α-Glucosidase inhibition, 15-lipoxygenase inhibition, and brine shrimp toxicity of extracts and isolated compounds fromTerminalia macropteraleaves

Abstract

Context: Terminalia macroptera Guill. & Perr. (Combretaceae), a tree that grows in West Africa, has been used in traditional medicine against a variety of diseases such as hepatitis, gonorrhea, skin diseases, and diabetes. Objective: To investigate enzyme inhibitory activity against a-glucosidase and 15-lipoxygenase (15-LO) and toxicity against brine shrimp of extracts and compounds from T. macroptera leaves. Materials and methods: Methanol extract, ethyl acetate, and butanol extracts obtained from the methanol extract, six isolated polyphenols (chebulagic acid, chebulic acid trimethyl ester, corilagin, methyl gallate, narcissin, and rutin), and shikimic acid were evaluated for enzyme inhibition and toxicity. Results: In enzyme inhibition assays, all extracts showed high or very high activity. Chebulagic acid showed an IC 50 value of 0.05 mM towards a-glucosidase and 24.9 ± 0.4 mM towards 15-LO, in contrast to positive controls (acarbose: IC 50 201 ± 28 mM towards a-glucosidase, quercetin: 93 ± 3 mM towards 15-LO). Corilagin and narcissin were good 15-LO and a-glucosidase inhibitors, as well, while shikimic acid, methyl gallate, and chebulic acid trimethyl ester were less active or inactive. Rutin was a good a-glucosidase inhibitor (IC 50 ca. 3 mM), but less active towards 15-LO. None of the extracts or the isolated compounds seemed to be very toxic in the brine shrimp assay compared with the positive control podophyllotoxin. Conclusion: Inhibition of a-glucosidase in the gastrointestinal tract may be a rationale for the medicinal use of T. macroptera leaves against diabetes in traditional medicine in Mali. The plant extracts and its constituents show strong inhibition of the peroxidative enzyme 15-LO.

Chemical characterization and anti-hyperglycaemic effects of polyphenol enriched longan (Dimocarpus longan Lour.) pericarp extracts

“…The four compounds corilagin (IC50 = 48.94 ± 1.38 µg/mL), (-)-epicatechin (IC50 = 184.58 ± 7.61 µg/mL), rutin (IC50 = 67.33 ± 0.62 µg/mL) and ellagic acid (IC50 = 77.36 ± 3.43 µg/mL) displayed dose dependent α-glucosidase inhibition activity in vitro (Fig. 2), which is in agreement with previous literature (Kam et al, 2013;Pham, Malterud, Paulsen, Diallo, & Wangensteen, 2014). However, gallic acid, methyl gallate and proanthocyanidin trimer A-type did not show α-glucosidase inhibition activity (IC50 > 250 µg/mL) in vitro.…”

“…In addition, gallic acid was revealed to be capable of promoting β-cell regeneration (Latha & Daisy, 2011) and (-)-epicatechin was observed to cause a significant rise of glucose consumption in human HepG-2 cells (Lv et al, 2014). The other identified phenolics rutin and 4-O-methylgallic acid displayed potential use in anti-diabetes for inhibition of carbohydrate digestion enzymes, anti-obese and antioxidant activity (Baboota et al, 2013;Pham et al, 2014;Sun et al, 2007;Zhang et al, 2013). Moreover, proanthocyanidins trimer was found to reduce the incidence of type 2 diabetes according to a recent study (Zamora-Ros et al, 2014).…”

“…The revealed nine phenolics include gallic acid, 4-Omethylgallic acid, corilagin, methyl gallate, (-)-epicatechin, proanthocyanidin trimer A-type, rutin, methyl brevifolin carboxylate and ellagic acid. Corilagin is the most abundant of ellagitannin molecules in LPE and has been reported to exhibit strong 15-lipoxygenase, α-glucosidase and mild α-amylase inhibitory activity in vitro (Gunawan-Puteri, Kato, & Kawabata, 2012; Pham et al, 2014). Ellagic acid, a common dietary phenolic compound found in numerous functional foods, also one of the major components of LPE, has a wide range of biological functions.…”

Structure–activity relationship of immunomodulating pectins from elderberries

“…The metabolites and degradation products from investigations [136]. Rutin has previously been reported to be a good 15-LO inhibitor, in good accordance with our findings [161]. Also in this test system the presence of glycosyl groups attached to the flavonoid aglycone decreased the inhibitory activity, which is in agreement with previous report [156].…”

Ethnopharmacology, Chemistry and Biological Properties of Four Malian Medicinal Plants

“…Shikimic acid was inactive [13]. Toxicity towards brine shrimp was low (LD 50 > 100 μg/mL for all extracts, >200 μM for all pure compounds) [14]. This test is commonly used as an indication of general toxicity [98].…”