Antimicrobial and antioxidant activities of the methanolic extracts of three Salvia species from Tunisia

A Review on Bioactive Anthraquinone and Derivatives as the Regulators for ROS

Anthraquinones are bioactive natural products, which are often found in medicinal herbs. These compounds exert antioxidant-related pharmacological actions including neuroprotective effects, anti-inflammation, anticancer, hepatoprotective effects and anti-aging, etc. Considering the benefits from their pharmacological use, recently, there was an upsurge in the development and utilization of anthraquinones as reactive oxygen species (ROS) regulators. In this review, a deep discussion was carried out on their antioxidant activities and the structure-activity relationships. The antioxidant mechanisms and the chemistry behind the antioxidant activities of both natural and synthesized compounds were furtherly explored and demonstrated. Due to the specific chemical activity of ROS, antioxidants are essential for human health. Therefore, the development of reagents that regulate the imbalance between ROS formation and elimination should be more extensive and rational, and the exploration of antioxidant mechanisms of anthraquinones may provide new therapeutic tools and ideas for various diseases mediated by ROS.

LC-MS metabolomics profiling of Salvia aegyptiaca L. and S. lanigera Poir. with the antimicrobial properties of their extracts

BACKGROUND

Salvia L. (Lamiaceae) found in almost all countries in temperate and tropical regions. Both S. aegyptiaca L. and S. lanigera Poir. have a rather wide distribution in Egypt (Mediterranean region, Gebel Elba and nearly the whole Sinai). Salvia species showed antibacterial and antifungal activities against several groups of food microorganisms and pathogens, so they are considered as a natural foods preservatives.

AIM

Investigate the phytochemical profiles of S. aegyptiaca & S. lanigera collected from their natural habitats in Egypt and test the antimicrobial activities of both species against some bacteria and fungi pathogenic strains.

METHODOLOGY

In the present study, S. aegyptiaca and S. lanigera were collected from their natural habitat. Total phenolics and flavonoids contents were measured for aerial parts of both Salvia spp.. The separation and identification of the pure active materials of both Salvia sp. by using LC-MS system (UHPLC-TSQ Quantum Mass Spectrometer). The antimicrobial activities of the ethanol, water and benzene extracts of the two species were tested against different pathogenic strains and compared with the standard antimicrobial drug (Gentamycin). Antimicrobial activity was determined by using agar disk diffusion method.

RESULTS

The phenolics content in S. lanigera 132.61±6.23 mg/g and S. aegyptiaca 125.19±4.97 mg/g, while the flavonoids content was 35.68±1.84 and 40.63±2.11 mg/g, respectively. Through LC-MS analysis, two compounds were detected in both species; heptadecanoyl coenzyme A, that the highest percentage (13.5%) in S. aegyptiaca and (11.5 %) in S. lanigera. Oenin, in a peak area of 3.1% in S. aegyptiaca and 1.2 % in S. lanigera. Ethanol extract of the two species had the most inhibitory effect against all tested microorganisms that exceeded the effect of the standard, except for Mucor reinelloids which was more sensitive to the water extract. Moreover, S. lanigera ethanol extract showed larger inhibition zone than S. aegyptiaca in all tested microorganisms except for Pseudomonas aeruginosa.

CONCLUSION

This study shows the important phytochemicals that improve the antibacterial and antifungal activities of Salvia aegyptiaca and S. lanigera.

Phytochemistry and Biological Properties of Salvia verbenaca L.: A Comprehensive Review

