Lavandula pedunculata (Mill.) Cav. Aqueous Extract Antibacterial Activity Improved by the Addition of Salvia rosmarinus Spenn., Salvia lavandulifolia Vahl and Origanum compactum Benth

Abstract

Lavender aqueous extracts are widely used in the Moroccan traditional medicine for their antibacterial properties. However, previous research have generally focused on investigating the antibacterial activity of lavender essential oils. The aim of this study is to evaluate the antibacterial activity of the Moroccan Lavandula pedunculata (Mill.) Cav. aqueous extract, alone, as well as in combination with extracts of other plant species known for their antibacterial activity: Salvia rosmarinus Spenn., Salvia lavandulifolia Vahl. and Origanum compactum Benth. We have tested the antibacterial activity of L. pedunculata, S. rosmarinus, S. lavandulifolia and O. compactum aqueous extracts individually and in combination against 34 strains using the agar dilution method. The combination effect was evaluated using the fractional inhibitory concentration (FIC). Polyphenol and tannin contents were determined using Folin-Ciocalteu reagent, and then some phenolic compounds were identified using UHPLC-MS. All the extracts displayed a large spectrum of antibacterial activity, especially against staphylococci, streptococci, Mycobacterium smegmatis and Proteus mirabilis. The minimum inhibitory concentration (MIC) values reached 0.15 ± 0.00 mg/mL for Staphylococcus warneri tested with S. lavandulifolia and 0.20 ± 0.07 mg/mL for Staphylococcus epidermidis tested with L. pedunculata or S. rosmarinus. Association of the L. pedunculata extract with S. rosmarinus, S. lavandulifolia and O. compactum showed synergistic effects (FIC ≤ 1). Moreover, the association of L. pedunculata with S. lavandulifolia was active against most of the Gram-negative strains resistant to the individual extracts. Determination of polyphenol and tannin contents showed the richness of the studied plants in these compounds. Additionally, chromatographic analysis demonstrated the high presence of rosmarinic acid in all the studied plant extracts. To our knowledge, this is the first study that shows the enhancing effect of the antibacterial activity of L. pedunculata aqueous extract combined with S. rosmarinus, S. lavandulifolia and O. compactum. These results confirm the effectiveness of the plant mixtures commonly used by traditional healers in Morocco and suggest that L. pedunculata might be used as an antibacterial agent either alone or, more efficiently, in combination with S. rosmarinus, S. lavandulifolia and O. compactum.

Phenolic Content, Antioxidant, Antibacterial, Antihyperglycemic, and α-Amylase Inhibitory Activities of Aqueous Extract of Salvia lavandulifolia Vahl

“…Our results agree with those of Salima Boutahiri et al, having identified rosmarinic acid, apigenin, luteolin, myricetin, herniarin, caffeic acid, protocatechuic acid, coumarin, cinnamic acid, vanillic acid, gallic acid, and chlorogenic acid in the aqueous extract of S. lavandulifolia leaves [ 17 ]. Salvador Cafligueral et al revealed the presence of apigenin, luteolin, rosmarinic acid, quercetin-3-O-β-D-glucoside, luteolin-7-O-β-D-glucoside, luteolin-4′-O-glucoronide, luteolin-7-O-rutinoside, and other compounds such as nepetin and 5-Hydroxy-7, 4′-dimethoxyflavone in the soluble fraction of petroleum ether and chloroform extracts from the leaves of S. lavandulifolia [ 45 ].…”

“…Our results are almost identical to those found by Boutahiri et al (2021) in terms of total polyphenol content. They found that the aqueous extract of S. lavandulifolia obtained by decoction contains 252.67 ± 5.40 mg EAG/g DE [ 17 ]. Polyphenols are considered the most abundant group of secondary metabolites in plants, through which they defend themselves against predators and intrusions [ 24 ].…”

“…According to the MBC/MIC ratio, the extract of S. lavandulifolia reported a bactericidal effect against Proteus mirabilis and fungicidal against strains Aspergillus niger , Candida albicans , Candida tropicalis , Saccharomyces cerevisiae , and Candida krusei . Based on these findings, Salvia lavandulifolia extract could potentially be used as natural preservatives in foods against well-known causative agents of foodborne illnesses such as S. aureus and E. coli [ 17 ]. In this work, the inhibitory activities of this extract are probably due mainly to the action of the majority compounds in this extract: rosmarinic acid, quercetin rhamnose, diosmetin-rutinoside, and catechin dimer [ 21 ].…”

“…It is generally used as a spice in the cosmetics industry [ 14 ]. Its leaves are used in traditional medicine as an antiseptic, healing, choleretic, astringent, and hypoglycemic remedy [ 15 , 16 ], and its antibacterial and antidiabetic activities had also been confirmed [ 17 ]. Diabetes is a group of metabolic diseases in which hyperglycemia is the main characteristic.…”

Phytochemical Profile, Antioxidant, Antimicrobial, and Antidiabetic Activities of Ajuga iva (L.)

“…This difference could be justified by the degree of polarity of each solvent to drive the phenolic compounds [ 84 ]. These phenolic compounds are secondary metabolites that have been extensively researched in a variety of medicinal plants, fruits, and vegetables [ 42 , 85 ]. They have antioxidant, antibacterial, and carbohydrase inhibitor properties.…”