Preparation of New Derivatives from α-Dihydro Grayanotoxin-II

Rhodojaponin-III and 10,14-epoxy-10-deoxy grayanotoxin-III were derived from grayanotoxin-I and -III, respectively. Preparation of 13 new derivatives from α-dihydro grayanotoxin-II was discussed. Some of them showed higher physiological activity than that of natural grayanotoxins.     

Anthocyanins: structural characteristics that result in unique metabolic patterns and biological activities

Interest in anthocyanins has increased immensely during the past decade. From these studies, it is clear that anthocyanins have unique properties: Anthocyanins are absorbed intact and absorption can be saturated; acylation of anthocyanins lowers their apparent absorption; anthocyanidin diglycosides in the form of sambubioside or rutinoside impart increased stability to the anthocyanin molecule; and the quantities excreted in urine are less than 0.1% of intake. However, 60-90% of the anthocyanins may disappear from the gastrointestinal tract within 4 h after a meal. What happens to the bulk of the anthocyanins that disappear is not clear. Degradation accounts for a part of this disappearance, but differs for the various aglycones and may be modified further by the nature of the aglycone glycosylation, which further complicates our understanding of this process. Anthocyanins may play an important role in health promotion in terms of obesity prevention, cardiovascular health, anti-inflammatory and anti-cancer effects.     

Anthocyanin and pH in the color of ‘Heavenly Blue’ morning glory

The major anthocyanin in blue morning glory flowers, peonidin 3-(dicaffeylsophoroside)- 5-glucoside, is stable in a neutral aqueous solution and is solely responsible for the color of the flowers. Co-ocurring flavonols based on quercetin at the pH's of epidermal cells have no effect on the color of the anthocyanin. Deep or strong reddish-purple buds change to moderate or light blue open flowers within a 4 hr period, and during this time the pH of epidermal tissue increases from ca 6.5 to 7.5.