Étude des caractéristiques physicochimiques et de l’activité antifongique des huiles essentielles d’Erigeron floribundus (Kunth.) Sch. Bip

L’usage des plantes médicinales connaît un regain d’intérêt. Cela est lié à la toxicité des produits chimiques, au coût élevé des médicaments chimiques, à l’éloignement et/ou l’insuffisance des centres de santé surtout en milieu rural. L’objectif général de cette étude était d’évaluer les potentialités thérapeutiques de l’huile essentielle des feuilles de l’espèce Erigeron floribundus utilisées en médecine traditionnelle en Côte-d’Ivoire. Les rendements en huile essentielle des feuilles d’Erigeron floribundus varient de 0,16 % pour les feuilles fraîches et de 0,31 % pour les feuilles séchées. Les indices physiques et chimiques de ces huiles essentielles sont en adéquation avec les critères de qualité des huiles essentielles selon la norme Afnor. L’effet antifongique des deux types d’huiles essentielles a été très remarquable sur les souches fongiques testées, notamment Trichophyton mentagrophytes et Aspergillus fumigatus, avec un effet moindre sur Candida albicans. Cette étude valide ainsi scientifiquement les usages traditionnels des extraits de la plante Erigeron floribundus en médecine traditionnelle.

Hydroethanolic Extracts of Erigeron floribundus and Azadirachta indica Reduced Plasmodium berghei Parasitemia in Balb/c Mice

Malaria is one of the most important infectious diseases in Africa especially in Cameroon. The nonaccessibility to current treatments for poor people and the appearance of drug-resistant Plasmodium falciparum parasites stimulate the search for alternative treatments. The aim of this study was to evaluate the antimalarial activity and the safety of hydroethanolic extracts from Erigeron floribundus and Azadirachta indica. The crude hydroethanolic extracts of E. floribundus (HEEF) and A. indica (HEAI) were prepared via maceration of the whole plant powder of E. floribundus and the leaves of A. indica in 70% ethanol. The antimalarial activity was determined according to Peter’s 4-day suppressive test using the murine model Plasmodium berghei/Balb C mice, while the acute and subacute toxicity tests were assessed according to the OECD 425 and 407 guidelines, respectively. The results indicate a reduction of parasitemia ranging from 49.75 ± 3.64 to 69.28 ± 1.36% for HEAI and from 30.46 ± 4.30 to 62.36 ± 2.32% for HEEI. Overall, HEEF and HEAI at doses of 60, 120, and 240 mg/kg b.w. and 75, 150, and 300 mg/kg b.w., respectively, showed a significant (p≤0.001) parasitemia reduction on P. berghei infecting BALB/c mice. HEEF and HEAI caused a significant (p<0.001) attenuation of body temperature drop in mice compared to negative control, except for the 150 mg/kg b.w. dose in the female group. Moreover, there was no mice mortality observed with these extracts even at 5000 mg/kg, while the aspartate amino transferase (ASAT) level of mice treated with 300 mg/kg b.w. of HEAI extract increased when compared with the control. The results of this study support the traditional use of these plants species extracts against malaria infection in rural zones of Northern Cameroon, therefore confirming their potential as sources for the development of efficient phytomedicines for malaria-poverty disease alleviation.

Biological Activities of the Essential Oil from Erigeron floribundus

Erigeron floribundus (Asteraceae) is an herbaceous plant widely used in the Cameroonian traditional medicine to treat various diseases of microbial and non-microbial origin. In the present study we evaluated the in vitro biological activities displayed by the essential oil obtained from the aerial parts of E. floribundus, namely the antioxidant, antimicrobial and antiproliferative activities. Moreover, we investigated the inhibitory effects of E. floribundus essential oil on nicotinate mononucleotide adenylyltransferase (NadD), a promising new target for developing novel antibiotics, and Trypanosoma brucei, the protozoan parasite responsible for Human African trypanosomiasis. The essential oil composition was dominated by spathulenol (12.2%), caryophyllene oxide (12.4%) and limonene (8.8%). The E. floribundus oil showed a good activity against Staphylococcus aureus (IZD of 14 mm, MIC of 512 &micro;g/mL). Interestingly, it inhibited the NadD enzyme from S. aureus (IC50 of 98 &micro;g/mL), with no effects on mammalian orthologue enzymes. In addition, T. brucei proliferation was inhibited with IC50 values of 33.5 &micro;g/mL with the essential oil and 5.6 &micro;g/mL with the active component limonene. The essential oil exhibited strong cytotoxicity on HCT 116 colon carcinoma cells with an IC50 value of 14.89 &micro;g/mL, and remarkable ferric reducing antioxidant power (TEAC= 411.9 &mu;mol TE/g).

Phenolic Constituents of Erigeron floribundus (Asteraceae), a Cameroonian Medicinal Plant

HPLC-MSn analysis of extracts of the Cameroonian medicinal plant Erigeron floribundus (Kunth) Sch. Bip. (Asteraceae) led to the identification of 40 different phenolic constituents. Four triterpene derivatives were isolated using semi-preparative HPLC and structures were elucidated on the basis of 1D and 2D NMR measurements. Compound 1, olean-3-oleil-12,18 diene, was a new natural product. Quali-quantitative measurements on the infusion obtained from dried aerial parts were also performed by HPLC-MSn and HPLC-DAD analysis showing that a cup of E. floribundus tea contains about 2.7 mg/mL of phenolics, with the caffeoyl quinic derivatives being the most abundant constituents.