The aim of this study was to characterize the polyphenolic composition by determination of chemical fingerprints of Methanolic extracts of Ocimum canum Sims, Ocimum basilicum L. and Ocimum gratissimum L. from Democratic Republic of Congo and to compare their antisickling activity of that of rosmarinic acid, the major compound to those of methanolic extracts. Phytochemical analysis performed by TLC and HPLC analysis, showed that rosmarinic acid is the most abundant phenolic acid in these Ocimum species according to the following order O. basilicum L., O. gratissimum L. and O. canum Sims. Methanolic extracts of these three species and pure rosmarinic acid showed significant antisickling activities with minimal concentration of normalization values of 0.18 ± 0.03, 0.23 ± 0.04, 0.26 ± 0.04 and 0.31 ± 0.05 mg/mL for rosmarinic acid, O. basilicum L., O. gratissimum L. and O. canum Sims methanolic extracts respectively. The antisickling activity order is the same as that of the rosmarinic acid content, indicating that this polyphenolic acid would be among the main active molecules in these extracts.

Objective: To carry out a phyto-chemical characterization of essential oil from Ocimum basilicum L. (O. basilicum) harvested in DR Congo and to assess the antioxidant potential of crude extracts with respect to the polarity for comparison reason.Methods: The phyto-chemical characterization of essential oil produced by hydro-distillation was performed by coupled gas chromatography-mass spectrometer analysis and the antioxidant potential evaluation by in vitro 2,2-diphenyl-1-picrylhydrazyl free radical scavenging activity method.Results: A previously weighed amount of fresh leaves of O. basilicum produced 0.65% of essential oil that led to the identification of a set of 84.44% out of 99.98% as major compounds (> 1.5%). The chemo-type of this essential oil was linalool-methyl chavicol. Chemical components of oil were characterized by oxygenated aromatic hydrocarbons (46.00%) and oxygenated monoterpenes (26.75%). With respect to the amount of components, methylchavicol also known as estragole (35.72%) constituted the very large quantity afterward linalool (21.25%) and then epi-α-cadinol (8.02%), α-bergamotene (6.56%), eugenol (4.60%), 1,8-cineole (4.04%), germacrene D (2.06%), thymol (1.64%), and (E)-citral (1.55%), respectively. Essential oil exhibited antioxidant potential and IC 50 = (1.180 ± 0.015) mg/mL. Non-polar crude extracts yields were low compared to the one of polar extracts. Only methanol and ethyl acetate had considerably manifested antioxidant potential with IC 50 values equal to (0.025 ± 0.013) mg/mL and (0.085 ± 0.012) mg/mL, respectively. As concerns to IC 50 values, essential oil was less active than methanol and ethyl acetate extracts. The methanol crude extract exhibited the highest activity. Non-polar extracts showed insignificant radical scavenging ability that did not allow assessing IC 50 values. These results highlighted the occurrence of antioxidant potential compounds in polar media.Conclusions: Essential oil and crude extracts of O. basilicum growing in DR Congo can be advocated as natural sources of antioxidant potential compounds not only in food but also in pharmaceutical industries. The high antioxidant potential of polar crude extracts highlights antioxidant character of its composition particularly butyl stearate and rosmarinic acid we isolated and identified, respectively in the methanol crude extract.

<abstract> <p>Each year more than 150, 000 tons of dyes are released in effluents by industries. These chemicals entities non-biodegradable and toxic can be removed from effluent by metallic nanomaterials. The aqueous extract of <italic>Manotes expansa</italic> leaves is used as reducing and stabilizing agent in the biogenic synthesis of Mn-CuO nanocomposites. The nanoparticles obtained were characterized using UV-visible spectroscopy, X-ray Diffraction (XRD), X-ray Fluorescence, Dynamic Light Scattering (DSL), and Scanning Electron Microscopy (SEM). The hemotoxicity of biosynthesized nanomaterials was assessed by evaluating their hemolytic activity using erythrocytes as a model system. The photocatalytic activity of Mn-CuO was carried out by photocatalytic degradation of Methylene Blue dye as a model. The results obtained by UV-vis spectroscopy showed a Plasmonic Surface Resonance band at 408 nm. XRD and X-ray fluorescence made it possible to identify the presence of particles of formula Mn_0.53Cu_0.21O having crystallized in a Hexagonal system (a = 3.1080 Å and c = 5.2020 Å). Spherical morphology and average height 49.34 ± 6.71 nm were determined by SEM and DSL, respectively. The hemolytic activity of biosynthesized nanomaterials revealed that they are not hemotoxic in vitro (% hemolysis 3.2%) and 98.3% of Methylene Blue dye was removed after 120 min under irradiation with solar light in the presence of Mn-CuO nanocomposites.</p> </abstract>