Antimicrobial activity of essential oil and major constituents of Salvia chloroleuca

The aerial parts of Salvia chloroleuca were collected at full flowering stage at Shahrestanak (Tehran province of Iran). The essential oil was isolated by hydrodistillation and analyzed by combination of capillary GC and GC-MS. Thirty-four components were identified, representing 98.5% of the total oil. beta-Pinene (10.6%), alpha-pinene (9.0%), beta-caryophyllene (9.0%), 1,8-cineole (9.0%) and carvacrol (7.9%) were the main components. The in vitro antimicrobial activity of the essential oil of S. chloroleuca was studied against seven Gram-positive and Gram-negative bacteria (Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus, S. epidermidis, Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae) and three fungi (Candida albicans, Saccharomyces cerevisiae and Aspergillus niger); the disc diffusion method and MIC values indicated that the oil exhibited moderate to high antimicrobial activity.     

Phytochemical analysis and in vitro antiviral activities of the essential oils of seven Lebanon species

The chemical composition of the essential oils of Laurus nobilis, Juniperus oxycedrus ssp. oxycedrus, Thuja orientalis, Cupressus sempervirens ssp. pyramidalis, Pistacia palaestina, Salvia officinalis, and Satureja thymbra was determined by GC/MS analysis. Essential oils have been evaluated for their inhibitory activity against SARS-CoV and HSV-1 replication in vitro by visually scoring of the virus-induced cytopathogenic effect post-infection. L. nobilis oil exerted an interesting activity against SARS-CoV with an IC(50) value of 120 microg/ml and a selectivity index (SI) of 4.16. This oil was characterized by the presence of beta-ocimene, 1,8-cineole, alpha-pinene, and beta-pinene as the main constituents. J. oxycedrus ssp. oxycedrus oil, in which alpha-pinene and beta-myrcene were the major constituents, revealed antiviral activity against HSV-1 with an IC(50) value of 200 microg/ml and a SI of 5.     

Gas chromatography-mass spectrometry study of the essential oils of Schinus longifolia (Lindl.) speg., Schinus fasciculata (Griseb.) I. M. Johnst., and Schinus areira L

The essential oil composition from the aerial parts of three Anacardiaceae growing in Bahía Blanca, Argentina was studied by gas chromatography and gas chromatography-mass spectrometry. The essential oils of S. longifolia and S. fasciculata have been studied for the first time. The major constituents were alpha-pinene (46.5%), beta-pinene (15.1%) and alpha-phellandrene (10.1%) for S. longifolia and limonene (10.9%), beta-phellandrene (6.16%) and alpha-phellandrene (5.6%) for S. fasciculata. The major components of the essential oil of S. areira were limonene (28.6%), alpha-phellandrene (10.1%), sabinene (9.2%) and camphene (9.2%) differing from the literature data. The essential oils from S. areira and S. longifolia exhibited a high biotoxicity in a brine shrimp assay with Artemia persimilis.     

Chemical composition, antioxidant and antimicrobial properties of the essential oils of three Salvia species from Turkish flora

Essential oils of three different Salvia species [Salvia aucheri var. aucheri (endemic), Salvia aramiensis and Salvia pilifera (endemic)] were screened for their possible antioxidant and antimicrobial properties as well as their chemical compositions. According to the gas chromatography (GC)/EIMS (gas chromatography/electron impact mass spectrum) analysis results; 41 (97.2%), 51 (98.5%) and 83 compounds (98.2%) were identified, respectively. While 1,8-cineole (30.5%), camphor (21.3%) and borneol (8.50%) are the major compounds for S. aucheri var. aucheri oil, beta-pinene (10.3%), was the main constituent for S. aramienesis together with 1,8-cineole (46.0%) and camphor (8.7%). In the case of S. pilifera oil, alpha-thujene (36.1%) and alpha-pinene (13.8%) determined as the major compounds. Antioxidant activity was employed by two complementary test systems namely 2,2'-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging and beta-carotene/linoleic acid systems. Antioxidant activity of S. aramiensis was found to be higher than those of the others for the both systems (12.26+/-1.09 and 92.46%+/-1.64 microg mg(-1), respectively). Additionally, antioxidant activities of BHT, curcumin, ascorbic acid and alpha-tocopherol were determined in parallel experiments. In the case of antimicrobial activity, similar activity pattern was obtained (both in disc diffusion and MIC tests). Antimicrobial activity of S. aramiensis was followed by S. aucheri var. aucheri and S. pilifera, respectively. In these experiments, the most sensitive microorganism Acinetobacter lwoffii was followed by Candida albicans.     

