Unlocking the in vitro anti-inflammatory and antidiabetic potential of Polygonum maritimum

Abstract

Context: Several Polygonum species (Polygonaceae) are used in traditional medicine in Asia, Europe and Africa to treat inflammation and diabetes.

Objective: Evaluate the in vitro antioxidant, anti-inflammatory and antidiabetic potential of methanol and dichloromethane extracts of leaves and roots of the halophyte Polygonum maritimum L.

Material and methods: Antioxidant activity was determined (up to 1 mg/mL) as radical-scavenging activity (RSA) of 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), copper (CCA) and iron (ICA) chelating activities and iron reducing power (FRAP). NO production was measured in lipopolysaccharide (LPS)-stimulated macrophages for 24 h at concentrations up to 100 μg/mL and antidiabetic potential was assessed by α-amylase and α-glucosidase inhibition (up to 10 mg/mL) assays. The phytochemical composition of the extracts was determined by gas chromatography-mass spectrometry (GC-MS).

Results: The methanol leaf extract had the highest activity against DPPH• (IC₅₀ = 26 μg/mL) and ABTS⁺• (IC₅₀ = 140 μg/mL), FRAP (IC₅₀ = 48 μg/mL) and CCA (IC₅₀ = 770 μg/mL). Only the dichloromethane leaf extract (LDCM) showed anti-inflammatory activity (IC₅₀ = 48 μg/mL). The methanol root (IC₅₀ = 19 μg/mL) and leaf (IC₅₀ = 29 μg/mL) extracts strongly inhibited baker’s yeast α-glucosidase, but LDCM had higher rat’s α-glucosidase inhibition (IC₅₀ = 2527 μg/mL) than acarbose (IC₅₀ = 4638 μg/mL). GC-MS analysis identified β-sitosterol, stigmasterol, 1-octacosanol and linolenic acid as possible molecules responsible for the observed bioactivities.

Conclusions: Our findings suggest P. maritimum as a source of high-value health promoting commodities for alleviating symptoms associated with oxidative and inflammatory diseases, including diabetes.

Keywords:

• Halophytes
• antioxidant activity
• oxidative stress
• macrophages
• nitric oxide
• α-amylase
• α-glucosidase

Acknowledgments

The authors thank the Faculty of Pharmacy and Center for Neurosciences and Cell Biology (University of Coimbra, Portugal) for kindly provide the murine leukemic monocyte-macrophage cell line (RAW 264.7).

Disclosure statement

The authors report that they have no conflicts of interest.

Additional information

Funding

This work was supported by the XtremeBio project (PTDC/MAR-EST/4346/2012) funded by Foundation for Science and Technology (FCT) and the Portuguese National Budget. This work benefited also from national funding through FCT project CCMAR/Multi/04326/2013. Luísa Custódio was supported by the FCT Investigator Program (IF/00049/2012). Nuno R. Neng and José M. F. Nogueira also acknowledge a FCT Post-Doc grant (SFRH/BPD/86071/2012) and funding (UID/Multi/00612/2013).