• Korean Journal of Pharmacognosy
• /
• v.43 no.3
• /
• pp.206-212
• /
• 2012

Ten flavonol glycosides were isolated from the EtOAc fraction of the MeOH extract of Metaplexis japonica Makino. Structures of the flavonoids were elucidated on the basis of spectroscopic data and comparison with literature values. The flavonoids were found to be mostly common flavonol 3-glycosides. It is of interest that the sacchaide parts of the isolates were pairs of arabinosides, glucosides, galactosides, rutinosides and robinobiosides of kaempferol and quercetin. All of these compounds were isolated for the first time from this plant.

• Journal of Applied Biological Chemistry
• /
• v.50 no.4
• /
• pp.304-307
• /
• 2007

• Journal of Life Science
• /
• v.21 no.3
• /
• pp.464-467
• /
• 2011

Quercetin is a major flavonoid present in onions, which acts as an antioxidant. Quercetin exists both as a free compound and conjugated with carbohydrates, primarily as glucosides in onion. Aged black onion was made through a 30 day aging process in which the onions were kept in an environment of $60^{\circ}C$ and high humidity (90% RH). Quercetin and quercetin glucosides were assayed in onion bulbs before and after the aging process, using high performance liquid chromatography-electrospray ion trap mass spectrometry (HPLC-ESI/MS/MS). Quercetin mono- and diglucosides were identified in fresh onion bulbs, whereas quercetin aglycone was the only form present in aged black onion bulbs. These findings indicate that the quercetin mono- and di-glucosides present in fresh onions undergo complete deglycosylation during the aging process. Such profiling will provide a rapid method that can be used to assess changes in the two major quercetin glycosides during the aging process of onion bulbs.

• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2010.10a
• /
• pp.12-12
• /
• 2010

Nature applied flavanoids, glucosinolates and peptides for a great variety of functions. Flavanoids and glucosinolates are rich source of antioxidants, generally present in colored fruits and vegetables. Quercetin and its glucosides areone of the best examples of flavonol used in daily diet. Whereas peptides can act as antimicrobial, chemical messenger, neurotransmitter etc that regulating various life processes. Aspartame, a dipeptide is used as artificial sweetener and oxytocin for medical purposes, gained importance in everyday life. So, flavanoids, glucosinolates, peptides and their derivatives continue to hold the attention of synthetic chemists, agriculturists and biologists. Apart from a variety of naturally occurring bioactive metabolites, we are aiming to extract, separate and synthesize new analogs of promising natural drug candidates.