Hypoglycemic effect of the dry leaf extract of Myrcia multiflora in streptozotocin-induced diabetic mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Myrcia multiflora (Lam) DC. is a medicinal plant used in folk medicine for diabetes control, mainly in the Brazilian Amazon. The leaves of this species has already demonstrated antidiabetic properties; however, in mice with type 2 diabetes (DM2), the cumulative effect of the consumption of the dry extract of M. multiflora leaves (Mm) has not yet been reported. AIM OF THE STUDY: To investigate the effect of the dry extract obtained from the infusion of the dried leaves of M. multiflora on the blood glucose levels of diabetic mice. MATERIALS AND METHODS: DM2 was induced in Swiss male mice by a single intraperitoneal injection of streptozotocin [150 mg/kg body weight (bw)]. The animals were divided into two control groups (healthy and diabetic without treatment) and three sample groups that received Mm (25 and 50 mg/kg bw) and acarbose (200 mg/kg bw) by gavage once daily for 28 days (D28). Additionally, biochemical parameters, thiobarbituric acid reactive species (TBARS) levels in the liver, and histopathological analyses of the kidneys and liver were performed. RESULTS: On the seventh day of treatment, a 74.7% reduction in glucose levels were observed in the group of diabetic animals treated with Mm (50 mg/kg bw) when compared to the beginning of the treatment. At D28, the hypoglycemic effect was maintained. The results of the biochemical and histopathological parameters and the TBARS levels suggest that this dry extract exerts nephro- and hepatoprotective effects. CONCLUSIONS: The findings demonstrate the potential that this extract has to inhibit the α-glucosidase enzyme, and it acts similarly to the positive control acarbose. Furthermore, this extract is nephro- and hepatoprotective. Therefore, this dry extract has the potential to be an adjuvant for DM2, which corroborates its use in folk medicine.

Hypoglycemic effect and toxicity of the dry extract of Eugenia biflora (L.) DC. leaves.

ETHNOPHARMACOLOGICAL RELEVANCE: The leaves of Eugenia biflora (Myrtaceae) are traditionally used by Amazonian populations for the control of diabetes. However, their chemical composition has not yet been described and pharmacological evidence has not been reported. OBJECTIVE: This study aimed to identify the chemical constituents and evaluate the hypoglycemic and toxic effect of the dry extract of the E. biflora leaves (DEEB). MATERIALS AND METHODS: DEEB, obtained by infusion, was analyzed using LC-HRMS and NMR, whose the catechin flavonoid was quantified using NMR. The antidiabetic effect of DEEB was evaluated according to its inhibition of the enzymes α-amylase and α-glucosidase, as well as the content of total phenols, free radical scavengingand antiglycation activities, and its in vitro cell viability. Oral maltose tolerance and chronic multiple dose tests (28 days) in streptozotocin-induced diabetic mice (STZ) were performed. The hypoglycemic effect and toxicity of this extract were evaluated in the multiple dose assay. Biochemical parameters, hemolysis, and levels of the thiobarbituric acid reactive species in the liver were investigated and histopathological analyses of the kidneys and liver were performed. RESULTS: Eight phenolic compounds were identified, with catechin (15.5 ± 1.7 mg g-1) being the majority compound and a possible chemical marker of DEEB. The extract showed inhibition activity of the enzyme α-glucosidase. Chronic administration of DEEB (50 mg/kg of body weight) reduced glucose levels in diabetic animals, similar to acarbose; however, DEEB (100 and 200 mg/kg bw) caused premature death of mice by D22 of the treatment. Our data indicate that one of the mechanisms of toxicity in DEEB may be related to the aggravation of oxidative stress in the liver. This histopathological study indicated that DEEB failed to minimize the progression of the toxicity of diabetes caused by STZ. CONCLUSIONS: This study demonstrated the hypoglycemic potential of E. biflora leaves. However, the prolonged use of this tea can be harmful to its users due to its considerable toxicity, which needs to be better investigated.

Libidibia ferrea (jucá) anti-inflammatory action: A systematic review of in vivo and in vitro studies.

Libidibia ferrea (Mart. ex Tul.) L. P. Queiroz (jucá) is a plant extensively used in the Brazilian folk medicine for the treatment of the inflammatory process. Primary studies have focused on the verification of these biological activities, highlighting the role of this plant in inflammatory conditions. This systematic review aimed to critically establish which part of the plant and what type of plant extract present the highest evidence of anti-inflammatory activity as in vivo and in vitro experimental models. This study has followed the recommendations by PRISMA and was registered in the PROSPERO database under number CRD42020159934. The literature review was carried out in several medical and scientific databases (Google Scholar, LILACS, ProQuest, PubMed, ScienceDirect, Scopus and Web of Science) in studies published up to February 2020 and updated on March 2021. No language restriction was made to this search. Eligibility criteria were adopted instead. The risk of bias was evaluated through SYRCLE's RoB tool for the in vivo studies. 609 studies were initiated to identify the whole and the subsequent steps of screening. 13 studies remained in the results (10 in vivo and 3 in vitro). In most studies the risk of bias was low or unclear. The high risk of bias was related to the risk of attrition and reporting bias. The fruit and the aqueous extract were identified as the most used in the studies carried out on the qualitative analysis and the results of the in vivo and in vitro studies were conducive to the anti-inflammatory action, a meta-analysis could not be performed due to heterogeneity between studies and the potential risk of bias to estimate the side effects. Therefore, the implementation of in vivo studies following the international guidelines could collaborate with analyses of the anti-inflammatory effect of jucá.