Structural analysis of water-soluble glucans from the root of Angelica sinensis (Oliv.) Diels

Two water-soluble glucans (designated APS-1cI and APS-1cII) were extracted from the roots of Angelica sinensis (Oliv.) Diels and further purified by anion-exchange and gel-filtration chromatography. Their molecular weights were determined to be 1.7 × 105 and 3.9 × 104 Da, respectively. The structures of the purified glucans were investigated by a combination of chemical and instrumental analysis, such as methylation analysis, periodate oxidation, GC–MS, as well as FTIR and NMR spectroscopy (1H, 13C, H–H COSY, HSQC, HMBC, TOCSY and NOESY). The data obtained indicated that APS-1cI was a linear α-glucan composed of only (1→6)-α-d-Glcp, and APS-1cII had a repeating unit consisting of (1→4)-α-d-Glcp and (1→6)-α-d-Glcp in a molar ratio of 4:1. Such glucans isolated from A. sinensis (Oliv.) Diels have not been previously reported.

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