTI） and Zn transport ratio from root to shoot （S/R） in Taide were exceed 1. 0. The maximum of Zn content was 583.9 mg/kg （ at 16 mmol·kg^-1） in Taide＇s shoot.

Anti-oxidant and anti-inflammatory activities of ultrasonicassistant extracted polyphenol-rich compounds from Sargassum muticum

Polypehnol is an important,potentially bioactive component of Sargassum muticum.In this study,ultrasonic assisted extraction of polyphenol-rich substances was performed using a 38%ethanol solution at a solid:liquid ratio of 1:30 at 68℃ for 32min,determined by single-factor and response surface methodology(RSM)optimization.The content of polyphenol was 5.66mg/g in the crude extract.Further extraction showed that the polyphenol mainly distributed in ethyl acetate(SKEE)and water phases(SKEW).The anti-oxidation test by electron spin resonance(ESR)spectrum showed that the SKEE had the strongest scavenging activity on DPPH(1,1-diphenyl-2-picrylhydrazyl)and alkyl radicals.SKEE was shown noncytotoxic but could inhibit the generation of cellular ROS,showing protective effects in H2O2 and AAPHinduced Vero cells and UV-B irradiated HaCaT cells.SKEE also signifi cantly inhibited the release of NO of LPS-induced RAW 264.7 cells.Therefore,the polyphenol-rich extracts in ethanol and ethyl acetate showed excellent anti-oxidant and anti-infl ammatory activities,which is beneficial to the development of high-value bio-substances.

Sperm quality improvement after natural anti-oxidant treatment of asthenoteratospermic men with leukocytospermia

Aim： To study the immune-modulating and anti-oxidant effects of beta-glucan, papaya, lactoferrin, and vitamins C and E on sperm characteristics of patients with asthenoteratozoospermia associated with leucocytosis. Methods： Fifty-one patients referred to our Sterility Center for semen analysis were selected. Sperm parameters were assessed before and after patient＇s treatment with beta-glucan, lactoferrin, papaya, and vitamins C and E. DNA damage was assessed by the acridine orange test and sperm structural characteristics were evaluated by transmission electron microscopy. Results： After 90 days of treatment, an increase in the percentage of morphologically normal sperm （17.0 ± 5.2 vs. 29.8 ± 6.5） and total progressive motility （19.0± 7.8 vs. 34.8 ± 6.8） were detected. Structural sperm characteristics as well as chromatin integrity were also improved after treatment. In terms of leukocyte concentration in seminal fluid, a significant reduction was recorded （2.2 ± 0.9 vs. 0.9± 0.2）. Conclusion： The treatment of an inflammatory process by the synergic action of immune modulators and anti-oxidants could protect sperm during maturation and migration, leading to improved sperm function. （Asian JAndrol 2008 Mar;. 10： 201-206）

Etomidate affects the anti-oxidant pathway to protect retinal ganglion cells after optic nerve transection

Our previous studies revealed that etomidate, a non-barbiturate intravenous anesthetic agent, has protective effects on retinal ganglion cells within 7 days after optic nerve transection. Whether this process is related to anti-oxidative stress is not clear. To reveal its mechanism, we established the optic nerve transection injury model by transecting 1 mm behind the left eyeball of adult male Sprague-Dawley rats. The rats received an intraperitoneal injection of etomidate(4 mg/kg) once per day for 7 days. The results showed that etomidate significantly enhanced the number of retinal ganglion cells retrogradely labeled with Fluorogold at 7 days after optic nerve transection. Etomidate also significantly reduced the levels of nitric oxide and malonaldehyde in the retina and increased the level of glutathione at 12 hours after optic nerve transection. Thus, etomidate can protect retinal ganglion cells after optic nerve transection in adult rats by activating an anti-oxidative stress response. The study was approved by the Animal Ethics Committee at Air Force Medical University, China(approval No. 20180305) on March 5, 2018.

Anti-Obesity, Anti-Atherosclerotic and Anti-Oxidant Effects of Pu-Erh Tea on a High Fat Diet-Induced Obese Rat Model