Application of multidimensional gas chromatography to the enantioselective characterisation of the essential oil of Eupatorium buniifolium Hooker et Arnott

The qualitative and quantitative composition of the essential oil from aerial parts of Eupatorium buniifolium Hooker et Arnott (Asteraceae) has been investigated for the first time. The essential oils were obtained by steam distillation of leaves and analysed by GC-MS; 44 components were identified. Monoterpene and sesquiterpene hydrocarbons, especially alpha-pinene (14.7%), beta-elemene (12.2%), germacrene D (11.5%), trans-beta-guaiene (6.5%) and (E)-caryophyllene (4.3%), were the major constituents found in the oils. The characterisation of E. buniifolium by enantioselective GC was performed by evaluation of the enantiomeric ratios of alpha-pinene, sabinene, beta-pinene, limonene, terpinen-4-ol and germacrene D.     

Chemical composition and antimicrobial activity of the essential oils of the Amazon Guatteriopsis species

The essential oils of Guatteriopsis blepharophylla, Guatteriopsis friesiana and Guatteriopsis hispida were obtained by hydrodistillation and analysed by GC and GC/MS. The main compound found in the leaf oil of G. blepharophylla was caryophyllene oxide (1) (69.25%). The leaf oil of G. friesiana contained predominantly beta-eudesmol (2) (51.60%), gamma-eudesmol (3) (23.70%), and alpha-eudesmol (4) (14.56%). The major constituents identified in the leaf of G. hispida were beta-pinene (38.18%), alpha-pinene (30.77%) and (E)-caryophyllene (20.59%). The antimicrobial activity of the essential oils was evaluated against 11 species of microorganisms. The oil of G. friesiana exhibited significant antimicrobial activity for all microorganisms tested, whereas that of G. hispida and G. blepharophyla had potent activity against Rhodococcus equi with MIC of 50 microg mL(-1). The major constituents of each oil were also tested separately, and showed lower activity compared to the oils. Moreover, mixtures of the main constituents, in the same proportions found in G. friesiana and G. hispida oils, did not show the same activity as the original oils.     

Essential oils from Azorean Laurus azorica

The essential oils isolated from leaves of ten and from unripe berries of eight populations of Laurus azorica (Seub.) Franco, collected on five islands of the Azorean archipelago, were analysed by GC and GC-MS. All oil samples were dominated by their monoterpene fraction (60-94%), alpha-pinene (15-37%) and 1,8-cineole (12-31%) being the main components of the leaf oils, while trans-beta-ocimene (27-45%) and alpha-pinene (12-22%) were the main components of the oils from the berries. The sesquiterpene fractions of the oils ranged from 3 to 17% and the main components were beta-caryophyllene (traces-8%) and beta-elemene (traces-3%) both in the leaf and berry oils. Some phenylpropanoid components were also present, in total amounting to 17%, trans-cinnamyl acetate (215% of the leaf oils) being the main component of this fraction. Cluster analysis of the enantiomeric composition of alpha- and beta-pinene in the oils from the leaves clearly showed two groups, one constituted by the two populations growing on the island S. Jorge, and the other constituted by the remaining populations.     

