In Vitro Antioxidant and Bactericidal Efficacy of 15 Common Spices: Novel Therapeutics for Urinary Tract Infections?

Abstract

Background and Objectives: Bacterial urinary tract infection (UTI) is the most common ailment affecting all age groups in males and females. The commercial antibiotics usage augments antibiotics resistance and creates higher recurrence rates of such communal infections. Hence, this study is aimed at investigating the antibacterial and antioxidant potentials of 15 common spices against 11 UTI-causing bacterial pathogens. Materials and Methods: The antioxidant potential of the methanolic extracts was analyzed as contents of total phenols and flavonoids; radical scavenging, total reducing power, the ferric reducing power assay. Urinary pathogens were subjected to spice extracts to investigate antibacterial assays. Results: Preliminary phytochemical study of spices was performed to find those containing alkaloids, flavonoids, phenolic compounds, and steroids that can be recognized for their noteworthy bactericidal effects. The outcome of the antioxidative potential from the four methods demonstrated the sequence of potent antioxidant activity: Acorus calamus > Alpinia galanga > Armoracia rusticana > Capparis spinosa > Aframomum melegueta. The total polyphenols and flavonoids in the studied species positively correlated with their antioxidant properties. The four most effective spices (A. calamus, A. galanga, A. rusticana, and C. spinosa) had a zone of inhibition of at least 22 mm. A. calamus, A. melegueta, and C. spinosa had the lowest minimum inhibitory concentration (MIC) value against Enterobacter aerogenes, Staphylococcus aureus and Proteus mirabilis. All 15 spices had the lowest minimum bactericidal concentration (MBC) value against most of the pathogenic bacteria. Conclusion: The four highly potent and unique spices noted for the in vitro control of UTI-causing pathogens could be pursued further in the development of complementary and alternative medicine against UTI-causing pathogens.

Keywords: MBC; MIC; antibacterial activity; antioxidant; spices; uropathogens.

Figure 1

The characteristics of antioxidant potentials of methanol extracts of 15 spices. The different letters in normal bars represent the significant variations at p < 0.05 by using Tukey′s method. (a) DPPH (%), (b) ABTS (mmol Trolox equiv/g dry mass) (c) TRP (mg of ascorbic acid equiv/g dry mass), and (d) FRAP (mmol Fe/g dry mass).

Figure 1

The characteristics of antioxidant potentials of methanol extracts of 15 spices. The different letters in normal bars represent the significant variations at p < 0.05 by using Tukey′s method. (a) DPPH (%), (b) ABTS (mmol Trolox equiv/g dry mass) (c) TRP (mg of ascorbic acid equiv/g dry mass), and (d) FRAP (mmol Fe/g dry mass).

Figure 2

(a) Total flavonoid and (b) total polyphenol content of methanolic extracts of 15 spices. The different letters in normal bars represent the significant variations at p < 0.05 by using Tukey′s method The quantity of flavonoid is articulated as mg of rutin equiv/g dry mass. The quantity of polyphenol is articulated as mg of gallic acid equiv/g dry extract.

Figure 3

The quality control study of standard antibiotic discs by disc well diffusion method with corresponding zone of inhibitions: A: Norfloxacin (10 µg); B: Gentamicin (10 µg); and C: Ciprofloxacin (5 µg) with ATCC strains: (1) E. coli-25922; (2) P. aeruginosa-27853; and (3) S. aureus-25923