Abstract
Salvia mirzayanii Rech. f. & Esfand is an endemic herbaceous plant belonging to the Lamiaceae family. The plant grows in the center and south of Iran and is broadly used in folk medicine. This review focuses on phytochemical and pharmacological data of S mirzayanii. Databases such as PubMed, Scopus, Web of Science, Scientific Information Database (Iranian database involving English and Persian articles), and Google Scholar were searched for terms “Salvia mirzayanii,” “Iranian sage,” “Marv-e-Talkh,” and “Moor-e-Talkh” in both Persian and English up to December 10, 2013. In line with the ethnopharmacological uses, antioxidant, immunomodulatory, anti-inflammatory, antimicrobial, and insecticidal activities of different preparations of S mirzayanii have been shown in recent studies. The antimicrobial activity against human pathogenic strains has mainly been attributed to the essential oil of S mirzayanii, which in numerous analyses has been investigated either in plants of different origin or prepared by differing extraction methods. Despite the studies on antioxidant or antimicrobial activities, profound research on the toxicity or clinical properties of the herb is missing.
Introduction
The family Lamiaceae encompasses almost 7000 species belonging to 236 genera. 1 Among those genera, Salvia (commonly known as Sage) is the largest genus with about 900 species and approximately 360 of those are found in Asia. 2 Throughout the world, many Sage species are traditionally used for various ailments including infection, colds, wounds, inflammation or memory loss. 3
Salvia is represented by 56 species in the flora of Iran and nearly one third of those are endemic. 4 One of the well-known endemic species is Salvia mirzayanii Rech. f. & Esfand (SM). 5 SM is growing in central and southern parts of Iran as a biennial or perennial flowering herb approximately 25 to 40 cm high with blue flowers. 6 Known as Iranian Sage, Moor-e-Talkh, or “Marv-e-Talkh” in local areas, the herb is traditionally administered for the management of various disorders. 7 Folk practitioners and local healers usually have reported the effectiveness of SM in diabetes, spasms, gastrointestinal disorders, infections, and inflammations. 8,9 In addition to these applications, SM is still used as an astringent and tonic in Iranian folk medicine.
Several investigations have been performed on the chemical constituents as well as on pharmacological properties of SM. To outline possible scopes for further studies, the current paper aimed to give a concise overview over phytochemical and pharmacological data published on SM. In this regard, respective databases as PubMed, Scopus, Web of Science, Scientific Information Database (Iranian database involving English and Persian articles), and Google Scholar were searched for terms “Salvia mirzayanii,” “Iranian sage,” “Marv-e-Talkh,” and “Moor-e-Talkh” in both Persian and English up to December 10, 2013.
Phytochemistry
Because of the high content and the fast and simple analysis, most of the phytochemical studies of SM focus on the composition of the essential oil. Until now, only few investigations dealt with other compounds, mainly phenolics.
Chemical Constituents of SM Essential Oil
Table 1 presents the most abundant essential oil constituents elucidated in 12 studies on SM oil. The major constituents of studied samples are monoterpenes. 10 –15 Cineol and α-terpinyl acetate were among the major compounds in all samples ranging from 6.2% to 21.2% and 5.2% to 22.6%, respectively. Similarly, linalool and linalyl acetate were reported among the major constituents in several SM oil samples. However, reports on other samples showed the lack or only low amounts of these 2 compounds, but the dominance of others as 5-neo-cedranol, eudesm-7(11)-en-4-ol, germacrene derivatives, and cadinenes. 9,16,17
It is obvious that origin, cultivation conditions, and growth stage as well as preparation and extraction method have high impact on both the quantitative and qualitative profile of the essential oil. 13,14,18
In 2 studies the effects of microwave-assisted extraction (MAE) or supercritical fluid extraction (SFE) versus common hydrodistillation on the composition of the essential oil were investigated. In MAE- and SFE-derived oils the acetylated compounds linalyl acetate and α-terpinyl acetate were among the major constituents whereas the deacetylated derivatives linalool and α-terpineol occurred at much higher concentrations in the hydrodistilled oils. These results confirm that hydrodistillation obviously leads to deacetylation of volatile acetates. Interestingly, a significant increase of 8-acetoxy linalool in the hydrodistilled oils as compared with SFE and MAE was observed as well. Thus, the acetyl group of linalyl acetate not only might be cleaved under supply of heat but also might migrate in the molecule. 7,14
Among the sesquiterpenes spathulenol, a tricyclic sesquiterpene alcohol, 19,20 bicyclogermacrene, 9,16,17 and teuclatriol as guaiane-type sesquiterpene have been reported in SM. 21 Among these sesquiterpenes, spathulenol, and bicyclogermacrene are quite frequent in SM, whereas teuclatriol was found in few samples only. Chemical structures of the main essential oil constituents of SM are represented in Figure 1.
