Tea Aqueous Extract Research Articles

Proteogenomics Study of Blastobotrys adeninivorans TMCC 70007-A Dominant Yeast in the Fermentation Process of Pu-erh Tea.

Blastobotrys adeninivorans plays an essential role in pile-fermenting of Pu-erh tea. Its ability to assimilate various carbon and nitrogen sources makes it available for application in a wide range of industry sectors. The genome of B. adeninivorans TMCC 70007 isolated from pile-fermented Pu-erh tea was sequenced and assembled. Proteomics analysis indicated that 4900 proteins in TMCC 70007 were expressed under various culture conditions. Proteogenomics mapping revealed 48 previously unknown genes and corrected 118 gene models predicted by GeneMark-ES. Ortho-proteogenomics analysis identified 17 previously unidentified genes in B. adeninivorans LS3, the first strain with a sequenced genome among the genus Blastobotrys as well. More importantly, five species specific genes were identified from TMCC 70007, which could serve as a barcode for strain typing and were applicable for fermentation process protection of this industrial species. The datasets generated from tea aqueous extract culture not only increased the proteome coverage and accuracy but also contributed to the identification of proteins related to polyphenols and caffeine, which were considered to change greatly during the microbial fermentation of Pu-erh tea. This study provides a proteome perspective on TMCC 70007, which was considered to be an important strain in the production of Pu-erh tea. The systematic proteogenomics analysis not only made a better annotation on the genome of B. adeninivorans TMCC 70007 as previous proteogenomics study but also provided solution for fermentation process protection on valuable industrial species with species specific genes uniquely identified from proteogenomics study.

Synergetic Effect of Green Tea Aqueous and Alcoholic Extracts with Ciprofloxacin Against some Standard bacterial Strains: In vitro study

Resistance to commonly-prescribed antibiotics is a global public health problem. Unfortunately resistance has been reported even to newer, potent and expensive antimicrobial agents thus, it necessary to find alternative treatment, such as medicinal plants either alone or in combination with antibiotics due to their fewer reported side effects moreover, their possible affordability and availability. Green Tea (GT) has potential benefits in many aspects most notably in cardiovascular diseases, cancer and obesity. The present study designed to investigate the antimicrobial activity of different concentrations of GT aqueous and alcoholic extracts against standard strains of Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923. Moreover, this study provides novel findings about the synergetic activity of GT alcoholic extract and Ciprofloxacin against Staphylococcus aureus ATCC 25923. Two standard antimicrobial susceptibility procedures were used, well diffusion method and broth dilution technique. The clear inhibition zone diameter (IZD) of each extract was measured. The results obtained showed that the GT alcoholic extract had promising antibacterial activity against S. aureus ATCC 25923 only whereas, the two tested strains were resistant to all concentrations of GT aqueous extract. Minimum inhibitory concentration (MIC) and Minimum bactericidal concentration (MBC) of the GT alcoholic extract against S. aureus ATCC 25923 were 225 mg/ml and 250 mg/ml respectively. Moreover, sub-MIC (200mg/ml) of GT alcoholic extract increased the IZD of Ciprofloxacin against S. aureus ATCC 25923 by 62.5 % which confirmed the synergistic effect. Finally, further studies in the GT with other organic solvents are of paramount importance and highly recommended.

Effect of Supplementing laying Japanese quail (Coturnix coturnix japonica) diets with Amla and Green Tea Extracts on the Product Performance and Biochemical Parameters

