Ginkgo Tea Research Articles

Development, Validation, and Application of High-Performance Liquid Chromatography with Diode-Array Detection Method for Simultaneous Determination of Ginkgolic Acids and Ginkgols in Ginkgo biloba.

Ginkgo biloba leaves (GBLs), which comprise many phytoconstituents, also contain a toxic substance named ginkgolic acid (GA). Our previous research showed that heating could decarboxylate and degrade GA into ginkgols with high levels of bioactivity. Several methods are available to measure GA in GBLs, but no analytical method has been developed to measure ginkgols and GA simultaneously. Hence, for the first time, an HPLC-DAD method was established to simultaneously determine GA and ginkgols using acetonitrile (0.01% trifluoroacetic acid, v/v) as mobile phase A and water (0.01% trifluoroacetic acid, v/v) as mobile phase B. The gradient elution conditions were: 0-30 min, 75-90% phase A; 30-35 min, 90-90% phase A; 35-36 min, 90-75% phase A; 36-46 min, 75-75% phase A. The detection wavelength of GA and ginkgol were 210 and 270 nm, respectively. The flow rate and injection volume were 1.0 mL/min and 50 μL, respectively. The linearity was excellent (R2 > 0.999), and the RSD of the precision, stability, and repeatability of the total ginkgols was 0.20%, 2.21%, and 2.45%, respectively, in six parallel determinations. The recoveries for the low, medium, and high groups were 96.58%, 97.67%, and 101.52%, respectively. The limit of detection of ginkgol C13:0, C15:1, and C17:1 was 0.61 ppm, 0.50 ppm, and 0.06 ppm, respectively. The limit of quantification of ginkgol C13:0, C15:1, and C17:1 was 2.01 ppm, 1.65 ppm, and 0.20 ppm, respectively. Finally, this method accurately measured the GA and ginkgol content in ginkgo leaves and ginkgo tea products (ginkgo black tea, ginkgo dark tea, ginkgo white tea, and ginkgo green tea), whereas principal component analysis (PCA) was performed to help visualize the association between GA and ginkgols and five different processing methods for GBLs. Thus, this research provides an efficient and accurate quantitative method for the subsequent detection of GA and ginkgols in ginkgo tea.

Medicinal Values and Potential Risks Evaluation of Ginkgo biloba Leaf Extract (GBE) Drinks Made from the Leaves in Autumn as Dietary Supplements.

Ginkgo tea and ginkgo wine are two familiar Ginkgo biloba leaf extract (GBE) drinks in the form of dietary supplements (DS) used for healthcare in east Asia. Nevertheless, a comprehensive evaluation of their safety and efficacy is still lacking. In this study, GBE drinks were prepared from naturally newly senescent yellow leaves (YL) and green leaves (GL) in autumn. Their total flavonoids, antioxidant capacity and prescribed ingredients were investigated. In brief, the proportions of total flavonoids, total flavonol glycosides (TFs), total terpene trilactones (TTLs) and ginkgolic acids in the GBE drinks all did not meet the standards of worldwide pharmacopoeias. Specifically, the levels of TFs in the ginkgo tea prepared from YL were significantly higher than that prepared from GL. Further analyses revealed a substandard ratio of isorhamnetin/quercetin and an accumulation of leaf-age-related compounds, which were both unqualified. The proportions of specific TTLs varied between the ginkgo tea and ginkgo wine, although no significant differences were detected in terms of the total levels of TTLs. Noticeably, numerous biflavones and thousands of times over the limiting concentration of ginkgolic acids, including newly identified types, were only detected in ginkgo wine. Finally, the use of the GBE drinks as DSs was comprehensively evaluated according to the acceptable daily intake. This study showed the limited healthcare effects of GBE drinks despite their powerful antioxidant capacity.

Amino acid metabolism reprogramming in response to changing growth environment in Ginkgo biloba leaves

Widely distributed in Ginkgo leaves, the amino acids play an important role in the tree growth and Ginkgo products quality determination. Nevertheless, the biosynthesis and accumulation of amino acids have not been fully studied, especially in response to complex environmental conditions. Here, we integrated and analyzed transcriptome and metabolome from Ginkgo leaves originated from clonal homogeneous materials including their different genders (female and male) grown in three different habitats to reveal the environmental response mechanism of amino acid metabolism. Principal component analysis revealed the environmental dependence of amino acid accumulation in Ginkgo leaves, that is, the content of amino acids differed significantly between samples from different environments, while it was similar between female and male samples grown in the same environment. Weighted gene correlation network analysis suggested that the overexpression of structural genes in phenylpropanoid biosynthesis pathway and genes encoding receptor-like kinases, which was regulated by multiple transcription factors, were closely related to the amino acids’ accumulation. Further, we indicated that environmental conditions directly affected the C and N flow allocation in leaves, thereby having an impact on the yield and quality (carbohydrates and amino acids contents) of Ginkgo tea.

