Extraction Optimization,Structural And Physicochemical Analysis,and In Vitro Antioxidant Activity Of Polysaccharides From Caragana Intermedia Kuang Et H.C.Fu Flowers

Caragana intermedia Kuang et H.C.Fu has been used over the years as Chinese medicine for treating many diseases,including uterine cervical cancer,breast cancer,irregular menstruation,neurodermatitis,cardiac arrhythmias,hypertension,etc.In recent years,polysaccharides have received tremendous attention due to the possession of a wide range of biological and pharmacological properties,including antitumor,antidiabetic,antioxidant,and antihypertensive activity.In this present study,four novel water-soluble polysaccharides（CIP-C,CIP-1S,CIP-2S,and CIP-3S）were isolated.The crude polysaccharide（CIP-C）was isolated by decoction,ethanol precipitation,TCA deproteinization,dialysis,and lyophilization,and taken through chromatographic techniques（DEAE 52-Cellulose ion exchange and DEAE-Sephadex G-100）and the purified polysaccharides（CIP-1S,CIP-2S,CIP-3S）were obtained.In order to get a high polysaccharides yield from Caragana intermedia Kuang,a single-factor experiment and an orthogonal array design（L₉（3）⁴）were employed to optimize the extraction conditions.The main factors influencing the yield of the polysaccharide that were investigated were the number of extractions,extraction time,and water-solid ratio.The optimized conditions were;the number of extraction（3 times）,extraction time（30mins）,and water to solid ratio（45ml/g）.The maximum polysaccharide yield obtained was17.9±0.73%（n=3）at 3 times extraction,30 mins extraction time,and 25ml/g water-solid ratio.The results revealed that the investigated factors impact the yield in the order:the number of extractions（5.69）>extraction time（3.53）>water-solid ratio（1.51）.The physicochemical and structural characteristics of CIPs were elucidated with Fourier transform infrared spectroscopy,UV spectroscopy,and chemical composition analysis.CIP-1S contained the highest content of total sugar（70.82±4.9%）,followed by CIP-C（50.97±1.64%）,CIP-3S（42.22±1.57%）,and CIP-2S（41.17±3.15%）.CIP-C and CIP-3S contained protein and polyphenols while CIP-1S and CIP-2S contained no or traces of these macromolecules.CIPs were predominantly made up of a hydroxyl group,carboxyl group,and pyranose ring.Furthermore,CIPs’antioxidant activity against hydroxyl and DPPH radicals were assessed.CIPs exhibited remarkable scavenging activity against DPPH radicals with IC₅₀of 0.23,0.89,1.63,and 0.63 mg/ml for CIP-C,CIP-3S,CIP-1S,and CIP-2S respectively.The hydroxyl ion scavenging activity of all the samples strongly correlated with the DPPH scavenging activity[R²>0.90]as relatively lower IC₅₀ values were also obtained for each sample’s antioxidant activity against the hydroxyl ion.This research has laid the foundation for further studies into the exploitation of polysaccharides from Caragana intermedia Kuang et H.C.Fu in the food and pharmaceutical industries.