title: Antimycobacterial evaluation and preliminary phytochemical investigation of selected medicinal plants traditionally used in Mozambique.
abstract: BACKGROUND
  Several medicinal plants are traditionally used in Mozambique to treat tuberculosis and related symptoms.
  
  
  OBJECTIVE
  It was aimed to assess the in vitro antimycobacterial activity of crude extracts from fifteen medicinal plants and to reveal main classes of compounds which may account for the activity of extracts.
  
  
  METHODS
  The plant materials were sequentially extracted by n-hexane, dichloromethane, ethyl acetate, and 70% ethanol. Decoction of each plant material was also prepared according to traditional use. Broth microdilution method was employed to screen extracts against two mycobacterial species: Mycobacterium smegmatis ATCC 607 and Mycobacterium tuberculosis H37Rv. The extracts with minimum inhibitory concentration(s) (MIC) below 125 μg/mL were considered active and further tested against different mycobacterial species and strains, namely Mycobacterium tuberculosis H37Ra, Mycobacterium bovis BCG ATCC 35734, Mycobacterium smegmatis mc(2) 155, Mycobacterium avium DSM 44156 and DSM 44157. Cytotoxic effect was evaluated against human macrophages from the monocytic THP-1 cells. Main classes of compounds in these active extracts were proposed from their (1)H NMR spectroscopic characterizations.
  
  
  RESULTS
  n-Hexane extracts of Maerua edulis and Securidaca longepedunculata, ethyl acetate extract of Tabernaemontana elegans and dichloromethane extract of Zanthoxylum capense were found to possess considerable activity against Mycobacterium bovis BCG and Mycobacterium tuberculosis H37Ra with MIC 15.6-62.5 μg/mL. Tabernaemontana elegans ethyl acetate extract displayed strong activity against Mycobacterium tuberculosis H37Rv (MIC 15.6 μg/mL). Except for Tabernaemontana elegans ethyl acetate extract which presented potent cytotoxic effects in THP-1 cells (IC(50)<4 μg/mL), the other three plant extracts showed moderate to none toxicity. Based on (1)H NMR spectroscopic analysis, major components in both Maerua edulis and Securidaca longepedunculata n-hexane extracts were linear chain unsaturated fatty acids. Zanthoxylum capense dichloromethane extract contained more complex constituents (mostly phenolic compounds). In the most potent extract, Tabernaemontana elegans ethyl acetate extract, the prominent compounds were identified as indole alkaloids.
  
  
  CONCLUSIONS
  The pronounced antimycobacterial activity of the medicinal plants Maerua edulis, Securidaca longepedunculata, Zanthoxylum capense, and Tabernaemontana elegans suggested that they might provide compounds which could be potential anti-TB drug leads.
authors.affiliation: Research Institute for Medicines and Pharmaceutical Sciences (iMed.UL), Faculdade de Farmácia, Universidade de Lisboa, Av. D. Forças Armadas, 1600-083 Lisboa, Portugal.
authors.forename: Xuan
authors.initials: X
authors.lastname: Luo
authors.forename: David
authors.initials: D
authors.lastname: Pires
authors.forename: José A
authors.initials: JA
authors.lastname: Aínsa
authors.forename: Begoña
authors.initials: B
authors.lastname: Gracia
authors.forename: Silva
authors.initials: S
authors.lastname: Mulhovo
authors.forename: Aida
authors.initials: A
authors.lastname: Duarte
authors.forename: Elsa
authors.initials: E
authors.lastname: Anes
authors.forename: Maria-José U
authors.initials: MJ
authors.lastname: Ferreira
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D009682:Magnetic Resonance Spectroscopy; D016488:Medicine, African Traditional; D008826:Microbial Sensitivity Tests; D009000:Monocytes / Q000187:drug effects; D009073:Mozambique; D009161:Mycobacterium / Q000187:drug effects* / Q000254:growth & development; D009162:Mycobacterium avium / Q000187:drug effects; D009163:Mycobacterium bovis / Q000187:drug effects; D020102:Mycobacterium smegmatis / Q000187:drug effects; D009169:Mycobacterium tuberculosis / Q000187:drug effects; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology* / Q000633:toxicity; D010946:Plants, Medicinal; D012997:Solvents / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D010936:Plant Extracts; D012997:Solvents