Evaluation of South African Equisetum arvense as an Antidiabetic, Antioxidant and Immune Booster using Economical Thin Layer Chromatography Bio-autography

Abstract

Introduction: Equisetum arvense (E. arvense) is an herbal medicinal plant that is mostly found in Limpopo and the North West Provinces of South Africa. Traditionally, the infusions and decoction of this plant are used in the management of type 2 diabetes, compromised immune system and oxidative stress related disorders. We investigated E. arvense in an attempt to authenticate its traditional use by cost-effective thin layer chromatography. Methods: The anti-diabetic activity was assayed by spraying a developed TLC plate with a buffered β-glucosidase enzyme and bovin solution and incubating at 36.9°C for 20 mins. A freshly prepared solution of 2-naphthyl-β-D-glucopyranoside and fast blue salt (1:4 v/v) was used for detecting inhibitory activity of the enzyme by the plant extract. Immune boosting potentials were evaluated by analysing for the presence or absence of β-sitosterol, a known immune booster in the 3 extracts (chloroform, ethanol, and water) and enriched fractions E and F. The antioxidant activity was investigated using 2,2-Diphenyl-1-Picryl-Hydrazyl (DPPH), H2O2 solution free radical scavenging as well as the reducing power of iron (+3) to (+2) by the extracts and enriched fractions. Standards and positive controls were used for the respective assays conducted. Results: Results obtained indicated the potentials of E. arvense extracts and enriched fractions as antidiabetic (inhibits β-glucosidase implicated in type 2 diabetes), immune boosting (presence of β-sitosterol) and antioxidant (IC50 values of 5.48 ± 0.13 - 12.38 ± 0.09 for FRAP, 12.00 ± 0.02 – 14.01 ± 0.23 for DPPH and 18.07 ± 0.06 - 62.01 ± 0.18 for H2O2) assays. The quantified amount of β-sitosterol and the antidiabetic compound in the plant ethanol extract were determined as 323.85 ng/mg and 130.04 mg/ml or 1.3 x 1011 ng/ml respectively. Conclusions: This study has preliminarily authenticated the traditional uses of E. arvense by rural South Africans.