Phloroglucinol dihydrate

Drug repurposing: In-vitro anti-glycation properties of 18 common drugs.[Pubmed:29300762]

PLoS One. 2018 Jan 4;13(1):e0190509.

Drug repositioning or repurposing, i.e. identifying new indications for existing drugs, has gained increasing attention in the recent years. This approach enables the scientists to discover "new targets" for known drugs in a cost and time efficient manner. Glycation, the non-enzymatic reaction of sugars with proteins or nucleic acids to form early glycation (Amadori or fructosamine) products, is a key molecular basis of diabetic complications. Inhibiting the process of non-enzymatic protein glycation is one of the key strategies to prevent glycation-mediated diabetic complications. The present study focuses on the anti-glycation activity of 18 drugs, commonly used for the treatment of gastrointestinal, central nervous system, inflammatory diseases, bacterial infections, and gout. This study was carried out by using two in-vitro protein anti-glycation assay models. Results revealed that nimesulide (3), a non-steroidal anti-inflammatory drug, possesses a good anti-glycation activity in in-vitro BSA-MG and BSA-glucose glycation models with IC50 values of 330.56 +/- 2.90, and 145.46 +/- 16.35 muM, respectively. Phloroglucinol dihydrate (11), a drug used for the treatment of gastrointestinal diseases, showed a weak activity in BSA-MG glycation model (IC50 = 654.89 +/- 2.50 muM), while it showed a good activity in BSA-glucose assay (IC50 = 148.23 +/- 0.15 muM). Trimethylphloroglucinol (9), a drug used for the treatment of pain related to functional disorders of the digestive and biliary tracts, also showed a good antiglycation activity in BSA-MG model (IC50 = 321.15 +/- 1.26 muM), while it was found to be inactive in in-vitro BSA-glucose assay (IC50 = 12.95% inhibition). These activities of drugs were compared with the anti-glycation activity of the standard, rutin (IC50 = 294.5 +/- 1.50 muM in BSA-MG glycation model, and IC50 = 86.94 +/- 0.24 muM in BSA- glucose model). Rest of the drugs exhibited a relatively weak antiglycation activity. This study identifies nimesulide (3), and Phloroglucinol dihydrate (11) as new inhibitors of in-vitro protein glycation for further investigations as potential anti-diabetic agents.

Polyphenols in brown algaeFucus vesiculosus andAscophyllum nodosum: Chemical defenses against the marine herbivorous snail,Littorina littorea.[Pubmed:24420835]

J Chem Ecol. 1981 Nov;7(6):1115-33.

Polyphenols from two brown algae,Fucus vesiculosus (L.) andAscophyllum nodosum (L.) Le Jolis, inhibited feeding by the herbivorous snail,Littorina littorea. The active compounds were characterized as phloroglucinol polymers with a wide molecular weight range (mol wt <30,000 to >300,000) by spectroscopic, Ultrafiltration, thin-layer chromatographic, and chemical degradation data. As little as 1% (dry wt) polyphenol in food reduced feeding by more than 50%, and polyphenolic extracts inhibited feeding entirely when present in concentrations of 2-5% (dry wt). Commercially available Phloroglucinol dihydrate and gallotannin, which are known herbivore feeding deterrents in terrestrial plants, inhibitedL. littorea feeding when added to food media in concentrations similar to those above. We conclude that polyphenols inF. vesiculosus andA. nodosum are functionally similar to terrestrial plant polyphenols (tannins) in providing chemical defenses against herbivores. This research is the first demonstration that chemical compounds defend these two dominant, perennial marine algae from the major herbivore found in their community.