Study on genes with altered expression in alpha-amanitin poisoned mice and evaluation on antagonistic effects of traditional Chinese medicines against toxicity of alpha-amanitin

Health Benefits of Silybum marianum: Phytochemistry, Pharmacology, and Applications

Silybum marianum (SM), a well-known plant used as both a medicine and a food, has been widely used to treat various diseases, especially hepatic diseases. The seeds and fruits of SM contain a flavonolignan complex called silymarin, the active compounds of which include silybin, isosilybin, silychristin, dihydrosilybin, silydianin, and so on. In this review, we thoroughly summarize high-quality publications related to the pharmacological effects and underlying mechanisms of SM. SM has antimicrobial, anticancer, hepatoprotective, cardiovascular-protective, neuroprotective, skin-protective, antidiabetic, and other effects. Importantly, SM also counteracts the toxicities of antibiotics, metals, and pesticides. The diverse pharmacological activities of SM provide scientific evidence supporting its use in both humans and animals. Multiple signaling pathways associated with oxidative stress and inflammation are the common molecular targets of SM. Moreover, the flavonolignans of SM are potential agonists of PPARγ and ABCA1, PTP1B inhibitors, and metal chelators. At the end of the review, the potential and perspectives of SM are discussed, and these insights are expected to facilitate the application of SM and the discovery and development of new drugs. We conclude that SM is an interesting dietary medicine for health enhancement and drug discovery and warrants further investigation.

Structure identification, antitumor activity and mechanisms of a novel polysaccharide from Ramaria flaccida (Fr.) Quél

It is an important aspect of current cancer research to search for effective and low-toxicity anticancer drugs and adjuvants. Polysaccharides, as immunomodulators, can improve the immune function of the body, kill tumor cells directly and prevent tumor development by increasing the resistance of the body to carcinogenic factors. The aim of the present study was to identify natural polysaccharide compounds with novel structure and antitumor activity via the separation and analysis of polysaccharide components from Ramaria flaccida (Fr.) Quél. (RF-1). In the present study, high-performance gel permeation chromatography, gas chromatography-mass spectrometry and nuclear magnetic resonance were used to identify the structure of polysaccharides from RF-1. Subsequently, the antitumor activity and mechanism of RF-1 were studied by establishing an in vivo S180 tumor model, and by using Illumina sequencing technology and enzyme-linked immunosorbent assay (ELISA). The present results revealed that the average molecular weight of RF-1 was 17,093 Da and that RF-1 was composed of the monosaccharides glucose and galactose, with a 2:1 ratio. The main chain of RF-1 consisted of (1→6, 2)-α-D-galactopyranose and (1→6, 4)- α-D-glucopyranose. One of the branched chains was linked to 4-O of the main glucose chain by (1→6)-α-D-glucopyranose and next linked by one (→4)-β-D-glucopyranose. The other two branched chains were both linked to 2-O of the main glucose chain by one (→4)-β-D-glucopyranose. In addition, RF-1 inhibited the growth of S180 tumors in vivo. When the concentration of RF-1 was 20 mg/kg, the inhibition rate of S180 tumors in mice was 48.4%. Compared with the blank control group, 1,971 differentially expressed genes were identified, of which 818 were upregulated and 1,153 were downregulated in the RF-1 group. A Gene Ontology enrichment analysis generated 47,091 assignments to biological processes, 5,250 assignments to cellular components, and 6,466 assignments to molecular functions. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis revealed that the Wnt and MAPK signaling pathways were significantly enriched. The number of differentially annotated genes in these two pathways was 19 and 33, respectively. Additionally, ELISA results revealed that the protein levels of interleukin (IL)-1β, IL-6, vascular endothelial growth factor (VEGF) and VEGF receptor in the RF-1 group were significantly downregulated compared with the S180 blank control group (P<0.01).

Inhibiting eukaryotic transcription: Which compound to choose? How to evaluate its activity?

This review first discusses ways in which we can evaluate transcription inhibition, describe changes in nuclear structure due to transcription inhibition, and report on genes that are paradoxically stimulated by transcription inhibition. Next, it summarizes the characteristics and mechanisms of commonly used inhibitors: α-amanitin is highly selective for RNAP II and RNAP III but its action is slow, actinomycin D is fast but its selectivity is poor, CDK9 inhibitors such as DRB and flavopiridol are fast and reversible but many genes escape transcription inhibition. New compounds, such as triptolide, are fast and selective and able to completely arrest transcription by triggering rapid degradation of RNAP II.