Pu-erh tea, a traditional Chinese beverage, has been believed to have many benefits to human health and without side effects. In this study, we systematically analyzed the main active components of Pu-erh tea and investigated its anti-obesity, anti-atherosclerotic and anti-oxidant effects using an obese rat model. Obesity was induced by feeding a high-fat diet and subsequently the experimental obese mice were fed with high-fat diet supplemented with low (2.5%), medium (5%) or high (7.5%) doses of Pu-erh tea powder for 6 weeks respectively. As result, the body weight gain of the rats was decreased by medium and high doses of Pu-erh tea treatments. Furthermore, the levels of serum total cholesterol (TC), triglyceride (TG) and atherosclerosis index (AI) were significantly lowered by Pu-erh tea compared to the control group. Conversely, high density lipoproteincholesterol (HDL-C) level of the rats was significantly elevated by Pu-erh tea treatments. In addition, Pu-erh tea treatments increased the activities of anti-oxidative enzymes such as superoxide dismutase (SOD) and glutathione peroxides (GSH-Px), whereas reduced the level of lipid peroxidation product malondialdehyde (MDA) in obese rats. Collectively, our find-ings revealed that Pu-erh tea exerts comprehensive benefits in anti-obesity, anti-atherosclerotic and anti-oxidant effects, therefore can be used as a promising functional food in obesity management.

Mineral Components and Anti-oxidant Activities of Tropical Seaweeds

Seaweeds are known to hold substances of high nutritional value; they are the richest resources of minerals important to the biochemical reactions in the human body. Seaweeds also hold non-nutrient compounds like dietary fiber and polyphenols. However, there is not enough information on the mineral compounds of tropical seaweeds. Also we are interested in the antioxidant activities of seaweeds, especially those in the tropical area. In this study, Indonesian green, brown and red algae were used as experimental materials with their mineral components analyzed by using an atomic absorption spectrophotometer. The catechins and flavonoids of these seaweeds were extracted with methanol and analyzed by high performance liquid chromatography （HPLC） ; the anti-oxidant activities of these seaweeds were evaluated in a fish oil emulsion system. The mineral components of tropical seaweeds are dominated by calcium, potassium and sodium, as well as small amounts of copper, iron and zinc. A green alga usually contains epigallocatechin, gallocatechin, epigallocatechin gallate and catechin. However, catechin and its isomers are not found in some green and red algae. In the presence of a ferrous ion catalyst, all the methanol extracts from the seaweeds show significantly lower peroxide values of the emulsion than the control, and that of a green alga shows the strongest anti-oxidant extract of this alga, which is significantly different from activity. The highest chelation on ferrous ions is also found in the the other methanol extracts in both 3 and 24 h incubations.

Synthesis, Molecular Structure, Anti-Plasmodial, Antimicrobial and Anti-Oxidant Screening of (E)-1-(Phthalazin-1-yl)-1-[(Pyridin-2-yl)Ethylidene]Hydralazine and 1-[2-(1-(pyridine-3- yl)ethylidene)hydrazinyl]phthalazine

Two new hydralazine hydrochloride-derived Schiff bases: (E)-1-(Phthalazin- 1-yl)-1-[(Pyridin-2-yl)Ethylidene]Hydralazine (PPEH), and 1-[2-(1-(pyridine- 3-yl)ethylidene)hydrazinyl]phthalazine (PEHP), were synthesized and partially characterized by spectroscopic and crystallographic methods including IR and X-ray. The single-crystal X-ray diffraction (SCXRD) analysis of PEHP indicates that the hydralazine moiety of both ligands possesses the exocyclic C=N bond. Both, PPEH and PEHP were tested as antimicrobials and antiparasites. Just PEHP could be considered as slightly antiplasmodial and antibacterial agent. In effect, PPEH showed low antimicrobial activity against one bacterial strain with Minimum Inhibitory Concentration (MIC) value of 250 μg/ml while PEHP showed very interesting activity against 18 out of 19 bacterial strains with MIC of 31.25 - 250 μg/ml compared to the standard drug, amoxicillin. PPEH and PEHP showed higher reducing activity on ferric ions compared to Vitamin C. On the other hand, both hidrazaline synthetized derivatives showed as better reducing agents than Vitamin C on ferric ions, while again, only the PEHP showed slightly high inhibition of lipid peroxidation using Vitamin C as standard. Regarding their catalase activity, both compounds showed concentration dependent effect, but Vitamin C continued showing a higher stimulatory effect on the enzyme activity. Additionally, while PPEH showed less than 80% inhibition in the preliminary antiplasmodial assay and so was not considered for the dose-response studies, PEHP displayed an inhibition percentage of 83.60% and 50% Inhibitory Concentration (IC50) value of 44.13 μg/mL compared to the standard drug, artemisinin and was classified as slightly active.

