Extraction, Characterization, and Antioxidant Activity of Polysaccharides from Ajwa Seed and Flesh

Abstract

The date palm has been cultivated in dry and hot areas of the planet for much of human history. In the Kingdom of Saudi Arabia, dates are the main crop used as a source of food. Among several species of date fruits, the Ajwa AL-Madinah date is unique, growing only in Al-Madinah geographical region. The Ajwa date is used in traditional medicine due to its abundant active components and therapeutic properties. This study investigates the structural properties and the antioxidant effects of water-soluble polysaccharides extracted from Ajwa flesh and seed. The polysaccharides were isolated by two techniques including hot water and ultrasonic extraction. After isolation and partial purification, the physicochemical properties of four samples of polysaccharides extracted from flesh and seed were studied by several techniques including FTIR, solid-state NMR, elemental analysis, and mass spectrometry. Several radical scavenging experiments were combined to study the antioxidant activity of the polysaccharide compounds. FTIR and NMR results showed a structure typical of heterogeneous polysaccharides. Mass spectrometry revealed that the polysaccharide samples were composed mainly of mannose, glucose, galactose, xylose, arabinose, galacturonic acid, and fucose. In addition, the physicochemical properties and composition of polysaccharides extracted from flesh and seed were compared. The extracted polysaccharides showed antioxidant activity, with 2, 2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging, Fe chelating ability, hydroxyl free radical scavenging ability, and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging. These results highlight their potential to be a useful nutritional element or supplemental medication.

Bioactive properties and gut microbiota modulation by date seed polysaccharides extracted using ultrasound-assisted deep eutectic solvent

“…Mannose, glucose, xylose, and arabinose were the principal monosaccharides in Ajwa date seeds, with xylose and arabinose present in the date flesh. Our findings concur with Dhahri et al (2023) , noting minimal or absent peaks for xylose and arabinose in the seed polysaccharides extracted using ultrasound, thereby confirming the consistency of our results. The molecular weight spectrum of UPS revealed multiple absorption peaks, suggesting that UPS is a heteropolysaccharide characterized by a diverse range of molecular weights, similar to the polysaccharides found in jujuba seeds ( Li et al, 2019 ).…”

“…The less intense absorption peaks at 2997 cm −1 are suggestive of the C—H stretching vibrations typical of polysaccharides ( Noorbakhsh & Khorasgani, 2023 ). Additionally, absorption bands at 1382 and 1415 cm^-1 align with the O–C=O bending vibrations of uronic acids present in the date seeds, corroborating the FTIR spectra characteristics of polysaccharides from Ajwa date seeds as described by Dhahri et al (2023) .…”

“…This sonication process facilitates the release of the encapsulated analytes and enhances their mass transfer by improving solvent penetration into the matrix. Dhahri et al (2023) yielded a 1.03% extraction rate of Ajwa date seed polysaccharide via ultrasound-assisted hot water extraction, whereas ( Noorbakhsh & Khorasgani, 2023 ) reported PS yield of 17.52 g/100 g via ultrasound-assisted alkaline hot water extraction. Our previous study has reported PS yield of 42.135 mg/g ( Subhash et al, 2024 ) when coupling DES extraction with microwave processing.…”

Study of the Mechanism of Hydrolysis of Hemicellulose from Lignocellulose during Alkali Thermal Pretreatment by Density Functional Theory and Experiment

“…The absorption peaks at 1350 cm −1 indicate the COO stretching vibration. 44 The absorption peak at 1030 cm −1 was the C−O−C stretching of the glycosidic ring. 45 3.6.…”

“…There is an absorption peak near 2900 cm –1 , which may be the tensile vibrations of -CH 3 , -CH 2 , and -CH. , The absorption peaks at 1630 cm –1 indicate the asymmetric stretching of the C–O group. , With an increase in the temperature and holding time, the level of the C–O group in the solution increases, which corresponds to the C–O group on the pyranose ring caused by the break of the glycosidic bond during the reaction. The absorption peaks at 1350 cm –1 indicate the COO stretching vibration . The absorption peak at 1030 cm –1 was the C–O–C stretching of the glycosidic ring …”