Chemical structures of the main essential oil constituents of Salvia mirzayanii.
Other Components
As already mentioned, studies of the nonvolatile compounds in SM are scarce until now.
Sesterterpenes are rare natural compounds and have mainly been detected in marine sponges and algae. 22 In plant kingdom they have been proven in several Salvia species. Salvimirzacolide was the first sesterterpene identified in SM. 23 Recently, 5 new sesterterpenes (Figure 2) have been isolated from the aerial parts of the herb and identified via nuclear magnetic resonance (1- and 2-dimensional), X-ray diffraction, and mass spectrometry analysis. 24
Chemical structures of sesterterpenes in SM.
In addition, several flavonoids have been reported in SM. Chrysoeriol, a methoxyflavonoid with antioxidant, muscle relaxant, anti-inflammatory and chemopreventive properties 25,26 was identified 27 as well as cirsimaritin for which a positive effect in the management of acute renal failure has been shown. 28 Besides these, the occurrence of salvigenin, eupatorin, and the 6,7,3′,4′-tetramethyl ether of 6-hydroxyluteolin has been proven 27,29 and rutin and luteolin were detected in a methanolic extract. 30
Data on the amounts of phenolic compounds in SM are scarce as well. Only 1 investigation has determined the total phenolic content of a methanolic extract of SM aerial parts as 44.92 ± 0.13 mg gallic acid equivalents/g. 31 In addition, common flavonoids as rutin or luteolin and phenolic compounds as catechin and rosmarinic acid were quantified in a methanol extract of the aerial parts of SM using high-performance liquid chromatography. The amounts of these compounds were 4.15, 2.17, 71.58, and 7.01 mg/kg in the extract, respectively. The total flavonoid content of this extract was 188.5 ± 38.5 mg catechin/g dried extract. 30 Chemical structures of these compounds are shown in Figure 3.
Chemical structures of phenolics in SM.
Pharmacological Activities
Traditional Uses
Salvia mirzayanii is widely used as a medicinal herb and spice by people of southern regions of Iran, especially in Hormozgan and Kerman provinces. Many medical applications such as the treatment and management of gastrointestinal disorders, skin infections and wounds, diabetes and hyperglycemia, inflammation, and general weakness are described. 6,21
Antimicrobial Properties
Because of the high amounts of oxygenated monoterpenes in the essential oil and the traditional use, SM oil has been repeatedly assessed for antimicrobial properties. 12,16,20,32,33 A direct comparison of these studies is not thoroughly possible. In all respective investigations, different bacterial strains and various test methods were applied. The antimicrobial activity of SM against Staphylococcus aureus, Candida albicans, and the plant pathogen Fusarium solani was evaluated using the disc diffusion method. SM essential oil showed good antimicrobial effects against the yeast and the plant pathogen as compared to positive standard antibiotics, but only low activity against S aureus. 16 Using the same experimental setup, some activity of SM essential oil against gram-positive bacteria was confirmed. However, SM volatile oil was not active against gram-negative strains. 20 Another study reported the effects of SM on a broader panel of microorganisms but minimum inhibitory concentration values of more than 1.25 mg/mL were extremely high and not supportive for an antibacterial activity. Nevertheless, the antibacterial and antifungal activities of the essential oil of SM were higher than those of the essential oils of Salvia hydrangea DC ex Benth and Salvia santolinifolia Boiss in this study. 12 As some of the constituents of SM essential oil such as linalool, linalyl acetate, α-terpinyl acetate and 1,8-cineol are well known for antimicrobial effects, 34 –36 these components are assumed to contribute to the antimicrobial activities.