The family Lamiaceae contains several plants used in traditional medicine to fight against different diseases. Salvia verbenaca L. (S. verbenaca) is one of the Lamiaceae species distributed around the Mediterranean regions. This plant exhibits different bioactive properties, including antibacterial, anticancer, antioxidant, antileishmanial, antidiabetic, immunomodulatory, and wound healing. This review was conducted to revise previous studies on S. verbenaca addressing its botanical description, geographical distribution, and phytochemical, pharmacological, and toxicological properties. Moreover, the main pharmacological actions of S. verbenaca major compounds were well investigated. Literature reports have revealed that S. verbenaca possesses a pivotal role in medicinal applications. The findings of this work noted that S. verbenaca was found to be rich in chemical compound classes such as terpenoids, phenolics, fatty acids, sterols, and flavonoids. Numerous studies have found that S. verbenaca essential oils and extracts have a wide range of biological effects. These results support the potential pharmacological properties of S. verbenaca and its traditional uses. This analysis can constitute a scientific basis for further refined studies on its pure secondary metabolites. Therefore, the outcome of the present work may support the perspective of identifying new therapeutical applications with detailed pharmacological mechanisms of S. verbenaca to prevent the development of some diseases such as neurodegenerative disorders. However, toxicological investigations into S. verbenaca are needed to assess any potential toxicity before it can be further used in clinical studies.

In vitro antioxidant, anticholinesterases, anti-α-amylase, and anti-α-glucosidase effects of Algerian Salvia aegyptiaca and Salvia verbenaca

In this study, Salvia aegyptiaca and Salvia verbenaca aerial part decoction and methanol extracts (SAE DE, SAE ME, SVR DE, and SVR ME) were screened for their in vitro antioxidant, anti-Alzheimer, and antidiabetic enzymes inhibition activities. The antioxidant properties of Salvia extracts were determined using DPPH radical scavenging, ABTS radical scavenging, Alkaline DMSO superoxide radical scavenging, β-carotene bleaching, reducing power, and metal chelating activity assays. All extracts showed high antioxidant capacity and the antioxidant properties with the best performance were detected in the SAE ME and SVR ME. The extracts of S. aegyptiaca and S. verbenaca showed a low inhibitory activity of acetylcholinesterase (AChE), whereas, the methanol extract of S. aegyptiaca had the highest inhibitory activity on butyrylcholinesterase (BChE) (71.60 ± 4.33% for 100 µg/ml) compared to the other extracts. In vitro inhibitory effect on diabetic enzymes showed that the ME inhibited α-amylase enzyme with an IC₅₀ 86 and 101 µg/ml for SAE and SVR, respectively. Similarly, both extracts inhibited α-glucosidase with (IC₅₀ 97 and 150 µg/ml, respectively). The decoction extracts exhibited lower activity on both enzymes. PRACTICAL APPLICATIONS: It is becoming evident that oxidative stress is involved in several acute and chronic diseases. Counteracting free radical generation has become one of the widest fields of research worldwide. This study deals with the in vitro antioxidant activity of two plants from the Salvia genus as well as the assessment of their in vitro inhibitory properties of four key enzymes implicated in diabetes and Alzheimer's disease. Concerning the practical applications of our work, it can be explored in its antioxidant part as a food supplement to prevent the excess of free radicals in the body and also in other industrial practices. Another potential use is in the prevention and amelioration of both diabetes and Alzheimer's disease symptoms for the extracts that had enzyme inhibitory activity, but this deserves further toxicological and in vivo studies.

Triterpenes from Salvia argentea var. aurasiaca and their antibacterial and cytotoxic activities

Five undescribed ursane-type triterpenes, identified as 1β,3β,15α-trihydroxy-urs-9(11)-12-diene (1), 1β,3β,15α,28-tetrahydroxy-urs-9(11),12-diene (2), 1β,3β-dihydroxy-urs-9(11),12-dien-28-al (3), 1β,3β,7β,15α,28-pentahydroxy-urs-12-ene (4), and 1β,3β,15α-trihydroxy-urs-11-en-28-al (5), together with five known compounds (6-10), were isolated from the acetone extract of the dried aerial parts of Salvia argentea L. var. aurasiaca (Pomel) Batt. et Trab. (Lamiaceae). Structures were elucidated on the basis of extensive spectroscopic analysis including HR-ESI-MS, 1D- and 2D-NMR techniques and comparison with literature data. The antibacterial evaluation of compounds 1-10 of the acetone extract of the dried aerial parts, in addition to nine compounds (11-19) previously isolated from the extract of the fresh aerial parts, by bioautography on Staphylococcus aureus followed by the determination of MIC values of active compounds by serial dilution technique against five bacteria, revealed that two compounds have an antibacterial effect comparable to antibiotics. The cytotoxic activity evaluation of compounds 1-19 showed that Six compounds exhibited an antiproliferative activity against K562 and HT1080 cells with IC₅₀ values ranging from 30.25 to 70.32 μM.