This study was conducted in the Poultry farm technical-Agriculture research center in Salah Aldeen to investigate amla and green tea extract effect to product performance and some blood parameters on Japanese quail. In total, 300 17 weeks old quail birds were used in this study and were randomly distributed into four treatments (three replicate each treatment (n=25). The treatment groups were control (basal diet) without supplement, 1% green tea extract (GT 1%), 1% amla (AM 1%) and 1% mixed (GT+AM 1%) respectively. The results show that amla extract improved egg production significantly (P≤0.05) compared to control. The egg weight and egg mass were not significant (P<0.05) between each group. Amla aqueous extract (1%) shows a significant difference in feed intake as compared to the control. Hematology traits revealed a significant increase in Red Blood Cell (RBC) and hemoglobin (Hb) in green tea and amla extracts compared with control and a significant difference was observed between the aqueous extract groups and control in PCV % value. The results showed that there are no significant differences between treatments in each of Total Protein, Albumin and Globulin, but the results indicated a significant decrease (P<0.05) of Triglyceride, Cholesterol and Glucose, in the treatments of amla and green tea aqueous extract compare the control treatment.

Gamma irradiated green synthesized zero valent iron nanoparticles as promising antibacterial agents and heavy metal nano-adsorbents

There is an urgent need to synthesize multifunctional high performance nanomaterials using green methods especially for wastewater treatment applications. Zero valent iron nanoparticles (ZVI NPs) were synthesized using a rapid, single step, and completely green method employing aqueous tea extract as both the reducing and capping agent. The synthesized ZVI NPs was further irradiated by 60Co gamma radiation source with a dose of 100 kGy. Both samples before and after irradiation were characterized using XRD, FT-IR, particles size, BET surface area, FESEM and HRTEM techniques. Gamma irradiation caused structural and morphological changes in the ZVI NPs sample. The crystallinity was improved significantly and the spherical particles fused together after radiation forming sheet like morphology. ZVI NPs were tested as nano-adsorbents for the removal of Cu2+ ions from aqueous solutions and as antibacterial agents. Various physicochemical parameters such as pH, dose and initial metal ion concentration were studied. ZVI NPs demonstrated 81.67 % and 97 % removal effeciencies before and after irradiation respectively. Recyclability of the adsorbent shows stable utilization through seven adsorption/desorption cycles. The effect of temperature was investigated on the adsorption process and the thermodynamic parameters were calculated and discussed. The antibacterial activity had been evaluated through MIC (minimum inhibitory concentration), MBC (minimum bactericidal concentration) and Agar disc diffusion method, before and after irradiation. Also for safety evaluation of the ZVI NPs; LD50 was estimated and showed safe use of the ZVI NPs therapy in-vivo. The reported results have significant implications in the area of remediation of water from bacteria with little cost, simple operation, high productivity and easiness of the equipment.

Antibacterial activities and mechanisms of vine tea extract and 2R, 3R-Dihydromyricetin on Escherichia coli

In this study, the antibacterial mechanisms of vine tea aqueous extract (VTE) and 2R, 3R-Dihydromyricetin (DMY) against Escherichia coli (E. coli) were investigated. The results showed they had good antibacterial activities on E. coli, and affected cell membrane and nucleoid. The minimum bactericidal concentrations of VTE and DMY were 3.2 and 1.25 mg/mL, respectively. The constituent leakage tests showed VTE and DMY caused significant increases of extracellular alkaline phosphatase (24.4 ± 0.4% and 5.3 ± 0.1%) and β-Galactosidase (27.6 ± 1.0% and 13.6 ± 0.5%), indicating the membrane integrity might be damaged. The lipids studies showed the ratio of unsaturated fatty acids to saturated fatty acids in treated groups were significant decrease (P < 0.05), indicating the membrane liquidity might be affected. Moreover, fluorescence experiments showed they could cause reduction of more than 82% of the DAPI-DNA and EB-DNA initial fluorescence intensity, indicating VTE and DMY could interacted with DNA through intercalate and grooving bindings. Furthermore, they showed good antibacterial activities in cabbage food model system. All over, the results suggested VTE and DMY might be applied as candidates of food preservatives for their good antibacterial activities and multiple targets.

