Abstract
Plant extracts have been used as alternatives to the conventional chemical water treatment. Moringa oleifera Lam. is one of the plants used for this purpose due to its antimicrobial and coagulant properties. However, there is no systematization of Moringa’s application methodology. Different parts of the plant, extraction methods and concentrations can be applied to remove several pathogens present in contaminated drinking water. In the present work, reported Moringa applications with antimicrobial effect were systematically reviewed, in order to identify effective methodology(ies) for water treatment. Forty-nine articles were screened for: (1) part of the plant used, (2) extraction method, (3) extract concentration, (4) targeted pathogens, and (5) inhibition zone obtained. Nine articles complied with these criteria and were carefully analyzed; eight of them reported on leaf extracts and only one on seed extracts. Two approaches were used: analysis by pathogen and overall analysis. A total of eight different extraction methods were reported. Extract concentrations used ranged from 0.02 to 800 mg mL−1 and were tested on twenty pathogens. Our analysis revealed that none of such methods is effective against all the tested pathogens. However, leaf extracts obtained with distilled water or with 95% ethanol were the most effective ones for a higher number of pathogens such as Escherichia coli and, possibly, Vibrio cholerae. Moreover, Moringa’s extract concentration of 30 mg mL−1 obtained by the 95% ethanol extraction method was the most efficient. Findings suggest an effective procedure to use Moringa, reinforcing its importance as an environmentally friendly alternative for water treatment in areas lacking a water supply system.
Highlights
According to the World Health Organization (WHO), contaminated drinking water is estimated to cause 502 000 diarrhoeal deaths each year [1]
Publications were included in the study when all of the following selection criteria were met: (1) corresponding to research articles i.e. publications structured as Introduction, Material, and Methods, and Results/Discussion, or similar; (2) available as Free Full-Text; (3) written in English or Portuguese; (4) published until the date of the search (31st July 2018); (5) publications’ results explicitly reporting the antimicrobial effect of Moringa oleifera (MO), describing the pathogenic targets, the extraction method, concentration of the extract, parts of the plant and the inhibition zone obtained
The analyzed articles tested extracts of MO leaves and seeds to determine their antimicrobial activity on twenty pathogens: Aeromonas caviae, Bacillus anthracis, B. cereus, Enterococcus cloacae, E. faecalis, Enterobacter ssp., Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, Pseudomonas aeruginosa, Salmonella typhi, Serratia marcescens, Shigella dysenteriae, Staphylococcus aureus, S. epidermidis, Streptococcus pneumoniae, S. pyogenes, S. thermophilus, Vibrio cholerae and V. parahaemolyticus
Summary
According to the World Health Organization (WHO), contaminated drinking water is estimated to cause 502 000 diarrhoeal deaths each year [1]. With a rapidly growing global population, demand for water is expected to increase by nearly one-third by 2050. The deterioration of water quality is expected to further escalate over the decades and this will increase threats to human health, the environment and sustainable development” [2]. The most commonly occurring diseases (and agents) transmitted through drinking of unsafe water are: infectious hepatitis (A, B and C viruses), cholera (Vibrio cholerae), bacillary dysentery (Shigella spp.), typhoid (Salmonella enterica), paratyphoid (Salmonella paratyphi), salmonellosis (Salmonella spp.), colibacillosis (Escherichia coli), giardiasis (Giardia lamblia), cryptosporidiosis (Cryptosporidium spp.) and amoebiasis (Entamoeba group) [4]
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