Ethnobotanical Survey, Preliminary Physico-Chemical and Phytochemical Screening of Salvia argentea (L.) Used by Herbalists of the Saïda Province in Algeria

An ethnobotanical study was carried out in the Saïda region among herbalists to evaluate the use of Salvia argentea (L.), a plant species native from North Africa belonging to the Lamiaceae family. Forty-two herbalists were interviewed individually, aged between 30 and 70 years, all males, 52.38% of them having received a secondary education level and having performing their duties for more than a decade. This study showed that Salvia argentea is used specifically in the treatment of diseases of the respiratory system. The leaves are the most commonly used part, usually in the form of powder and exclusively administered orally. The preliminary results of the physicochemical characterization and the phytochemical screening of the powdered leaves of Salvia argentea attest to their safety and confer them a guarantee of phytotherapeutic quality.

Chemical composition of volatile and fixed oils from of Salvia argentea L. (Lamiaceae) growing wild in Sicily

The chemical compositions of the essential oil and of the non-polar extracts (petroleum ether, dichloromethane) of the aerial parts (flowers, leaves and stems) of Salvia argentea L. were determined by GC-FID and gas chromatography-mass spectrometry analysis. 14-Hydroxy-α-humulene (40.1%) was recognised as the main constituents of the essential oil of S. argentea, together with 1,3,8-p-menthatriene (12.1%), globulol (7.4%) and β-sesquiphellandrene (5.8%). Tritriacontane (9.9% and 14.1%), heptacosane (8.4% and 10.5%), hentriacontane (8.3% and 10.9%), tetradecanal (8.4% and 10.2%) and methyldotriacontane (7.9% and 7.6%) were recognised as the main constituents of the extracts in petroleum ether and dichloromethane, respectively, whereas methyl linolenate (36.6% and 13.5%) and methyl myristoleate (10.5% and 18.5%) were recognised as the main constituents of the methylated extracts.

Biological activities of Wiedemannia multifida (Linnaeus) Bentham and Wiedemannnia orientalis Fisch. & Mey

OBJECTIVE

To evaluate total phenolic, antioxidant and antimicrobial activities of methanolic extracts of the Wiedemannia multifida (W. multifida) and Wiedemannnia orientalis (W. orientalis).

METHODS

Phosmomolybdenum assay, DPPH radical scavenging activity and β-carotene-linoleate bleaching were used to evaluate the antioxidant capacity.

RESULTS

The total phenolics were found to be (22.45±0.60) and (9.53±0.00) mg gallic acid equivalents (GAE)/g in W. multifida and W. orientalis extracts, respectively. The predominant phenolic compounds identified by HPLC-DAD in the both extracts were rutin+ellagic acid and kaempferol. Total antioxidant capacity and DPPH radical scavenging activity of W. multifida were higher than W. orientalis. In β-carotene-linoleic acid system, both extracts exhibited strong inhibition against linoleic acid oxidation. Antimicrobial activity was assessed by the agar diffusion method against fifteen microorganisms. Both extracts exhibited remarkable antibacterial activity.

CONCLUSIONS

The present study suggests that methanolic extracts of W. multifida and W. orientalis could be a good source of antioxidant and antimicrobial agents in foods, pharmaceuticals preparations.

