Quality evaluation with reference to clitoriacetal and in vitro antioxidant activities of Clitoria macrophylla root

Clitoria macrophylla Wall. (syn. Clitoria hanceana Hemsl.), is commonly known in Thai as Nontai-yak, An-chan-pa, or Ueang-chan-pa, which belongs to Leguminosae family. According to traditional Thai medicine, the root has been used for the treatment of skin diseased as well as for pest control in horticulture and animal husbandry. The aim of this study is to investigate for the pharmacognostic specification, the clitoriacetal content, and in vitro antioxidant capacities of C. macrophylla roots from 12 different sources throughout Thailand. Clitoriacetal content was quantitatively analyzed by thin-layer chromatography (TLC) - densitometry with winCATS software and TLC image analysis with ImageJ software. Antioxidant activities were evaluated by 2, 2-diphenyl-1-picrylhydrazyl radical scavenging, ferric reducing antioxidant power assay, β-carotene bleaching assay, total phenolic, and total flavonoid contents. The pharmacognostic specification of C. macrophylla roots in Thailand was established. The loss on drying, total ash, acid-insoluble ash, and water contents should be not more than 6.40%, 12.29%, 8.89%, and 8.16% of dry weight, whereas ethanol and water-soluble extractive values should be not less than 4.95% and 14.72% of dry weight, respectively. Furthermore, the clitoriacetal content of C. macrophylla roots determined by TLC-densitometry and TLC image analysis was found to be 2.20 ± 1.31 and 2.22 ± 1.16 g/100 g of dry roots, respectively. The clitoriacetal contents of both methods were not significantly different using paired t-test. Moreover, the ethanolic extract of C. macrophylla roots showed its antioxidant potential compared to the standard butylated hydroxyl toluene and quercetin.