Antioxidative Activity of the Blue Pigment Formed in aD-Xylose-Glycine Reaction System

Abstract

A blue compound was prepared from 1 M D-xylose and 0.1 M glycine, and designated Blue-M1, an intermediate color product of melanoidins. As melanoidins are well known to have antioxidative activity as well as high scavenging activity against active oxygen species, the antioxidative activity of Blue-M1 against the peroxidation of linoleic acid was investigated, in addition to the scavenging activity of Blue-M1 toward hydroxyl and DPPH radicals. Blue-M1 suppressed the peroxidation of linoleic acid as effectively as melanoidins did. The scavenging activity of Blue-M1 toward hydroxyl and DPPH radicals was also as strong as that of melanoidins. Blue-M1 showed higher activity with increasing concentration. The pyrrolopyrrole ring and a methine bridge between two pyrrolopyrrole rings in Blue-M1 could be related to the ability for radical scavenging activity, but not four carboxyl groups.

Determination of Caffeine Content and Antioxidant Activity of Coffee

“…The variations in protection factors have been explained due to the difference in concentrations of lipid soluble constituents of coffee extracts like polyphenolic acids, melanoids and volatile heterocyclic compounds [39]. Inspite of the experimental differences, the Rancimat assay and the FRAP assay were found to show similar trends when comparing extracts of different coffee samples in their ranking order of antioxidant activities.…”

“…Particularly, Wembera coffee exhibited relatively strong reducing power (better able to donate an electron) in comparison with other extracts, which may be due to its high contents of water soluble antioxidants. Literatures reveal coffee beans contain efficient water soluble antioxidants, such as chlorogenic acids, caffeic acids, ferulic acids, p-coumaroic acids, melanoids and alkaloids; [20], [38], [39], [46] and their content depends mainly on the coffee species, origin and degree of roasting [13], [23], [44], [54], [64]. Hence the coffee samples in this study were roasted in same way, the variation in their reducing power might be due the difference in their geographical locations (origin) and their species.…”

“…This might be happened due to the presence of different concentration of lipophilic antioxidants such as polyphenolic acids, melanoids and heterocyclic compounds [38], [39] in coffee extracts that slow down the oxidation process of the substrate through donation of hydrogen atom.…”

“…In living system, antioxidants have played an important role in scavenging excessive free radicals [35] such as reactive oxygen species (ROS) and reactive nitrogen species (RNS) [36]- [39] which are formed during normal cellular metabolism in high concentration [33], [40]. Researchers have shown that the intake of cereals, fruits, vegetables, tea, and coffee [41], [42] are important to lower risk of diseases that are formed as consequence of free radicals [43].…”

“…Among those dietary species, coffee is a major source of antioxidants and is estimated to provide half of total antioxidant intake in several populations [20], [41], [42]. Thus, coffee extracts have received a lot of attention in recent years and numerous studies have proven that the biologically active components of the extracts such as chlorogenic acids (caffeoylquinic acids [29], dicaffeoylquinic acids [29], feruloylquinic acids [29], [30], [31]), [34] and pcoumaroylqunic acids [29]), melanoidns [37], [39], [44] and lipid soluble heterocyclic compounds (alkaloids) [45], [46] play significant role for its antioxidant behavior in both vitro and vivo [32].…”