Reactive oxygen species

Occurrence, Biogenesis, and Synthesis of Biologically Active Carbazole Alkaloids

In this critical review the applications of gold catalysed reactions in total synthesis during the years since our last article are reviewed. At the end of this article a literature analysis is conducted to evaluate the progress in this field.

Gold catalysis in total synthesis – recent achievements

Saponins, classification and occurrence in the plant kingdom

A simple, green method is described for the synthesis of Gold (Au) and Silver (Ag) nanoparticles (NPs) from the stem extract of Breynia rhamnoides. Unlike other biological methods for NP synthesis, the uniqueness of our method lies in its fast synthesis rates (~7 min for AuNPs) and the ability to tune the nanoparticle size (and subsequently their catalytic activity) via the extract concentration used in the experiment. The phenolic glycosides and reducing sugars present in the extract are largely responsible for the rapid reduction rates of Au(3+) ions to AuNPs. Efficient reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of AuNPs (or AgNPs) and NaBH(4) was observed and was found to depend upon the nanoparticle size or the stem extract concentration used for synthesis.

Catalytic reduction of 4-nitrophenol using biogenic gold and silver nanoparticles derived from Breynia rhamnoides.

Anti-hepatitis B virus activity of chlorogenic acid, quinic acid and caffeic acid in vivo and in vitro.

Chemical constituents from Dendrobium densiflorum.

Natural products, containing inherently large-scale structural diversity than synthetic compounds, have been the major resources of bioactive agents and will continually play as protagonists for discovering new drugs. However, how to access this diverse chemical space efficiently and effectively is an exciting challenge for medicinal chemists and pharmacologists. While virtual screening, which has shown a great promise in drug discovery, will play an important role in digging out lead (active) compounds from natural products. This review focuses on the strategy of virtual screening based on molecular docking and, with successful examples from our laboratory, illustrates the efficiency of virtual screening in discovering active compounds from natural products. On the other hand, the sequencing of the human genome and numerous pathogen genomes has resulted in an unprecedented opportunity for discovering potential new drug targets. Chemogenomics has appeared as a new technology to initiate target discovery by using active compounds as probes to characterize proteome functions. Natural products are the ideal probes for such research. Binding affinity fingerprint is a powerful chemogenomic descriptor to characterize both small molecules and pharmacologically relevant proteins. Therefore, this review also discusses binding affinity fingerprint strategy for identifying target information from the genomic data by using natural products as the probes.

Virtual Screening on Natural Products for Discovering Active Compounds and Target Information

Immunomodulatory sesquiterpene glycosides from Dendrobium nobile.

Chemical studies on the constituents of Dracaena cochinchinensis led to the discovery of eight new flavonoid derivatives ( 1- 8) along with 14 known compounds ( 9- 22). The identification and structural elucidation of these isolates were based on spectral analyses. All isolates were tested for antibacterial activities against Helicobacter pylori (ATCC43504) and thrombin inhibitory effects. As a result, new flavonoid derivatives 6 and 7 and (2 S)-4',7-dihydroxy-8-methylflavan ( 11) were found to be most efficacious against H. pylori (ATCC43504) with MIC values of 29.5, 29.5, and 31.3 microM, respectively, and the seven new flavonoid derivatives ( 1- 7) and one known biflavonoid ( 9) were observed to exhibit moderate thrombin inhibitory activity.

https://pubs.acs.org/doi/pdf/10.1021/np070260v

Wei-Min Zhao

Papers

Anti-hepatitis B virus activity of chlorogenic acid, quinic acid and caffeic acid in vivo and in vitro.

Chemical constituents from Dendrobium densiflorum.

Virtual Screening on Natural Products for Discovering Active Compounds and Target Information

Immunomodulatory sesquiterpene glycosides from Dendrobium nobile.

Anti-Helicobacter pylori and thrombin inhibitory components from Chinese dragon's blood, Dracaena cochinchinensis.