Oxidants and Anti-Oxidants in Turbot Seminal Plasma and Their Effects on Sperm Quality

In this research, the concentration and activity of oxidants and anti-oxidants in turbot semen, and their effects on sperm quality were studied. The results showed that superoxide dismutase(SOD), catalase, glutathione reductase(GR), uric acid, vitamin E(VE) and vitamin C(VC) were more abundant in seminal plasma than in spermatozoa. The variation for each of them was specific. In seminal plasma, the activity of SOD and GR increased from November 15, November 30 to December 15, and then decreased on December 30. The concentrations of both VC and uric acid decreased during the first 3 sampling times and increased on December 30. The oxidants in seminal plasma accumulated to the highest on December 30. Lactic acid(LA) and ATP levels decreased to the lowest on December 30. The correlation analysis showed that GR had the significant positive relevance to sperm motility and VSL/VCL, while ·OH had negative relevance to them.

Aliskiren Augments the Activities of Anti-Oxidant Enzymes in Liver Homogenates of DOCA Salt-Induced Hypertensive Rats

Hypertension is a serious problem that is recently thought to be associated with damaging effects on target organs partially via oxidative stress. On the other hand, there is accumulating literature describing some sort of therapeutic interaction between antioxidant enzymes in vital organs and hypertension. Therefore, the aim of this study is to investigate the possible effect of a direct renin inhibitor, aliskiren, used in treatment of hypertension via renin-angiotensin-aldosterone system (RAAS), on selected anti-oxidant enzymes in hepatic homogenates in DOCA salt-induced hypertesnive albino rats. Thirty male wister albino rats were assigned randomly into 3 groups (n = 10/ group). Group 1 received no treatement and serves as control. Group 2 received 0.5% carboxymethylcellulose sodium ip as a solvent of aliskiren, as a direct renin inhibitor (DRI). Group 3 received aliskiren 100 mg/kg/day ip for 4 weeks through gastric tube. Systolic blood pressure (SBP) was measured every week and its mean was recorded at the end of the study. Superoxide dismutase (SOD) enzyme in RBCs lysates, activities of catalase (CAT) and glutathione peroxidase enzymes and thiobarbituric acid reactive substance (TBARS), as a marker of lipid peroxidation, in hepatic homogenates were measured at the end of the study. DRI produced a marked reduction in mean SBP of hypertensive rats. It also significantly (p < 0.05) increased the activities of measured anti-oxidant enzymes while it significantly (p < 0.05) reduced TBARS in liver homogenates. These results indicated that renin possesses an oxidative effect in the liver in hypertensive rats. Aliskiren, in addition to its powerful anti-hypertensive effect, it could induce a great anti-oxidant effect in liver homogenates of DOCA salt-hypertensive rats.

Phytochemicals Screening, Phenolic Estimation and Evaluation for Anti-Oxidant, Anti-Inflammatory and Anti-Microbial Activities of Sequentially Soxhlet Extracted Coconut Testa

Background: In many coconut industries, the outer layer of thin brown skin of coconut kernel known as testa is peeled out as a byproduct. Despite the testa is rich in fat and plenty of polyphenolic compounds, it has been underutilized either as animal feed, serving as raw materials for bio-diesel production or discarded directly. Anticipating coconut testa (CT) as a natural source of multiple phyto-chemicals, its exploitation for the pharmacological activity or utilization as value added product is required which may reduce the disposal costs as well. Methods: Secondary metabolites from CT were extracted sequentially with different organic solvents based on polarity in the soxhlet apparatus followed by extraction with sterilized water. The crude dried extracts thus prepared were evaluated for qualitative screening of phytochemicals and quantitative estimation of total phenols, flavonoids and tannin content. Moreover, the antioxidant, anti-inflammatory and anti-microbial activities were also investigated. Results: Phytochemicals screening revealed the presence of polyphenolic compounds in methanolic fraction including phenols (822.60 ± 16.36 mg/g), flavonoids (103.30 ± 9.78 mg/g) and tannin (663.50 ± 19.26 mg/g), whereas non-phenolic compounds were present in other fractions. While methanolic fraction showed invariably the highest anti-oxidant activity in multiple assay methods, non-phenolic compounds in aqueous and chloroform fractions exhibited high anti-inflammatory activity. Antimicrobial activity was observed by both phenolic and non-phenolic compounds. Conclusion: The findings of the study reveal that CT is a rich source of various polyphenolic and non-phenolic natural antioxidants, anti-inflammatory and antimicrobial compounds. These findings are promising and form the basis to identify the number of active components and their characterization.

