Study On The Fingerprint Of Pumpkin Seed And The Correlation Of Antioxidant Activity

Pumpkin seeds(Semen Moschatae)are the dry and mature seeds of Cucurbitaceae squash(Cucurbita moschata Duch),which are rich in nutrition and have certain medicinal values.It is an important natural resource for both food and medicine.In order to evaluate the quality of pumpkin seeds scientifically and effectively,the chromatographic fingerprint of pumpkin seeds was established by HPLC,the antioxidant activity of pumpkin seeds was evaluated by DPPH method and FRAP method,and the correlation between fingerprint and antioxidant activity was discussed by similarity analysis and cluster analysis.The effects of different extraction techniques and processing methods on antioxidant activity,chemical composition and hepatoprotective activity of pumpkin seeds were also investigated.In this study,pumpkin seeds were firstly extracted by heating and refluxing with ethanol,and the 30% ethanol elution was determined to be the antioxidant active portion of pumpkin seeds by macroporous resin column chromatography combined with DPPH free radical scavenging method.Then DPPH free radical scavenging method and FRAP method were used to determine the antioxidant activity of 10 batches of pumpkin seeds from different sources,and the total phenolic content and total flavonoid content were determined.The standard fingerprint of 10 batches of pumpkin seeds was established by HPLC.A total of 18 common peaks were determined by comparing peak area,symmetry and resolution.In order to investigate the relationship between total flavonoid content,total phenolic content and chromatographic peak area and antioxidant activity of pumpkin seeds,Pearson correlation coefficient method and multivariate correlation analysis were used to evaluate the spectral-effect relationship.The results showed that there was a positive correlation between total phenol content and antioxidant activity,and 7 of the 18 common peaks were related to the antioxidant activity.That is,the higher the total phenolic content,the more active peaks,the stronger the antioxidant activity it has.The effects of three extraction techniques and four processing methods(raw,baking,shelling,shelling and baking)on the antioxidant capacity of 42 batches of pumpkin seeds were also investigated.The results showed that raw pumpkin seeds with the most active chromatographic peaks and highest total phenolic content possessed the strongest antioxidant activity and hepatoprotective activit followed by baked pumpkin seeds and shelled pumpkin seeds.Shelled and baked pumpkin seeds exhibited the weakest antioxidant activity.It indicated that shelling and baking negatively influenced the antioxidant activity of pumpkin seeds.