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 3log10 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.

Evaluation of Different Fractions of Garcinia kola Extracts against Multidrug Resistant Clinical Bacterial and Fungal Isolates

“…16,[25][26] Therefore, the variation in MICs seen with different studies and also different antibacterial activities reported from extracted fractions could be due to methods and solvent used in the various extractions procedure. Other workers like Penduka and Okoh 22 reported MIC of 10mg/ml. Therefore, it is important to harmonise the extraction procedure so as to see a consistent and reproducible results that will serve as a reference.…”

“…It was also found to be active against a strain of Candida albicans clinical isolate (CFI 1), an observation that was similar to the work of Penduka and Okoh. 22 The butanol fraction of the extract was found to be active against all the A. baumannii isolates and candida albicans (CFI 1). According to Akinpelu et al 16 butanol extract of G. kola, exhibited antibacterial activity against Bacillus anthracis and E. coli sensitive isolates.…”

“…However, a number of studies documented a contrary view, observing that their aqueous extract had little or no antibacterial activity. [21][22][23] Thus pointing to the fact that reports of the antimicrobial effects of G. kola varies between available reports. Interestingly, in the present investigation, a strain of A. baumannii (AC3) clinical isolate that was resistant to colistin, a last line antibiotic, was sensitive to this fraction of G. kola.…”

Identification of the AntiListerial Constituents in Partially Purified Column Chromatography Fractions of Garcinia kola Seeds and Their Interactions with Standard Antibiotics

“…The extracts were prepared using the method of Basri and Fan [ 20 ] as outlined by Penduka and Okoh [ 21 ]. Briefly, the method involved the steeping of the seed powder in n-hexane solvent for 48 h with shaking in an orbital shaker at 50 rpm (Stuart Scientific Orbital Shaker, UK), followed by centrifugation at 3 000 rpm for 5 min (Beckman Model TJ-6RS Centrifuge, UK), filtration using a Whatman no.…”