Comparison of Lipid Peroxidation and Anti-Oxidant Ac-tivities in Pre-Eclamptic &Normal Pregnancies in Nigerian Population

Purpose: To compare the serum malondialdehyde (MDA) and total antioxidant status in women with preeclampsia and normal pregnancy in our environment. Materials & Methods: This was a 3-year, cross-sectional, case control study of 100 preeclamptic and 200 normotensive pregnant women at Ladoke Akintola University of Technology (LAUTECH) Teaching Hospital, Osogbo, Nigeria. The study protocol was reviewed and approved by our Institutional Ethical Review Committee and all participants gave their consent. The fasting serum of recruited patients were analysed for Malondialdehyde (MDA) with rapid, sensitive and specific Thiobarbituric Acid (TBA) assay, while the Total Antioxidant status (TAS) was determined using the capacity of the biological fluids to inhibit the production of thiobarbituric acid reactive substances (TBARS) from sodium benzoate under the influence of the free oxygen radicals derived from Fenton’s reaction. Results: The mean serum MDA was significantly higher in the preeclamptic group (2.96 nmol/ mL) than the value recorded (1.23 nmol/mL) in the control group (P = 0.0001). Conversely, significantly lower mean TAS (0.46 nmol/mL vs 0.62 nmol/mL) was noticed in the preeclamptic group (P = 0.0001). Conclusion: The study showed significant increase in lipid peroxidation and failure of compensatory antioxidant functions in preeclamptic pregnant Nigerian women.

Overall Estimation of Anti-Oxidant Activity by Mammal Macrophage

Super oxide anion had been known as a critical role in a phagocytic cell when microorganisms invade inside. However, this radical seldom need for a clean environment such in a developed country. Moreover, this agent sometimes triggered as serious factor in the site of inflammation. There are many papers which concerned newly found anti-oxidative substances. However, many reports only focused on the molecular basis in vitro, how oxidative stress damaged the human tissue. The key factor for oxidative stress needs to be discussed first for immunological standpoint, such as armed reduction treaty. In other words, minimum armed force is necessary for an invasion by outer or inner irregular cells. On the basis of phagocytic function of the cell in vivo, we tried to access anti-oxidative activity by employing peritoneal murine macrophage and human monocyte. So, the purpose of this study is to establish a conventional but tailor made system for which is useful for evaluating the anti-oxidative activity to different constition. Especially in human peripheral monocyte, the sample was tested each constitution such in granulocyte rich type and lymphocyte rich typ. In order to establish the direct estimation by phagocytic cell, a murine peritoneal exudates cell suspension was obtained after one week of oral administration with anti-oxidative sample. The samples we selected were traditional Chinese medicine, Shi-Quan-Da-Bu-Tang (SDT), Bu-Zong-Ye-Qi-Tang (BYT) and Shao-Chin-Rong-Tang sCRT), Agaricus, Chlorella, and Propolis. The amount of generated super oxide anion was calculated through measuring the optical density change of this supernatant using cytochrome-C which was reduced by generated super oxide anion in the phagocytic cell. The generated super oxide anion after administration of Agaricus, Chlorella, SDT, BYT, sCRT and Propolis were 2.64, 1.95, 1.24, 1.25, 2.88, 2.55 × 10﹣5 mmol/ml, respectively, whereas 2.85 × 10﹣5 mmol/ml in control group. The fermented sample from SDT, BYT, sCRT and microfied Propolis were also tested and the value of super oxide anion were 0.62, 0.84, 1.50 and 2.55 × 10﹣5 mmol/ml, respectively. In this report, we discussed the direct method for measuring the generated super oxide anion of macrophages, especially from different constitution.

The profiles of lipid peroxidation and anti-oxidant activities in gestational diabetes mellitus &normal pregnancies in Nigerian population

Purpose: To compare the Lipid peroxidation and Total antioxidant status in women with gestational diabetes mellitus and normal pregnancy in our environment. Materials & Methods: This was a 2-year, cross sectional, case control study of 25 gestational diabetes mellitus (GDM) and 75 matched normal pregnant women at Ladoke Akintola University of Technology (LAUTECH) Teaching Hospital, Osogbo, Nigeria. The study protocol was reviewed and approved by our Institutional Ethical Review Committee and all participants gave their consents. The fasting serum of recruited patients were analysed for lipid peroxidetion product malondialdehyde(MDA), based on MDA reaction with thiobarbituric acid (TBA), with rapid, sensitive and specific Thiobarbituric Acid (TBA) assay, while the Total Anti-oxidant status (TAS) was determined using the capacity of the biological fluids to inhibit the production of thiobarbituric acid reactive substances (TBARS) from sodium benzoate under the influence of the free oxygen radicals derived from Fenton’s reaction. Results: The mean serum MDA was significantly higher in the GDM group (3.64 nmol/mL) than the value recorded (1.33 nmol/ mL) in the control group (P vs. 0.66 nmol/mL) was noticed in the GDM group (P < 0.0001). Conclusion: The study showed significant increase in lipid peroxidation and failure of compensatory antioxidant functions in GDM Nigerian women.

