Contribution à l’étude de la désinfection de l’eau par photosensibilisation avec des extraits de plantes

L’étude de la désinfection de l’eau par photosensibilisation avec des extraits de plantes, en milieu de culture riche en tryptophane (1 %), a révélé que les extraits aqueux de Cassia occidentalis, Cassia alata, Carica papaya, Phyllanthus niruri et de Coleus kilimandschari ont un effet photosensibilisateur. Des extraits aqueux de Lantana camara, Cymbopogon citratus et de Hibiscus rosa-sinensis présentent un effet bactéricide. La désinfection de l’eau par photosensibilisation avec des extraits alcaloïdiques et non alcaloïdiques de Cassia alata, Cassia occidentalis, Carica papaya, Phyllanthus niruri et de Coleus kilimandschari a montré que les extraits non alcaloïdiques ont un effet photosensibilisateur. Par contre, les extraits alcaloïdiques ont révélé un effet bactéricide. L’effet photosensibilisateur trouvé pour les extraits non alcaloïdiques est directement lié à la présence des quinones et anthraquinones qui génèrent l’oxygène singulet en présence de la lumière solaire. L’oxygène singulet ainsi généré, attaque et endommage les microorganismes présents dans le milieu. Le temps d’ensoleillement nécessaire à l’inactivation des coliformes et autres bactéries est d’une heure pour une concentration de 2 ml d’extraits par litre d’eau polluée

Correlation between antioxidants and antiradical activities with in vitro antimalarial activity of Phyllanthus odontadenius

International audienceThis work aims to bring out the correlation between antioxidants and antimalarial activities of secondary metabolites of Po M2 plants (flavonoids, tannins and phenolic compounds contents) and their in vitro antimalarial activity by antioxidant activities justification. Field experiments were conducted both. Seeds from to one plant of Phyllanthus odontadenius were irradiated with 150 Gy dose (M1 seeds) and cultured first in vitro following transfer of M1 plants in field. Seeds from M1 plants were cultured for obtaining M2 plants which are used as biological material in this work after their harvest. In addition, phytochemical screening was carried out using reagent methods combined with spectrophotometric methods revealed the presence of flavonoids, tannins and phenolic compounds. The in vitro antimalarial activity assays on isolate Plasmodium falciparum were determined using microscopic method revealed that the highest in vitro antimalarial activity was extracted from 1503 plants (1.43 ± 0.17 μg/mL) justified by the highest of tannin content (0.76 ± 0.13 mg/g) and ratio between IC50 from DPPH and flavonoids quantity (15.52%) and that from DPPH and total phenolic compounds (5.17%). However, ratio between IC50 from DPPH or ABTS radicals and total phenolic contents were low than these of IC50 from DPPH or ABTS and flavonoid contents for each plant extract. Evaluation of extracts antioxidant activity was determined using DPPH and ABTS as radicals. This work confirm that there is correlation between in vitro antimalarial activity and antioxidants and antiradical activities of secondary metabolites of P.o. M2 plants (flavonoids, tannins and total phenolic compounds). When IC50 for DPPH test is high, in vitro antimalarial activity is also high, and, in opposite, when IC50 for ABTS is low, in vitro antimalarial activity is high

Antisickling activity of butyl stearate isolated from Ocimum basilicum (Lamiaceae)

Objective: To perform phytochemical analyses on the leaves of Ocimum basilicum L. (O. basilicum), to elucidate the structure of isolate and then perform the antisickling activity on the crude extract and on the isolate. Methods: The Emmel test performed on the acidified methanolic extract of this plant was used to evaluate the antisickling activity. The structure characterization of the active compound was performed using chromatographic techniques for the separation and the spectroscopic ones for structure elucidation (1H-NMR, 13C-NMR, COSY, HMBC). Results: The chemical screening on the crude extract revealed the presence of polyphenols (flavonoids, anthocyanins, leucoanthocyanins, tannins, quinones) alkaloids, saponins, triterpenoids and steroids. The obtained extract after evaporation yielded 34.50 g (11.5%) out of 300 g of powdered leaves of O. basilicum. The acidified methanolic extract and butyl stearate showed an interesting antisickling activity. Conclusions: The acidified methanolic extract and butyl stearate from O. basilicum displayed a good antisickling activity. To the best of our knowledge, this is the first time to report the antisickling activity of this compound in this plant. The synthesized compound presented the same spectroscopic characteristics than the natural one and the antisickling activities of its derivatives are understudying