Covalent interaction of ascorbic acid with natural products

Abstract

While ascorbic acid (Vitamin C) is mostly known as a cofactor for proline hydroxylase and as a biological antioxidant, it also forms covalent bonds with natural products which we here refer to as 'ascorbylation'. A number of natural products containing an ascorbate moiety has been isolated and characterized from a variety of biological sources, ranging from marine algae to flowering plants. Most of these compounds are formed as a result of nucleophilic substitution or addition by ascorbate, e.g. the ascorbigens from Brassica species are ascorbylated indole derivatives. Some ascorbylated tannins appear to be formed from electrophilic addition to dehydroascorbic acid. There are also examples of annulations of ascorbate with dietary polyphenols, e.g., epigallocatechin gallate (EGCG) and resveratrol derivatives. Herein is a survey of thirty-three ascorbylated natural products and their reported biological activities.

Ascorbigen – Occurrence, Synthesis, and Analytics

“…It has been the subject of analytical and pharmacological investigations since the early 1950s, but was initially described only as a component of rather complex mixtures [1][2][3][4][5][6][7][8][9]. Later, ascorbigen was also found in other vegetables, such as Brussel sprouts, cauliflower, and broccoli, and seems to be a characteristic key compound in cruciferous greens [11][12][13][14][15]. Later, ascorbigen was also found in other vegetables, such as Brussel sprouts, cauliflower, and broccoli, and seems to be a characteristic key compound in cruciferous greens [11][12][13][14][15].…”

Vitamins C and E: Beneficial effects from a mechanistic perspective

“…There are many examples of covalent adducts of vitamin C, including Michael adducts, with natural products in the plant kingdom, of which ascorbigen is most well known [122]. The reaction of ascorbate with acrolein (2-propenal), a ubiquitous electrophile originating from LPO and combustion of organic matter [123], and with other α,β-unsaturated aldehydes/ketones has been reported in the organic chemistry literature [121, 124].…”

Hot water treatment in combination with calcium ascorbate dips increases bioactive compounds and helps to maintain fresh-cut apple quality

“…The decrease could be a consequence of formation of a complex of ascorbic acid from CaAsc with natural products of coumaric acid (Kesinger and Stevens, 2009). The use of HWT increased the quercetin and phloridzin levels but decreased coumaric and procyanidins (B1, B2, C1) levels.…”