Ruyan Hou

New triterpenoids and other constituents from a special microbial-fermented tea-Fuzhuan brick tea.

Fuzhuan brick tea, a special microbial-fermented tea prepared from the leaves of Camellia sinensis var. sinensis, is a traditional beverage used in China throughout history. Phytochemical investigation of this material led to the identification of three new triterpenoids, 3beta,6alpha,13beta-trihydroxyolean-7-one (1), 3beta-acetoxy-6alpha,13beta-dihydroxyolean-7-one (2), and 3beta-O-(8-hydroxyoctanoyl)-12-oleanene (3), together with 11 known compounds, friedelin (4), beta-amyrone (5), beta-amyrin (6), alpha-spinasterone (7), alpha-spinasterol (8), 22,23-dihydro-alpha-spinasterone (9), 22,23-dihydro-alpha-spinasterol (10), alpha-phytol (11), alpha-tocopherol (12), alpha-tocoquinone (13), and caffeine (14). The structures of 1-13 were determined by spectroscopic and chemical methods. Compounds 1 and 2 are the first two examples of triterpenoids possessing a 6-hydroxy-7-one function. All of the compounds, except 6, 8, 10, 11, and 14, were isolated from tea and Camellia spp. for the first time. The antibacterial activities of 1 were assessed against some enteric pathogenic microbes. Compound 1 showed no cytotoxic activity against A-549, Bel-7402, and HCT-8 cell lines.

Determination of quality constituents in the young leaves of albino tea cultivars

Albino tea has received increased attention due to its brisk flavour. To identify changes in the key chemical constituents conveying important qualities to albino tea, the metabolite profiles of four albino cultivars and one green tea cultivar were analysed. Compared to the green tea control, significantly decreased contents of chlorophyll (Chl) (p<0.01), total carotenoids (p<0.05), caffeine (p<0.01), and total catechins (p<0.05) were found in albino tea leaves with a few exceptions, whereas increases were noted in the Chl a/b ratio and the contents of both zeaxanthin and free amino acids, including theanine. Multivariate analysis identified catechins and carotenoids as the most important contributors to the metabolic profile variance between the albino and green tea cultivars. High levels of amino acids, along with low levels of chlorophylls, catechins and caffeine, contribute to the qualities of albino tea, which include reduced astringency and bitterness, along with a strong umami taste.

Optimized combination of dilution and refined QuEChERS to overcome matrix effects of six types of tea for determination eight neonicotinoid insecticides by ultra performance liquid chromatography–electrospray tandem mass spectrometry

Liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) is a primary tool for analysis of low volatility compounds in complex matrices. However, complex matrices, such as different types of tea, complicate analysis through ionization suppression or enhancement. In this study, sample preparation by a refined QuEChERS method combined with a dilution strategy removed almost all matrix effects caused by six types of tea. Tea samples were soaked with water and extracted with acetonitrile, cleaned up with a combination of PVPP (160mg) and GCB (20mg), and dried. Dried extracts were diluted with 20mL acetonitrile/water (15:85, v/v) before analysis by UPLC-MS/MS. The average recoveries of eight neonicotinoid insecticides (dinotefuran, nitenpyram, thiamethoxam, imidacloprid, clothianidin, imidaclothiz, acetamiprid, and thiacloprid) ranged from 66.3 to 108.0% from tea samples spiked at 0.01-0.5mgkg(-1). Relative standard deviations were below 16% for all recovery tests. The limit of quantification ranged from 0.01 to 0.05mgkg(-1).

Novel triterpenoid saponins from residual seed cake of Camellia oleifera Abel. show anti-proliferative activity against tumor cells.

