The anthocyanin in the purplish-red flowers of carnation (Dianthus caryophyllus) has been considered for many years as cyanidin 3-glucoside (Cy 3-G). However, from chromatographic studies on the flower color in carnation, we previously found that the major anthocyanin was not Cy 3-G but an acylated one attached to an unknown organic acid.In the present studies, we have isolated and crystallized this anthocyanin from purplish-red flowers of carnation and analyzed it by chemical and spectroscopic means. This pigment was identified as cyanidin 3-malylglucoside (Cy 3-MG). Furthermore, by means of direct chromatographic comparison with this pigment, it was also found that Cy 3-MG was widely present in the purplish-red flower cultivars and in the same color hybrids which were obtained from intervarietal crossing of carnations.In addition, we have recently identified another anthocyanin, peralgonidin 3-malylglucoside (Pg3-MG) from a red flower carnation cultivar. Therefore, these results strongly suggest that malylation of anthocyanin is characteristic in the flowers of carnation.
Anthocyanin pigments (shiso AN) were extracted from the purple leaves of Perilla ocimoides L. var. crispa (Japanese name, "shiso") and were examined regarding the anthocyanin composition and their stability to heating, ultraviolet (UV)-light irradiation, and effects under the coexistence of additives such as polysaccharides and glycyrrhizinate (GR). The results obtained were as follows. 1)By means of high-performance liquid chromatography (HPLC) and HPLC-mass spectrometry (LC/MS) analyses, the structures of three isolated anthocyanins from shiso AN were presumed to be cyanidin 3, 5-diglucoside, cyanidin 3-(6-p-coumarylglucoside)-5-glucoside; shisonin and cyanidin 3-(6-p-coumarylglucoside)-5-(6-malonylglucoside); malonylshisonin, while the remaining components have not been identified yet. 2)A major pigment estimated to be malonylshisonin in shiso AN was shown to be the most labile under heating and UV-light irradiation. 3)Addition of polysaccharides essentially did not increase the absorbance (ABS) of shiso AN solution as compared with that of non-addition; however GR addition increased the ABS. 4)When shiso AN solution containing added polysaccharides was heated to 100°C for 8h (heating), the sample with alginate addition was stabler than that the non-addition sample. While under UV-light irradiation for 8h (UV), the fading ratio of every polysaccharide containing shiso AN was lower than that of non-addition samples. 5) Shiso AN solution containing added GR decreased in fading ratio compared with the non-addition sample under both heating and UV conditions.
The suppressive effect on the postprandial blood glucose rise through alpha-glucosidase (AGH) inhibition was investigated in this study in order to clarify an antihyperglycemic function of 6-O-caffeoylsophorose (CS) from diacylated anthocyanin. The administration of CS (100 mg/kg) following maltose (2 g/kg) to Sprague-Dawley rats resulted in the maximal blood glucose level after 30 min being significantly decreased by 11.1% compared to the control. A reduction in the serum insulin secretion was also observed in parallel to the decrease in blood glucose level. No blood glucose change was apparent when sucrose or glucose was ingested, suggesting that the antihyperglycemic effect of CS was achieved by maltase inhibition, rather than by sucrase or glucose transport inhibition. An AGH inhibitory assay demonstrated that the non-competitive maltase inhibition of CS was partly due to acylation by phenolic acid with sugar, the presence of hydroxyl groups in the aromatic ring, and the presence of an unsaturated alkyl chain in the acylated moiety.
