Preparation and Antioxidative Effects of Soybean Peptides

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Effects of Propolis on Peripheral White Cells, Antioxidative Activity and Tumor Growth in Irradiated mice

The effect of continuous water-soluble propolis administration on radioactivity-induced reduction of hemocytes, and the antioxidant and antitumor effects were investigated. Following a 1-week adjustment period, water-soluble propolis was administered intraperitoneally to male ICR mice at a dose of 100 mg/kg every other day for 2 weeks. Following administration, 2 Gy whole-body irradiation was performed and the counts of leukocytes, lymphocytes, and granulocytes and monocytes in the peripheral blood were determined 1, 3, 7, 15 and 30 days after irradiation. In the second experiment, water-soluble propolis was similarly administered to the mice for 2 weeks after a 1-week adjustment period, and 2 Gy whole-body irradiation was performed. The antioxidant effects in hemocytes were then investigated using 2,2＇-azobis（2-amidinopropane） dihydrochloride （AAPH）, a radical generator. In the third experiment, 1×10^6 Sarcoma-180 cells were inoculated into the right thigh of mice, which were divided into four groups： control, water-soluble propolis-treated, 6 Gy irradiated and water-soluble propolis-treated ＋ 6 Gy irradiated groups, and changes in tumor size were measured for 20 days. Results show that administration of water-soluble propolis inhibits the reduction of hemocytes caused by whole-bodv irradiation, enhances antioxidant effects against radioactivity, and inhibits tumor growth.

Protective effect of long-chain polyunsaturated fatty acids on hepatorenal syndrome in rats

BACKGROUND Hepatorenal syndrome(HRS)is the most prevalent form of acute kidney injury in cirrhotic patients.It is characterized by reduced renal blood flow and represents the most severe complication in cirrhotic patients with advanced disease.Previous research has indicated that antioxidants can delay the onset of a hyperdynamic circulatory state in cirrhosis and improve renal function in HRS patients.Regular omega-3 supplementation has significantly reduced the risk of liver disease.This supplementation could represent an additional therapy for individuals with HRS.AIM To evaluated the antioxidant effect of omega-3 polyunsaturated fatty acid supplementation on the kidneys of cirrhotic rats.METHODS Secondary biliary cirrhosis was induced in rats by biliary duct ligation(BDL)for 28 d.We used 24 male Wistar rats divided into the following groups:I(control);II(treated with omega-3,1 g/kg of body weight);III(BDL treated with omega-3,1 g/kg of body weight);and IV(BDL without treatment).The animals were killed by overdose of anesthetic;the kidneys were dissected,removed,frozen in liquid nitrogen,and stored in a freezer at-80℃for later analysis.We evaluated oxidative stress,nitric oxide(NO)metabolites,DNA damage by the comet assay,cell viability test,and apoptosis in the kidneys.Data were analyzed by one-way analysis of variance,and means were compared using the Tukey test,with P≤0.05.RESULTS Omega-3 significantly decreased the production of reactive oxygen species(P<0.001)and lipoperoxidation in the kidneys of cirrhotic rats treated with omega-3(P<0.001).The activity of the antioxidant enzymes superoxide dismutase and catalase increased in the BDL+omega-3 group compared to the BDL group(P<0.01).NO production,DNA damage,and caspase-9 cleavage decreased significantly in the omega-3-treated BDL group.There was an increase in mitochondrial electrochemical potential(P<0.001)in BDL treated with omega-3 compared to BDL.No changes in the cell survival index in HRS with omega-3 compared to the control group(P>0.05)were observed.CONCLUSION The study demonstrates that omega-3 can protect cellular integrity and function by increasing antioxidant enzymes,inhibiting the formation of free radicals,and reducing apoptosis.