Comparison of the Antimicrobial Efficacy of Green and Black Tea Extracts Against E.Coli: In Vitro and In Vivo Study -

Green and black tea is one of the most popular beverages consumed worldwide. Moreover, during the last two decades it has received much attention in regard to its beneficial effects on various human health problems .This study aimed to investigate the antibacterial effect of hot and cold extracts of green tea and black tea separately against E. coli and after infecting the burned skin rat with them, also to screen the effect of both types of tea on rat liver and kidney. Sixteen male rats divided into four Groups (4 animals each), Group 1: untreated rat (control). Group 2: burn rats infected with E.coli(1.5×108 bacteria /ml). Group 3: burn treated by Green tea aqueous extract (1000 µg/ml) for E.coli bacteria. Group 4: burn treated by black tea extract (800 µg/ml) for E.coli bacteria. The tea extracts antimicrobial activity was analyzed by agar diffusion inhibition assay and minimum inhibitory concentration. Results exhibited that E. coli in particular, have high levels of resistance against 13 antimicrobial and response only to Imepeneme and Meropenem . Hot watery green tea extract is more effective against bacterial type than cold once. Based on assessment of inhibition zones. E. coli was more sensitive black tea extraction, according to the inhibitions zone. Depending on MIC, we concluded that hot extract from two types of teas have the best antibacterial effect than cold extract demonstrated that the best MIC against E.coli is hot green tea extract (400 µg/ml) then hot black tea extract (600 µg/ml) followed by cold green tea extract (800 µg/ml) and less activity is cold black tea extract (1000 µg/ml). Infected rats showed inflammation and hemorrhage. While treating rats with tea extracts dermally approximately restored kidney normal histological architecture and liver became nearly normal in histological structure. Black tea extract showed greater effectiveness in tissue recovery than green once.

Ameliorating Effect of Green Tea Aqueous Extract against Histo pathophysiological Changes Induced by Ciprofibrate in the liver of Male Albino Rats

Background: The liver is a specific target for drug toxicity because of its role in removal and metabolism of chemicals by converting drugs into another forms that can be readily removed from the body. It is known that the main function of the liver is the elimination of toxins that may enter the body, thus becoming vulnerable damaged during this mechanism, which can be revealed as bleeding, congestion, necrosis or other conditions of liver injury. Ciprofibrate belongs to widely used class of lipid-regulating agents, which stimulate hepatic cells and the hepatic cell becomes uncontrollably divided, causing liver growth. It causes liver cell proliferation in addition to other pleiotropic effects such as peroxisome proliferation and induction of certain peroxisomal and cytosolic enzymes in liver. Objective: The present study aimed to evaluate the potential beneficial effects of green tea aqueous extract administration against the biochemical and histological alterations induced in the liver by ciprofibrate in male rats. Materials and Methods: In the current study 3 groups of 6 male rats were used (Control group, 100mg\Kg body weight, and Cipro 100mg\Kg body weight with green tea). The rats have been treated daily orally by gavages for 21 days. On the last day of the experiment the animals were killed then blood samples and parts from the liver were collected. Liver function was examined for the serum Alanine Aminotransferase (ALT), Aspartate Aminotransferase (AST), alkaline phosphates (ALP), enzyme activities, and serum total &amp; direct bilirubin concentrations. The histopathological investigation was conducted for the liver tissues of all groups. Results: Treatment of male rats with 100 mg\Kg body weight of ciprofibrate caused a significant increase in serum ALT, AST, and ALP activities, total, and direct bilirubin concentration. Histologically, there were histological changes in central vein area and portal zones, revealed congestion in blood sinusoids, necrosis in hepatic cells, and damage in central vein lining epithelium. Co-administration of green tea aqueous extract with Ciprofibrate significantly improved the structural changes in the liver and the serum ALT, AST, and ALP activities, total, and direct bilirubin concentrations were significantly declined. Conclusion: It can be concluded that Ciprofibrate treatment induced elevation in liver function tests and severe histopathological changes and green tea aqueous extract was able to protect the liver against these effects in male rats. So, the patients should be advised to take green tea aqueous extract while they are treated by ciprofibrate.

