The genus Artemisia L. in the northern region of Saudi Arabia: essential oil variability and antibacterial activities

Abstract Four species of the genus Artemisia L. (Artemisia monosperma, Artemisia scoparia, Artemisia judaica and Artemisia sieberi) growing in the northern region of Saudi Arabia were investigated with respect to their volatile oil contents. The yield of oil varied between 0.30 and 0.41%, % (w/w). A. monosperma showed the highest number of compounds with 30 components representing 93.78% of oil composition. However, A. judaica showed the lowest number of compounds with only 16 components representing 87.47% of essential oil. A. scoparia and A. sieberi are both composed of 17 components, representing 97.14 and 94.2% of total oil composition. A. sieberi and A. judaica were dominated by spathulenol (30.42 and 28.41%, respectively). For A. monosperma, butanoic acid (17.87%) was a major component. However, A. scoparia was a chemotype of acenaphthene. (83.23%). Essential oil of studied species showed high antibacterial activities against common human pathogens.


Introduction
The genus Artemisia L. is an annual or a perennial herb or shrub found in northern temperate region (Abad et al. 2012;Osman et al. 2014). Artemisia has a therapeutic history reaching back over two millennia (Zinczuk et al. 2007) and it is widely used in folk remedies (Negahban et al. 2007;Petretto et al. 2013). It is one of the most widely studied genera for its morphological and chemical diversity (Chanotiya & Singh 2012). Artemisia species comprise, actually, important medicinal plants which are currently the subject of phytochemical attention because of their essential oil production, biological and chemical diversity (Petretto et al. 2013).
The Kingdom of Saudi Arabia is a huge arid land with an area of about 2,250,000 km 2 covering the major part of the Arabian Peninsula, characterised by different ecosystems and diversity of plant species (Abdel Khalik et al. 2013;Osman et al. 2014). The major part of the country consists of dry land territories with species-poor plant assemblage. In the northern region of the country (125,000 km 2 ), the genus Artemisia is represented by four species (Artemisia scoparia, Artemisia monosperma, Artemisia sieberi and Artemisia judaica). A scoparia and A. monosperma are widespread in the region of 'Al-Hamad' (rocky habitats) and 'Al-Widiyens' (Wadies) region. However, A. sieberi and A. judaica are found in scattered populations in sandy-soil habitats.
Essential oils generally have a broad spectrum of bioactivity owing to the presence of several active ingredients or secondary metabolites which work through various modes of action. The genus Artemisia is industrially important due to its antimicrobial, insecticidal, antioxidant and antimalarial properties as well as its perfumery compounds (Negahban et al. 2006;Rustaiyan et al. 2009;Verdian-rizi 2009;Petretto et al. 2013;Zafar Haider et al. 2014).
The aim of the present research is to study the chemical diversity of four different species belonging to genus Artemisia: A. judaica L., A. monosperma del., A. scoparia Waldst. & Kit. and A. sieberi Besser. However, the antibacterial activities against Gram-positive and Gramnegative strains will be the focus of the second part of the present investigation.