Antibacterial and Antioxidant Effects of Three Chlorogenic Acid Extracts

[Objectives] To study the antibacterial and antioxidant effects of chlorogenic acid extracts of Gynura procumbens,Lonicera japonica,and Eucommia ulmoides leaves,and provide a reference for their usage as natural food preservatives and antioxidants. [Methods]The disc diffusion method was applied to study the antibacterial activity of chlorogenic acid extracts of G. procumbens,L. japonica,and E. ulmoides leaves against several common pathogens. In the antioxidant effects,study was carried out on the anti-lipid peroxidation,reducing capacity,and DPPH free radical scavenging capacity of chlorogenic acid extracts of G. procumbens,L. japonica,and E. ulmoides leaves,respectively.[Results]Three chlorogenic acid extracts had strong inhibitory effects on bacteria,especially the inhibition on Staphylococcus aureus. At the concentration of 100 mg/m L,the bacteriostatic ring of chlorogenic acid extracts of G. procumbens,L. japonica,and E. ulmoides leaves reached 21. 4,23. 6 and 24. 7 mm respectively. Besides,these chlorogenic acid extracts had significant inhibitory effect on Escherichia coli and Salmonella,but the inhibitory effect on the yeast was not obvious; the antibacterial intensity of antibacterial compounds was chlorogenic acid extracts of E. ulmoides > chlorogenic acid extracts of L. japonica > chlorogenic acid extracts of G. procumbens. Among these three chlorogenic acid extracts,the chlorogenic acid extracts of E. ulmoides had higher anti-lipid peroxidation,reducing capacity,and DPPH free radical scavenging capacity than other two chlorogenic acid extracts. [Conclusions] This paper reveals that among chlorogenic acid extracts of G. procumbens,L. japonica,and E. ulmoides leaves,the chlorogenic acid extracts of E. ulmoides leaves have a stronger antibacterial activity and antioxidant activity.

Effects of Chinese Herbal Medicine Feed Additives on Growth Performance and Dietary Nutrient Metabolism of Black-bone Chickens

[Objectives]To study the effects of Chinese herbal medicine feed additives on the growth performance and dietary nutrient metabolic rate of black-one chickens.[Methods]480 pieces of 1-day-old Donglan Black-bone Chickens were selected and divided into 4 groups,with 6 replicates in each group,with 20 pieces in each replicate.Among them,group A was the control group and was fed the basal diet;the groups B,C,and D were the experimental groups,which were separately supplemented with 0.25%,0.50%and 1.00%of Chinese herbal medicine additives in the basal diet,and the experimental period was 70 d.At the end of the feeding experiment,24 experimental chickens with similar body weight were selected from each group,and the same design of the feeding experiment was used to continue to feed the original diet for the metabolic experiment to determine the nutrient metabolic rate.[Results]Except the 50-70 d stage,the average daily gain(ADG)of group B in other stages was increased by 5.00%-9.15%(P<0.05),and the average body weight of group B at 70 d was also increased by 4.86%(P<0.05);the ADG of group C at 36-49,1-49 and 1-70 d and the average individual weight at 70 d were also higher than that of group A by 5.90%,2.66%,2.68%and 2.57%,respectively(P>0.05);at 36-49 d,the average daily feed intake(ADFI)of group A was higher than that of group B by 6.04%(P<0.01),and was also higher than that of groups C and D by 5.12%and 4.13%(P<0.05),respectively;at 1-49 d,the ADFI of group A was higher than that of group C by 2.86%(P<0.05),and there was no significant difference between the four groups of experimental chickens at each stage(P>0.05);at 22-35 and 1-70 d,the feed to gain ratio(F/G)of group B was 6.32%and 3.41%lower than that of group A(P<0.05),and at 36-49 and 1-49 d,the F/G of group B was even lower;at 36-49 d,the F/G of group C was 10.15%lower than that of group A(P<0.05),and at 1-49 d,it was also lower than that of group A by 5.29%(P<0.01);there was no significant difference between the two groups at other stages.In terms of nutrient metabolism:the three different amounts of this additive have increased the metabolic rate of DM,CP,CF,NFE,CA,Ca,P,TE and other nutrients in the diet to varying degrees,especially the addition of 0.25%and 0.50%had the significant increase.[Conclusions]The addition of 0.25%Chinese herbal medicine additives in the diet can significantly improve the growth performance and main nutrient metabolic rate of Donglan Black-bone Chickens.