Protective effect of Moringa oleifera and green tea aqueous extract in combination against beta-cyfluthrin induced mutagenicity in albino rats

The present work was designed to investigate the mutagenicity effect of beta-cyfluthrin in bone marrow of male albino rats and the protective role of the combined aqueous extract of dried leaves of Moringa oleifera (MO) and green tea (GT). Twenty adult male rats were divided randomly into 4 groups, each containing five rats per group. The route of administration was orally gavage for 28 consecutive days. Rats in Group (a) were given distilled water and served as control, rats in Group (b) were given beta-cyfluthrin at a dose of 6.75 mg/kg b.wt (1/20 of estimated LD50). Rats in Group (c) were given aqueous extract of (MO+GT) as the only source of drinking fluid, for 28 days. Rats in Group (d) were given the same doses of group (b) and enabled continuously to an aqueous of (MO+GT) extract as the only source of drinking fluid. Animals were sacrificed humanely at the end of study. The micronucleus and chromosomal aberrations assays were used as mutagenicity tests. The results showed that beta-cyfluthrin administration alone increased the frequency of micronucleated polychromatic erythrocytes (MNPCEs) and induced several of chromosomal aberrations (CAs) in bone marrow cells of treated rats compared to control group. While the aqueous extract of (Mo+GT) in combination against the mutagenic potential of beta-cyfluthrin significantly decrease the (MNPCEs) and (CAs). In conclusion, this study confirmed the genotoxic potential of beta-cyfluthrin but also revealed the strong protective effect of aqueous leaves extract of Moringa oleifera and Green tea in combination as anti-mutagenic agents.

White Tea Reduced Bone Loss by Suppressing the TRAP/CTX Pathway in Ovariectomy-Induced Osteoporosis Model Rats

Osteoporosis is an important skeletal disease characterized by bone weakness and high risk of fracture in postmenopausal women. Tea consumption is known to play an important role in the prevention or alleviation of osteoporosis. However, the therapeutic effects of aqueous extracts of white tea (WT) have not been evaluated in osteoporosis rat models. The aim of this study was to investigate the potential anti-osteoporotic role of WT in ovariectomized (OVX) rats. WT was given orally at 0.5% w/v doses for 12 weeks in OVX rats. Biochemical parameters in blood samples, bone tartrate-resistant acid phosphatase (TRAP), C-terminal telopeptide of type 1 collagen (CTX) and estradiol levels were evaluated. Bone mineral density and bone mineral content values were measured in the left femur. In addition to histopathological examination, osteolcalcin, osteopontin and TUNEL levels were determined. OVX group data demonstrated that bone loss occurred by thinning of the metaphyseal growth plates of the femur. Similarly, the levels of TRAP and CTX, markers of osteoclastic activity, were found to be high concurrently with a decrease in femoral bone mineral density. In addition, increased osteolcalcin and osteopontin levels were present in the metaphyseal growth zones. On the other hand, while TRAP and CTX levels were suppressed in the OVX-WT group, bone mineral content increased. In ad­dition, TUNEL, osteocalcin and osteopontin positivity decreased in the right femoral metaphysis growth zones, proliferating zone and resting zone cells. These results showed that chronic WT consumption has a protective effect by reducing bone resorption in OVX-induced osteoporotic rats.

