Abstract
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.
Highlights
Diabetes mellitus is characterized by chronic hyperglycemia and disorders of carbohydrate, lipid, and protein metabolism associated with absolute or relative deficits in insulin action and/or secretion [1, 2]
In comparison with other studies performed on J. regia, Rahimzadeh et al [46] reported that the aqueous macerated extract prepared from the leaves of this plant harvested in Iran has a very high alpha-amylase inhibitory power with an IC50 value of 320 ± 0:07 μg/mL, which is still more than 40 times more active than the one we found for the aqueous macerate in our study with an IC50 = 13424:33 ± 284:55 μg/mL
The present study allowed us to reveal for the first time the mineral composition and hypoglycemic properties via the three tests of inhibition of alpha-amylase, alpha-glucosidase, and beta-galactosidase enzymes of Moroccan Juglans regia bark
Summary
Diabetes mellitus is characterized by chronic hyperglycemia and disorders of carbohydrate, lipid, and protein metabolism associated with absolute or relative deficits in insulin action and/or secretion [1, 2]. In Morocco, between 2011 and 2015, the number of diabetics increased from 1.5 million people to more than 2 million, an increase of 25% in 5 years. 80% of diabetes cases are type 2 and mainly are people over 40 years of age and obese [4]. Recent studies have shown a significant increase in the number of children and adolescents with this disease, which may be associated with bad eating habits and a lack of physical activity. This leads to increasing rates of BioMed Research International obesity, which is considered a risk condition for the development of type 2 diabetes [5]
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