A study on the anti–Helicobacter pylori effect of native Iranian plants proved a SM methanol extract to be the most potent one. In that evaluation, the extract showed the maximum inhibitory effect on different H pylori isolates with minimum inhibitory concentrations of 32 to 64 μg/mL. 33 These results underline that polar compounds in SM contribute to antimicrobial effects.
An antimicrobial activity of SM is comprehensible and in accordance with the activity of other sage species. Nevertheless, broader and more thorough investigations against human pathogenic microorganisms of better quality would be desirable.
Fumigant Toxicity and Repellency Effect
Traditionally, fumigation of SM aerial parts is believed to be effective against insects. Thus, an investigation was carried out to evaluate the insecticidal activity of SM against 1-day old adult beetles from the species Callosobruchus maculatus F. and Tribolium confusum J. du Val. The results of this study revealed that C maculatus was highly susceptible to SM essential oil with the LC50 value of 2.6 μL/L air and the time until 50% of the beetles died (LT50) for 37.0, 111.1, 148.1, and 185.2 μL/L air were 9.7, 8.5, 7.2, and 7.1 hours, respectively. On the contrary, no mortality of T confusum was observed, but the repellency (%) of 1 μL of SM essential oil on T confusum was 83.33% compared with 23.33% on C maculatus. 37
Based on this very first indication of an insecticidal potential of the essential oil of SM, further studies in this field might be feasible.
Antioxidant and Radical Scavenging Activity
As phenolic compounds such as flavonoids exhibit antioxidant activity, methanolic or ethanolic extracts of SM containing different flavonoids and phenolcarbonic acids were evaluated for this activity via various antioxidant evaluation tests, for example, 2,2-diphenyl-1-picryl hydrazyl (DPPH assay), ferric reducing antioxidant power (FRAP assay), and trolox equivalent antioxidant capacity (TEAC assay) as well as β-carotene bleaching assay. 17,30,38 –41 In a study comparing the antioxidant and antiglycating activities of three Salvia species, SM showed the weakest antioxidant effect. The formation of advanced glycation end-products in the in vitro glycation of bovine serum albumin (BSA) after incubation with fructose was significantly reduced by SM at doses of 50 and 100 μg/mL over the observation period. Additionally, the extract significantly decreased fructose-induced fibrillar structure formation of BSA in a dose-dependent manner. 30
Comparison of extracts from cultivated and wild SM in the DPPH assay did not showed any significant difference in activity between cultivated plants (IC50 34.64 μg/mL) wild ones (IC50 38.44 μg/mL). The total phenol content was similar as well. 17
In another study comparing extracts of different Salvia, species SM remained without activity in the DPPH assay and only low activity in the FRAP assay. 31
In a recent investigation, an SM ethanol extract showed antioxidant and radical scavenging activities in different assays, and protective effects against H2O2-induced cytotoxicity in nonimmortalized fibroblasts. 38 This extract was fractionated and 2 of the resulting fractions possessed radical scavenging activity in the DPPH assay (IC50 = 37.9 ± 0.85 and 40.05 ± 1.4 μg/mL, respectively), which was comparable to quercetin (IC50 = 38.84 ± 0.86 μg/mL). 39
To sum up, several studies of very different quality reported a radical scavening and antioxidant potential of polar extracts from SM. These activities are plausible because of the content of flavonoids and rosmarinic acid.
Cytotoxic Activity
Cytotoxic activity of SM essential oil on human fetal skin fibroblast (HFSF) and human fetal liver fibroblast (HFLP) cell lines has been evaluated. The IC50 values for the evaluation on HFSF and HFLP were 625 and 1250 μg/mL, respectively. 20
Anti-Inflammatory Effects
The impact of a SM methanol extract on nitric oxide (NO) production in lipopolysaccharide-stimulated mouse macrophages was weak. At the concentration of 50 μg/mL, 66.2% ± 8% of inhibition was achieved. The extract did not inhibit the LPS-induced production of the pro-inflammatory cytokines tumor necrosis factor-α and interleukin-1β. 42
These data are not sufficiently supportive for the traditional use of SM in inflammations and the result underlines the feasibility of further in vivo tests.