Four oleanane-type triterpenoid saponins were isolated from the seed cake of Camellia oleifera Abel.: camelliasaponin B1 and three new saponins, oleiferasaponin C1-C3 (1-3). Their structures were identified as 22-O-angeloyl-camelliagenin B 3-O-[β-d-galactopyranosyl-(1→2)]-[β-d-galactopyranosyl-(1→2)-α-l-arabinopyranosyl-(1→3)]-β-d-glucopyranosiduronic acid methyl ester (1); 22-O-angeloyl-camelliagenin A 3-O-[β-d-galactopyranosyl-(1→2)]-[β-d-glucopyranosyl-(1→2)-β-d-galactopyranosyl-(1→3)]-β-d-glucopyranosiduronic acid methyl ester (2); and 28-O-cinnamoyl-camelliagenin B 3-O-[β-d-galactopyranosylz-(1→2)] [β-d-galactopyranosyl(1→2)-α-l-arabinopyranosyl-(1→3)]-β-d-glucopyranosiduronic acid methyl ester (3) through 1D and 2D NMR, HR-ESI-MS, as well as GC-MS spectroscopic methods. The anti-proliferative activities of these four compounds were investigated on five human tumor cell lines (BEL-7402, BGC-823, MCF-7, HL-60 and KB). Compounds 1 and 2 and camelliasaponin B1 showed significant cytotoxic activities.

Comparison of the dissipation behaviour of three neonicotinoid insecticides in tea.

The dissipation behaviour of three neonicotinoids – thiamethoxam, imidacloprid and acetamiprid – was compared in tea shoots, in Chinese green and black tea, and after tea infusion in hot water. The simple and rapid analytical procedures for the quantification of these three residues in these matrices were developed using HPLC with ultraviolet (UV) detection. Degradation rates in tea shoots of neonicotinoids applied in either recommended or double dosages followed first-order kinetics, with half-lives of 1.62 or 1.58 days for thiamethoxam, of 2.45 or 2.67 days for imidacloprid, and of 3.24 or 3.85 days for acetamiprid, respectively. Through harvest and processing the residue retentions for thiamethoxam, imidacloprid and acetamiprid were 85.0%, 84.1% and 70.6% of the initial dosages in green tea, and 77.1%, 52.4% and 57.4% in black tea. These three residues all showed high transfer rates through green or black tea brewing of 80.5% or 81.6% for thiamethoxam, of 63.1% or 62.2% for imidacloprid, and of 78.3% or 80.6% for acetamiprid. Waiting periods between the last application and harvest of at least 12, 17 and 20 days were suggested for thiamethoxam, imidacloprid and acetamiprid, respectively, after application at their recommend dosages to ensure levels below a maximum residue limit (MRL) of 0.05 mg kg−1.

Effective Extraction Method for Determination of Neonicotinoid Residues in Tea

Sample preparation using an absorbent for removal of polyphenols and a solid-phase extraction (SPE) cartridge for cleanup followed by high-performance liquid chromatography (HPLC) has been investigated for the simultaneous determination of eight neonicotinoid insecticides (dinotefuran, nitenpyram, thiamethoxam, imidacloprid, clothianidin, imidaclothiz, acetamiprid, and thiacloprid). After tea samples were soaked with water and extracted with acetonitrile, sample extracts were treated with an appropriate amount of polyvinylpolypyrrolidone (PVPP) to effectively remove polyphenols. The treated extract was cleaned up with a Carb-PSA cartridge. Neonicotinoid insecticides were eluted with acetonitrile from the cartridge and dried. The extract was redissolved with methanol/water (1:9, v/v) and analyzed by conventional HPLC coupled with an ultraviolet detector. The recoveries of eight neonicotinoid insecticides in tea samples were 71.4-106.6% at 0.1-1.0 mg kg(-1) spiked levels. Relative standard deviations were <10% for all of the recovery tests. The established method was simple, effective, and accurate and could be used for monitoring neonicotinoid insecticides in tea.

Adsorptive removal of fluoride from drinking water using porous starch loaded with common metal ions

In this study, porous corn starch was loaded with Zr, Al, Fe or La to produce the composites PS-Zr, PS-Al, PS-Fe and PS-La. Fluoride adsorption from water was tested at different biosorbent dosages, contact times, solution pH values and initial fluoride concentrations. The biosorbents were characterized by microscopy and spectroscopy. PS-Zr was shown superior defluoridation capacity over a pH range of 3.0-9.0. The adsorption process could be described by the Langmuir isotherm model and the Lagergren pseudo-second-order kinetic model. The maximum fluoride adsorption capacity calculated to be for PS-Zr was 25.41mg/g. Our results revealed that PS-Zr could be employed as an effective biosorbent for removal of fluoride from drinking water.