Effects of β-glucosidase and α-rhamnosidase on the Contents of Flavonoids, Ginkgolides, and Aroma Components in Ginkgo Tea Drink.

Ginkgo tea is a kind of health food produced from Ginkgo biloba leaves. The market of Ginkgo tea encountered many difficulties because of its bad palatability and vague function statement. In this study, two kinds of glycosidase were used to improve the flavor of Ginkgo tea, and three kinds of bioactivities were selected to investigate the health care function of the tea infusion. The aroma components extracted by headspace absorb (HSA) method during the making of Ginkgo tea were analyzed by GC-MS. The flavonoids and ginkgolides released into the tea infusion were studied by HPLC. A combination of β-glucosidase (β-G) and α-rhamnosidase (α-R) was applied during the making of the tea. The contents of characteristic aroma components and the release of total flavonoids and ginkgolides were increased significantly by adding β-G and α-R. The composition of flavone glycosides was changed greatly. The free radical scavenging, inhibition of inflammatory cell activation, and tumor cytotoxicity activities of the tea were demonstrably improved. According to the release of active components, Ginkgo tea can be brewed repeatedly for at least three times. The enzymes used here show potential application prospects in the making of Ginkgo tea or tea drink to get higher contents of flavonoids, ginkgolides, and aroma components.

Soil microbiological properties and enzyme activity in Ginkgo–tea agroforestry compared with monoculture

Agroforestry practice is believed to be an effective means of maintaining and improving soil fertility, and is widely used by farmers around the world. To gain better understanding of the effects of agroforestry practice on soil fertility, the organic carbon content, total nitrogen content, microbial biomass, basal respiration, and activity of soil enzymes at three soil depths (0–10, 10–20, and 20–30 cm) of Ginkgo (Ginkgo biloba L.)–tea (Camellia sinensis (L.) O. Kuntze) agroforestry systems were investigated. Study plots were established in Yushan Farm in Changshu, Jiangsu Province, China. These involved two densities of Ginkgo trees mixed with tea (G1 and G2) and monoculture tea systems (G0). The results showed that C, N, microbial biomass, and enzyme activity were higher in surface soil than in soil from the middle and lower layers whereas pH and metabolic quotient increased with soil depth. pH, microbial biomass C, N, basal respiration, and catalase and invertase activity in the 0–10 cm layer were significantly lower for G0 than for G1 and G2. Polyphenoloxidase activity in the 0–10 cm layer was significantly lower for G2 than for G0 and G1. Metabolic quotient in the 20–30 cm layer was significantly higher for G0 than for G2. The activity of soil enzymes, including catalase, dehydrogenase, urease, protease, and invertase, significantly and positively correlated with soil organic carbon and total nitrogen. The results of this study suggest that growing tea with Ginkgo could be regarded as good agroforestry practice which could enhance accumulation of organic matter in soil, improve the activity of soil enzymes, and maintain soil productivity and sustainability.

Ginkgo as a Green Reducing Agent for Gold Nanoparticles and Nanoplatelets

ABSTRACT Ginkgo leaf tea has been used as a reducing agent for gold nanoparticles and nanoplatelets. Synthesis is performed via direct heating and microwave heating. Anisotropic nanoplatelet formation is diminished in favor of isotropic nanoparticle formation as the reaction temperature is increased via direct heating. When microwave mediation is used, the extinction spectra indicate less difference among the sols, suggesting athermal effects. Molecular weight filtration studies of the ginkgo tea and the microwave-mediated heating results indicate that the reducing agent in the ginkgo leaf tea is a large molecule, like a protein, rather than a small molecule, like a simple sugar.

Isolation of medically important fungi from <italic>Ginkgo biloba</italic> leaves and crude ginkgo supplements

We observed fungal growth in Ginkgo biloba leaves in the middle of the growth season and isolated Phoma sp. and Curvularia sp. from the affected leaves. We also isolated Aspergillus sp. and Curvularia sp. from brown spots of apparently healthy leaves; Aspergillus sp., Chaetomium sp., Fusarium sp., Penicillium sp. and Aureobasidium sp. from tissue explants from brown spots of Ginkgo tea flakes (from three different suppliers); and Chaetomium sp., Penicillium sp., Aspergillus sp. and Aureobasidium pululans from cold-brewed Ginkgo flake tea (from one supplier). Fungus was not recovered from any of the eight samples of hot-brewed (at 75°C or 90°C for 5 minutes) Ginkgo tea tested, coldor hot-brewed powdered Ginkgo tea (from two suppliers) and three different brands of Ginkgo tea bags. This data indicated that G. biloba leaves and crude supplements derived from crushed Ginkgo leaves could be contaminated by fungi known to be opportunistic pathogens. Name of the department and institution or hospital where the work was done: Department of Biology, Utah Valley University, Orem, UT 84058, USA The source of any support received: Partially supported by a grant from UVSC Foundation, Orem, UT to RHK.