Essential oil composition and variability of Thymus lotocephalus and Thymusxmourae

The composition of the essential oils of four populations of Thymus lotocephalus G. López and R. Morales and one population of T.xmourae Paiva and Salgueiro, two endemic taxa from Portugal, was investigated mainly by GC and GC-MS. Txmourae is a natural hybrid between T. lotocephalus and T. mastichina (L.) L. subsp. donyanae R. Morales, which essential oil was analysed for the first time. In its oil, it was possible to find compounds of both parents, which could enable us to confirm its intermediate status between those two taxa. 1,8-Cineole and borneol were the main constituents in the essential oil of T.xmourae, whereas linalool, geranyl acetate and 1,8-cineol were the major ones in T. lotocephalus. Intermedeol was also an important constituent in the oils of both taxa. Nevertheless, the volatile oils of the four populations investigated of T. lotocephalus showed important differences among the main constituents. In order to study their infraspecific variability, the results obtained in the analysis of individual plants were submitted to a Principal Component and Chemometric Cluster Analyses. Five types of essential oils were found: linalool, 1,8-cineole, linalool/1,8-cineole, linalyl acetate/linalool and geranyl acetate.     

Chemical classification of the essential oils of the Iranian Salvia species in comparison with their botanical taxonomy

The essential oils of eight Salvia species collected from different localities in Iran were analyzed by gas chromatography/mass spectrometry (GC/MS). The analytical results were compared with those previously published for related Iranian sage species in order to identify chemical markers for these species. Salvia eremophila, S. hypoleuca, and S. reuteriana are endemic, while S. atropatana, S. chloroleuca, S. santolinifolia, S. aegyptiaca, and S. macrosiphon also grow wild in neighboring countries. We categorized the Iranian Salvia species into four main chemotypes according to their essential-oil constituents: those which are dominated by 1) monoterpenes, 2) mono- and sesquiterpenes, or 3) sesquiterpenes as the major constituents, and 4) those containing low-molecular-weight acids, aldehydes, and esters, and green-leaf volatiles (GLVs). Likely due to the chemical diversity of different Salvia chemotypes, this categorization was supported by principal component analysis (PCA) for the group sampled here, but not for the values reported in the literature. We identified the following chemical markers: α-pinene, β-pinene, 1,8-cineol, linalool, and borneol in monoterpene-rich species, or β-caryophyllene, germacrene D, bicyclogermacrene, spathulenol, and caryophyllene oxide in sesquiterpene-rich species. Among these, α-pinene, β-caryophyllene, and germacrene D are the most common and abundant in the Salvia species investigated. In accordance with their close biological taxonomy, the chemical similarity of the essential oils of S. santolinifolia and S. eremophila is so high that we may consider them chemically identical.     

Antimicrobial activity of essential oils isolated from Portuguese endemic species of Thymus

AIMS: Thymus species are wild species mostly found in the arid lands of Portugal. Possible antimicrobial properties of Thymus essential oils have been investigated. The chemical composition of the essential oils and the antimicrobial activity of Thymus mastichina (L) L. subsp. mastichina, T. camphoratus and T. lotocephalus from different regions of Portugal were analysed. METHODS AND RESULTS: Hydrodistillation was used to isolate the essential oils and the chemical analyses were performed by gas chromatography (GC) and GC coupled to mass spectrometry. The antimicrobial activity was tested by the disc agar diffusion technique against Candida albicans, Escherichia coli, Listeria monocytogenes, Proteus mirabilis, Salmonella spp. and Staphylococcus aureus. Pure linalool, 1,8-cineole and a mixture (1 : 1) of these compounds were included. Linalool, 1,8-cineole or linalool/1,8-cineole and linalool/1,8-cineole/linalyl acetate were the major components of the essential oils, depending on the species or sampling place. The essential oils isolated from the Thymus species studied demonstrated antimicrobial activity but the micro-organisms tested had significantly different sensitivities. CONCLUSIONS: The antimicrobial activity of essential oils may be related to more than one component. SIGNIFICANCE AND IMPACT OF THE STUDY: Portuguese endemic species of Thymus can be used for essential oil production for food spoilage control, cosmetics and pharmaceutical use. Further studies will be required to elucidate the cell targets of the essential oil components.     

