Research progress on pesticide residues of Panax ginseng / 中国中药杂志

Panax ginseng, a perennial herb, is prone to diseases and insect pests in the growth process, which are primarily prevented and treated by pesticides. However, due to the lack of standardization in the types, frequencies, and doses of pesticides, pesticide residues have become the main exogenous pollutants of P. ginseng. To explore the risk of pesticide residues in P. ginseng, this paper summarized and analyzed the common pesticide residues in P. ginseng, detection techniques, and pesticide residue limit stan-dards based on the published literature in recent years. The results revealed that the main pesticide residues in P. ginseng were organochlorine pesticides, such as tetrachloronitrobenzene, pentachloronitrobenzene, and hexachlorobenzene, and the detection techniques were dominated by gas chromatography(GC), liquid chromatography(LC), or those combined with mass spectrometry(MS). Because of the long half-life and difficulty in degradation, organochlorine pesticides have become the main factor affecting the export of P. ginseng. It is worth mentioning that P. ginseng has been classified as food in Japan, South Korea, the European Union, and other countries, and the standards of pesticide residues and limits are stricter than those in China. The quality and safety of P. ginseng are prerequisites for the efficacy of Chinese medicine and the development of traditional Chinese medicine. The formulation of scientific and effective standards for pesticide application and limits would promote the high-quality development of the P. ginseng industry.

Effects of magnesium supply level on growth, nutrient element absorption and distribution, and quality of Panax quinquefolium / 中国中药杂志

This study aims to investigate the effects of different magnesium supply levels on the growth, nutrient absorption and distribution, and quality of Panax quinquefolium, and to determine the optimum content of exchangeable magnesium in soil. Three-year-old plants of P. quinquefolium were used in this study, and eight magnesium supply gradients(CK, Mg1-Mg7) were designed for indoor pot experiment(cultivation in soil). The plant growth indexes, nutrient element content in soil and plant, and root saponin content were determined at the end of the growth period. The correlation analysis of nutrient element content in aboveground and underground parts of P. quinquefolium showed significantly negative correlations of magnesium-calcium, magnesium-potassium, and magne-sium-manganese. With the increase in magnesium supply level, the biological absorption coefficient of magnesium increased, while that of total nitrogen, potassium, iron, and manganese decreased; the biological transfer coefficient of magnesium decreased, while that of nitrogen, phosphorus, calcium, iron, and manganese increased. The saponin content was analyzed by principal component analysis, which showed the comprehensive score in the order of Mg4(2.537), Mg2(1.001), Mg3(0.600), Mg1(0), Mg7(-0.765), CK(-0.825), Mg6(-0.922), and Mg5(-1.663). The partial least squares-path modeling(PLS-PM) showed that the correlation coefficients of exchangeable magnesium and pH with quality were-0.748 and-0.755, respectively, which were significant. Magnesium-calcium, magnesium-potassium, and magnesium-manganese showed antagonism in the nutritional physiology of P. quinquefolium. Excessive application of magnesium can lead to the imbalance of nutrient elements in P. quinquefolium. The content of exchangeable magnesium in soil suitable for the quality formation of P. quinquefolium was 193.34-293.34 mg·kg~(-1). In addition to exchangeable magnesium, pH was also important to the quality formation of P. quinquefolium. Therefore, exchangeable magnesium and pH could be regarded as monitoring factors for the quality formation of P. quinquefolium.

Progress of studies on ATP-binding cassette transporters and transportation of secondary metabolites in medicinal plants / 中国中药杂志

ATP-binding cassette(ABC) transporters are one of the largest protein families in organisms, with important effects in regulating plant growth and development, root morphology, transportation of secondary metabolites and resistance of stress. Environmental stress promotes the biosynthesis and accumulation of secondary metabolites, which determines the quality of medicinal plants. Therefore, how to improve the accumulation of secondary metabolites has been a hotspot in studying medicinal plants. Many studies have showed that ABC transporters are extremely related to the transportation and accumulation of secondary metabolites in plants. Recently, with the great development of genomics and transcriptomic sequencing technology, the regulatory mechanisms of ABC transporters on secondary metabolites have attached great attentions in medicinal plants. This paper reviewed the mechanisms of different groups of ABC transporters in transporting secondary metabolites through cell membranes. This paper provided key theoretical basis and technical supports in studying the mechanisms of ABC transporters in medicinal plant, and promoting the accumulation of secondary metabolites, in order to improve the quality of medicinal plants.

Anti-obesity effects of alpha-lipoic acid mediated by suppression of hypothalamic AMP-activated protein kinase.

AMP-activated protein kinase (AMPK) functions as a fuel sensor in the cell and is activated when cellular energy is depleted. Here we report that alpha-lipoic acid (alpha-LA), a cofactor of mitochondrial enzymes, decreases hypothalamic AMPK activity and causes profound weight loss in rodents by reducing food intake and enhancing energy expenditure. Activation of hypothalamic AMPK reverses the effects of alpha-LA on food intake and energy expenditure. Intracerebroventricular (i.c.v.) administration of glucose decreases hypothalamic AMPK activity, whereas inhibition of intracellular glucose utilization through the administration of 2-deoxyglucose increases hypothalamic AMPK activity and food intake. The 2-deoxyglucose-induced hyperphagia is reversed by inhibiting hypothalamic AMPK. Our findings indicate that hypothalamic AMPK is important in the central regulation of food intake and energy expenditure and that alpha-LA exerts anti-obesity effects by suppressing hypothalamic AMPK activity.