New HPTLC methods for analysis of major bioactive compounds in mate (Ilex paraguariensis) tea

New HPTLC (high-performance thin-layer chromatography) methods to evaluate major bioactive compounds in mate (Ilex paraguariensis) tea were developed. Identification of compounds was based on HPTLC-MS (high-performance thin-layer chromatography–mass spectrometry), parallel to other techniques. Quantitative evaluation of the main methylxanthines and phenolic compounds in this species was accomplished by two HPTLC methods which can be performed consecutively on one single plate. A solvent system for the separation of the identified saponins is also described for qualitative evaluations. The methods for quantification were validated in terms of: robustness; LOD and LOQ (limits of detection and quantification); repeatability; intra-day and inter-day variation; ruggedness; and accuracy. The methods have proven to be suitable for evaluation of mate tea aqueous and methanolic extracts, with the advantages of: high-throughput; reduced need of plates and application procedures; and high sensitivity – low LODs and LOQs were achieved. Aqueous extracts of nineteen mate teas of different type, geographical origin and age were evaluated in terms of methylxanthines, phenolic compounds and pH. By means of principal component analysis, distinctive characteristics between mate teas could be observed.

Cold plasma decontamination of brown rice grains: Impact on biochemical and sensory qualities of their corresponding seedlings and aqueous tea infusions

Germinated brown rice is nutritionally superior to its ungerminated counterpart. However, germination may allow multiplication of grain-associated contaminants. Therefore, in the present study, the suitability of corona discharge plasma jet (CDPJ) as a disinfectant prior to germination was tested. CDPJ was generated under atmospheric pressure conditions using a 20 kV DC power source and at 1.5 A current. CDPJ treatment of brown rice was found effective in the decontamination of grain contaminants, namely aerobic bacteria as well as yeasts and molds. Moreover, the treatment unaffected germination rate and positively affected the weight and length of their (treated grains) corresponding seedlings. DPPH and ABTS radical scavenging activities as well as total phenolic content of the seedlings were positively influenced by CDPJ treatment. Also, the plasma treatment did not alter the sensory qualities of corresponding aqueous tea infusions. In conclusion, CDPJ could potentially be used for the improvement of microbial quality and safety of brown rice grains, with positive effects on biochemical qualities and no negative effects on sensory characteristics of their corresponding seedlings and aqueous tea infusions.

Effects of Chitosan Coating with Green Tea Aqueous Extract on Lipid Oxidation and Microbial Growth in Pork Chops during Chilled Storage.

Lipid oxidation and microbial growth are the major causes of meat quality deterioration. Natural ingredients in meat products have been proposed as a strategy to prevent quality deterioration during cold storage. This study aimed to assess the effects of added chitosan coating, alone and in combination with green tea water extract (GTWE), on the quality of pork chops during prolonged cold storage. For evaluating oxidative and antimicrobial stabilities, 72 fresh pork samples were subjected to four treatments (n = 18 per treatment): T0 (non-coated chops without GTWE); T1 (chitosan-coated chops without GTWE); T2 (chitosan-coated chops plus 0.1% of GTWE); and T3 (chitosan-coated chops plus 0.5% of GTWE). Pork samples were stored at 0 °C and subjected to physicochemical evaluation (pH, colour, and lipid oxidation) and microbiological analyses (mesophilic and pyschrotrophic counts) at 0, 5, 10, 15, 20 and 25 days of storage. GTWE presented high total phenolic content (> 500 mg gallic acid equivalents/g); the incorporation of chitosan coatings increased (p < 0.05) free radical scavenging activity (FRSA, >90% of inhibition) and microbial growth inhibition (>50% for all tested pathogens), depending on the concentration. Further, GTWE inclusion in pork samples (T2 and T3) reduced (p < 0.05) pH, lipid oxidation and microbial counts, as well as colour loss in meat and bone throughout storage. Chitosan coating with GTWE could be used as an additive for the preservation of pork meat products.

Effective disposal of methylene blue using green immobilized silver nanoparticles on graphene oxide and reduced graphene oxide sheets through one-pot synthesis.

