Abstract
2-O-α-d-Glucopyranosyl-l-ascorbic acid (AA-2G) is one of the stable ascorbic acid (AA) derivatives known as provitamin C agents. We have previously synthesized two types of monoacylated derivatives of AA-2G, 6-O-acyl-2-O-α-d-glucopyranosyl-l-ascorbic acids having a straight-acyl chain of varying length from C4 to C18 (6-sAcyl-AA-2G) and a branched-acyl chain of varying length from C6 to C16 (6-bAcyl-AA-2G) in order to improve the bioavailability of AA-2G. In this study, 6-sAcyl-AA-2G and 6-bAcyl-AA-2G per se showed the inhibitory effects on hyaluronidase activity and degranulation. 6-sAcyl-AA-2G exhibited strong inhibitory effects on hyaluronidase activity and degranulation in a concentration-dependent manner, and the inhibitory effects tended to become stronger with increasing length of the acyl chain. 2-O-α-d-Glucopyranosyl-6-O-hexadecanoyl-l-ascorbic acid (6-sPalm-AA-2G), which has a straight C16 acyl chain, was the most potent effective for inhibition of hyaluronidase activity and for inhibition of degranulation among the 6-sAcyl-AA-2G derivatives and the two isomers of 6-sPalm-AA-2G. Furthermore, percutaneous administration of 6-sPalm-AA-2G significantly inhibited IgE-mediated passive cutaneous anaphylaxis reaction in mice. These findings suggest that 6-sPalm-AA-2G will be useful for treatment of allergies.
Highlights
Ascorbic acid (AA), known as vitamin C, has various physiological and pharmacological activities such as antiscorbutic activity [1], anti-oxidation [2], enhancement of iron absorption [3] and drug metabolism [4]
Among the derivatives, and the activity of 6-sPalm-AA-2G was comparable to that of oxatomide. These results suggest that 6-sPalm-AA-2G is the most effective for inhibition of degranulation activity. These results suggest that 6-sPalm-AA-2G is the most effective for inhibition of degranulation activity as well as inhibition of hyaluronidase activity
6-sPalm-AA-2G slightly increased calcium ionophore A23187-stimulated degranulation but there was no statistically significant difference between control and treatment groups. These results suggested that 6-sPalm-AA-2G suppressed the degranulation by inhibiting the upstream region of a signal transmission pathway of antigen-induced degranulation, while it had no effect on calcium channels expressed on the cell membranes of RBL-2H3 cells and on the increase of intracellular calcium
Summary
Ascorbic acid (AA), known as vitamin C, has various physiological and pharmacological activities such as antiscorbutic activity [1], anti-oxidation [2], enhancement of iron absorption [3] and drug metabolism [4]. 2-O-α-D-Glucopyranosyl-L-ascorbic acid (AA-2G, Figure 1) is one of the stable ascorbate derivatives [6]. AA-2G has been permitted by the Japanese Government as a quasi-drug and food additive, and it is being used as a medical additive in the field of cosmetics. In order to improve the bioavailability of AA-2G, we have synthesized two types of monoacylated derivatives of AA-2G: 6-O-acyl-2-O-α-D-glucopyranosyl-L-ascorbic acids having a straight-acyl chain of varying length from C4 to C18 (6-sAcyl-AA-2G, Figure 1) and having a 2-branched-acyl chain of varying length from C6 to C16 (6-bAcyl-AA-2G, Figure 1) [11,12]. In order to improve the bioavailability of AA-2G, we have synthesized two types of monoacylated derivatives of AA-2G: 6-O-acyl-2-O-α-D-glucopyranosyl-L-ascorbic acids having a straight-acyl chain of varying length from C4 to C18 (6-sAcyl-AA-2G, Figure 1) and having a 2-branched-acyl chain of varying length from C6 to C16 (6-bAcyl-AA-2G, Figure 1) [11,12]. 6-sAcyl-AA-2G and 6-bAcyl-AA-2G
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