Anti-Diabetes Mellitus Potential of MTHP-2-a Purified and Identified by Mass Spectrometry and NMR Technology

Abstract

Murraya tetramera Huang (MTH) is a traditional medicinal plant in western Guangxi and southeastern Yunnan, China. Residents commonly use it as tea. Preliminary experiments conducted by our research team revealed that the Murraya tetramera Huang polysaccharides (MTHPs) exhibit significant inhibitory effects on alpha-glucosidase (α-glucosidase) and alpha-amylase (α-amylase). In this study, MTHPs were purified using diethylaminoethyl cellulose-52 (DEAE-52) anion-exchange chromatography and Sephadex G-75 gel chromatography, resulting in a homogeneous polysaccharide named MTHP-2-a. Structural analysis indicates that MTHP-2-a has a weight-average molecular weight (Mw) of 62.25 kDa. It primarily consists of rhamnose (Rha), arabinose (Ara), galactose (Gal), and glucose (Glc). The backbone fragments include Araf-(1 ⟶, ⟶ 3)-Rhap-(1 ⟶, ⟶ 3)-Araf-(1 ⟶, ⟶ 5)-Araf-(1 ⟶, Glcp-(1 ⟶, ⟶ 2)-Araf-(1 ⟶, ⟶ 2,5)-Araf-(1 ⟶, Galp-(1 ⟶, ⟶ 4)-Galp-(1 ⟶, ⟶ 3)-Galp-(1 ⟶, ⟶ 6)-Glcp-(1 ⟶, ⟶ 6)-Galp-(1 ⟶, and ⟶ 3,6)-Galp-(1 ⟶. In vitro antidiabetic activity assays demonstrate that MTHP-2-a effectively inhibits α-amylase and α-glucosidase, with IC₅₀ values of 1.24 ± 0.02 and 0.32 ± 0.004 mg/mL, respectively. For comparison, the well-known antidiabetic drug acarbose exhibited similar inhibitory effects, with IC₅₀ values of 1.80 ± 0.06 mg/mL for α-amylase and 0.21 ± 0.006 mg/mL for α-glucosidase. These results suggest that MTHP-2-a exhibits comparable inhibitory potency to acarbose, a widely used antidiabetic agent. Furthermore, through both in vitro and in vivo experiments, MTHP-2-a can significantly exhibit hypoglycemic effects. The molecular structure and sugar composition of MTHP-2-a were purified and elucidated for the first time, revealing its strong potential for antihyperglycemic activity. These findings provide new insights into the pharmacological properties of MTHP and lay the foundation for its future development as an antidiabetic drug, supporting further pharmacological studies and preclinical trials.