Glycemia-reducing effects of Bolivian nutraceutical plants / Efectos reductores de la glucemia de las plantas nutracéuticas bolivianas

INTRODUCTION: The prevalence of diabetes type 2 is increasing worldwide, thus the search of novel alternative ther¬apies is needed. According to their traditional use, we selected five Bolivian plants Chenopodium quinoa (CQ) Ama¬ranthus caudatus (AC), Chenopodium pallidicaule (CP), Lupinus mutabilis (LM) and Smallanthus sonchifolius (SS) that are traditionally used to control glycemia. METHODS: The effect of a single oral administration of Ethanolic (EtOH), hydro-ethanolic (EtOH70) and aqueous (Aq) extracts from all plant species were tested for their effect on blood glucose in non-fasted mice and during the oral glucose tolerance test (OGTT). The effect on insulin secretion was evaluated in mice pancreatic islets. RESULTS: EtOH70 extracts of all the plants showed glucose-reducing effect at the highest dose evaluated (2000 mg/ kg b.w.). EtOH70 extracts improved the glucose tolerance evaluated by the OGTT in mice fasted for 12 hours. The extracts have different effects on glucose homeostasis since just extracts of AC, LM and CQ but not CP and SS in¬creased insulin secretion as shown on mice pancreatic islets. The phytochemical qualitative characterization of EtOH70 extracts detected phenolic acids and flavonoids in AC, CP and CQ; alkaloids in LM and anthocyanidins in SS. None of EtOH70 extracts tested showed in vitro or in vivo acute toxicity at concentrations where they exhibit glucose lowering effects. CONCLUSIONS: We report here that extracts from AC, CQ, CP, LM and SS exhibit glucose lowering effect while just AC, CQ and LM stimulate directly the insulin secretion

INTRODUCCIÓN: La prevalencia de diabetes tipo 2 está aumentando en todo el mundo, por lo que se necesita la búsqueda de nuevas terapias alternativas. Según su uso tradicional, seleccionamos cinco plantas bolivianas Chenopodium quinoa (CQ) Amaranthus caudatus (AC), Chenopodium pallidicaule (CP), Lupinus mutabilis (LM) y Smallanthus sonchifolius (SS) que se usan tradicionalmente para controlar la glucemia. MÉTODOS: Se evaluó el efecto de la administración oral única de extractos etanólicos (EtOH), hidroetanólicos (EtOH70) y acuosos (Aq) de las plantas mencionadas para determinar su efecto sobre la glucosa en sangre en ratones en o sin ayunas y durante la prueba de tolerancia a la glucosa oral (PTGO). El efecto sobre la secreción de insulina se evaluó en islotes pancreáticos de ratones. RESULTADOS: Los extractos de EtOH70 de todas las plantas disminuyeron la glucemia a la dosis más alta evaluada (2000 mg / kg b.w.). Los extractos de EtOH70 mejoraron la tolerancia a la glucosa evaluada mediante la PTGO en ratones con ayuno de 12 horas. Los extractos tienen diferentes efectos sobre la homeostasis de la glucosa, ya que solo los extractos de AC, LM y CQ pero no CP y SS aumentaron la secreción de insulina como se muestra en los islotes pancreáticos de los ratones. La caracterización cualitativa fitoquímica de extractos de EtOH70 detectó ácidos fenólicos y flavonoides en AC, CP y CQ, alcaloides en LM y antocianidinas en SS. Ninguno de los extractos de EtOH70 probados mostró toxicidad aguda in vitro o in vivo a concentraciones en las que exhiben efectos reductores de glucosa. CONCLUSIÓN: Los extractos de AC, CQ, CP, LM y SS exhiben un efecto reductor de la glucosa, mientras que solo AC, CQ y LM estimulan directamente la secreción de insulina

Lupinus mutabilis Extract Exerts an Anti-Diabetic Effect by Improving Insulin Release in Type 2 Diabetic Goto-Kakizaki Rats.

Lupinus mutabilis (LM) is a legume part of Bolivian traditional diet that has a nutraceutical property reducing blood glucose levels. The prevalence of type 2 diabetes is increasing worldwide thus; the search for novel anti-diabetic drugs is needed. Based on its traditional use, we evaluated the anti-diabetic effect of LM in the spontaneously diabetic Goto-Kakizaki (GK) rat, a model of type 2 diabetes and in Wistar (W) rats as healthy control. LM seeds hydroethanolic extract, analyzed by gas chromatography-mass spectrometry and high-performance liquid chromatography-high resolution mass spectrometry, is a complex mixture of volatile and non-volatile components. A single oral administration of LM extract (2000 mg/kg b.w.) improved glucose tolerance during the oral glucose tolerance test (OGTT) (30⁻120 min) in GK and W rats (p < 0.0001). The long-term treatment with LM (1000 mg/kg b.w.), for 21 days, improved the area under the curve (AUC) of glucose during OGTT at day 20, in both GK (p < 0.01) and W rats (p < 0.01). The HbA1c (GK rats, p < 0.05 and W rats, p < 0.0001) and the non-fasting glucose (GK rats, p < 0.05) were also reduced. LM increased both serum insulin levels (2.4-fold in GK rats and 2.5-fold W rats), and the glucose-induced (16.7 mM glucose) insulin release in isolated islets from treated animals (6.7-fold in GK rats, and 6.6-fold in W rats). Moreover, LM (10 mg/mL) stimulated in vitro glucose induced (16.7 mM glucose) insulin release in batch incubated GK and W rat islets (p < 0.0001). In perifused GK rat islets, insulin release in 16.7 mM glucose was increased 95.3-fold compared to untreated islets (p < 0.0001), while no significant differences were found in perifused W rat islets. The LM mechanism of action, evaluated using inhibitory compounds of the insulin secretion pathway, showed that LM-dependent insulin secretion was reduced 42% by diazoxide (p < 0.001), 70% by nifedipine (p < 0.001), 86.7% by H89 (p < 0.0001), 70.8% by calphostine-C (p < 0.0001) and 93% by pertussis toxin (p < 0.0001). A similar effect was observed in W rats islets. Our findings provide evidence that LM has an anti-diabetic effect through stimulation of insulin release. The effect is-dependent on L-type calcium channel, protein kinase A and C systems, and G protein-coupled exocytosis and is partially mediated by K-ATP channels.