This study reveals the feasibility of exploring highly efficient, cost-effective, and stable green adsorbents for the treatment of contaminated water. Here silver nanoparticles (AgNPs) were immobilized onto nanosheets of graphene oxide (GO) through in situ reduction process using green tea aqueous extract. GO reduction to reduced graphene oxide (rGO) and AgNPs decoration on rGO also occurred simultaneously. The impacts of the extract concentration, contact time, and temperature on the synthesis process have been investigated. The synthesized nanocomposites were examined by XRD, FTIR, Raman, SEM, TEM, and TGA. The GO nanosheets were decorated by AgNPs with a crystalline structure and an average particle size of 25 ± 3nm. The temperature and the extract concentration were considerably affecting the type of the resulting nanocomposites. The GO/Ag nanocomposites were formed at room temperature (27°C) using different extract concentration (2-18% (v/v)), while the rGO/Ag nanocomposite was formed only at a higher temperature (95°C) with higher extract concentration (18%). The methylene blue (MB) dye was picked as a water pollutant to explore the adsorption ability of the nanocomposites. The adsorption behavior of the GO/Ag nanocomposites was examined under diverse factors (MB concentration, adsorbent dosage, pH, and contact time) to achieve optimization. The adsorption data concurs with Langmuir isotherm giving maximum adsorption up to 633mgg-1. Adsorption kinetics demonstrate good pseudo-second-order compliance. Spontaneous and endothermic nature of adsorption was affirmed via thermodynamic parameters. The nanocomposites could be utilized as eco-friendly and reliable adsorbents in wastewater treatment, as a result of their exceptional productivity and reusing potential.

Antibacterial activity of watery and ethanolic extracts of Black Tea and peppermint (In vitrostudy)

Background:The most important medical challenge is the emergence of bacterial resistant to traditional antibiotics. So the need for new pharmaceutical compound derived from daily intake plant material. Mint and black tea used extensively in Arabic area as hot or cold drink &#x0D; Objective: investigate the bacterial activity of mint and black tea aqueous extract against many bacterial genera.&#x0D; Material and methods: from the local market of Baghdad Province, Iraq, dry black tea was obtained; while, peppermint (Mentha piperita L) was harvested from Iraqi plants during April 2020. Active ingredients extracted using either ethanol or water and their antibacterial activity evaluated against Staphylococcus aureus, S.epidermidis, Citrobacter sp and Klebsiella sp using well diffusion agar under invitro laboratory condition.&#x0D; Results: Dried powder of each extract appeared with different color range from brown to black. Results recognized that S. aureus was susceptible to watery and ethanolic extract of both black tea and peppermint extracts. While, S. epidermidis showed resist to both plant extract and solvents used in extraction except minor inhibition with ethanolic extract of tea at 0.3% dose dose. Citrobacter spp gave susceptibility to watery extract of black tea as well as, watery and ethanolic of mint extract. Otherwise, Klebsiella spp. Growth inhibited by watery extract of black tea while, no bioactivity existed upon mint extract treatment. &#x0D; Conclusion: Dose dependent manner existed for watery and ethanolic extracts for both plant material in their antibacterial activity.&#x0D;

Fubrick tea attenuates high-fat diet induced fat deposition and metabolic disorder by regulating gut microbiota and caffeine metabolism.

Fubrick tea aqueous extract (FTEs) has been reported to improve lipid metabolism and gut microbiota communities in mice and humans. However, it is still unclear how FTEs prevents obesity through gut microbiota, and whether some other regulatory mechanisms are involved in the process. Here, we found that FTEs supplementation effectively alleviated the body weight gain, visceral fat accumulation, dyslipidemia, and impaired glucose tolerance induced by a high-fat diet (HFD), and fecal microbiota transplantation (FMT) from FTEs-treated mice showed similar protective effects as FTEs supplementation in mice fed with a HFD. The results confirmed that gut microbiota played key roles in attenuating HFD-induced fat deposition and metabolic disorder. In particular, FTEs reversed HFD-induced gut microbiota dysbiosis via increasing the relative abundances of Bacteroides, Adlercreutzia, Alistipes, Parabacteroides, and norank_f_Lachnospiraceae, and reducing that of Staphylococcus. Interestingly, FTEs could still alleviate HFD-induced lipid accumulation in mice treated with antibiotics, which had increased relative abundances of Bacteroidetes, Bacteroides, and Bacteroides_uniformis sp. In addition, supplementation with FTEs also modified the serum metabolome, especially the "caffeine metabolism" pathway. Furthermore, FTEs supplementation increased the concentrations of caffeine, theophylline, and theobromine in serum, which were positively correlated with an abundance of norank_f_Lachnospiraceae. Overall, FTEs exerts beneficial effects against obesity induced by HFD, and the underlying mechanism is partially related to the reprogramming of intestinal microbiota, while the metabolism of caffeine in FTEs also played an important role in the process. This study provides a theoretical basis for the further study of the anti-obesity effects of FTEs and the consideration of gut microbiota as a potential target for the treatment of obesity induced by a HFD.

