Aloe vera carbohydrates regulate glucose metabolism through improved glycogen synthesis and downregulation of hepatic gluconeogenesis in diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Aloe vera (L.) Burm.f. is an ancient medicinal plant that belongs to the family Asphodelaceae. It has a rich source of bioactive constituents such as carbohydrates, polyphenols, peptides, sterols and tannins, etc. Aloe vera has multiple biological activities such as anti-inflammatory, antioxidant and antidiabetic activity etc. AIM OF THE STUDY: The present study investigated the antidiabetic mechanism of Aloe vera carbohydrate fraction (AVCF) and aimed to provide insights into the regulation of carbohydrate metabolism enzymes in glucose homeostasis.

MATERIALS AND METHODS

The antidiabetic effect of AVCF was evaluated using α-amylase, α-glucosidase inhibition, glucose diffusion and glucose uptake assay. The in vitro AVCF effect on insulin secretion, cell proliferation and inflammatory markers were determined using streptozotocin-induced oxidative stress on RIN-m5F cells. Streptozotocin-induced male Wistar diabetic rats were treated for 21 days with AVCF (54 mg/kg bw). The in vivo AVCF effect was measured on fasting plasma glucose, insulin, glucagon, hexokinase, glycogen synthase and glucose-6-phosphatase, levels in diabetic rats. Histopathological studies for organ-specific effects in the pancreas, liver and small intestine were also conducted.

RESULTS

AVCF-treated RIN-m5F cells significantly increased BrdU levels, with insulin secretion, and decreased TNF-α, IL-6 and nitric oxide levels. AVCF treated streptozotocin-induced diabetic rats showed significantly decreased fasting plasma glucose, glucagon and glucose-6-phosphatase levels with a concomitant increase in insulin, hexokinase, and glycogen synthase levels and, glycogen content. These findings corroborate with the improved hepatic glycogen content in the PAS stained histological section of the liver of AVCF treated diabetic rats.

CONCLUSION

These results suggest that CF of Aloe vera improved glucose metabolism by activation of glycogenesis and down-regulation of gluconeogenesis thereby, maintaining glucose homeostasis. Hence, AVCF can be used as an alternative medicine in the alleviation of diabetes mellitus symptoms.

Aloe vera and its two bioactive constituents in alleviation of diabetes -proteomic & mechanistic insights

ETHNOPHARMACOLOGICAL RELEVANCE

Aloe barbadensis Miller, commonly known as Aloe vera has been used since time immemorial for treatment of various diseases such as cancer, inflammatory disorders, diabetes, wound healing etc. AIM: Diabetes mellitus is a complex disorder and understanding the molecular mechanisms involved is a key to identify different markers for early diagnosis of the disease. The proteomic approach offers a plethora of opportunities to identify markers and targets involved in pathogenesis of diabetes. The present study was undertaken to understand the mechanism of action of Aloe vera and its two constituents (Carbohydrates and Polypeptides) in the alleviation of diabetes in streptozotocin-induced diabetic rats through a proteomics approach.

METHODS

Different groups of rats were fed with Aloe vera extract, carbohydrate fraction and peptide/polypeptide fraction for three weeks. The diabetic rats fed with Aloe vera and its two fractions restored the glucose and insulin levels to normal. The plasma of the rats was depleted with IgG and albumin and proteomic analysis was carried out. Apolipoproteins (dyslipidemia), complement factors (inflammatory pathways), zonulin (intestinal permeability), anti-oxidant related proteins were selected in this study as these are involved in the progression of diabetes.

RESULTS

It was observed that Aloe vera extract is involved in the alleviation of diabetes through these pathways while the carbohydrate fraction alleviates diabetes through an anti-oxidant mechanism and glucose uptake while the polypeptide fraction alleviates diabetes through the restoration of intestinal permeability by reduced zonulin levels.

CONCLUSION

The constituents of Aloe vera works different pathways involved in diabetes and the synergistic effect of these constituents make Aloe vera extract a prospective candidate, which can alleviate diabetes through regulation of the pathways involved in the progression of diabetes.

