Unusual secondary metabolites from Astragalus halicacabus LAM

The structures and biological functions of polysaccharides from traditional Chinese herbs

Most of traditional Chinese medicine substances come from herbal plants. The medicinal quality of herbal plants varies with the locations of cultivation, the parts of the herb collected, the season of the herb collected, and the herb processing method. Polysaccharides are major components of the herb plants and their biosynthesis is partly controlled by the genes but mostly influenced by the availability of the nutrition and determined by the various environmental factors. In recent decades, polysaccharides isolated from different kinds of Chinese herbs have received much attention due to their important biological activities, such as anti-tumor, anti-oxidant, anti-diabetic, radiation protecting, antiviral, hypolipidemic, and immunomodulatory activities. Interestingly, different batches of the same herb can obtain different polysaccharide fractions with subtle differences in molecular weight, monosaccharide compositions, glycosidic linkages, and biological functions. Even with these variations, a large number of bioactive polysaccharides from different kinds of traditional Chinese herbs have been purified, characterized, and reported. This review provides a comprehensive summary of the latest polysaccharide extraction methods and the strategies used for monosaccharide compositional analysis plus polysaccharide structural characterization. Most importantly, the reported chemical characteristics and biological activities of the polysaccharides from the famous traditional Chinese herbs including Astragalus membranaceus, Ginseng, Lycium barbarum, Angelica sinensis, Cordyceps sinensis, and Ophiopogon japonicus will be reviewed and discussed. The published studies provide evidence that polysaccharides from traditional Chinese herbs play an important role in their medical applications, which forms the basis for future research, development, and application of these polysaccharides as functional foods and therapeutics in modern medicine.

Triterpenoids

Covering: 2013. Previous review: Nat. Prod. Rep., 2015, 29, 1028-1065This review covers the isolation and structure determination of triterpenoids reported during 2013 including squalene derivatives, lanostanes, holostanes, cycloartanes, cucurbitanes, dammaranes, euphanes, tirucallanes, tetranortriterpenoids, quassinoids, lupanes, oleananes, friedelanes, ursanes, hopanes, serratanes, isomalabaricanes and saponins; 350 references are cited.

The Anti-Oxidant and Antitumor Properties of Plant Polysaccharides

Oxidative stress has been increasingly recognized as a major contributing factor in a variety of human diseases, from inflammation to cancer. Although certain parts of signaling pathways are still under investigation, detailed molecular mechanisms for the induction of diseases have been elucidated, especially the link between excessive oxygen reactive species (ROS) damage and tumorigenesis. Emerging evidence suggests anti-oxidant therapy can play a key role in treating those diseases. Among potential drug resources, plant polysaccharides are natural anti-oxidant constituents important for human health because of their long history in ethnopharmacology, wide availability and few side effects upon consumption. Plant polysaccharides have been shown to possess anti-oxidant, anti-inflammation, cell viability promotion, immune-regulation and antitumor functions in a number of disease models, both in laboratory studies and in the clinic. In this paper, we reviewed the research progress of signaling pathways involved in the initiation and progression of oxidative stress- and cancer-related diseases in humans. The natural sources, structural properties and biological actions of several common plant polysaccharides, including Lycium barbarum, Ginseng, Zizyphus Jujuba, Astragalus lentiginosus, and Ginkgo biloba are discussed in detail, with emphasis on their signaling pathways. All of the mentioned common plant polysaccharides have great potential to treat oxidative stress and cancinogenic disorders in cell models, animal disease models and clinical cases. ROS-centered pathways (e.g. mitochondrial autophagy, MAPK and JNK) and transcription factor-related pathways (e.g. NF-[Formula: see text]B and HIF) are frequently utilized by these polysaccharides with or without the further involvement of inflammatory and death receptor pathways. Some of the polysaccharides may also influence tumorigenic pathways, such as Wnt and p53 to play their anti-tumor roles. In addition, current problems and future directions for the application of those plant polysaccharides are also listed and discussed.

A review of recent research progress on the astragalus genus

Astragalus L., is one of the largest genuses of flowering plants in the Leguminosae family. Roots of A. membranaceus Bge. var. mongholicus (Bge.) Hsiao, A. membranaceus (Fisch.) Bge. and its processed products are listed in the China Pharmacopeia for “qi deficiency” syndrome treatment. However, more and more researches on other species of Astragalus have been conducted recently. We summarize the recent researches of Astragalus species in phytochemistry and pharmacology. More than 200 constituents, including saponins and flavonoids, obtained from 46 species of Astragalus genus were collected for this article. In pharmacological studies, crude extracts of Astragalus, as well as isolated constituents showed anti-inflammatory, immunostimulant, antioxidative, anti-cancer, antidiabetic, cardioprotective, hepatoprotective, and antiviral activities. The goal of this article is to provide an overview of chemical and pharmacological studies on the Astragalus species over the last 10 years, which could be of value to new drug or food supplement research and development.