Foliar and cortex oleoresin variability of silver fir (Abies alba Mill.) in Albania

Terpene composition of needle and cortical oleoresin from lateral shoots were analyzed by GC/MS for four Silver fir (Abies alba Mill.) populations scattered in natural species range in Albania. More than sixty compounds were detected in the needle oleoresin, which was characterized by a high content of alpha-pinene, camphene, beta-pinene, limonene and bornyl acetate. Three monoterpenes, alpha-pinene, beta-pinene and limonene, and two sesquiterpenes, beta-caryophyllene and germacrene D, comprised the majority of cortical oleoresin. The terpene composition differences among the populations that led to the recognition of two chemotypes. The needle oleoresin from the provinces of Puka, Bulqiza and Llogara were characterised by high amounts of beta-pinene, camphene and alpha-pinene and low amounts of limonene, while that from Drenova had high amounts of beta-pinene and limonene. A similar pattern was found in the cortical oleoresin with the exception of camphene that was a minor contributor. Geographical and seasonal variation between the populations was, also, investigated. Multivariate analysis of both needle and cortical oleoresin separated Drenova (southeastern population) from the other sites. When both major monoterpenes and sesquiterpenes were considered four chemical profiles could be attributed. Based on their chemical profiles, the populations can be divided into two groups: Populations with high content of beta-pinene and alpha-pinene but a low content of limonene (Puka, Bulqiza and Llogara), typical of most of A. alba populations in all its distribution range. Population with a high content of limonene and a moderate content of beta-pinene and alpha-pinene (Drenova).     

Chemical composition of the essential oils of two Alpinia species from Hainan Island, China

The essential oils of two Alpinia species, ie. A. hainanensis and A. katsumadai, from Hainan Island, China were analyzed by using GC-MS. The major constituents in the leaf oil of A. hainanensis were ocimene (27.4%), beta-pinene (10.1%), 9-octadecenoic acid (6.5%), n-hexadecanoic acid (5.8%), 9,12-octadecadienoic acid (5.4%), and terpinen (4.3%). The oil constituents obtained from the flowers of A. hainanensis were ocimene (39.8%), beta-pinene (17.7%), terpinene (5.5%), p-menth-1-en-ol (4.9%), caryophyllene (4.9%), and phellandrene (4.4%). In A. katsumadai, the major constituents in the leaf oil were p-menth-1-en-ol (22.0%), terpinen (19.0%), 4-carene (9.1%), 1,8-cineole (8.3%), and camphor (5.6%). The major constituents in the flower oil were p-menth-1-en-ol (21.3%), 1,8-cineole (20.2%), terpinen (12.6%), phellandrene (7.0%), 4-carene (6.4%), and beta-pinene (5.2%).     

Antifungal activity of essential oil and its constituents from Calocedrus macrolepis var. formosana Florin leaf against plant pathogenic fungi

Resistance to conventional fungicides causes the poor disease control of agriculture. Natural products from plants have great potential as novel fungicide sources for controlling pathogenic fungi. In this study antipathogenic activity of the leaf essential oil and its constituents from Calocedrus macrolepis var. formosana Florin were evaluated in vitro against six plant pathogenic fungi. Chemical analysis of leaf oil by GC/MS allowed identification of alpha-pinene (44.2%), limonene (21.6%), beta-myrcene (8.9%), beta-caryophyllene (8.2%), caryophyllene oxide (2.4%), alpha-cadinol (1.6%), beta-pinene (1.2%), and T-muurolol (1.1%) as main components. Sesquiterpenoid components of the oil were more effective than monoterpenoid components of the oil. In particular, T-muurolol and alpha-cadinol strongly inhibited the growth of Rhizoctonia solani and Fusarium oxysporum, with the IC(50) values < 50 microg ml(-1). These compounds also efficiently inhibited the mycelial growths of Colletotrichum gloeosporioides, P. funerea, Ganoderma australe and F. solani. These results showed that T-muurolol and alpha-cadinol possess antifungal activities against a broad spectrum of tested plant pathogenic fungi and could be used as potential antifungal agents for the control of fungal diseases in plants.     

