Activités antifongique, anti radicalaire, anti-inflammatoire et cytotoxique des huiles essentielles de quelques plantes médicinales de la famille des Annonaceae du Tchad et du Cameroun.

Abstract

Fungal infections, cancer and other diseases associated with free radical generation and inflammation are currently a critical public health issue that needs innovative control measures. In order to contribute to the search for solutions, this study was designed to assess the antifungal, radical scavenging, anti-inflammatory, and antineoplastic activities of essential oils from four Annonaceae plants (Monodora myristica, Xylopia aethiopica, Xylopia parviflora, and Uvaria angolensis) collected in Chad and Cameroon. Essential oils were extracted by hydrodistillation, and their chemical compositions determined using Gas Chromatography and Gas Chromatography coupled with Mass Spectrometry. The antifungal activity of the oils were evaluated using the microdilution method; the antiradical activity was evaluated following the DPPH° free radical scavenging potential; the anti-inflammatory activity was assessed following the inhibitory effect of oils against the 5-lipoxigenase; and the anticancer activity was evaluated by determining cell viability in the presence of MTT [3-(4,5-dimethylthiazolyl)-2,5-diphenyl-tetrazolium bromide], using flow cytometry. The yields of extraction of the essential oils ranged from 0.10 to 4.86%, depending on plant species, plant organ collected and its origin. The highest yield was obtained with the fruits of X. aethiopica from Cameroon (4.86%). The results from the chemical analyses indicated that samples from Monodora and Xylopia from both origins contained mainly monoterpenoids (75-94%), with α-phellandrene (52.7-67.1%) and -pinene (24.6-35.7%) as respective major constituents.The essential oil of M. myristica from Chad showed higher content in lomonene (14.9%) as compared to the Cameroonian sample (1.8%). The essential oil from Uvaria angolensis leaf contained mainly sesquiterpenoids (50.3%), and 12.5% of monoterpenoids only.The major constituent of this sample was an aromatic compound (benzyl benzoate) with 32.8%. The essential oils from the fruits of X. aethiopica, X. parviflora, and M. myristica, and leaves of U. angolensis inhibited the growth of Candida albicans ATCC24433, Candida parapsilosis ATCC22019 and Cryptococcus neoformans IP95026 with Minimum Inhibitory Concentrations ranging from 5 to 10 mg/ml. The essential oil from U. angolensis exhibited the highest radical scavenging potential, with a 50% scavenging concentration (SC50) of 7.69 g/l, followed by essential oils from M. myristica, X. aethiopica, and X. parviflora that showed SC50 between 8.9 and 11.74 g/l. The essential oils from X. aethiopica, X. parviflora, and M. myristica exerted 10-20% moderate inhibition of the 5-lipoxigenase and no activity was recorded from essential oil of U. angolensis.. All the oils samples from both origins significantly inhibited cancer cells (MCF-7) growth after 72 hours incubation, with a notable selectivity relative to normal cells (ARPE-19). Selectivity indices ranged from 1.375 to 10. Cells cycles were stopped at phases G0/G1 and S followed by apoptosis. The results obtained from this investigation indicated that essential oils from Annonaceae plants contain bioactive secondary metabolites, with potential effects against fungal infections, free radicals, inflammatory and cancer cells. Further detailed investigations are required to confirm these findings and formalize their eventual use to control the targeted affections.