Evaluation of Antimicrobial Potential and Comparison of HPLC Composition, Secondary Metabolites Count, and Antioxidant Activity of Mentha rotundifolia and Mentha pulegium Extracts.

Souheila Naghmouchi,Mayasar Al-Zaban,Nada K Alharbi,Olufunmiso Olusola Olajuyigbe

doi:10.1155/2021/9081536

Abstract

In the present study, the relationship between the phenolic counts, chemical composition, and biological activities of two Mentha species (Mentha rotundifolia (MR) and Mentha pulegium (MP)) was analyzed. The characterization of the action mode against pathogenic bacteria and the inhibition of spore germination of two fungal species using prepared methanolic extracts were studied here for the first time. The obtained data highlighted the presence of positive correlation between the secondary metabolites contents and the biological activities of the investigated extracts. In fact, HPLC analysis showed that the major components in both the extracts were eriocitrin and rosmarinic acid (25 and 20 mg/ml and 12 and 8 mg/ml in methanolic extracts of MR and MP, respectively). Moreover, the MR extract was rich in polyphenols and presents the highest antioxidant activity than MP ones. In addition, both extracts possess an antimicrobial activity against four Gram-positive and five Gram-negative bacteria and one yeast species (Candida albicans) and were able to inhibit the spore germination of two fungi species (Aspergillus niger and Aspergillus flavus). But, the significant activity was observed in the presence of MR methanolic extract. The effect of time on cell integrity of E. coli and L. monocytogenes determined by time-kill and bacteriolysis assays showed that the MR extract had a rapid bacteriolytic effect compared to the MP extract, and their capacities were significant against Gram-negative bacteria than positive ones. Based on the obtained data, it can be concluded that Saudi Mentha species have high pharmacological and industrial importance and they can be used in preparation of food or drugs.

Highlights

Several programs have been carried out to discover and develop numerous antimicrobial agents of biological, chemical, synthetic, or natural origin
Plant Material. e leaves of Mentha rotundifolia L. and Mentha pulegium were collected separately from an agronomical region situated in Al-Kharj in Saudi Arabia and identified according to the “Flora of the Kingdom of Saudi” [16]. e samples were dried in the shade away from light at room temperature
In the current study, the method described by Klepser et al [24] and modified by Viljoen et al [25] was used to evaluate the effect of M. rotundifolia and M. pulegium methanolic extracts against two representing Gram-positive and -negative bacteria

Summary

Introduction

Several programs have been carried out to discover and develop numerous antimicrobial agents of biological, chemical, synthetic, or natural origin. One of the important traditional sources of raw materials for medicine as well as for production of new preservatives was medicinal plants [4] Due to their chemical composition and secondary metabolites, the plant extracts play important roles in disease resistance and inhibit the growth of toxic microorganisms in food [5,6,7,8,9]. In addition to M. pulegium, Mentha rotundifolia L. is one of the mint species which have significant importance, both medicinally and commercially. Several researchers have determined the chemical composition and biological activities of Mentha extract, but according to our knowledge, there are no available studies focused on the characterization of the action mode of Mentha species against bacteria. E characterization of the action mode against E. coli and L. monocytogenes was assessed by time-kill and lysis assays

Materials and Methods

Antioxidant Activity

Results and Discussion

Dynamics Action of the Methanolic Extract