Antioxidant and -amylase inhibition activities in vitro of various solvent extracts of Thymus schimperi Ronniger

Abstract

Thymus schimperi Ronniger is a wild endemic herb to Ethiopia, and is traditionally used as food flavoring, preservative as well as medicinal ingredient. This paper reports the total phenolic and flavonoid contents, antioxidant capacity and α-amylase inhibition activity of various solvent extracts of the dried leaves. The acetone extracts contained the highest total phenolic content (122.0±11.6 mg GAE/g). Total flavonoid content was the highest in methanol extract (45.1±2.9 mg QRE/g). The aqueous methanol extract showed the highest 2,2-diphenylpicrylhydrazyl (DPPH) radical scavenging ability (IC 50 =11.0±1.0 µg/ml), iron reducing power (60.1±1.0 mg AAE/g), and total antioxidant capacity (1.1±0.1 mg BHTE/g). The water extract exhibited the highest iron chelating activity (IC 50 = 65.4±1.1 µg/ml) while the methanol extract exhibited the highest percentage of α-amylase inhibition activity (IC 50 = 335. 6±90.4 µg/ml). Except for iron chelating activity, all antioxidant activities were positively correlated with total phenolic and flavonoid contents. The study revealed that antioxidant and α-amylase inhibitory activities of the crude extract were variable when extracted by different solvents indicating a high potential to be used as natural antioxidants in food preservation as well as for preventing oxidative stress mediated human disorders.

Evaluation of In vitro Antidiabetic Potential of Thymus schimperi R. and Thymus vulgaris L.

“…But α-amylase enzyme inhibitory activities of these extracts were significantly lowers (p < 0.05) than the α-amylase enzyme inhibitory activity of acarbose. The α-amylase inhibition capacity of aqueous: methanol (20: 80, v/v) extract of T. schimperi of our previous study (Engeda et al, 2015) was weaker (IC50 = 0.44 mg/mL) than that of the present study (IC50 = 0.33 mg/mL). This variation may be because of the geographical location and growing conditions of T. schimperi, such as soil and climate (Yang et al, 2018).…”

“…T. vulgaris L. is an important medicinal plant (Golmakani and Rezaei, 2008;Al-Bayati, 2008) which has been used for centuries as spice, home remedy, drug, perfume and insecticide, and also reported to have antidiabetic activity (Rime et al, 2014). So far, there are few studies on α-amylase inhibition activities of the dried leaf T. schimperi (Engeda et al, 2015). Therefore, the objective of the present study was to compare TPC, TFC and in vitro antidiabetic potentials of hot water and aqueous: methanol (20:80, v/v) extracts of the dried leaves of T. schimperi and T. vulagaris.…”

Effect of Extraction Solvents on Antioxidant and α-amylase Inhibition Activities of Spiced Green Chili Paste: An In Vitro Study

“…These findings are in agreement with previous investigation by Engeda (2015)] who reported that maximum extract yield from paste of spiced red chili pepper was obtained when water solvent was used. The variations in extract yield using different solvents might be explained by the polarity of extracted components and solvents applied (Engeda 2015;Engeda et al, 2015). According to the report by Elsorady and Ali (2015) on peanut skin extracts, the presence of water increased permeability of seed tissue and thus enabled a better mass transport.…”

Effect of Extraction Solvents on Total Phenolic Contents and in vitro Antioxidant Activity of the Leaves of Lippia adoensis var. Koseret Sebsebe

“…DPPH radical is scavenged by antioxidants through the donation of hydrogen forming the reduced DPPH. The color changes from purple 2, 2-diphenyl-1-picrylhydrazyl radical to reduced yellow diamagnetic 2, 2-diphenyl-1-picrylhydrazine molecule, which can be quantified by its absorbance reduction at wavelength 520 nm (Engeda et al, 2015). As the concentration of sample increased, the percent inhibition of DPPH radical also increased (Durairaj et al, 2008).…”