The Comparison of Green Tea Aqueous Extract and Catechin Effect on Pituitary-Gonadal Axis in Rat Models of Type 1 Diabetes

The Comparison of Green Tea Aqueous Extract and Catechin Effect on Pituitary-Gonadal Axis in Rat Models of Type 1 Diabetes

Pu-Erh Tea Relaxes the Thoracic Aorta of Rats by Reducing Intracellular Calcium.

Previous studies suggested that pu-erh tea aqueous extract could lower blood pressure and ameliorate hypertension symptoms. However, the antihypertension mechanisms of pu-erh tea remain unclear. In this work, the direct effects of pu-erh tea on vessels and cells were investigated by detecting isometric tension and intracellular calcium ([Ca2+]i), respectively. Additionally, to identify the main active components, the aqueous extract of pu-erh was separated by organic solvents to obtain various fractions, and the effects of these fractions on arteries were assessed. The results showed that pu-erh aqueous extract vasodilated rat thoracic aortas preconstricted by phenylephrine or KCl. These vasodilation effects were not significantly affected by the removal of the endothelium or by preincubation with potassium channel blockers (tetraethylammonium, glibenclamide, aminopyridine, or barium chloride). Moreover, pu-erh aqueous extract could reduce the vessel contractibility induced by CaCl2 and phenylephrine under KCl-depolarizing or Ca2+-free buffer conditions, respectively. Furthermore, pu-erh aqueous extract attenuated the KCl-induced increase in [Ca2+]i in cultured rat aortic smooth muscle A7r5 cells. In addition, the chloroform precipitate of pu-erh aqueous extract produced the most potent vasodilation. Theabrownins (the characteristic components of pu-erh tea) accounted for 41.91 ± 1.09 % of the chloroform precipitate and vasodilated arteries in an endothelium-independent manner. In addition, the vasodilation effect of caffeine was verified. In conclusion, theabrownins and caffeine should be the two main active components in pu-erh tea. Pu-erh aqueous extract vasodilated arteries in an endothelium-independent manner, which might partly be attributed to the decrease in extracellular Ca2+ influx. Moreover, our study provided data on the potential mechanism of the hypotensive actions of pu-erh tea, which might improve our understanding of the effect of pu-erh tea on the prevention and treatment of hypertension.

Catalytic performance of bulk and colloidal Co/Al layered double hydroxide with Au nanoparticles in aerobic olefin oxidation

A Co/Al layered double hydroxide material was synthesized in both bulk and exfoliated (colloidal) forms. Anion exchange with methionine allowed immobilization of Au nanoparticles previously prepared by a biomimetic method using an anti-oxidant tea aqueous extract to reduce the Au salt solution. The catalytic performance of bulk and exfoliated clays Au-hybrid materials was assessed in aerobic olefin epoxidation. Both catalysts were very active towards the epoxide products and with very interesting substrate conversion levels after 80 h reaction time. The Au-exfoliated material, where the nanosheets work as large ligands, yielded higher product stereoselectivity in the case of limonene epoxidation. This arises from a confined environment around the Au nanoparticles wrapped by the clay nanosheets modulating access to the catalytic active centres by reagents. Mechanistic assessment was also accomplished for styrene oxidation by DFT methods.

