Plantas medicinais utilizadas por pessoas com Diabetes mellitus controlam o estresse oxidativo e apresentam baixa toxicidade: avaliação in silico, in vitro e in vivo da “Pata-de-vaca” e “Macela”

Abstract

Medicinal plants are extensively used in traditional medicine to treat Diabetes mellitus (DM) and its complications. Chronic hyperglycemia in DM is pointed as responsible for oxidative stress development. The aims of this study were: i) to evaluate which plants are used in traditional medicine by people with DM in Uruguaiana/RS; ii) to evaluate the antidiabetic, antioxidant and toxicological potential for two of these plants in silico, in vitro e in vivo. For this, a research with 105 DM patients from Uruguaiana/RS was conducted to investigate their medicinal plants consumption habits (Manuscript 1). From the interviewed people, 67.6% say they do use medicinal plants. The four more used plants were “cow paw” (Bauhinia), jambolan (Syzygium jambolanum; Syzygium cumini), chamomile (Matricaria recutita), and macela (Achyrocline satureioides). The most used form of consumption was the infusion; in more than 80% of the cases, the consumption frequency was daily. Predictions in silico for the major phytoconstituents of the most used plants showed that some compounds presented probable antidiabetic activity (Manuscript 1). In sequence, the antidiabetic, antioxidant and toxicological potential of Bauhinia forficata Link subsp. pruinosa (BF) was tested in silico, in vitro and in vivo, in the last case using mice with chronic hyperglycemia (Manuscript 2). Results show that the phytoconstituents previously identified in the BF infusion (quercetin3-o-(2-rhammosyl)rutinoside; kampferol 3-o-(2-rhammnosyl)rutinoside; quercentin-3-O-rutinoside; and kaempferol-3-o-rutinoside) show high prediction in silico as antioxidants and low prediction as antidiabetic agents and toxic agents (mutagenicity, cardiotoxicity and hepatotoxicity). The antioxidant prediction was confirmed in vivo and ex vivo. BF was able to reduce lipid peroxidation and to control the reactive dichlorofluroscein species (DCF-RS) levels in erythrocytes from hyperglycemic mice. In the same way, the low antidiabetic prediction was ratified, since both hyperglycemia and other classic DM symptoms (polyuria, polydipsia, polyphagia, and weight loss) were not controlled by BF treatment (Manuscript 2). Besides, the BF action in the hepatic damages induced by hyperglycemia was evaluated in mice with DM (Article 1). Diabetic mice showed high levels of NQO-1 in pancreas, and of DCF-RS and lipid peroxidation in the liver, as well as decrease in the activity of hepatic catalase. BF treatment was able of normalizing these parameters. However, it did not have any effects over hyperglycemia, hepatomegaly, carbonylated proteins, non-protein thiols, and the 𝛿- aminolevulinate dehydratase activity (Article 1). Additionally, the antidiabetic, antioxidant, and toxicological potential of Achyrocline satureioides (AS) was tested (Article 2). The toxicity was predicted in silico and, after, evaluated in vitro with the comet assay using human lymphocytes. The median lethal dose (LD50) was evaluated in nauplii of Artemia salina. Results showed that the AS major compounds (quercetin, isoquercitrin, and caffeic acid) presents high prediction as antioxidants and low toxicity prediction, except for quercetin. The antioxidant activity was confirmed both in crude aqueous extract (infusion) and in isolated compounds. The determined LD50 classifies the plant as non-toxic. The comet assay showed no genotoxic potential for AS infusion (Article 2). Our data confirm the extensive use of plants by people with DM. In the same way, our analysis point oxidative stress as one of the mechanisms involved in tissue damages resulting of DM. The analysis also showed that the protective effects resulting of the BF treatment could be assigned to its antioxidant capacity, demonstrated in vitro and ex vivo, since no antidiabetic potential was identified in silico and in vivo. In the same line, the high antioxidant potential and the low toxicological prediction, point AS as a possible alternative treatment to the damage caused by oxidative stress. In summary, the results here presented allow us to conclude that BF plant, used in traditional medicine to treat DM and its complications, does not show direct antidiabetic effects. However, the antioxidant potential observed in both, BF and AS, make them possible complementary treatments to DM, especially considering the diabetic complications resulting of the oxidative stress increase. In this context, perspectives to future investigations on the use of these plants as complementary therapy to the traditional clinic treatment are open.