In vitro biological activities of aqueous extracts of Tetrapleura tetraptera (Schumach. & Thonn.) taub. and Aframomum citratum (C. Pereira) K.Schum from three Agroecologic Zones in Cameroon

Abstract

Objective: To investigate some phytochemical constituents and biological activities of twelve samples of Tetrapleura tetraptera (Schumach & Thonn.) taub. and nine samples of Aframomum citratum (C. Pereira) K. Schum fruits collected in the bimodal forest zone (ZONE V), the unimodal forest zone (ZONE IV) and the highlands zone (ZONE III) in Cameroon. Methods: Fresh fruits extracts were obtained by aqueous infusion (100 °C during 15 min) and evaluated by spectrophotometric methods for total polyphenol (TPP), total flavonoids (TFLV) contents and antioxidant (DPPH, total antioxidant capacity by the phosphomolybdenum method, iron reducing power or ferric reducing antioxidant power and inhibition of beta carotene discoloration assays) and anti-inflammatory (inhibitions of protein denaturation and 5-LOX represented by INH.PROT and INH.5- LOX respectively) properties. Principal component analysis was performed. Results: For both species, fruits from ZONE V have the highest TPP, TFLV levels and biological activities. TPP and TFLV content of Aframomum citratum and Tetrapleura tetraptera fruits are positively and significantly (P<0.05) correlated. The biological activities of all extracts (0.25, 2.5, 25, 250 mg/mL) were dosedependent and the extracts have shown strong antioxidant and anti- inflammatory activities, but less than references (ascorbic acid, diclofenac, quercetin, and butylated hydroxytoluene). There was a positive correlation between TPP, TFLV and total antioxidant capacity, ferric reducing antioxidant power, and inhibition of beta carotene discoloration assays, and inverse correlations were observed with the IC50 (g/mL) of DPPH, INH.5-LOX and INH. PROT assays for both species. Conclusions: The fruits exhibit variabilities and those from ZONE V for both species are economically and healthcare challenging for herbalists, pharmaceutical firms, scientists and consumers. Indeed, most important extraction yield of bioactive compounds correlated with significant biological activities and the use of less material compared with an implementation in other Agro-ecologic Zones with the same results are noted.

Keywords

• biological activities; non-timber forest products; antioxidant; anti-inflammatory; agro-ecologic zone; protein denaturation