Effects of hydroethanolic extracts of Balanites aegyptiaca (L.) Delile (Balanitaceae) on some resistant pathogens bacteria isolated from wounds

Abstract

Background

The bark of Balanites aegyptiaca (L.) Delile (Balanitaceae) is widely used in the Togolese folk medicine for the treatment of wounds, malaria and skin diseases. This study aimed to evaluate the antioxidant properties and the activity of the bark extract of this plant against some resistant bacteria isolated from wounds.

Materials and methods

The antimicrobial activity was assayed using the NCCLS microdilution while the DPPH free radical scavenging and ferric reducing antioxidant power (FRAP) were used for the antioxidant activity. The susceptibility to conventional antibiotics of bacteria was assessed by an agar disk diffusion method using commercial disk. Phenolics were quantified using spectrophotometric methods.

Results

The hydroethanolic extracts of the bark inhibited in vitro the growth of Pseudomonas aeruginosa and Staphylococcus aureus in a dose-dependent manner. Bacteriostatic effects were observed on 15 (33%) and 21 (47%) strains of Staphylococcus aureus and Pseudomonas aeruginosa respectively. The MICs and MBCs against Staphylococcus aureus strains ranged respectively from 2.5 to 12.5 µg/mL and 2.5 to 50 µg/mL. Concerning Pseudomonas aeruginosa, these values were equal (12.5 µg/mL). Multidrug resistance was 95% against six antibiotics for Pseudomonas aeruginosa and 91% against five antibiotics for Staphylococcus aureus. The DPPH radical scavenging and the FRAP assays yielded weak antioxidant activity, closely linked with the total phenolic contents.

Conclusion

This study indicated that the bark extract of Balanites aegyptiaca possess bioactive compounds implicated in the free radical scavenging and antibacterial activities, justifying the use of the plant in the traditional medicines.

Introduction

The increased side effects, lack of curative treatment for several chronic diseases, high cost of conventional medicines, microbial resistance and emerging diseases are some reasons for the renewed public interest in herbal medicines (Pawardhan et al., 2005). The desert date (Balanites aegyptiaca, family: Balanitaceae) is one of the most commonly used medicinal plant in the traditional healthcare practices in Africa and South Asia (Hall, 1992, Jaiprakash et al., 2003). The Bark, fruits, seeds, root and leaves of this plant are widely used for the treatment of malaria, wound, jaundice, intestinal worm infection, syphilis, epilepsy, skin disease and dysentery (Daya and Vaghasiya, 2011, Katewa et al., 2004, Gad et al., 2006). The oil from the fruits exhibited anticancer activity against lung, liver and brain human carcinoma cell line (Ashaal et al., 2010). The saponin extracts from fruits of the plant have mosquito larvicidal activity (Zarroug et al., 1990) and showed significant anti-inflammatory, antinociceptive activities in the carrageen-induced oedema in the rat. Abdel-Rahim et al. (1986) reported that the whole fruit of Balanites aegyptiaca has hypocholesterolemic property. Acetone and methanolic extracts of stem bark protect Wistar albino rats against viper venom at lethal dose (0.194 mg/mL), when administered intramuscularly.

In Togo, different parts of Balanites aegyptiaca are used traditionally for medicinal purposes: malaria, skin and wounds diseases. Chronic wounds seem to be arrested in a stage dominated by inflammatory process in which, there is continuing influx of Polymorphonuclear Leukocytes (PMNLS). The activated PMNLS release cytolytic enzymes, free oxygen radicals and inflammatory mediators that cause extensive collateral damages to the host tissues. The presence of bacteria is most likely to influence this imbalance (Rani et al., 2013). Staphylococcus aureus and Pseudomonas aeruginosa are reported among the pathogenic bacteria widely known to cause significant impact on impairing wounds healing (Gjodsbol et al., 2006, Kirketerp-Moller et al., 2008, Fazli et al., 2009). These pathogens have been increasingly recognized for ability to cause significant nosocomial infections (Hota et al., 2009, Michel, 2013), including pneumonia, urinary tract infections, surgical wounds infections, and blood stream infections (Pukatzki et al., 2001). Particularly, Pseudomonas aeruginosa produce a shielding mechanism that offers protection from the phagocytic activity of Polymorphonuclear Leukocytes (PMNs). This phenomenon is the main cause of inefficient by antibiotic treatment (Bjarnsholt et al., 2008). The fact that Staphylococcus aureus and Pseudomonas aeruginosa are multidrug-resistant to treatment with antibiotics demands, alternative strategies to treat infections with these pathogens. In the present work, an attempt is made to assess the antioxidant properties and the microbial activities of Balanites aegyptiaca bark extracts on resistant bacteria isolated from wounds including Staphylococcus aureus and Pseudomonas aeruginosa.