Cleome arabica belongs to the family of Capparaceae. It has attracted a great deal of attention in recent years for its pharmaceutical potentials due to its antioxidant, antihypercholisterolemic, anti-cancer and chemoprotective activities for the treatment of a number of diseases.

The main study was to evaluate the α-amylase inhibitory and antioxidant activities of extracts from Cleome arabica collected on two seasons (December 2016 and May 2017) in the town of Laghouat steppe region of Algeria. In addition, the purpose of the study was to investigate a new natural inhibition of α-amylase using an in vitro model, as well as to find a natural anti-diabetic compound from the plant.

The extracts were prepared with two solvent systems: hydroalcoholic and acetonic solvent systems. The polyphenolic contents of methanol and acetone extracted samples were evaluated in vitro in two different ways: total phenolic contents and total flavonoid content. The antioxidant activity was determined using 1, 1-diphenyl-2-picrylhydrazyl radical, test enzyme inhibitory effect against α-amylase of n-hexane, chloroform and ethyl acetate were investigated with spectrophotometric methods.

The phenolics and flavonoid contents varied from (2.87 to 107.21mg Gallic acid equivalent/ 100g dry matter) and from (0.12 to 88.50 mg Quercetin equivalent /100g) respectively for the beginning of maturity stage (December) in all plant organs. The radical scavenging activity values of the 1, 1-diphenyl-2-picrylhydrazyl radical test ranged between 0.009 to 0.481 mg/ml in different plant organ extracts. The inhibitory effect of the Cleome arabica extracts on α-amylase was also investigated and concentrations that gave 50% inhibition of maximal activity were found in acetonic extract with finest values (0.11 and 1.01 mg/ml) in the beginning and the end of maturity stage respectively at ethyl acetate and n- hexane fraction for the pods and roots, respectively.

This study is the first report on potential inhibition of these plant extracts on the digestive enzyme, α-amylase. The results indicate that Cleome arabica of Algeria is a powerful natural antioxidant and also could provide natural biologically active agents to be used in the management of diabetes.