Polyphenols extracted from Aronia melanocarpa by combined enzymatic and ultrasonication and their antioxidant potential and antimicrobial activity

The extraction of polyphenols from Aronia melanocarpa was carried out using a combination of enzymatic and ultrasound.After single-factor and orthogonal design and experiment,the optimized polyphenol extraction conditions were 1%enzyme,1:40 material-to-liquid ratio,55℃,60 min ultrasonication,70%ethanol,and the final extraction amount was 88.634 mg/g,which displayed a 25.15%and 34.08%improvement compared with the single ultrasonication and enzymatic extraction methods,respectively.Significant antibacterial effects of polyphenols were shown against Staphylococcus aureus,Escherichia coli and Bacillus subtilis.Further antioxidation effects were evaluated,and the superoxide anion radical scavenging rate,hydroxyl radical scavenging rate and DPPH free radical scavenging rate reached 45.2%,83.5%and 85.4%,respectively.This combined enzymatic and ultrasonic extraction method exhibited the advantages of high extraction rate,saving solvent consumption and extraction time,but also provided a new method for the development and utilization of natural antimicrobial and antioxidant health products.

Phenolic profile and chronic gastric ulcer healing effects of Cameroonian propolis

Background:Gastric ulcers continue to affect millions of people worldwide,with reported cases of fatalities and the diagnosis,prevention and treatment constitute a burden on the patients especially in case of chronic ulcers which are difficult to treat.Natural medicines such as propolis provide suitable therapeutic alternatives in the treatment and curation of ulcers.Objective:This work focused on the evaluation of the phenolic profile and healing effect of Cameroonian propolis on gastric ulcers in rats.Methods:Identification and quantification of phenolic compounds in the propolis extract was done using HPLC-DAD.Chronic gastric ulcers were induced using ethanol(70%;1 mL/200 g p.o.)/indomethacin(1 mg/kg p.o.),and“unhealed”gastric ulcerations were induced using acetic acid(30%)/indomethacin(1 mg/kg p.o.).The animals were administered with the vehicle(Tween 20,1 mL/100 g p.o.),propolis extract(200 mg/kg,400 mg/kg and 600 mg/kg p.o.)or sucralfate(50 mg/kg p.o.),once daily for ten to fourteen days.At the end of each treatment period,the animals were sacrificed and ulcer indices,gastric mucus weight,histological and oxidative stress parameters were assessed.Results:Eight phenolic compounds were identified and quantified and most abundant were Caffeic acid(45.31±0.25μg/g),Chrysin(37.65±0.17μg/g)and p-Hydroxy benzoic acid(34.14±0.21μg/g).The treatment of ulcerated rats(chronic and unhealed gastric ulcer models)with propolis extract at 200 mg/kg,400 mg/kg and 600 mg/kg resulted in reduction of ulcer index compared to negative controls in both models.Histological ob-servation of stomach tissues showed that treatment with propolis extract led to a dose-dependent normalization of the mucosa.There was a significant increase(P<0.05;P<0.01 and P<0.001)in mucus weight that accom-panied the healing of the ulcers.Furthermore,doses of 200 mg/kg,400 mg/kg and 600 mg/kg of the propolis extract induced an increase in the amounts of SOD,catalase,nitrite and GSH while MDA concentrations decreased in both models.Conclusion:The healing effect of propolis extract is due to the stimulation of mucus production followed by an improvement of in vivo antioxidant status.These results support the use of propolis in the development of new pharmacological strategies for the management of peptic ulcers disease.

Oxidative Stress and Role of Natural Plant Derived Antioxidants in Animal Reproduction

The experimental knowledge on the role of oxidative stress,and beneficial and detrimental effects of plant derived antioxidants in male and female animal reproduction are reviewed in this article.Free radical-induced oxidative stress in animal reproduction causes great loss to livestock industry.Antioxidant therapy has been implicated to be effective in preventing diseases resulted from oxidative stress.Considering the advantages of lower side effects of natural antioxidants than those of synthetic antioxidants,plants or their extracts have been extensively utilized in animals.Although many advances have been gained on application of plant derived antioxidants in alleviating oxidative stress,debatable issues still exist.Because many opposite effects were observed even using plant extracts containing similar bioactive substances in the same animal species.Therefore,plant derived antioxidants,like free radicals,are ＂double-edged swords＂ in animal reproduction,representing that they may exhibit beneficial or detrimental effects in animal reproduction,including spermatogenesis,semen functions,estrous cycles,ovulation,ovary functions,endometrium,embryo development,and pregnancy.Besides dose-dependent manner as an explanation of plant extracts＇ dual function,future studies are needed to investigate the mechanism of double-edged actions of plant derived antioxidants in different animal reproduction systems.

