Growth and saikosaponin production of the medicinal herb Bupleurum chinense DC. under different levels of nitrogen and phosphorus

Dried roots of Bupleurum spp. have been used medicinally in China for over 2000 years. The roots, which are called Bupleuri Radix, are used in at least 66% of the formulations/prescriptions in traditional Chinese medicine and Kampo medicine. Demand for Bupleuri Radix is increasing and B. chinense is one of the most important Bupleurum spp. in China. We conducted a 2-year pot experiment to investigate the effect of nitrogen (N) and phosphorus (P) fertilizer on biomass production and root saikosaponin a (SSa) and saikosaponin d (SSd) content of B. chinense. The experiment included seven combinations of N and P fertilizer. The results showed that medium levels of N and P fertilizer significantly increased the biomass and SSa content of B. chinense roots, but had no significant effect on root SSd content. The application of moderate amounts of N or P fertilizer increased total SSa and SSd yield significantly compared to the unfertilized control, but the greatest increase in total SSa and SSd yield occurred when N and P were applied together. This suggests that N and P have a synergistic effect on B. chinense growth and saikosaponin production. When high amounts of N and P fertilizer were used total SSa and SSd yields declined. This implied that there was a nutrient supply threshold for the biosynthesis of saikosaponins. Total SSa and SSd yields were greater in treatments which received only P fertilizer compared to treatments that received only N fertilizer. Our results reinforce the importance of soil testing and the application of recommended amounts N and P fertilizers for the cultivation of B. chinense. (C) 2008 Elsevier B.V. All rights reserved

Saikosaponin accumulation and antioxidative protection in drought-stressed Bupleurum chinense DC. plants

Dried root of Bupleurum spp. is one of the most popular ingredients in many oriental medicinal preparations. Potted Bupleurum chinense DC. seedlings were subjected to progressive drought stress by withholding irrigation followed by a rewatering phase. The changes in antioxidant system, hydrogen peroxide (H(2)O(2)), superoxide radicals (O(2)(-)), and malondialdehyde (MDA) contents as well as saikosaponin a (SSa) and saikosaponin d (SSd) content in B. chinense roots were investigated. Additionally, the antioxidant activity of the roots extract was evaluated. The results showed that B. chinense root appeared highly resistant to water deficit. Both SSa and SSd content increased with the progressive water deficit, however, decreased tinder severe drought conditions or after water recovery. Moderate drought treatment resulted in 83% increase in SSa content and 22% increase in SSd content compared to the well-hydrated treatment. And increased SSa and SSd content during drought were accompanied by enhanced O(2)(-) content and superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) activity until severe drought stress. Notably, in vitra antioxidant tests demonstrated that the lipid peroxidation inhibition capacity was positively correlated with the content of SSa and SSd, particularly significant at p=0.05 with SSd content. These results suggest that B. chinense roots exhibit effective antioxidative protection mechanism to withstand drought stress. And it could be speculated that drought-induced SSa and SSd accumulation in B. chinense roots may be stimulated via active oxygen species, and consequently involve in mitigating the oxidative damage due to its high anti-lipid peroxidation capacity. (c) 2009 Published by Elsevier B.V

Variation in concentrations of major bioactive compounds in Prunella vulgaris L. related to plant parts and phenological stages

Prunella vulgaris L. (Labiatae) contains a variety of structurally diverse natural products, primarily rosmarinic acid (RA), ursolic acid (UA) and oleanolic acid (OA), which possess a wide array of biological properties. In the present study, P. vulgaris was harvested at three developmental stages (vegetative, full-flowering and mature-fruiting stages), dissected into stem and leaf tissues and assayed for chemical contents using high performance liquid chromatography. Significant changes in the concentrations of the major secondary metabolites (RA, UA and OA) were observed at the different development stages. The highest concentrations of RA, UA and OA were found at the full-flowering stage (15.83 mg/g dry weight (DW) RA, 1.77 mg/g DW UA and 0.65 mg/g DW OA). Among the different aerial parts of the plant, the concentrations of RA, UA and OA were higher in the leaves than in the stems at the different developmental stages. These results suggest that the full-flowering stage is characterized by the highest concentrations of bioactive compounds. Therefore, this stage may be the optimum point for harvesting P. vulgaris plants. In additional, the leaves of P. vulgaris demonstrated higher RA, UA and OA concentrations than the stems, suggesting higher utilization potential

Optimisation of potassium chloride nutrition for proper growth, physiological development and bioactive component production in Prunella vulgaris L.

