Anthocyanins as potent inhibitors of pentosidine synthesis: Antioxidant-mediated effects.

Pentosidine (PEN), an advanced glycation end product (AGE), is associated with various age-related diseases and schizophrenia. This study aimed to identify the natural compounds that inhibit PEN synthesis from glucuronic acid using an in vitro system. A screening of 93 natural compounds revealed 47 that reduced PEN synthesis by > 50 %, with eight inhibiting it by > 80 %.

HPLC analysis of ammonium glycyrrhizate listed in the European, United States, and Japanese Pharmacopoeias under reported and modified conditions: revision of the peak assignment for 18α-glycyrrhizin in the European and United States Pharmacopoeias.

We examined ammonium glycyrrhizate listed in the monographs of the European Pharmacopoeia (EP) and United States Pharmacopoeia (USP) as well as in the reagents and solutions used in the general test of the Japanese Pharmacopoeia by performing HPLC on their sample standards or reference reagents under reported and modified conditions. Comparative experiments involving five authentic samples, namely, 18β-glycyrrhizin (1), 18α-glycyrrhizin (2), licorice-saponin G2 (3), licorice-saponin H2 (4), and galacturonic acid-replaced glycyrrhizin (the 4″-epimer of 18β-glycyrrhizin) (5), led us to propose the revision of the peak assignment of 18α-glycyrrhizin (2) and postscript a possible co-existence of galacturonic acid-replaced glycyrrhizin (5) as a hidden component in the EP and USP. We also proposed that the α-configuration used in the nomenclature of the glycosidic bond between aglycone and the sugar units of ammonium glycyrrhizate and impurities in the EP and USP should be revised to the β-configuration.

Is 18α-Glycyrrhizin a real natural product? Improved preparation of 18α-Glycyrrhizin from 18β-Glycyrrhizin as a positive standard for HPLC analysis of licorice extracts.

18α-Glycyrrhizin is an epimer of 18β-glycyrrhizin, a major component of licorice (Glycyrrhiza sp.), which is widely used as a traditional medicine. Whether 18α-glycyrrhizin is a real natural product has been debated in the long history of glycyrrhizin chemistry because 18β-glycyrrhizin is epimerizable to a more thermodynamically stable 18α-glycyrrhizin under aqueous alkali conditions.

Quercetin 3,5,7,3',4'-pentamethyl ether from Kaempferia parviflora directly and effectively activates human SIRT1.

Sirtuin 1 (SIRT1), an NAD-dependent deacetylase, is a crucial regulator that produces multiple physiological benefits, such as the prevention of cancer and age-related diseases. SIRT1 is activated by sirtuin-activating compounds (STACs). Here, we report that quercetin 3,5,7,3',4'-pentamethyl ether (KPMF-8), a natural STAC from Thai black ginger Kaempferia parviflora, interacts with SIRT1 directly and stimulates SIRT1 activity by enhancing the binding affinity of SIRT1 with Ac-p53 peptide, a native substrate peptide without a fluorogenic moiety.

Potential Therapeutic Agents, Polymethoxylated Flavones Isolated from Kaempferia parviflora for Cataract Prevention through Inhibition of Matrix Metalloproteinase-9 in Lens Epithelial Cells.

Natural flavonoids have powerful antioxidant activity and have been reported to show promising protective effects against cataracts. The plant Kaempferia parviflora (K. parviflora) is indigenous to southeast Asia, including Thailand, and typically contains polymethoxylated flavones.