Phenylpropanoid, Sapnol A, Lignan and Neolignan Sophorosides, Saposides A and B, Isolated from Canadian Sugar Maple Sap

Kazuko Yoshikawa,Toshihiro Hashimoto,Sakiko Tani,Chihiro Baba

doi:10.3390/molecules18089641

Abstract

One new phenolic compound, sapnol A (1), and two new aromatic sophorosides, named saposides A (2) and B (3) were isolated from sugar maple sap. In addition, seven known phenolic compounds 4–10 were isolated. These structures were determined on the basis of NMR experiments as well as chemical evidence. Furthermore, all the isolated compounds 1–10 were tested for antioxidative activity by the superoxide dismutase (SOD)-like assay.

Highlights

Maple syrup is a premium natural sweetener obtained by concentrating maple sap collected from certain maple species, primarily Acer saccharum (Aceraceae), which is a tree native to NorthAmerica [1]
The phenylpropanoid sapnol A (1), lignan sophoroside saposide A (2), and neolignan sophoroside saposide B (3) were isolated from sugar maple sap collected from A. saccharum (Aceraceae), together with seven known compounds, which included phenylpropanoids 4, 10 and neolignans 5–9
Some phenolics in maple syrup are possibly formed under the conditions of intensive heating involved in transforming sap to syrup

Summary

Introduction

Maple syrup is a premium natural sweetener obtained by concentrating maple sap collected from certain maple species, primarily Acer saccharum (Aceraceae), which is a tree native to North. Among the phytochemicals that have been previously reported from maple syrup, the phenolic components predominate [2,3,4]. A comprehensive investigation of maple sap phenolics is necessary to evaluate the native components and biological properties of this natural sweetener. The MeOH fraction that showed antioxidant activity at. 15.5 μg/mL was subjected to bioassay-guided separation, fractionated by silica gel column chromatography, and further purified by reversed-phase HPLC to give three new compounds, designated as sapnol A (1), and saposides A (2) and B (3), along with seven known compounds, wilfordiol A (4) [6], threo-2-[4-[2,3-dihydro-3-(hydroxymethyl)-5-(3-hydroxy-propyl)-7-methoxy-2benzofuranyl]-2,6-dimethoxyphenoxy]-1-(4-hydroxy-3-methoxyphenyl)-1,3-propanediol (5). We describe the isolation, purification, and structural elucidation of 1–10 determined primarily by extensive NMR experiments, chemical degradation, and antioxidant activity by the superoxide dismutase (SOD)-like activity of all the isolated compounds

Results and Discussion

General

Materials

Extraction and Isolation

Acid Hydrolysis of 2 and 3

Conclusions