Research Progress of Mechanism of Action of Resveratrol

Resveratrol is a kind of polyphenolic compound that widely exists in plants and has extensive physiological pharmacological function and is very useful for human health. For the mechanism of action and function of RV, people are doing a variety of groundbreaking researches. Results show that the molecular mechanism of RV is embodied in aspects such as oxidative stress and diseases of neuropathy, anti-oxygenation and pro-oxidant effect and RV target molecule, etc. This article mainly summarized the mechanism of action of resveratrol in these aspects.

Effect of black and white sesame on lowering blood lipids of rats with hyperlipidemia induced by high-fat diet

Sesamum indicum has various biological effects,and this study aimed to investigate its hypolipidemic effect.A hyperlipidemia rat model was established by feeding rats with high-fat diets in this study,then the hyperlipidemia rats were fed with different doses of black and white sesame seeds and black and white sesame kernels.The serum and liver biochemical indicators of the rats were determined,and liver pathology analysis was conducted to evaluate the hypolipidemic effect of sesame.The results showed that the blood lipid of SD(Sprague-Dawley)rats fed with high-fat diet for three weeks was higher than 200 mg/d L,indicating that the hyperlipidemia rat model was successfully established.At the same dose,the final body weights of the rats of white sesame seed and kernel groups were higher than those of the black sesame seed and kernel groups;and the weights of the black and white sesame seed groups were lower than those of the black and white sesame kernel groups.The liver indexes of the normal control group and the experimental groups were significantly lower than the model control group(P<0.05),indicating that black and white sesame seed and kernel could reduce the lipid accumulation on the liver.The malondialdehyde(MDA)values of the liver in the normal control group and the experimental groups were significantly lower than that in the model control group(P<0.05).The total antioxidant capacity(T-AOC),high density lipoprotein cholesterol(HDL-C),glutathione peroxidase(GSH-Px)and total superoxide dismutase(T-SOD)in the liver of each experimental group were significantly higher than those in the model control group(P<0.05).Based on the above results as well as pathological observation and analysis,we found that the black and white sesame seeds and kernels could improve fatty liver lesions and lipid metabolism disorder and could reduce lipid accumulation on the liver,thereby protecting the liver from damage and reducing the risk of fatty liver.Moreover,black and white sesame seeds,black and white sesame kernels can reduce the levels of total cholesterol(TC)and triglyceride(TG)in serum,and high dose of black sesame seeds(30%black sesame seeds)and low dose of black sesame kernels(10%black sesame kernels)were more beneficial for the recovery of hyperlipidemia and fatty liver.The above results indicated that black and white sesame has hypolipidemic effect.

Neuroprotective effect of antioxidant compounds

Neurodegenerative diseases affect millions of individuals worldwide.It has been estimated that the number of patients affected by neurodegenerative diseases such as Alzheimer’s disease（AD）,Parkinson’s disease（PD）,Huntington’s disease（HD）,

Effect of Antioxidants on Endothelial Cell Reactive Oxygen Species (ROD Generation and Adhesion of Leukocytes to Endothelial Cells

Objective To investigatewhether antioxidants inhibit adhesion of leukocytes to endothelium and furthermore, whether all antioxidants regulate NF-KB activation through a redox sensitive mechanism. Methods The effect of the antioxidative substances pyrrolidin dithiocarbamat (PDTC), dichloroisocumarin (DCI), chrysin and probucol on the endothelial leukocyte adhesion were examined under near physiological flow conditions. The antioxidative activity of antioxidants was measured in a DCF fluorescence assay with flow cytometry. The activation of NF-kB in endothelial cells was investigated in a gel shift assay. Results PDTC and probucol did not show an inhibitory effect to the formation of intracellular H2O2 in TNFa activated human vascular endothelial cells (HUVEC) . Chrysin showed a moderate effect. DCI showed a strong antioxidative effect. In contrast, PDTC and chrysin inhibited the adhesion of HL 60 cells to TNFa-stimulated HUVEC. DCI and probucol did not have influence on the adhesion within the area of the examined shear stresses. Only PDTC inhibited the TNFa-induced activation of NF-KB in endothelial cells. Conclusion The inhibition of the endothelial leukocyte adhesion by antioxidative substances is not to be explained by its antioxidative characteristics only. The inhibitory effect of PDTC on NF-KB activation was probably not related to its antioxidative properties. Endothelial cell Antioxidants NF-kappa-B

