Non-communicable diseases represent new challenges for the mankind in the fight for health improvement.Among these diseases, diabetes is a major contributor. Diabetes is a serious chronic disease that occurs when the pancreas does not produce enough insulin or when the body is unable to use the insulin produced effectively. This survey was performed in Kwango, Kongo-Central and Kinshasa provinces respectively between October 2016 and September 2017. A questionnaire was administered to the target population in order to collect relevant data. Plant identification was carried out at the herbarium of University of Kinshasa. The findings revealed that the inventoried medicinal flora is made up of 68 species which are divided into 34 families of 58 genera; the leaf is the most commonly used part in the treatment of diabetes while maceration is the most commonly used method of preparation. The use of medicinal plants is reported in almost all age groups from 20-89 years of age but with a predominance among people aged 40-49 years. Trees and phanerophyte species predominate in the flora studied; the majority of users of these medicinal plants have a primary level of education. In-depth phytochemical and pharmacological studies need to be carried out on these plants with a view to their scientific validation in the diabetes management.

Diabetes mellitus is a major public health problem in the world. In Africa, more than 80% of patients use plants for their treatment. However, the methods of validation of endogenous knowledge usually used are costly. The alternative method developed in this study aims at creating hyperglycemia <i>in vitro</i> and exploiting the metabolic pathway involving glucose oxidase for UV-visible spectrophotometric screening of medicinal plants’ antidiabetic activity. The evolution of glucose oxidation as a function of drug concentration is followed by UV-visible spectrophotometry. The formation of the stable complex between the enzyme and the inhibitor is studied using molecular docking. Drugs used (Gliben) and plant extracts exhibited an <i>in vitro</i> hypoglycemic effect by reducing exponentially, <i>in vitro</i>, the level of free glucose. The results also showed that <i>L. multiflora</i> is more active than <i>V. amygdalina</i> (IC₅₀: 1.36 ± 0.09 mg/mL Vs IC₅₀: 3.00 ± 0.54 mg/mL). Gliben (0.5 mg/mL) and <i>L. multiflora</i> (2 mg/mL) reduced both the rate of oxidation of glucose by glucose oxidase (catalytic power V_max: 0.84 ± 0.11 mg*mL^-1*min^-1 for Gliben and 1.72 ± 0.13 mg*mL^-1*min^-1 for ^{L. multiflora}); and the affinity of this enzyme for its substrate-glucose (K_M: 15.11 ± 2.72 mg*mL^-1 for Gliben and 9.17 ± 1.56 mg*mL^-1 for <i>L. multiflora</i>) when these results are compared to enzyme catalysis in the absence of inhibitor (V_max: 2.86 ± 0.44 mg*mL^-1*min-1; K_M: 8.07 ± 1.96 mg*mL^-1). The binding of GOX (1GAL) to selected phytocompounds derived from <i>L. multiflora</i> was confirmed by molecular docking. The most stable complexes were obtained for four compounds; <b>8</b> (-10.1±0.0 Kcal/mol), <b>6</b> (-9.5±0.1 Kcal/mol), <b>3</b> (-8.3±0.0 Kcal/mol) and <b>9</b> (-8.2±0.1 Kcal/mol). Among these, compounds <b>8</b> and <b>6</b> formed complexes with the enzyme stabilized by hydrogen bonds, the compound <b>8</b> forms 5 hydrogen bonds (<b>ASN514</b>, <b>ASP424</b>, <b>ARG95</b>, <b>TYP68</b>, <b>LEU65</b>) while compound <b>6</b> forms 2 hydrogen bonds (<b>ASN514</b> and <b>SER422</b>). However, no H-bonding interaction occurs in the complex that involves ligands <b>9</b> and <b>3</b> despite their high binding energy (-8.2±0.1 Kcal/mol and -8.3±0.0 Kcal/mol respectively). Glucose oxidase can serve as a marker enzyme for<i> in vitro</i> antidiabetic activity evaluation of medicinal plants.

The leaves and seeds of Aframomum alboviolaceum and Aframomum angustifolium are specifically used by traditional healers in the Democratic Republic of Congo (DRC) for the treatment of several pathologies. The aim of present study was to determine the microscopic characteristics and phytochemical composition of these species of the genus Aframomum. The microscopic study of these plants revealed the presence of punctate vessels, fiber cluster with calcium oxalate crystals, isolated unicellular hair, fibers, starch grains, spiral vessel fragments, fiber fragments, and indistinct parenchyma fragments. Phytochemical screening revealed several chemical groups such as phenolic acids, flavonoids, coumarins, alkaloids, terpenes, iridoids, saponins etc. The determination of total polyphenols, flavonoids and tannins gave contents ranging from 14.95 ± 0.45 and 63.98 ± 2.04 mgGAE/g, 0.16 ± 0.01 and 10.68 ± 0.32 mgQE/g and between 1.28 ± 0.03 and 28.51 ± 0.56 mg CAE/g respectively. In general, the leaves are richer in secondary metabolites, polyphenols, flavonoids and tannin than the seeds. Both plants also contain iron, magnesium, calcium and sodium. To our knowledge, this is the first time that histological elements have been identified in the leaves and seeds of A. angustifolium.