Abstract
Plants with diverse therapeutic properties are indigenous to Namibia. Concoctions of Colophospermum mopane and Acrotome inflata are widely used traditionally in the management of respiratory, gastrointestinal and wound infections. Limited studies have validated these traditional uses particularly against resistant bacteria strains such as Pseudomonas spp. This study aimed to determine the antimicrobial activity and phytochemistry of extracts of C. mopane and A. inflata, medicinal plants indigenous to Namibia. Phytochemical analysis and antimicrobial testing were done on leaves and barks of C. mopane and A. inflata whole plant. Voucher specimens were collected from Omugulugoonime village, Oshikoto region and validated at the National Botanical Research institute, Windhoek. Crude extraction of dried plants was done by maceration with ethanolic and aqueous solvents. Phytochemical screening was done using methods described by Harborne (1998) and/or Tiwari et al (2011). The antimicrobial activity against wild types of Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtillis and Candida albicans was done using the disc-agar-diffusion method. The mean diameters of the zones of inhibition (mm) for each extract were determined against each test organism. The antimicrobial activity (zones of inhibition) of ethanolic extracts (5 mg/ml) of C. mopane bark (10±0.6 mm) and leaves (10±1.2 mm) and A. inflata (8.7±0.6 mm) against P. aeruginosa is comparable to that of penicillin G (14±1.4 mm). Aqueous extracts leaves and bark of C. mopane showed activity against P. aeruginosa and S. aureus. The activity of the ethanolic extracts against B subtillis was: C. mopane leaves (7.3±0.6 mm), C. mopane bark (8.7±0.6 mm) and A. inflata (11.3±3.21 mm) and Penicillin G (26±1.4 mm). Both ethanolic and aqueous extracts did not have activity on C. albicans. Aqeous extracts of A. inflata had no activity on Pseudomonas and B. subtillis. Organic extracts of Colophospermum mopane and A. inflata exhibit antimicrobial potential against Pseudomonas and Bacillus species. The alkaloids, flavonoids and tannins should be further purified and characterized for antipseudomonal activity. Key words: Antipseudomonal, Namibia, Colophospermum mopane, Acrotome inflate.
Highlights
The sub-Saharan Africa is indigenous to over 50,000 species flora and ethno-medicines (Clarkson et al, 2004; Cowan, 1999; Hosttetmann et al, 1996; Iwu, 2014)
The ethanolic extracts of the bark of C. mopane were positive for alkaloids, sterols and steroidsand coumarins
The enthanolic extracts of leaves of C. mopane and the whole plant of A. inflata were positive for coumarins (Table 1)
Summary
The sub-Saharan Africa is indigenous to over 50,000 species flora and ethno-medicines (Clarkson et al, 2004; Cowan, 1999; Hosttetmann et al, 1996; Iwu, 2014). There is a rise in patients living with non-communicable diseases and the WHO has estimated that 3 out of 4 patients with hypertension reside in subSahara region (WHO, 2016). This calls for action for further research for efficacious and cost-effective medicines from the indigenous plants and/or ethnomedicines. The global surge in resistance against essential antimicrobials has had its greatest impact on health care in the sub-Saharan region and is a public health concern (Wagate et al, 2009; Parekh and Chanda, 2007). Antimicrobial resistance has led to use of more expensive medicines and or treatments, further constraining health care systems (Kamaraj et al, 2012)
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