Phytochemical screening, Antimycobacterial activity of three medicinal Cameroonians plants and Acute toxicity of hydroethanolic extract of Vitellaria paradoxa

Tuberculosis (TB) is an infectious disease caused by the Mycobacterium tuberculosis (M. tuberculosis) complex, resposible  for health problems in developing countries. In Africa, various medicinal plants are traditionally used to treat  TB.  The aim of this study is to carry out the phytochemical screening, to evaluate the antimycobacterial activity of the crude extracts of three medicinal plants present in Cameroon (Zingiber officinale, Vitellaria paradoxa and Alstonia boonei) and the acute toxicity of hydroethanolic extract of Vitellaria paradoxa. The phytochemical screening was obtained by hydroethanolic extraction  and decoction. Inhibitory parameters of antimycobacterial activities were determined using the microplate alamar blue assay against M. tuberculosis H37Rv (ATCC 27294) and on one M. tuberculosis clinical strain. The crude extract with the best antimycobacterial activity was used for the acute toxicity assessment according to the OECD protocol. The results of the phytochemical screening revealed the presence of triterpenes and steroids in all the extracts, whereas  phenols were only present in the decoction of Alstonia boonei. All extracts tested showed antimycobacterial activities. The hydroethanolic extract of V. paradoxa  presented the best antimycobacterial activity with MICs of 78.13 and 625 μg/mL and MBCs of 78.13 and 2500 μg/mL respectively on M. tuberculosis H37Rv and on M. tuberculosis clinical strain. The results of the acute toxicity evaluation of V. paradoxa  showed a lethal dose 50  greater than 5000 mg/kg compared to control. The antimycobacterial activity of all the plant extracts used in this study justifies the traditional use of these medicinal plants on the treatment of  TB. Keywords: Zingiber officinale, Vitellaria paradoxa, Alstonia boonei, Phytochemical screening, Antimycobacterial activity, Acute toxicity

Synergistic Effects of Essential Oils and Antibiotics Against Some Bacterial Strains

The emergence of antibiotics resistances become an alarming situation due to the resurgence of cases. Scientific community explore therapeutics alternatives, including essentials oils and their combination with antibiotics. The designed study aimed to evaluate the combined effects of essentials oils from Drypetes Gosswelleri, Echinops giganteus, Melaleuca leucadendron essentials oils and antibiotics against strains implicated in infectious deseases. The antibacterial effect of essentials oils and antibiotics (Ciprofloxacine and Ceftriaxone) was carried out against Pseudomonas aeruginosa, Klebsiella pnemoneae, Salmonella enteritidis, Staphylococcus aureus and Bacillus cereus strains using the microdilution method. The synergistic effects were studied by the isobologram method to conclude on the interaction type. The results revealed that the essential oils were active against all the tested bacteria. Drypetes Gosswelleri EO showed the strongest activity with MICs ranging from 1.46 μg/mL to 11.71  µg/mL, followed by Echinops giganteus essential oil with MICs ranging from 2.92 µg/mL to 23.43 µg/mL and Melaleuca leucadendron had the lowest activity with MICs ranging from 5.88µg/mL to 750µg/mL. The combinations realized between Drypetes Gosswelleri and Echinops giganteus EOs and with two antibiotics use to evaluate the interaction type agains Salmonella enteritidis and Staphylococcus aureus. MICs obtained with the combinations are lower than those obtained with the EOs and antibiotics tested individually. The isobolograms plotted inform about a synergistic effects of combinations made with Drypetes Gosswelleri, Echinops giganteus EOs, Ciprofloxacin and Ceftriaxone against S. enteritidis and S. aureus strains. Based on the results obtained, the combinations between EOs and the antibiotocs, represent an interesting therapeutic alternative. Keywords: antibacterial, essential oil, combination, isobolograms, synergistics, Minimale Inhibitory Concentration, Minimale Bactericidal Concentration