Antioxidant and anti-glycation capacities of some medicinal plants and their potential inhibitory against digestive enzymes related to type 2 diabetes mellitus.
Plants preparations are used by traditional medicine in the treatment of various diseases, such as type-2 diabetes mellitus. Some medicinal plants are capable of controlling the complications of this metabolic disease at different levels, for example, providing antioxidant compounds that act against oxidative stress and protein glycation and others which are capable of inhibiting the catalysis of digestive enzymes and thus contribute to the reduction of hyperglycemia and hyperlipidemia. Our objective was to investigate the antioxidant and anti-glycation activities of some medicinal plants and their potential inhibitory against α-amylase, α-glucosidase and pancreatic lipase activities.
Based on the ethnobotanical researches carried out by academic studies conducted at the Federal University of Uberlandia, ten plants traditionally used in the treatment of type-2 diabetes mellitus were selected. Ethanol (EtOH) and hexane (Hex) extracts of specific parts of these plants were used in enzymatic assays to evaluate their inhibitory potential against α-amylase, α-glucosidase and lipase, as well as their antioxidant (DPPH, ORAC and FRAP) and anti-glycation (BSA/fructose model) capacities.
The results indicate that EtOH extract of four of the ten analyzed plants exhibited more than 70% of antioxidant and anti-glycation capacities, and α-amylase and lipase inhibitory activities; no extract was able to inhibit more than 40% the α-glucosidase activity. The EtOH extracts of Bauhinia forficata and Syzygium. cumini inhibited α-amylase (IC50 8.17 ± 2.24 and 401.8 ± 14.7 μg/mL, respectively), whereas EtOH extracts of B. forficata, Chamomilla recutita and Echinodorus grandiflorus inhibited lipase (IC50 59.6 ± 10.8, 264.2 ± 87.2 and 115.8 ± 57.1 μg/mL, respectively). In addition, EtOH extracts of B. forficata, S. cumini, C. recutita and E. grandiflorus showed, respectively, higher antioxidant capacity (DPPH IC50 0.7 ± 0.1, 2.5 ± 0.2, 1.3 ± 0.2 and 35.3 ± 9.0 μg/mL) and anti-glycation activity (IC50 22.7 ± 4.4, 246.2 ± 81.7, 18.5 ± 2.8 and 339.0 ± 91.0 μg/mL).
EtOH extracts of four of the ten species popularly cited for treatment of type 2 diabetes mellitus have shown promising antioxidant and anti-glycation properties, as well as the ability to inhibit the digestive enzymes α-amylase and lipase. Thus, our results open new possibilities for further studies in order to evaluate the antidiabetic potential of these medicinal plants.
Franco RR
，da Silva Carvalho D
，de Moura FBR
，Justino AB
，Silva HCG
，Peixoto LG
，Espindola FS
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Annona muricata Linn. leaf as a source of antioxidant compounds with in vitro antidiabetic and inhibitory potential against α-amylase, α-glucosidase, lipase, non-enzymatic glycation and lipid peroxidation.
Annona muricata leaves are used in traditional medicine to manage diabetes mellitus and its complications. The aim of this study was to evaluate the potential in vitro antidiabetic properties of Annona muricata leaf by identifying its main phytochemical constituents and characterizing the phenolic-enriched fractions for their in vitro antioxidant capacity and inhibitory activities against glycoside and lipid hydrolases, advanced glycation end-product formation and lipid peroxidation. Ethanol extract of A. muricata leaf was subjected to a liquid-liquid partitioning and its fractions were used in enzymatic assays to evaluate their inhibitory potential against α-amylase, α-glucosidase and lipase, as well as their antioxidant (DPPH, ORAC, FRAP and Fe2+-ascorbate-induced lipid peroxidation assays) and anti-glycation (BSA-fructose, BSA-methylglyoxal and arginine-methylglyoxal models) capacities. In addition, identification of the main bioactive compounds of A. muricata leaf by HPLC-ESI-MS/MS analysis was carried out. Ethyl acetate (EtOAc) and n-butanol (BuOH) fractions showed, respectively, antioxidant properties (ORAC 3964 ± 53 and 2707 ± 519 μmol trolox eq g-1, FRAP 705 ± 35 and 289 ± 18 μmol trolox eq g-1, and DPPH IC50 4.3 ± 0.7 and 9.3 ± 0.8 μg mL-1) and capacity to reduce liver lipid peroxidation (p < .01). Also, EtOAc and BuOH, respectively, inhibited glycation in BSA-fructose (IC50 45.7 ± 13.5 and 61.9 ± 18.2 μg mL-1), BSA-methylglyoxal (IC50 166.1 ± 21.6 and 413.2 ± 49.5 μg mL-1) and arginine-methylglyoxal (IC50 437.9 ± 89.0 and 1191.0 ± 199.0 μg mL-1) assays, α-amylase (IC50 9.2 ± 2.3 and 6.1 ± 1.6 μg mL-1), α-glucosidase (IC50 413.1 ± 121.1 and 817.4 ± 87.9 μg mL-1) and lipase (IC50 74.2 ± 30.1 and 120.3 ± 50.5 μg.mL-1), and presented lower cytotoxicity, when compared to the other fractions and crude extract. Various biomolecules known as potent antioxidants were identified in these fractions, such as chlorogenic and caffeic acids, procyanidins B2 and C1, (epi)catechin, quercetin, quercetin-hexosides and kaempferol. This study presents new biological activities not yet described for A. muricata, which contributes to the understanding of the potential effectiveness in the use of the A. muricata leaf, especially its polyphenols-enriched fractions, for the management of diabetes mellitus and its complications.
Justino AB
，Miranda NC
，Franco RR
，Martins MM
，Silva NMD
，Espindola FS
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Corn silk (Zea mays L.), a source of natural antioxidants with α-amylase, α-glucosidase, advanced glycation and diabetic nephropathy inhibitory activities.
The oxidative stress plays a critical role in the progression of diabetes mellitus (DM) and its complications. Corn silk is a traditional medicine used to treat DM. The aim of this study is to investigate the antioxidant capacity of corn silk, as well as its inhibitory potential on DM and diabetic nephropathy (DN). The ethanol extract of corn silk (CS) was liquid-liquid fractionated to get petroleum ether fraction (PCS), ethyl acetate fraction (ECS), n-butanol fraction (BCS) and water fraction (WCS). The Folin-Ciocalteu and AlCl3 assay showed that silk corn contained considerable amount of phenolics and flavonoids, ECS and BCS were the two phenolic-enriched fractions with highest TPC and TFC values. The ECS and BCS showed the highest total antioxidant activity and reducing power, as well as the strongest scavenging activity against DPPH and hydroxyl radicals, compared to CS and other fractions. The ECS and BCS displayed appreciable anti-hyperglycaemic effect indicated by the significant inhibition on α-amylase and α-glucosidase in enzymatic assays. In BSA-glucose model, ECS and BCS effectively inhibited the formation of advanced glycation end products (AGEs). In addition, the anti-diabetic nephropathy activity assay displayed that CS, ECS and BCS significantly inhibited the production of Col IV, FN and IL-6 in high-glucose stimulated mesangial cells at 200 μg/mL. These findings suggested the antioxidant activities of corn silk could contribute, at least in part, to its traditionally claimed therapeutic benefits on DM and DN. The phenolic-enriched CS fractions could be considered as a source of natural antioxidants and further developed for the prevention and treatment of DM and its complications including DN.
Wang KJ
，Zhao JL
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