Analysis of Naturally Occurring Fluoride in Commercial Teas and Estimation of Its Daily Intake through Tea Consumption

The aim of this study was to determine the levels of fluoride in commercial teas and to estimate the contribution of tea consumption to the fluoride recommended daily allowance. A total of 558 tea products in 6 categories, green tea, black tea, oolong tea, puer tea, white tea, and reprocessed tea, were collected in the period from 2010 to 2013. The levels of fluoride in infusions of these teas were determined by a fluoride-ion selective electrode. The mean fluoride level in all of the tea samples was 85.16 mg/kg. For each category of tea, the mean fluoride levels were 63.04, 99.74, 52.19, 101.67, 159.78, and 110.54 mg/kg for green tea, black tea, white tea, puer tea, oolong tea, and reprocessed tea, respectively. The fluoride content of tea from 4 tea zones in descending order were Southernxa0tea zone (111.39 mg/kg) > Southwest tea zone (78.78 mg/kg) > Jiangnan tea zone (71.73 mg/kg) > Jiangbei tea zone (64.63 mg/kg). These areas produced teas with lower fluoride levels than available foreign-produced tea (161.11 mg/kg). The mean chronic daily intake (CDI) was 0.02 mg/(kg•day) or 1.27 mg/kg. Generally, consuming tea from these 6 categories does not result in the intake of excessive amounts of fluoride for the general population.

Novel use of PVPP in a modified QuEChERS extraction method for UPLC-MS/MS analysis of neonicotinoid insecticides in tea matrices

A rapid UPLC-ESI (+)-MS/MS method was developed and validated for simultaneous determination of eight neonicotinoid insecticides (dinotefuran, nitenpyram, thiamethoxam, clothianidin, imidacloprid, acetamiprid, thiacloprid and imidaclothiz) in tea samples based on a refined QuEChERS extraction method. In order to eliminate the matrix effect and obtain satisfactory recoveries, an inexpensive and excellent absorbent material, polyvinylpolypyrrolidone (PVPP), was used to eliminate polyphenols from tea matrices. Further, combinations of PVPP and the commonly used sorbents PSA and GCB were investigated in this study. The optimized ‘quick, easy, cheap, effective, rugged and safe’ protocol is briefly described as follows. Tea samples were soaked in water and extracted with acetonitrile. Sample extracts were treated with 400 mg PVPP to remove polyphenols from tea matrices, and then cleaned up with a combination of PSA (25 mg), GCB (100 mg) and C18 (50 mg). Finally, the dried extract was dissolved in acetonitrile/water (15u2006:u200685, v/v) and analyzed by UPLC-MS/MS. The recovery ratios from tea for eight neonicotinoid insecticides ranged from 60–109% at 0.01–0.5 mg kg−1 spiked levels. Relative standard deviations were <15.4% for all of the recovery tests. The limit of quantification was below 0.01 mg kg−1. The developed method was simple, effective, and sensitive. This method should prove to be highly useful for monitoring neonicotinoid insecticides in commercial tea products.

Two New Oleanane-Type Saponins with Anti-Proliferative Activity from Camellia oleifera Abel. Seed Cake

Two new oleanane-type saponins, named oleiferasaponins C4 (1) and C5 (2), were isolated from Camellia oleifera Abel. seed cake residue. Their respective structures were identified as 16α-hydroxy-22α-O-angeloyl-23α-aldehyde-28-dihydroxymethylene-olean-12-ene-3β-O-[β-d-galacto-pyranosyl-(1→2)]-[β-d-glucopyranosyl-(1→2)-β-d-galactopyranosy-(1→3)]-β-d-glucopyranosid-uronic acid methyl ester (1) and 16α-hydroxy-22α-O-angeloyl-23α-aldehyde-28-dihydroxy-methylene-olean-12-ene-3β-O-[β-d-galactopyranosyl-(1→2)]-[β-d-galactopyranosyl-(1→3)]-β-d-glucopyranosiduronic acid methyl ester (2) through 1D- and 2D-NMR, HR-ESI-MS, and GC-MS spectroscopic methods. The two compounds exhibited potent cytotoxic activities against five human tumor cell lines (BEL-7402, BGC-823, MCF-7, HL-60 and KB).