Monosaccharide Composition And In Vitro Antioxidant, Antidiabetic, And Anticholinesterase Activities Of Pectins Extracted From Opuntia Stricta (Haw) Cladodes

Abstract

Pectins isolated from the cladodes of Opuntia stricta (Haw.) were extracted using two methods aqueous extraction (WE) and oxalate extraction (OE) and thoroughly characterized for their monosaccharide composition as well as their bioactivities. The extractions yielded 13.84% of WE and 6.12% of OE. Gas chromatography (GC) analysis revealed a high content of neutral sugars, particularly arabinose, with highest content in OE (31.69%) and WE (24.46%).

In vitro antioxidant assays revealed that pectins obtained via oxalate extraction (OE) consistently exhibited greater activity than those obtained by water extraction (WE). OE pectins demonstrated higher DPPH radical scavenging capacity (14.63% vs. 10.21%) and metal ion chelation (33.95% vs. 27.33%). Similarly, in the β-carotene/linoleate bleaching assay, OE showed enhanced antioxidant activity (20.17%) compared to WE (12.35%). In the ABTS•+ assay at 200 µg/mL, OE pectins also outperformed WE, with scavenging activity reaching 26.54% versus 16.04%.

Regarding digestive enzyme inhibition, both WE and OE pectins exhibited moderate activity (IC₅₀ > 200 µg/mL), with maximum inhibitions of 23% for α‑glucosidase and approximately 16% for α‑amylase at 200 µg/mL. Additionally, cholinesterase inhibitory activity remained limited, with OE showing slightly higher activity than WE against butyrylcholinesterase (29% vs. 24%). These results indicate that OE pectins may possess a modestly enhanced inhibitory potential compared to WE pectins.

These results indicate that Opuntia stricta pectins possess remarkable antioxidant activity and structural characteristics that may support neuroprotection through indirect mechanisms, despite exhibiting limited inhibition of cholinesterase and key digestive enzymes. This study enhances the understanding of O. stricta pectins functional properties and underscores their potential as bioactive ingredients in nutraceutical and pharmaceutical applications.