Compounds from the aerial parts of Piper bavinum and their anti-cholinesterase activity.

A new alkenylphenol, bavinol A (1), together with six known compounds (2-7) were isolated from the aerial parts of Piper bavinum (Piperaceae). The chemical structures of these compounds were determined by spectroscopic analyses including 2D NMR spectroscopy. The anti-Alzheimer effects of compounds 1-7 were evaluated from acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activity assays. Bavinol A (1), ampelopsin (3), and violanthin (4) exhibited AChE inhibitory activities with IC50 values of 29.80, 59.47 and 79.80 µM. Compound 1 also showed the most potent BChE inhibitory activity with an IC50 value of 19.25 µM.

Cholinesterase inhibitors from the roots of Harpagophytum procumbens.

Inhibition of cholinesterase has been proposed to be a therapeutic target for the treatment of Alzheimer's diseases. In our preliminary screening study on the acetylcholinesterase (AChE) inhibitory activity, an ethyl acetate soluble fraction of the roots of Harpagophytum procumbens (Pedaliaceae) was found to inhibit AChE activity at the concentration of 100 µg/mL. Ten compounds (1-10) were isolated from the active fraction and evaluated for their inhibitory effect on AChE and butyrylcholinesterase (BChE). Among the isolates, verbascosides (5, 6, and 8) containing a caffeoyl and a 3,4-dihydroxyphenethyl groups in their structures, showed effective AChE inhibitory activity and also possessed BChE inhibitory activity. The findings suggest that verbascoside derivatives may be partially related to the anti-Alzheimer effect of this medicinal plant.

Simultaneous quantification and validation of caffeoylquinic acids and flavonoids in Hemistepta lyrata and peroxynitrite-scavenging activity.

Traditionally, Hemistepta lyrata is consumed as a mountainous vegetable or a medicinal herb to treat inflammation, fever, hemorrhage, and hemorrhoids. In order to provide the scientific evidence of traditional uses of this plant, we identified and quantified thirteen active substances (caffeic acid, chlorogenic acid, and 3,5-di-O-caffeoylquinic acid as caffeoylquinic acids; apigenin, isorhoifolin, acacetin, linarin, diosmetin, diosmin, pectolinarigenin, and pectolinarin as flavones or their glycosides; kaempferol 3-O-rutinoside and rutin as flavonol glycosides) from H. lyrata and evaluated their peroxynitrite-scavenging activity. The chromatographic separation was performed on a Capcell Pak C18 column (5µm, 250mm×4.6mm i.d.) with a gradient elution of 0.05% TFA (trifluoroacetic acid) and 0.05% TFA in MeOH-CH(3)CN (60:40). Validation of HPLC methods on the linearity, LOD, LOQ, intra-day and inter-day variabilities, recovery, and repeatability proved that this method is selective, sensitive, precise, accurate, and reproducible. In peroxynitrite-scavenging assay, caffeic acid derivatives (chlorogenic acid, caffeic acid, and 3,5-di-O-caffeoylquinic acid) exhibited relatively lower IC(50) values than other substances tested. And HPLC simultaneous quantification showed that the 70% MeOH extract and the BuOH fraction contain a higher quantity of caffeic acid derivatives (17.82 and 30.09mg/g, consecutively). Therefore, caffeic acid derivatives could be the main contributors to the peroxynitrite-scavenging activity of H. lyrata than other phenolic substances.