HPLC-FRAP methodology and biological activities of different stem bark extracts of Cajanus cajan (L.) Millsp

• Published in: Journal of pharmaceutical and biomedical analysis 2021-01, Vol.192, p.113678-113678, Article 113678
• Main Authors: Sinan, Kouadio Ibrahime, Mahomoodally, Mohamad Fawzi, Eyupoglu, Ozan Emre, Etienne, Ouattara Katinan, Sadeer, Nabeelah Bibi, Ak, Gunes, Behl, Tapan, Zengin, Gokhan
• Format: Article
• Language: English
• Subjects: Antioxidants; Bioactive compounds; Enzyme inhibition; Natural products; Pigeon pea
• ISSN: 0731-7085; 1873-264X
• DOI: 10.1016/j.jpba.2020.113678

•Different stem bark extracts of Cajanus cajan (L.) Millsp. prepared from four solvents were investigated.•Antioxidant and enzyme inhibitory effects were tested.•High performance liquid chromatography-FRAP system was performed.•Methanol extract exhibited the strongest antioxidant effects.•The results might be valuable for designing novel pharmacological applications. Cajanus cajan. (L.) Millsp. (C. cajan) (Family: Fabaceae) also known as pigeon pea, is a famous food and cover/forage crop bearing a high amount of key amino acids (methionine, lysine and tryptophan). This study investigated into the total phenolic (TPC), flavonoid content (TFC), antioxidant [2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2 -azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing antioxidant power (FRAP), cupric reducing antioxidant capacity, total antioxidant capacity (TAC) (phosphomolybdenum) and metal chelating] activities and enzyme [α-amylase, α-glucosidase, tyrosinase, acetyl-(AChE), butyryl-(BChE) cholinesterase] inhibitory effects of four extracts (methanol, hexane, ethyl acetate, aqueous) prepared from C. cajan stem bark. Direct identification of antioxidants was also conducted using the high performance liquid chromatography-ferric reducing antioxidant power (HPLC-FRAP) system. The highest TPC and TFC were recorded with the methanolic (23.22 ± 0.17 mg GAE/g) and ethyl acetate extracts (19.43 ± 0.24 mg RE/g), respectively. The methanolic extract exhibited important antioxidant activity with DPPH (38.41 ± 0.05 mg Trolox equivalent (TE)/g), ABTS (70.49 ± 3.62 mg TE/g), CUPRAC (81.86 ± 2.40 mg TE/g), FRAP (42.96 ± 0.59 mg TE/g) and metal chelating (17.00 ± 1.26 mg ethylenediaminetetraacetic acid equivalent/g). p-coumaric and caffeic acid were the predominant antioxidants in the samples. Results from enzymatic assays showed the potential abilities of hexane extract in inhibiting the AChE, BChE, α-amylase and α-glucosidase enzymes. From the results obtained in this study, it can be concluded that C. cajan can be considered as a promising source of antioxidants and key enzyme inhibitors that can be exploited for future bioproduct development.