Dataset Information

Chemical constituents from acid hydrolyzates of Panax quinquefolius total saponins and their inhibition activity to α-glycosidase and protein tyrosine phosphatase 1B.

ABSTRACT:

Objective

To investigate the hypoglycemic components from the acid hydrolyzates of Panax quinquefolius total saponins, and screen the active compounds by in vitro inhibitory activities to α-glycosidase enzymes and protein tyrosine phosphatase-1B (PTP1B).

Methods

The hydrolyzates were chromatographed repeatedly over silica gel column, and the structures of the compounds were determined by means of NMR. The in vitro bioassay was performed through the inhibitory effects on α-glucosidase or/and PTP1B.

Results

Eight compounds were isolated, which identified as 20(S)-panaxadiol (1), (20S,24R)-dammarane-20,24-epoxy-3β,6α,12β,25-tetraol (2), 20(R)-dammarane-3β,12β,20,25-tetraol (3), 20(S)-dammarane-3β,6α,12β,20,25-pentol (4), 20(R)-dammarane-3β,12β,20,25-tetrahydroxy-3β-O-β-d-glucopyranoside (5), β-sitosterol (6), oleanolic acid (7) and 20(S)-protopanaxadiol (8). Compound 5 was ginseng triterpenoid isolated from the acid hydrolysates of total saponins from P. quinquefolius for the first time. In this paper, the possible in vitro inhibitory activities were investigated. Compound 5 exhibited significantly inhibitory activity against α-glucosidase, and the IC₅₀ value [(0.22 ± 0.21) µmol/L] was about 43-fold lower than positive control. For the PTP1B inhibition assay, compound 5 indicated the strongest inhibitory effect with IC₅₀ of (5.91 ± 0.38) µmol/L, followed by compound 4 with IC₅₀ of (6.21 ± 0.21) µmol/L, which were all showed competitive inhibitory pattern by using a Lineweaver-Burk plot.

Conclusion

These results supported the potential application of dammaranes from acid hydrolyzates of P. quinquefolius total saponins can be used as ingredients of ancillary anti-diabetic agent or functional factor.

SUBMITTER: Han SW

PROVIDER: S-EPMC9476787 | biostudies-literature | 2020 Apr

REPOSITORIES: biostudies-literature

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Publications

Chemical constituents from acid hydrolyzates of <i>Panax quinquefolius</i> total saponins and their inhibition activity to α-glycosidase and protein tyrosine phosphatase 1B.

Han Si-Wen SW Shi Sheng-Ming SM Zou Yu-Xiao YX Wang Zhi-Cheng ZC Wang Yan-Qun YQ Shi Lin L Yan Ting-Cai TC

Chinese herbal medicines 20200314 2

<h4>Objective</h4>To investigate the hypoglycemic components from the acid hydrolyzates of <i>Panax quinquefolius</i> total saponins, and screen the active compounds by <i>in vitro</i> inhibitory activities to α-glycosidase enzymes and protein tyrosine phosphatase-1B (PTP1B).<h4>Methods</h4>The hydrolyzates were chromatographed repeatedly over silica gel column, and the structures of the compounds were determined by means of NMR. The <i>in vitro</i> bioassay was performed through the inhibitory ...[more]

PMID: 36119797

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Project description:A new paradigm in metallobiochemistry describes the activation of inactive metalloenzymes by metal ion removal. Protein tyrosine phosphatases (PTPs) do not seem to require a metal ion for enzymatic activity. However, both metal cations and metal anions modulate their enzymatic activity. One binding site is the phosphate binding site at the catalytic cysteine residue. Oxyanions with structural similarity to phosphate, such as vanadate, inhibit the enzyme with nanomolar to micromolar affinities. In addition, zinc ions (Zn2+) inhibit with picomolar to nanomolar affinities. We mapped the cation binding site close to the anion binding site and established a specific mechanism of inhibition occurring only in the closed conformation of the enzyme when the catalytic cysteine is phosphorylated and the catalytic aspartate moves into the active site. We discuss this dual inhibition by anions and cations here for PTP1B, the most thoroughly investigated protein tyrosine phosphatase. The significance of the inhibition in phosphorylation signaling is becoming apparent only from the functions of PTP1B in the biological context of metal cations as cellular signaling ions. Zinc ion signals complement redox signals but provide a different type of control and longer lasting inhibition on a biological time scale owing to the specificity and affinity of zinc ions for coordination environments. Inhibitor design for PTP1B and other PTPs is a major area of research activity and interest owing to their prominent roles in metabolic regulation in health and disease, in particular cancer and diabetes. Our results explain the apparent dichotomy of both cations (Zn2+) and oxyanions such as vanadate inhibiting PTP1B and having insulin-enhancing ("anti-diabetic") effects and suggest different approaches, namely targeting PTPs in the cell by affecting their physiological modulators and considering a metallodrug approach that builds on the knowledge of the insulin-enhancing effects of both zinc and vanadium compounds.