Carbonic Anhydrase III S-Glutathionylation Is Necessary for Anti-Oxidant Activity

Carbonic anhydrase isozyme CA3 protects cells against oxidative stress. Ectopic expression of murine Ca3, but not Ca2, protects proto-oncogene Evi1 expressing Rat1 fibroblast cells (ca3low) against hydrogen peroxide (H2O2) induced stress. Ca3 is S-glutathionylated via glutathione adducts with cysteines 181 and 186. Substitution of both Ca3 cysteines with serine fails to protect cells from oxidative stress. Insertion of cysteine at 181 and 186 in Ca2 is insufficient for conferring efficient anti-oxidant activity. This shows for the first time that S-glutathionylation of cys181 and cys186 residues is required for Ca3 anti-oxidant activity but that additional factors are also required.

Electrochemical Determination of Rate Constants for Reactions of OH and its Application in the Evaluation of Anti-Oxidant Actions of Rheum

A single-sweep oscillopolarographic procedure is descrital which allows detethenahon of rateconstants for reachons of oH. For a wide range of compounds, the results fit well with rate constantspreviously obtained with other methods. Rate constants for reactions of six kinds of active compoundscontalned in rheum, a tradihonal Chinese herb, have been deteboned by this method. Rcationmechanism ha5 also been discussed.

Effect of BEDGEN 40 on Growth, Anti-Oxidant Activity and Resistance against Aeromonas Hydrophila Infection in Tilapia （Oreochromis niloticus x O. aureus）

The globe artichoke has become important as a medicinal herb in recent years following the discovery of cynarin. This bitter-tasting compound, which is found in the leaves, improves liver and gall bladder function, stimulates the secretion of digestive juices, especially bile, and lowers blood cholesterol levels. The leaves are anticholesterolemic, antirheumatic, cholagogue, digestive, diuretic, hypoglycaemic and lithontripic. BEDGEN 40 , a compound made with Cynara scolymus L. （artichoke） extract and choline chloride was evaluated for growth performance and anti-oxidant activity in tilapia. There were four treatment groups; group 1 was fed only with a basal diet and served as the control, group 2 - 4 were experimental groups that received 150, 300, or 600 mg/kg BEDGEN 40 , respectively, added to the basal diet and fed for 8 weeks. The results showed signifi- cant differences for weight gain, feed conversion, and protein efficiency in fish diets containing 150, 300, or 600 mg/kg BEDGEN 40 compared to the control. Generally, BEDGEN 40 improved the body condition factor and hepatosomatic index of tilapia, and reduced liver fat content. Fish consum- ing BEDGEN 40 also exhibited improved liver antioxidant status. BEDGEN 40 （300, or 600 mg/kg） was also found to significantly reduce the mortality of tilapia subsequently challenged with Aeromonas hydrophila.

Study on Hydrogen Storage Properties,Anti-Oxide Ability and Rate Limiting Step of ZrCr-Based Alloy after Introducing Cobalt as Additive

In this work,the microstructure,hydrogen storage properties,anti-oxide ability and rate limiting step of Zr(Cr_(1−x)Co_(x))_(2)(x=0,0.2,0.4 and 0.6)alloys have been investigated.After studying the crystal structure,we found that all alloy samples could show C14-type phase but the alloy sample x=0 could also show a small amount of Cr phase.Rietveld fitting showed that lattice parameter and unit cell volume of C14-type phase decreased with increasing x.After further research,it was clear that the first hydrogen absorption capacity decreased with increasing x.But introducing more Co content had a positive influence on the effective hydrogen storage capacity and cyclic hydrogen absorption and desorption properties of the alloy sample.We also found that adding Co to ZrCr_(2)alloy could improve its anti-oxide ability.In addition to this,the rate limiting step model was also studied.

Anti-oxidation properties of ZrB_2 modified silicon-based multilayer coating for carbon/carbon composites at high temperatures

To improve the anti-oxidation ability of silicon-based coating for carbon/carbon （C/C） composites at high temperatures, a ZrB2 modified silicon-based multilayer oxidation protective coating was prepared by pack cementation. The phase composition, microstructure and oxidation resistance at 1773, 1873 and 1953 K in air were investigated. The prepared coating exhibits dense structure and good oxidation protective ability. Due to the formation of stable ZrSiO4-SiO2 compound, the coating can effectively protect C/C composites from oxidation at 1773 K for more than 550 h. The anti-oxidation performance decreases with the increase of oxidation temperature. The mass loss of coated sample is 2.44% after oxidation at 1953 K for 50 h, which is attributed to the decomposition of ZrSiO4 and the volatilization of SiO2 protection layer.