New anti-infective agents are urgently needed to fight microbial resistance. Methicillin-resistant Staphylococcus aureus (MRSA) strains are particularly responsible for complicated pathologies that are difficult to treat due to their virulence and the formation of persistent biofilms forming a complex protecting shell. Parasitic infections caused by Trypanosoma brucei and Leishmania mexicana are also of global concern, because of the mortality due to the low number of safe and effective treatments. Female inflorescences of hop produce specialized metabolites known for their antimicrobial effects but underexploited to fight against drug-resistant microorganisms. In this study, we assessed the antimicrobial potential of phenolic compounds against MRSA clinical isolates, T. brucei and L. mexicana. By fractionation process, we purified the major prenylated chalcones and acylphloroglucinols, which were quantified by UHPLC-UV in different plant parts, showing their higher content in the active flowers extract. Their potent antibacterial action (MIC < 1 µg/mL for the most active compound) was demonstrated against MRSA strains, through kill curves, post-antibiotic effects, anti-biofilm assays and synergy studies with antibiotics. An antiparasitic activity was also shown for some purified compounds, particularly on T. brucei (IC₅₀ < 1 to 11 µg/mL). Their cytotoxic activity was assessed both on cancer and non-cancer human cell lines.

The carob tree (Ceratonia siliqua L.) is currently considered one of the most valuable fruit and forest trees in various fields and sectors of activity. It is a versatile plant, belonging to the Fabaceae family. It is widely used in traditional medicine to treat many diseases such as diabetes, hypertension, and gastrointestinal disorders, given that all its parts (leaves, flowers, pods, seeds, wood, bark, and roots) are useful and hold value in many areas. Its importance has increased significantly in recent years. Originating from the Middle East, it is recognized for its ecological and industrial significance. Previous studies conducted on Ceratonia siliqua L. have revealed the presence of several compounds, including polyphenols, flavonoids, carbohydrates, minerals, and proteins. The carob tree demonstrates antihypertensive, antidepressant, anti-obesity, and antihyperglycemic activities. This plant is known for its medicinal and therapeutic virtues. Moreover, it is particularly interesting to consider the pharmacological activities of the major phytochemical compounds present in the different extracts of this plant, such as phenolic acids, for example, coumaric and gallic acids, as well as flavonoids such as kaempferol and quercetin. Therefore, this review aims to analyze some aspects of this plant, especially the taxonomy, cytogeography, traditional uses, phytochemical constituents, and pharmacological activities of Ceratonia siliqua L., in addition to its biological properties.

Salvia lavandulifolia Vahl essential oil is becoming more popular as a cognitive enhancer and treatment for memory loss. It is high in natural antioxidants and has spasmolytic, antiseptic, analgesic, sedative, and anti-inflammatory properties. Its aqueous extract has hypoglycemic activity and is used to treat diabetic hyperglycemia, but few studies have focused on it. The objective of this work is to evaluate the various biological and pharmacological powers of Salvia lavandulifolia Vahl leaf aqueous extract. Quality control of the plant material was first carried out. Followed by a phytochemical study on the aqueous extract of S. lavandulifolia leaves, namely phytochemical screening and determination of total polyphenols, flavonoids, and condensed tannins contents. Then, the biological activities were undertaken, in particular the antioxidant activity (total antioxidant activity and trapping of the DPPH° radical) and the antimicrobial activity. The chemical composition of this extract was also determined by HPLC-MS-ESI. Finally, the inhibitory effect of the α-amylase enzyme as well as the antihyperglycaemic effect was evaluated in vivo in normal rats overloaded with starch or D-glucose. The aqueous extract obtained by use of the decoction of leaves of S. lavandulifolia contains 246.51 ± 1.69 mg EQ of gallic acid/g DE, 23.80 ± 0.12 mg EQ quercetin/g DE, and 2.46 ± 0.08 mg EQ catechin /g DE. Its total antioxidant capacity is around 527.03 ± 5.95 mg EQ of ascorbic acid/g DE. At a concentration of 5.81 ± 0.23 µg/mL, our extract was able to inhibit 50% of DPPH° radicals. Moreover, it showed bactericidal effect against Proteus mirabilis, fungicidal against Aspergillus niger, Candida albicans, Candida tropicalis, and Saccharomyces cerevisiae, and fungistatic against Candida krusei. A marked antihyperglycemic activity (AUC = 54.84 ± 4.88 g/L/h), as well as a significant inhibitory effect of α-amylase in vitro (IC₅₀ = 0.99 ± 0.00 mg/mL) and in vivo (AUC = 51.94 ± 1.29 g/L/h), is recorded in our extract. Furthermore, its chemical composition reveals the presence of 37.03% rosmarinic acid, 7.84% quercetin rhamnose, 5.57% diosmetin-rutinoside, 5.51% catechin dimer, and 4.57% gallocatechin as major compounds. The antihyperglycemic and α-amylase inhibitory activities, associated with the antioxidant properties of S. lavandulifolia, justify its use in the treatment of diabetes in traditional medicine and highlight its potential introduction into antidiabetic drugs.

Cichorium intybus L. (Asteraceae) is an important industrial crop, as well as a medicinal plant which produces some bioactive compounds implicated in various biological effects with potential applications in human health. Particularly, roots produce hydroxycinnamic acids like 5-caffeoyquinic acid and 3,5-dicaffeoylquinic acid (di-CQA). The present investigation relates to the use of methyl jasmonate for enhancing phenolic compounds accumulation and production in hairy root cultures of C. intybus. Elicitated hairy root growth rate increased 13.3 times compared with the initial inoculum in a period of 14 days and di-CQA production represented about 12% of DW. The elicitation has also promoted the production of tricaffeoylquinic acid never described in the chicory roots and identified as 3,4,5-tricaffeoyquinic acid by means of nuclear magnetic resonance. Our study confirmed the strong anti-oxidant effect of di-CQA. Our results also confirmed globally a selectivity of action of di-CQA against Gram-positive bacteria, in particular against some strains of Staphylococcus and Streptococcus. However, a non-negligible antibacterial activity of di-CQA against Pseudomonas aeruginosa was also underlined (MIC = 0.156 mg.mL⁻¹ against some P. aeruginosa strains). The influence of di-CQA has been explored to evaluate its impact on the physiology of P. aeruginosa. Di-CQA showed no effect on the biofilm formation and the production of extracellular pyocyanin. However, it demonstrated an effect on virulence through the production of pyoverdine with a dose-dependent manner by more than 7-fold when treated at a concentration of 128 µg·mL⁻¹, thus suggesting a link between di-CQA and iron sequestration. This study shows that elicitated hairy root cultures of chicory can be developed for the production of di-CQA, a secondary metabolite with high antibacterial potential.

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.