The response and anti-stress mechanisms of nitrifying sludge under long-term exposure to Cd Se quantum dots

The wide application of CdSe quantum dots(QDs)increases its stress risk to sewage treatment systems.This study evaluated the response of nitrification performance,floc characteristics and microbial community of nitrifying sludge under long-term exposure to CdSe QDs.Results showed CdSe QDs(≥1 mg/L)would decrease the activity of ammonia monooxygenase(AMO).Under the stress of 30 mg/L CdSe QDs,the activity of AMO was reduced by 66%,while the activities of hydroxylamine oxidase and nitrite oxidoreductase were enhanced by 19.1%and 26%,respectively.Thus,the final nitrification effects were not adversely affected,and the production rates of NO_(2)^(-)-N and NO_(3)^(-)-N were accelerated.Additionally,CdSe QDs improved biomass concentration in sludge and maintained the stability of sludge settleability.High throughput sequencing analysis showed that CdSe QDs evidently reduced the abundance and diversity of microbial community in nitrifying sludge.The abundances of amino acid metabolism and lipid metabolism were enriched.Moreover,CdSe QDs decreased the fluorescence intensity of tryptophan-like protein from 2,326 to 1,179 a.u.in loosely bound extracellular polymeric substances(EPSs)and from 3,792 to 3,117 a.u.in tightly bound EPSs.To relieve CdSe QD stress,the polysaccharide content increased from0.31 to 0.61 mg/g MLSS and intracellular antioxidant defense was activated.With CdSe QD level increasing to 30 mg/L,the total antioxygenic capacity and the activities of catalase were enhanced up to 411%and 143.2%,respectively.Thereby,CdSe QDs had little adverse effects on cell membrane integrity,microbial metabolism and the abundance of Nitrospirae.

Senescence accelerated mice(SAM):A model of aging and effects of antioxidants,Toki-shakuyakusan

Senescence accelerated mice (SAMP8) have a shorter lifespan with deficits in learning and memory, compared with control SAMR1 mice (Takeda, Elsevier Science BV, 1994).

Effect of Yisui Shengxue Granule (益髓生血颗粒) on the Oxidative Damage of Erythrocytes from Patients with Hemoglobin H Disease

Objective： To investigate the effect of Yisui Shengxue Granule （益髓生血颗粒, YSSXG）, a complex Chinese medicine, on the oxidative damage of erythrocytes from patients with hemoglobin H （HbH） disease. Methods： Twenty-two patients with HbH disease and 22 healthy volunteers were observed. YSSXG was given to patients with HbH disease for 3 months. Before and after the 3-month treatment, blood parameters [hemoglobin （Hb）, red blood cells （RBCs）, and reticulocyte percent （Ret）] were examined; inclusion bodies in erythrocytes were observed by transmission electron microscopy （TEM）; activities of antioxidant defense enzymes [superoxide dismutase （SOD）, glutathione peroxidase （GSH-Px）, and catalase （Cat）] and erythrocyte membrane malondialdehyde （MDA） concentrations were determined. Results： In patients with HbH disease, measured values of RBC and Hb obtained from the first to the third months after treatment with YSSXG were significantly higher than before treatment （P〈0.01）. Measured values of Ret from the second to the third months aftertreatment were significantly lower than before treatment （P〈0.05 and P〈0.01, respectively）. Prior to treatment with YSSXG, TEM images of RBCs showed the presence of numerous inclusion bodies. After treatment with YSSXG, the amount and volume of inclusion bodies decreased. Treatment with YSSXG also led to a significant increase in SOD activity （P〈0.01）, a decrease in Cat activity （P〈0.01）, and no significant differences in GSH-Px activity （P〉0.05） or MDA concentration （P〉0.05）. However, compared with the healthy counterparts, SOD, GSH-Px, and Cat activities presented at high levels （P〈0.01） both before and after treatment. Conclusions： YSSXG could improve the degree of hemolysis and anemia in patients with HbH disease. The mechanism may be related to its antioxidative effects, which could elevate the activity of total SOD in erythrocytes and efficiently inhibit the oxidative precipitation of β-globin chains.

