title: In vitro anti-listerial activities of crude n-hexane and aqueous extracts of Garcinia kola (heckel) seeds.
abstract: We assessed the anti-Listerial activities of crude n-hexane and aqueous extracts of Garcinia kola seeds against a panel of 42 Listeria isolates previously isolated from wastewater effluents in the Eastern Cape Province of South Africa and belonging to Listeria monocytogenes, Listeria grayi and Listeria ivanovii species. The n-hexane fraction was active against 45% of the test bacteria with zones of inhibition ranging between 8-17 mm, while the aqueous fraction was active against 29% with zones of inhibition ranging between 8-11 mm. The minimum inhibitory concentrations (MIC) were within the ranges of 0.079-0.625 mg/mL for the n-hexane extract and 10 to >10 mg/mL for the aqueous extract. The rate of kill experiment carried out for the n-hexane extract only, revealed complete elimination of the initial bacterial population for L. grayi (LAL 15) at 3× and 4× MIC after 90 and 60 min; L. monocytogenes (LAL 8) at 3× and 4× MIC after 60 and 15 min; L. ivanovii (LEL 18) at 3× and 4× MIC after 120 and 15 min; L. ivanovii (LEL 30) at 2, 3 and 4× MIC values after 105, 90 and 15 min exposure time respectively. The rate of kill activities were time- and concentration-dependant and the extract proved to be bactericidal as it achieved a more than 3log(10) decrease in viable cell counts after 2 h exposure time for all of the four test organisms at 3× and 4× MIC values. The results therefore show the potential presence of anti-Listerial compounds in Garcinia kola seeds that can be exploited in effective anti-Listerial chemotherapy.
authors.affiliation: Applied and Environmental Microbiology Research Group (AEMREG), Department of Biochemistry and Microbiology, University of Fort Hare, Alice, South Africa; E-Mail:  aokoh@ufh.ac.za.
authors.forename: Dambudzo
authors.initials: D
authors.lastname: Penduka
authors.forename: Anthony I
authors.initials: AI
authors.lastname: Okoh
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D029763:Garcinia kola / Q000737:chemistry* / Q000378:metabolism; D006586:Hexanes / Q000737:chemistry; D008087:Listeria / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D012639:Seeds / Q000737:chemistry / Q000378:metabolism; D014867:Water / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D006586:Hexanes; D010936:Plant Extracts; D014867:Water; C026385:n-hexane
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