Caffeine: The Allelochemical Responsible for the Plant Growth Inhibitory Activity of Vietnamese Tea (Camellia sinensis L. Kuntze)

The present study aimed to examine the phytotoxic potential of seven Vietnamese tea samples based on the specific and total activity of caffeine and tea extracts on test plants. The sandwich method results indicated that the inhibitory effect of tea samples on the radicle and hypocotyl growth of lettuce seedlings was dependent on the concentration and type of tea samples, and also the presence of agar soluble allelochemicals. Among the seven tea samples, the leachates from Vinatea-green tea showed the highest inhibition on the radicle growth of lettuce seedlings with 50% suppression at 0.12 mg dry leaves/mL of agar. Caffeine concentration in tea samples analyzed by high-performance liquid chromatography (HPLC) varied from 20.7 to 38.2 µg/mL of dry leaves. The specific activity (EC50 value) of pure caffeine was 75 µg/mL, and the highest total activity of caffeine estimated in Vinatea-green tea was 0.51 [no unit]. Caffeine from green and oolong tea may be considered as one of the contributors to the inhibitory activity of the crude extract. Moreover, the phytotoxicity of pure caffeine and aqueous tea extracts was highly selective on the growth of different plant species. The concentration of caffeine detected from tea farm soil ranged from 0.137 to 0.145 µg/g soil. The results indicated that caffeine might be considered as a promising allelochemical from Vietnamese tea and can be a good candidate for weed management.

Green synthesis of silver nanoparticles using aqueous extract of Stachys lavandulifolia flower, and their cytotoxicity, antioxidant, antibacterial and cutaneous wound‐healing properties

In a biological process where the herbal tea (Stachys lavandulifolia) aqueous extract was applied as a capping and reducing agent, nanoparticles (NPs) of silver (Ag) were synthesized. These AgNPs were characterized using Fourier transform‐infrared spectroscopy, field emission‐scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, transmission electron microscopy and ultraviolet–visible spectroscopy. The synthesized AgNPs had great cell viability dose‐dependently [investigating the effect of the plant on human umbilical vein endothelial cell line] and indicated this method was non‐toxic. In this study, the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) free radical scavenging test was carried out to examine antioxidant properties, which revealed similar antioxidant properties for AgNPs and butylated hydroxytoluene. Agar diffusion tests were applied to determine the antibacterial characteristics. The macro‐broth tube test was run to determine minimum inhibitory concentration. All data of antibacterial and cutaneous wound‐healing examinations were analyzed by SPSS 21 software (Duncan post hoc test). AgNPs showed higher antibacterial property than all standard antibiotics (p ≤ 0.01). Also, AgNPs prevented the growth of all bacteria at 2–8 mg/ml concentrations and destroyed them at 2–16 mg/ml concentrations (p ≤ 0.01). For the in vivo experiment, after creating the cutaneous wound, the rats were randomly divided into six groups: untreated control; treatment with Eucerin basal ointment; treatment with 3% tetracycline ointment; treatment with 0.2% AgNO3 ointment; treatment with 0.2% S. lavandulifolia ointment; and treatment with 0.2% AgNPs ointment. These groups were treated for 10 days. For histopathological and biochemical analysis of the healing trend, a 3 × 3‐cm section was prepared from all dermal thicknesses at day 10. Use of AgNPs ointment in the treatment groups substantially reduced (p ≤ 0.01) the wound area, total cells, neutrophil, macrophage and lymphocyte, and remarkably raised (p ≤ 0.01) the wound contracture, hydroxyl proline, hexosamine, hexuronic acid, fibrocyte and fibrocytes/fibroblast rate compared with other groups. Seemingly, AgNPs can be used as a medical supplement owing to their non‐cytotoxic, antioxidant, antibacterial and cutaneous wound‐healing properties.