Neuroprotective and Anti-Apoptotic Activities
Neuroprotective effects of SM and other Salvia species were evaluated in rat pheochromocytoma cells (PC12) treated with different concentrations of methanolic extracts (10, 25, 50, and 100 μg/mL) before challenge with H2O2 as oxidative stress. Cell viability was reduced to 28% by H2O2. In contrast, incubation of the cells with 10, 25, 50, and 100 μg/mL of SM significantly restored cell viability by 2.84-, 3.01-, 3.29-, and 3.45-fold, respectively. At a concentration of 10 μg/mL, the extract exhibited a protective effect on genomic DNA from nerve growth factor–differentiated PC12 cells against oxidative damage. By morphological observations the neuroprotective effect of SM in PC12 cells was confirmed by their resistance to the damaging effects of H2O2. Pretreatment with the extract (at 10, 25, 50, and 100 μg/mL) also reduced the malondialdehyde release from neuronal phospholipid bilayers following peroxidative disruption with H2O2 to 1.29-, 1.38-, 1.53-, and 1.59-fold, respectively. 30 In this assessment, glutamylcysteine synthetase (γ-GCS) and hemeoxygenase-1 (HO-1) were used to determine the effects of the extract under oxidative stress conditions. HO-1 is a redox-sensitive enzyme and highly inducible in response to different compounds inducing oxidative stress. In cells pretreated with the extract at different doses before challenge with H2O2 increased HO-1 levels were observed as compared to H2O2 alone. The extract exhibited capacity to upregulate the important antioxidant enzyme γ-GCS as well. The decrease of superoxide dismutase and catalase levels after exposure to H2O2 was restored by the extract in a dose-dependent manner. 30
In a similar investigation, the anti-apoptotic effects of SM have been evaluated against H2O2-induced cytotoxicity in neuron-like PC12 cells, which served as a model for neuronal signaling pathways and differentiation. Cell growth was monitored measuring cell body area, average neurite length and average neurite width. The changes in average cell body and neurite length of cells exposed to H2O2 were significantly improved by pretreatment with the methanol extract (10-100 μg/mL) in a dose-dependent manner. Additionally, the number of primary neurites and the ratio of nodes to primary neurites after pretreatment with the extract were significantly higher as compared with cells after H2O2 exposure. The pretreatment also prevented the accumulation of reactive oxygen species relative to H2O2 treatment. This study showed that the extract interfered with the intrinsic pathway of apoptosis via attenuation of cytochrome c release to cytoplasm and reduction of Bax (an apoptosis promoter) to Bcl-2 (an apoptosis inhibitor) ratio as well as via inhibition of outer mitochondrial membrane disruption. Concerning the underlying mechanism of the anti-apoptotic effect, a decrease in the caspase-3 level of in PC12 cells was shown in the presence of the extract (10, 25, 50, and 100 μg/mL for 24 hours) as measured via Western blot analysis. Additionally, a reduction in levels of PARP-1, a key factor in apoptosis, was determined. The concentration of glutathione, which was decreased about 2.23-fold in the presence of H2O2, after pretreatment with the extract at concentrations of 10, 25, 50, and 100 μg/mL for 24 hours increased to 6.80 ± 0.38, 7.04 ± 0.14, 7.72 ± 0.32, and 7.83 ± 0.33 μmoL/mg protein, respectively). 41
Anti-Hyperglycemic Activity
The anti-hyperglycemic activity of a methanol extract of SM was evaluated in streptozocin-induced diabetic rats. Animals were treated with the extract at single doses of 50, 100, 200, and 400 mg/kg body weight via intraperitoneal injection 24 hours after challenge and subsequently received a daily dose of 400 mg/kg for 12 days. 24 hours after the last dose, for the extract at 400 mg/kg, a significant (P < .01) reduction in serum glucose concentration was observed. Moreover, the histopathological study of liver, spleen and pancreas revealed no degenerative changes after the administration of the extract in both normal and diabetic animals. 43
These data support reports of a traditional use in diabetes. 21
Immunomodulatory Effects
