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.

Three diynes, octadec-17-ene-9,11-diynoate ethyl (1: ), 8-hydroxy-octadeca-13,17-diene-9,11-diynoate ethyl (2: ), and 8-hydroxy-octadec-13-ene-9,11-diynoate ethyl (3: ), were isolated from seed oil. The structure assignment of these three compounds was based according to chemical and spectroscopic data. They were screened against, the parasite that causes malaria. micro-test (Mark III, supported by the World Health Organization) was developed to assess the response of to the isolated three compounds, and statistical analysis were performed for determination of the concentration that inhibits 50% of the parasite maturation (IC). Two of the three diynes (2: and 3: ) showed a very effective antimalarial activity with an IC of 4.5 and 1.7 µM, respectively. Compound 3: exhibited better activity than quinine (IC 1.9 µM), the drug reference, while compound 1: had no antimalarial activity (IC > 125 µM). In the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) cytotoxicity screening, all compounds showed no toxicity (mean IC of 90 µM for each compound).