Results and discussion
The different chemical constituents identified in the essential oil of the four investigated species are listed in Table S2, in order of their elution from the HP-5MS column. The yields of the essential oils from A. monosperma, A. scoparia, A. judaica and A. sieberi were found to be 0.41% (v/w), 0.40, 0.39 and 0.38%, respectively. According to Abad et al. (2012), the quality and yield of essential oils from Artemisia species are influenced by several factors such as harvesting season, the geographic location and chemotype or subspecies (Reale et al. 2014). Previous researches revealed yield varying from 0.84 (A. scoparia, Kaur et al. 2010) to 0.4% for A. vulgaris L. (Sujatha et al. 2008).
Results concerning the essential oil composition of the four species are summarised in Table S2. GC and GC-MS analyses of the essential oil lead to the identification of 50 compounds. A. monosperma showed the highest number of identified compounds with 30 components representing 93.78% of the total oil composition. However, A. judaica showed the lowest number of identified compounds with only 16 components representing 87.47% of the total essential oil. The rest two species A. scoparia and A sieberi are composed of 17 components representing, respectively, 97.14 and 94.2% of the total oil composition.
The major components of the studied species belong to different chemical groups: A sieberi and A judaica were dominated by an oxygenated sesquiterpene (spathulenol: 30.42 and 28.41%, respectively). For A. monosperma, a potent odorant (butanoic acid: 17.87%) was the major component. However, A. scoparia was a chemotype of acenaphthene (83.23%). With regard to A. scoparia, results showed that sesquiterpenoids hydrocarbons were the major portion (83.7%) with acenaphthene (83.23%) as the main compound. This portion was relatively high in A. sieberi (22.68%) and acenaphthene was the main component (11.34%). The rest of the species showed that oxygenated sesquiterpenoids were the major fraction: This fraction represented, for A. monosperma, 43.62% of the total oil composition with clovene (6.29%) as a major component. However, A. sieberi showed that oxygenated sesquiterpenoids were 40.15% of the total oil composition with spathulenol (30.41%) as a major compound. The fourth species, A. judaica showed that oxygenated sesquiterpenoids were present with the portion of 34.59% and two components were major: spathulenol (28.42%) and 2-propenoic acid, 3-phenyl-ethyl ester (22.46%). Monoterpenoids were important portions for both A. judaica and A. sieberi with a percentage of 33.12 and 26.87%, respectively, of the total oil compositions.
The composition of the essential oils of the studied species in Saudi Arabia compared to other countries reported in the literatures (Table S3) shows several interesting points. It is well known that the essential oils of taxa belonging to Artemisia vary according to species (Abad et al. 2012). Our results are not in agreement with previous studies. However, A. monosperma (30 compounds) is described previously as a chemotype of 1,8-cineole and camphor (Zhu et al. 2013). In Saudi Arabia, Khan et al. (2012) identified 130 compounds and reported that β-pinene and α-terpinolene were the major components of A. monosperma. In the present study, butanoic acid is the major component, while previous investigation reported butanoic acid as a minor compound of Artemisia absinthium (dhen et al. 2014).
The chemical composition of A. scoparia showed 17 compounds with acenaphthene as a major component. In India, Joshi et al. (2010) showed the dominance of phenyl alkynes (61.2-85.5%) and γ-terpinene (11.1%) in the essential oil of A. scoparia (Table S3). The essential oil from the aerial parts of A. scoparia species from Tajikistan revealed a total of 32 compounds representing 98% of the total oil composition and A. scoparia oil was mainly dominated by the diacetylenes 1-phenyl-2,4-pentadiyne (34.2%). A judaica and A sieberi both were dominated by spathulenol (30.42 and 28.41%, respectively). This ingredient was described as a major component of the essential oil of Valeriana officinalis (Samaneh et al. 2010) and one of the major components of Eucalyptus oleosa essential Oils (Ben Marzoug et al. 2011). For the genus Artemisia, Kordali et al. (2005) showed that spathulenol is one of the main compounds of the Turkish Artemisia species (Artemisia dracunculus and A. absinthium). Several studies focusing on A. sieberi in Iran showed that β-thujone, α-thujone and camphor were mainly the major components (Ensieh et al. 2007;Negahban et al. 2007;Khosravi et al. 2011) (Table S3). Whereas, piperitone and camphor were the major ingredients for A. judaica in Egypt (Sallam et al. 2011) and Libya (Janaćković et al. 2015).
The second part of the present research is an attempt to test the antibacterial activities of the four studied species' EOs against micro-organisms by evaluating the sensitivity of bacterial strains towards its oil. Results showed that the EOs have great potential antibacterial activities against five bacteria strains (Figure 1). The highest activity was observed for the essential oil of A. monosperma against Streptococcus agalactiae with the strongest inhibition zones (37.5 mm higher than the inhibition zone recorded for the ampicillin) followed by the activities against Enterococcus faecium (35.5 and 35 mm, respectively, for the oil of A. seiberi and A. scoparia). Moreover, S. agalactiae is highly sensitive to the essential oils of A. seiberi, A. scoparia and A. judaica with inhibition zones around 34 mm. S. aureus showed inhibition zones ranging from 17 to 26.92 mm, respectively for the essential oil of A. monosperma, A. scoparia, A. judaica and A. seiberi. However, the antibacterial activities of the EOs of the four species were higher than 14 mm as an inhibition zone for two strains (Salmonella typhimurium and Escherichia coli). Previous works interested in antibacterial activities of taxa belonging to genus Artemisia showed antibacterial activities against common human pathogens (E. coli, S. typhimurium, Pseudomonas aeruginosa, Klebsiella pneumoniae and S. aureus (Blagojević et al. 2006;Ornano et al. 2015;Sampietro et al. 2015).

Conclusion
With regard to four Artemisia species from Saudi Arabia, the results presented here indicate a completely different chemical profile with respect to the other Artemisia ssp. essential oils studied so far (India, Libya) or so near (Egypt and Iran). Indeed, compounds such as spathulenol, butanoic acid and acenaphthene, the main compounds in studied species, were never detected in other Artemisia species at this high rate. Sesquiterpenes represent more than 90% for A. scoparia oil, more than 60% for A. sieberi oil and about the half of the constituents of both oils of A. monosperma and A. judaica. The EOs of studied species displayed high antimicrobial activities on the tested common human pathogens (E. coli, Salmonella enteritidis).

Supplementary material
Supplementary material relating to this article with respect to Experimental section and tables of results and discussion are available online.

Disclosure statement
No potential conflict of interest was reported by the authors.