In vitro α-Glucosidase and α-Amylase Activities of Wild and Cultivated Amaranthus spp. and Isolated Compounds

Abstract

Introduction: Diabetes mellitus is a serious metabolic disorder that affects many South Africans. There is urgent need for alternative and affordable diabetic therapy from edible wild plants which have been used by the indigenous people for many years. This study presents in vitro antidiabetic effects of methanol leaf extracts of wild and cultivated Amaranthus spp. and isolated compounds. Methods: The inhibitory effects against yeast α-glucosidase and porcine α-amylase were determined using a dilution series of ethanolic extracts of wild and cultivated leaf extracts and isolated compounds of Amaranthus spp. The aerial parts of the plant material were subjected to silica gel chromatography to yield three compounds. Results: Wild A. hybridus showed potent α-glucosidase enzyme activity (89.92±0.04%) at the lowest concentration tested (0.125 mg/mL) in comparison to acarbose which exhibited 80.20±0.13% inhibition at the same concentration. Cultivated A. cruentus extracts inhibited α-glucosidase enzyme activity (84.95 ± 0.04%) at the lowest concentration compared to cultivated A. hybridus which exhibited inhibitory activities of 72.28 ± 0.06%. In addition, three compounds namely, α-spinasterol, palmitic acid and pheophorbide A-methyl ester isolated from wild A.cruentus were tested for in vitro antidiabetic activity. Palmitic acid demonstrated the highest inhibition against α-glucosidase for all the concentrations tested. Tested separately, the isolated compounds were weaker α-amylase enzyme inhibitors however, when the compounds were combined, inhibition of α-amylase increased to 58.49± 002% at 0.5 mg/mL. Conclusions: Extracts and compounds of Amaranthus showed strong α-glucosidase activity inhibition and mild α-amylase activity inhibition suggesting that the extracts and compounds slow glucose absorption.

The Impact of 10 Unmalted Alternative Adjuncts on Wort Characteristics

“…After pre-gelatinization, the glucose concentrations decreased, and the maltose and maltotriose concentrations increased, indicating the presence of substantial alpha-glucosidase activity in these unmalted alternative adjuncts, which were inactivated upon pre-gelatinization. The presence of these enzymes in these adjuncts has indeed been reported in the past [20][21][22][23][24], except for teff. There may be different forms of alpha-glucosidases, as previously reported for millet [25], where the alpha-glucosidases had optimal activity at pH 3.5 to 6.0 and a temperature of 60 • C. Buckwheat alpha-glucosidases preferred shorter maltodextrins over longer maltodextrins (DP = 13) [24], whereas millet alpha-glucosidases had higher affinity for polysaccharides than for maltose [25].…”

Screening of Manilkara zapota (L) P. Royen stem bark ethanolic extract for in vitro α-glucosidase inhibition, preliminary antidiabetic effects, and improvement of diabetes and its complications in alloxan-induced diabetes in Wistar rats

“…The EMZSB has exhibited significant (p < 0.01) α-glucosidase inhibition with an IC 50 value of 119.79 ± 1.52 µg mL −1 as compared to AEMZSB, when acarbose was the reference standard. These findings of moderate α-glucosidase inhibitory effects by EMZSB inclined us to rely on the provenance of a profusion of the varied amount of phytochemicals in this bark like spinasterol (Nkobole et al 2021), (+)-dihydrokaempferol (Saltos et al 2015), lupeol acetate (Srisurichan and Pornpakakul 2015), stigmasterol (Kumar et al 2013), ergosterol peroxide (Eawsakul et al 2021), and hederagonic acid (Xiao-An et al 2010) which were earlier reported for their α-glucosidase inhibition capabilities.…”

Determination of nutritional composition, enzyme inhibitory activity and antioxidant activity of pretreated, dehydrated <em style="mso-bidi-font-style: normal;">Amaranthus viridis</em> L. Leaves

“…It was reported that, at the lowest tested concentration of 0.125 mg/mL, wild A. hybridus had strong α-glucosidase enzyme activity (89.92±0.04%), whereas acarbose showed an inhibition of 80.20±0.13% at the same concentration. Cultivated A. hybridus showed inhibitory activities of 72.28 ± 0.06%, while cultivated A. cruentus extracts inhibited αglucosidase enzyme activity (84.95 ± 0.04%) at the lowest tested concentration (Nkobole et al, 2021).Compared with the aforementioned results it is evident that different varieties of Amaranthus plant may possess different α-glucosidase enzyme inhibitory activities. The genomic diversity of different species within the genus Amaranthus may be the primary reason to demonstrate different biological properties.…”

“…Further, antioxidant activity of different parts of the plant in terms of total phenolic content, DPPH radical scavenging activity, ferrous ion chelating activity and ferric reducing antioxidant power were reported by Popoola, 2022b andSalvamani et al, 2016). The antidiabetic activity (Helen & Bency, 2019;Nkobole et al, 2021;Oluwagunwa et al, 2021), lipid lowering activity (Ashok Kumar et al, 2012b;Oluwagunwa et al, 2021), anti-inflammatory activity (Haider et al, 2023;Salvamani et al, 2016Salvamani et al, , 2016 were reported. However, acetylcholinesterase and butyrylcholinesterase inhibitory activity of A. viridis was not reported in recent literature.…”

“…Nutritional and phytochemical constituents in fresh A viridis plant have been investigated previously (Ahmed et al, 2013;Bang et al, 2021;Kekere & Totolaye, 2020;Nadeeshani et al, 2018;Nkobole et al, 2021;Popoola, 2022a andOba, 2019a). Further, antioxidant activity of different parts of the plant in terms of total phenolic content, DPPH radical scavenging activity, ferrous ion chelating activity and ferric reducing antioxidant power were reported by Popoola, 2022b andSalvamani et al, 2016).…”