Abstract: Hainan is one of the main producing areas of Dendrobium candidum. To study and compare the differences of D.candidum among various regions,the alcohol extracts and aqueous extracts of D.candidum from eight areas of Hainan were obtained.The contents of the extracts were determined,the antioxidant and antidiabetic activities were tested.The correlation between biological activities and constituents were further investigated.The results indicated that the extracts of D.candidum obtained from Qiongzhong,Sanya and Baoting in Hainan province showed higher antioxidant activity in DPPH radical scavenging activity and reducing power activity.The aqueous extract of D.candidum obtained from Danzhou showed the highest inhibition capacity on α-amylase activity.The results of correlation analysis showed that the contents of uronic acid,total polyphenols and total triterpenoids highly correlated with DPPH radical scavenging rate and ferric reducing power.The correlation coefficient of total polyphenols content with DPPH radical scavenging (r=0.904, P<0.01) and ferric reducing power (r=0.861, P<0.01) was higher than others.The results would be helpful for the application of D.candidum in food and pharmaceutical industries.

Key words: Hainan, Dendrobium candidum, antioxidant activity, correlation coefficients