Bioactive constituents of Salvia chrysophylla Stapf

The dichloromethane extract of the aerial parts of Salvia chrysophylla Stapf (Lamiaceae), which is an endemic species to south-western Anatolia, was studied for non-volatile secondary metabolites for the first time in this study. Structures of the isolated compounds were elucidated as sclareol, β-sitosterol, salvigenin, oleanolic acid and ursolic acid. The lipid peroxidation inhibitory activity and the DPPH free radical scavenging activity of the pure isolates were investigated to establish their antioxidant potential. Their anticholinesterase activity was carried out by the Ellman assay against both enzymes, acetylcholinesterase (AChE) and butyrylcholinesterase, and diterpene sclareol exhibited fairly good activity against both the enzymes while the two triterpenoids oleanolic and ursolic acids exhibited selective activity against AChE.

Chemical composition of 8 eucalyptus species' essential oils and the evaluation of their antibacterial, antifungal and antiviral activities

BACKGROUND

In 1957, Tunisia introduced 117 species of Eucalyptus; they have been used as fire wood, for the production of mine wood and to fight erosion. Actually, Eucalyptus essential oil is traditionally used to treat respiratory tract disorders such as pharyngitis, bronchitis, and sinusitis. A few investigations were reported on the biological activities of Eucalyptus oils worldwide. In Tunisia, our previous works conducted in 2010 and 2011 had been the first reports to study the antibacterial activities against reference strains. At that time it was not possible to evaluate their antimicrobial activities against clinical bacterial strains and other pathogens such as virus and fungi.

METHODS

The essential oils of eight Eucalyptus species harvested from the Jbel Abderrahman, Korbous (North East Tunisia) and Souinet arboreta (North of Tunisia) were evaluated for their antimicrobial activities by disc diffusion and microbroth dilution methods against seven bacterial isolates: Haemophilus influenzae, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus agalactiae, Streptococcus pneumoniae and Streptococcus pyogenes. In addition, the bactericidal, fungicidal and the antiviral activities of the tested oils were carried out.

RESULTS

Twenty five components were identified by GC/FID and GC/MS. These components were used to correlate with the biological activities of the tested oils. The chemical principal component analysis identified three groups, each of them constituted a chemotype. According to the values of zone diameter and percentage of the inhibition (zdi, % I, respectively), four groups and subgroups of bacterial strains and three groups of fungal strains were characterized by their sensitivity levels to Eucalyptus oils. The cytotoxic effect and the antiviral activity varied significantly within Eucalyptus species oils.

CONCLUSIONS

E. odorata showed the strongest activity against S. aureus, H. influenzae, S. agalactiae, S. pyogenes, S. pneumoniae and against all the tested fungal strains. In addition, E. odorata oil showed the most cytotoxic effect. However, the best antiviral activity appeared with E. bicostata. Virus pretreatment with E. bicostata essential oil showed better antiviral activity (IC(50) = 0.7 mg/ml, SI = 22.8) than cell-pretreatment (IC(50) = 4.8 mg/ml, SI = 3.33). The essential oil of E. astringens showed antiviral activity only when incubated with virus prior to cell infection. This activity was dose-dependent and the antiviral activity diminished with the decreasing essential oil concentration.

Comparative Study of the Antioxidant Activities of Eleven Salvia Species

The lipid peroxidation-inhibiting activities of aqueous methanolic extracts of eleven Salvia species (Fam. Lamiaceae) were evaluated in an enzyme-independent biological system. The total polyphenol contents and the amounts of the most abundant phenoloids of the genus, caffeic and rosmarinic acids, were also determined. The EC50 values of the extracts displayed substantial differences. All of the investigated species except S. jurisicii (EC50 191.2 μg/mL) exhibited higher activities than that of ascorbic acid (EC50 123.8 μg/mL), the reference compound. Among the studied species, S. scabiosifolia (EC50 5.4 μg/mL) demonstrated the highest effect, followed in sequence by S. dumetorum, S. transsylvanica, S. officinalis l albiflora, S. nemorosa l albiflora and S. recognita (EC50 6.5 – 10.2 μg/mL). The close correlation was confirmed between the antioxidant activities and the total phenol contents of the extracts. For caffeic and rosmarinic acids, the correlation was much weaker, indicating the important role of other polyphenols in the antioxidant activity.