Applicability of Isolates and Fractions of Plant Extracts in Murine Models in Type II Diabetes: A Systematic Review

Mineral Analysis, In Vitro Evaluation of Alpha-Amylase, Alpha-Glucosidase, and Beta-Galactosidase Inhibition, and Antibacterial Activities of Juglans regia L. Bark Extracts

In traditional medicine, various parts of the plant Juglans regia L. are used to treat several pathological conditions including diabetes and infectious and periodontal diseases. This includes the bark of Juglans regia. The present study is aimed at evaluating for the first time the mineral composition, investigating the antidiabetic and antibacterial properties of Moroccan J. regia bark, and finally determining the correlations between the chemical composition of the tested extracts and their biological activities. The mineral composition was determined using inductively coupled plasma atomic emission spectroscopy. Then, nine extracts were prepared by different methods and modalities of extractions and investigated for their antidiabetic activities, via tests of inhibition of alpha-amylase, alpha-glucosidase, and beta-galactosidase enzymes, and for their antibacterial activities against six strains involved in infectious diseases and periodontology. Finally, the correlation between the chemical compositions of the different extracts prepared and their antidiabetic and antibacterial potencies was determined by Principal Component Analysis (PCA). J. regia is an important source of mineral elements, mainly Fe (19849.8), K (3487.8), Mg (2631.03), and P (691.02) mg/kg plant material. All the extracts of J. regia possess antidiabetic activity, and in particular, the macerated acetone extract gave the highest inhibitory activity against alpha-amylase (IC₅₀ value of 5445.33 ± 82.58 μg/mL), alpha-glucosidase (IC₅₀ value of 323.7 ± 1.71 μg/mL), and beta-galactosidase (IC₅₀ value of 811.2 ± 8.32 μg/mL). For the results of antibacterial activity, the macerated acetone extract at the concentration of 80 mg/mL was found to be the most active by inducing inhibition diameters of 12, 17, 18, 11, 14.5, and 16 mm against Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, and Listeria innocua, respectively. PCA allowed us to deduce that the extracts richer in polyphenols, in particular, the two acetone and ethanol macerates, have a better antidiabetic activity against alpha-glucosidase as well as a better antibacterial activity. The results of the present study revealed that the aqueous and organic macerate extracts showed a better antidiabetic activity and justified the use of J. regia bark as an antibacterial and antiseptic agent in traditional Moroccan medicine in the treatment of dental affections.

Mineral Content, Chemical Analysis, In Vitro Antidiabetic and Antioxidant Activities, and Antibacterial Power of Aqueous and Organic Extracts of Moroccan Leopoldia comosa (L.) Parl. Bulbs

Medicinal plants are a rich source of bioactive phytochemicals or bionutrients. Studies carried out during the past few decades have shown that these phytochemicals play an important role in preventing metabolic diseases such as cancer and diabetes. The present study was dedicated to the analysis of mineral and chemical composition and evaluation of antidiabetic, antioxidant, and antibacterial properties of aqueous and organic extracts of Leopoldia comosa, a plant with a long history of therapeutic and food use. Mineral content was determined using inductively coupled plasma atomic emission spectroscopy. Chemical composition was carried out by extraction of essential oils, preparation of aqueous and organic extracts, and qualitative and quantitative analysis. The biological study consisted of the evaluation of antidiabetic activity by inhibition of three enzymes, antioxidant activity by five tests, and antibacterial activity by the disc diffusion method. The correlation between chemical composition and antidiabetic and antioxidant properties was explored by PCA. The results showed that L. comosa contains high levels of Fe, K, P, Na, Cu, Mg, and Ca with values, respectively, in the order of 33552, 1843.14, 756.36, 439.65, 303.9, 272.37, and 20.55 mg/kg. Quantitative analysis showed that the diethyl ether extract had the highest content of polyphenols (129.75 ± 0.29 µg GAE/mg E), flavonoids (988.26 ± 0.18 µg QE/mg E), and tannins (30.22 ± 0.15 µg CE/mg E). All extracts of L. comosa possess inhibitory activity of alpha-amylase, alpha-glucosidase, and beta-galactosidase enzymes, mainly the decocted and the acetone extract. The antioxidant results showed that organic extracts are more active than aqueous extracts especially diethyl ether extract which was similarly found to have an antibacterial effect on Listeria innocua and Proteus mirabilis. PCA allowed us to deduce that phenolic compounds, flavonoids, and tannins are strongly correlated with antioxidant and antidiabetic activity. L. comosa may have potential remedy in the prevention of metabolic disease.

Picrorhiza kurroa Enhances β-Cell Mass Proliferation and Insulin Secretion in Streptozotocin Evoked β-Cell Damage in Rats

Autoimmune destruction of insulin producing pancreatic β-cells leads to insulin insufficiency and hyperglycemia in type 1 diabetes mellitus. Regeneration of β-cells is one of the proposed treatment for type 1 diabetes and insulin insufficiency. Picrorhiza kurroa is a medicinal herb and is traditionally being used for the treatment of various diseases. Previous studies reported the hypoglycemic potential of P. kurroa. However, its potential role in β-cell induction in insulin secretion have not been fully investigated. Here, we characterized the hydro alcoholic extract of P. kurroa rhizome (PKRE) and further studied its β-cell regeneration and induction of insulin secretion potential in streptozotocin (STZ) induced diabetic rats as well as in insulin producing Rin5f cells. ¹H-NMR revealed the presence of more than thirty metabolites including picroside I and II in PKRE. Further, we found that PKRE treatment (100 and 200 mg/kg dose for 30 days) significantly (p ≤ 0.05) protected the pancreatic β-cells against streptozotocin (STZ) evoked damage and inhibited the glucagon receptor expression (Gcgr) in hepatic and renal tissues. It significantly (p ≤ 0.05) enhanced the insulin expression and aids in proliferation of insulin producing Rin5f cells with elevated insulin secretion. Furthermore it significantly (p ≤ 0.05) increased insulin mediated glucose uptake in 3T3L1 and L6 cells. On the contrary, in diabetic rats, PKRE significantly (p ≤ 0.05) decreased high blood glucose and restored the normal levels of serum biochemicals. Altogether, our results showed that PKRE displayed β-cell regeneration with enhanced insulin production and antihyperglycemic effects. PKRE also improves hepatic and renal functions against oxidative damage.