Prunella vulgaris L. is an important medicinal plant with a variety of pharmacological activities, but limited information is available about its response to potassium chloride (KCl) supplementation. P. vulgaris seedlings were cultured in media with four different KCl levels (0, 1.00, 6.00 and 40.00 mM). Characteristics relating to the growth, foliar potassium, water and chlorophyll content, photosynthesis, transpiration, nitrogen metabolism, bioactive constituent concentrations and yield were determined after three months. The appropriate KCl concentration was 6.00 mM to result in the highest values for dry weight, shoot height, spica and root weight, spica length and number in P. vulgaris. The optimum KCl concentration resulted in a maximum net photosynthetic rate (Pn) that could be associated with the highest chlorophyll content and fully open stomata conductance. A supply of surplus KCl resulted in a higher concentration of foliar potassium and negatively correlated with the biomass. Plants that were treated with the appropriate KCl level showed a greater capacity for nitrate assimilation. The Pn was significantly and positively correlated with nitrate reductase (NR) and glutamine synthetase (GS) activities and was positively correlated with leaf-soluble protein and free amino acid (FAA) contents. Both KCl starvation (0 mM) and high KCl (40.00 mM) led to water loss through a high transpiration rate and low water absorption, respectively, and resulted in increased concentrations of ursolic acid (UA), oleanolic acid (OA) and flavonoids, with the exception of rosmarinic acid (RA). Moreover, the optimum concentration of KCl significantly increased the yields of RA, UA, OA and flavonoids. Our findings suggested that significantly higher plant biomass; chlorophyll content; Pn; stronger nitrogen anabolism; lower RA, UA, OA and flavonoid accumulation; and greater RA, UA, OA and flavonoid yields in P. vulgaris could be expected in the presence of the appropriate KCl concentration (6.00 mM)

Effects of different water management options and fertilizer supply on photosynthesis, fluorescence parameters and water use efficiency of Prunella vulgaris seedlings

BACKGROUND: Prunella vulgaris L. is a medical plant cultivated in sloping, sun-shaded areas in China. Recently, owing to air-environmental stress, especially drought stress strongly inhibits plant growth and development, the appropriate fertilizer supply can alleviate these effects. However, these is little information about their effects on P. vulgaris growing in arid and semi-arid areas with limited water and fertilizer supply. RESULTS: In this study, water stress decreased the photosynthetic pigment contents, inhibited photosynthetic efficiency, induced photodamage in photosystem 2 (PS2), and decreased leaf instantaneous WUE (WUEi). The decreased net photosynthetic rate (Pn) under medium drought stress compared with the control might result from stomatal limitations. However, fertilizer supply improved photosynthetic capacity by increasing the photosynthetic pigment contents and enhancing photosynthetic efficiency under water deficit. Moreover, medium fertilization also increased WUEi under the two water conditions, but fertilizer supply did little to alleviate the PS2 photodamage caused by drought stress. Hence, drought stress was the primary limitation in the photosynthetic process of P. vulgaris seedlings, while the photosynthetic characteristics of the seedlings exhibited positive responses to fertilizer supply. CONCLUSIONS: Appropriate fertilizer supply is recommended to improve photosynthetic efficiency, enhance WUEi and alleviate photodamage under drought stress

Effects of different potassium chloride supplies on net photosynthetic rate (Pn), intercellular CO₂ concentration (C_i), transpiration rate (Tr) and stomatal conductance (Cond) in the leaves of <i>P. vulgaris</i>.

<p>Note: Each value is presented as the mean ± SE (n = 6). Values that are followed by a different letter in the same line are significantly different according to Duncan's multiple range test (<i>P</i><0.05). K0, K1, K2 and K3 indicate 0, 1.00, 6.00 and 40.00 mM KCl, respectively.</p

Effects of different potassium chloride concentrations on the contents of rosmarinic acid (RA), ursolic acid (UA), oleanolic acid (OA) and total flavonoids in the spicas of <i>P. vulgaris</i>.

<p>Note: Each value represents the mean ± SE (n = 3). Values that are followed by a different letter in the same line are significantly different according to Duncan's multiple range test (<i>P</i><0.05). K0, K1, K2 and K3 indicate 0, 1.00, 6.00 and 40.00 mM KCl, respectively.</p

Effects of different potassium chloride supplies on foliar K, water and chlorophyll contents and growth parameters of <i>P. vulgaris</i>.

<p>Note: Each value represents the mean ± SE (n = 10). The values that are followed by the different letter in the same lines are significantly different according to Duncan's multiple range test (<i>P</i><0.05). K0, K1, K2 and K3 indicate 0, 1.00, 6.00 and 40.00 mM KCl, respectively.</p