YGS40, an active fraction of Yi-Gan San, reduces hydrogen peroxide-induced apoptosis in PC12 cells

In our previous study, we have elucidated the chemical profile ofYGS40, a fraction of Yi-Gan San （YGS）, used for the treatment of Alzheimer＇s disease （AD）. Oxidative stress-induced apoptosis is implicated in neurodegenerative disorders such as AD. The aim of the present study was to explore the protective effects of YGS40 against hydrogen peroxide （H202）-induced apoptosis in PC12 cells and the underlying mechanisms. PC12 cells were exposed to 100 μmol·L 1 of H202 for 12 h with or without YGS40 pretreatment. Cytotoxicity was determined by MTT （3, （4, 5-dimethylthiazole-2-yl） 2, 5-diphenyl-tetrazolium bromide） and lactate dehydrogenase （LDH） release assays; apoptosis was detected by Annexin V/propidium iodide coupled staining and by determining caspase-3 activity and Bax and Bcl-2 protein levels. Mitochondrial membrane potential （MMP） was assessed by the retention of rhodamine123; and the activities of superoxide dismutase （SOD） and malondialdehyde （MDA） were measured using commercially available enzymatic kits. Pretreatment with YGS40 significantly prevented H2O2-induced cytotoxicity and protected the cells against H2O2-triggered apoptosis characterized by extemalization of membrane phosphatidylserine and caspase-3 activation and the increased ratio of Bax/Bcl-2 in PC12 cells. Further studies showed that YGS40 suppressed H2O2-induced MMP loss, increased SOD activity, and decreased MDA level. These findings suggest that YGS40 may be beneficial for the prevention and treatment of oxidative stress-mediated disorders.

Determination of flavonoids,polyphenols and antioxidant activity of Tephrosia purpurea:a seasonal study

OBJECTIVE： Tephrosia purpurea （Linn.） Pers. is widely used in traditional medicine to treat liver disorders, febrile attacks, enlargement and obstruction of liver, spleen, and kidney. In the present study investigations were carried out to determine the seasonal impact on the content of flavonoid glycosides and on antioxidant activities so as to identify the optimal time of harvesting. METHODS： The plant materials were collected in different seasons during 2013-2014. Air-dried, powdered plant materials were extracted with 95% ethanol and ethanol：water （1：1 ） by ultrasound-assisted extraction process. Their chemical composition in terms of total polyphenol and flavonoid contents （TPCs and TFCs） was determined using modified colorimetric Folin-Ciocalteu method and aluminum chloride colorimetric assay respectively. To determine the in vitro antioxidant activity, diphenyl-picryl hydrazyl （DPPH） radical-scavenging assay and total antioxidant capacity by phosphomolybdate antioxidant assay were carried out. High-performance liquid chromatography （HPLC）/photo-diode array （PDA） analysis was used to quantify the flavonoid glycosides in the samples collected in different seasons. Correlation studies were also carried out between antioxidant activities and TPCs. RESULTS： The highest TPC and TFC were found to be in the 95% ethanolic extract of the August sample and the lowest in the 50% hydro-alcoholic extract of the plant sample collected in winter season. It was observed that in both the assays used to determine the antioxidant activity, the 95% ethanolic extracts in all the seasons showed a higher activity than their respective 50% hydro- alcoholic extracts with an increase in activity as we go from cold to hot to rainy seasons. Based on correlation analysis, DPPH radical-scavenging activities as well as the spectrophotometrically measured phosphomolybdenum complex were also strongly correlated with TPC of the extracts, The most abundant flavonoid glycoside was quercetin-3-O-rhamnoglucoside in all the seasons. The content of all flavonoids was observed highest in the 95% ethanolic extract of the plant collected in August （TP-3）. The 50% hydro-alcoholic extract of the plant collected in December （TP-6） showed the lowest amount of flavonoids and antioxidant activity. CONCLUSION： The findings of this study confirmed that the metabolism and production of flavonoids in T. purpurea are vigorously affected by seasonal factors. Significant differences were observed in the TPC, TFC and flavonoid glycoside composition in the 95% ethanolic as well as 50% hydro-alcoholic extracts of 7： purpurea collected in different seasons. Since the 95% ethanolic extract of the August sample （TP-3）, which also happens to be its flowering season, exhibited the highest TPC, TFC and antioxidant activities in both DPPH and phosphomolybdate assays as well as contained the highest content of allflavonoids, it could be recommended as the optimal season of harvesting T. purpurea with respect to its pharmaceutically important constituents, i.e., flavonoids.