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

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

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.

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).

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.

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.