A study of the impact of a SM methanol extract on activated human peripheral blood lymphocytes resulted in significant stimulatory activity on lymphocyte proliferation at 0.01 to 10 μg/mL and but the stimulatory effect decreased at higher concentrations of the extract (50-200 μg/mL). The stimulation index for 0.1 μg/mL was the highest (stimulation index >2). Accordingly, higher release of interleukin-2 was observed in activated cells, which had been treated with lower amounts of the extract (approximately 5-fold after 0.1 μg/mL). The stimulatory effect at low concentrations showed that cellular compartments could be affected by the extract via local immune reaction. To determine whether the inhibitory effect on immunity at higher concentrations was because of apoptosis in proliferative lymphocytes, phytohaemagglutinine-treated lymphocytes were exposed to the extract (10-200 μg/mL). Flow cytometric assessment showed that the extract at concentrations of 100 and 200 μg/mL caused G1 arrest with an increased number of cells with sub-G1 DNA content. The induction of apoptosis by the extract was additionally proven by the typical DNA laddering in internucleosomal DNA fragmentation analysis of mitogen-stimulated human lymphocytes. 8
Salvia mirzayanii methanol extract was also injected to mice to assay the effects on the humoral immunity as measured by thickness of the foot pad after challenge. Outcomes revealed improvement of the response at both primary and secondary exposure to the antigen after administration of lower concentrations of extract. In other words, mice treated with concentrations of 1 and 50 mg/kg body weight extract showed delayed hypersensitivity reaction as well as higher concentration in antibody titer. After a dose of 100 mg/kg, the effect was decreased. 8 Because of the fact that teuclatriol and spathulenol, isolated in an activity-guided approach from the extract, showed considerable antiproliferative effects on human peripheral lymphocytes with IC50 values of 74.2 ± 5.4 and 85.4 ± 11.08 μg/mL, respectively, the immunomodulation by SM was attributed to these compounds. 19,21
Other Effects
The growth promotional effect of SM essential oil as a dietary supplement in chickens was also evaluated in comparison to virginiamycin (100 ppm). The animals in 3 groups received SM essential oil (200, 400, or 600 ppm/group orally for 42 days). A group of animals received virginiamycin, a growth stimulatory antibiotic, orally for 42 days (positive control). An additional group was also considered without any treatment (negative control). Results showed an increased feed intake at 200 and 600 ppm of essential oil and also significant decreases in cholesterol, high-density lipoprotein, and low-density lipoprotein as compared with that of the negative control. In the group receiving 400 ppm of essential oil, an increase in chickens’ bursa of Fabricius was shown compared with the other treatments. This can be incorporated with the higher antibody titer. The highest weight gain was observed at after 200 ppm of essential oil at 22 to 42 days of age. Concerning the carcass characteristics, it was observed that gizzard and total gastrointestinal tract weights were reduced by the antibiotic. Level of eosinophils was decreased in groups treated by the essential oil. Results of this study outlined that low level intake of SM essential oil can improve the immunological function. However, the oil showed inhibitory effects on immune system in high levels. 44
Conclusion and Further Suggestions
Salvia mirzayanii is extensively applied by traditional practitioners in central and southern Iran. Apart from the identification and analysis of chemical constituents, most investigations on the pharmacological activities of SM have been performed as in vitro studies.
These studies have shown antimicrobial, insecticidal, antioxidant, anti-hyperglycemic, immunomodulatory and neuroprotective properties of the essential oil or alcoholic extracts from SM. Despite numerous studies on the antimicrobial effects of SM, no evaluation of the mechanisms underlying these antimicrobial effects have been performed until now. Informal reports from rural healers imply that fumigation of SM can control insects and airborne pathogens as well as related respiratory ailments. Based on this information, further investigations of the insecticidal activities and new studies on the antiviral effects of SM would be of interest. The results of numerous studies on antioxidant or radical scavenging effects may be a basis for detailed in vivo research on anti-inflammatory activities of SM.
On the other hand, the lack of any toxicity assessment on this plant is obvious. Since this herb is widely used by people in Iran, acute and chronic toxicity as well as teratogenicity of SM should be investigated.
Footnotes
Author Contributions
Both authors endorsed the data and conclusions and thus have made substantive contributions to the study. Both authors have also read and approved the finished article.
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
Ethical Approval
For this study no ethical approval was necessary as neither humans nor animals were involved.