Role of zonulin and GLP-1/DPP-IV in alleviation of diabetes mellitus by peptide/polypeptide fraction of Aloe vera in streptozotocin- induced diabetic wistar rats

ETHNO-PHARMACOLOGICAL RELEVANCE

The genus Aloe has a long history of usage in medicine. Aloe barbadensis Miller, commonly known as Aloe vera, is said to possess anti-diabetic, anti-inflammatory, anti-cancer, anti-microbial, immunomodulation, wound healing properties.

AIM OF THE STUDY

In diabetes mellitus, loss in intestinal permeability is observed with high levels of zonulin and low levels of glucagon-like peptide-1 (GLP-1) leading to hyperglycemia. The aim of the study was to understand the role of peptide/polypeptide fraction (PPF) of Aloe vera in the alleviation of diabetes through maintaining the intestinal permeability by regulating the zonulin and GLP-1 levels.

MATERIALS AND METHODS

The PPF of Aloe vera was obtained through trichloroacetic acid precipitation. The anti-diabetic potential of the PPF was tested through DPP-IV inhibition, glucose diffusion assay, and by using Rin-m5F cells. The anti-diabetic potential of the PPF was tested at a dose of 0.450 mg/kg bw in vivo using streptozotocin-induced diabetic Wistar rats. The effect of PPF on fasting plasma glucose, insulin, glucagon, Zonulin, GLP-1, DPP-IV, levels were studied in diabetic rats. The histopathological studies of the pancreas, small intestine, and liver were carried out for organ-specific effects.

RESULTS

PPF has the ability to reduce fasting plasma glucose levels with concomitant increase in insulin levels in streptozotocin-induced diabetic rats. It was also observed that increase in GLP-1 levels with a decrease in DPP-IV and zonulin levels thereby mitigating the loss of intestinal permeability. These findings correlate with the small intestine's histopathological observation where the excessive proliferation of epithelium in the small intestine of diabetic rats was reduced after PPF treatment.

CONCLUSION

These results suggest that the PPF of Aloe vera alleviates diabetes through islet cell rejuvenation via GLP-1/DPP-IV pathway and thereby suggesting the usage of PPF as an alternate medicine for diabetes mellitus with the possibility to reduce the intestinal permeability and zonulin levels.

Cu/TEMPO catalyzed dehydrogenative 1,3-dipolar cycloaddition in the synthesis of spirooxindoles as potential antidiabetic agents

A series of spiro-[indoline-3,3′-pyrrolizin/pyrrolidin]-2-ones, 4, 5 and 6 were synthesized in a sequential manner from Cu–TEMPO catalyzed dehydrogenation of alkylated ketones, 1 followed by 1,3-dipolar cycloaddition of azomethine ylides via decarboxylative condensation of isatin, 2 and l-proline/sarcosine, 3 in high regioselectivities and yields. The detailed mechanistic studies were performed to identify the reaction intermediates, which revealed that the reaction proceeds via dehydrogenative cycloaddition. Additionally, the regio and stereochemistry of the synthesized derivatives were affirmed by 2D NMR spectroscopic studies. The synthesized derivatives were explored further with molecular docking, in vitro antioxidant, and anti-diabetic activities.

A series of spiro-[indoline-3,3′-pyrrolizin/pyrrolidin]-2-ones were synthesized from Cu–TEMPO catalyzed dehydrogenation followed by 1,3-dipolar cycloaddition of azomethine ylides via decarboxylative condensation, resulting in high regioselectivities and yields.

Macrophage migration inhibitory factor: a potential marker for cancer diagnosis and therapy

Macrophage migration inhibitory factor (MIF) is a pluripotent cytokine which plays roles in inflammation, immune responses and cancer development. It assists macrophages in carrying out functions like phagocytosis, adherence and motility. Of late, MIF is implicated in almost all stages of neoplasia and expression is a feature of most types of cancer. The presence of MIF in almost all tumors and all stages of cancer makes it an interesting candidate for cancer therapy. This review explores the roles of MIF in neoplasia.