Evaluation of characteristic aroma compounds of Citrus natsudaidai Hayata (Natsudaidai) cold-pressed peel oil

The characteristic aroma compounds of Citrus natsudaidai Hayata essential oil were evaluated by a combination of instrumental and sensory methods. Sixty compounds were identified and quantified, accounting for 94.08% of the total peel oil constituents. Limonene was the most abundant compound (80.68%), followed by gamma-terpinene (5.30%), myrcene (2.25%) and alpha-pinene (1.30%). Nineteen compounds which could not be identified in the original oil were identified in the oxygenated fraction. Myrcene, linalool, alpha-pinene, beta-pinene, limonene, nonanal, gamma-terpinene, germacrene D, and perillyl alcohol were the active aroma components (FD-factor > 3(6)), whereas beta-copaene, cis-sabinene hydrate and 1-octanol were suggested as characteristic aroma compounds, having a Natsudaidai-like aroma in the GC effluent. Three other compounds, heptyl acetate, (E)-limonene oxide and 2,3-butanediol, which each showed a high RFA value (>35) were considered to be important in the reconstruction of the original Natsudaidai oil from pure odor chemicals. The results indicate that 1-octanol was the aroma impact compound of C. natsudaidai Hayata peel oil.     

Antimicrobial activity of a traditionally used complex essential oil distillate (Olbas(?) Tropfen) in comparison to its individual essential oil ingredients

Plant extracts and essential oils have been widely studied and used as antimicrobial agents in the last decades. In our study we investigated the antimicrobial activities of Olbas(?) Tropfen (in the following named Olbas), a traditionally used complex essential oil distillate, in comparison to its individual essential oil ingredients. Olbas (10g) consists of three major components such as peppermint oil (5.3g), eucalyptus oil (2.1g), and cajuput oil (2.1g) and of two minor constituents like juniper berry oil (0.3g) and wintergreen oil (0.2g). The composition of Olbas and the five individual essential oils were characterized by GLC-MS. According to GLC-MS analysis 1,8-cineol is the main component of the complex essential oil distillate followed by menthol and menthone. The minimum inhibitory and minimum microbicidal concentrations of Olbas and each of the single essential oils were evaluated in 17 species/strains of bacteria and fungi. Time-kill assay was performed to compare the microbicidal activity of Olbas and peppermint oil during several time intervals. Olbas displayed a high antimicrobial activity against all test strains used in this study, among them antibiotic resistant MRSA (methicillin-resistant Staphylococcus aureus) and VRE (vancomycin-resistant Enterococcus). Its antimicrobial activity was comparable to that of peppermint oil which was the most potent one of all individual essential oils tested. In the time kill assay Olbas as well as peppermint oil demonstrated similar microbicidal activities. Based on its wide antimicrobial properties Olbas can be a useful agent for the treatment of uncomplicated infections of skin and respiratory tract.     

Chemical composition and in-vitro antimicrobial activity of the essential oils of three Greek Achillea species

The chemical composition of the essential oils of Achillea holosericea, Achillea taygetea, Achillea fraasii was determined by GC/MS analysis. Among the ninety-five assayed constituents, camphor, borneol and 1,8-cineol were found to be the major components. The in-vitro antimicrobial activity of these essential oils was evaluated against six bacteria indicating that the first is totally inactive, while the other two possess moderate to strong activities mainly against the Gram negative strains. The essential oil of A. fraasii was also active against the tested pathogenic fungi.     

Antimicrobial activity and chemical composition of the essential oil of Nepeta crispa Willd. from Iran

The composition and antimicrobial activity of the essential oil of Nepeta crispa Willd., an endemic species from Iran, was studied. The oil was obtained from the aerial parts of the plant and analyzed by GC and GC/MS. Twenty-three compounds, accounting for 99.8% of the total oil, were identified. The main constituents were 1,8-cineol (47.9%) and 4aalpha,7alpha,7abetanepetalactone (20.3%). The antimicrobial activity of essential oil of N. crispa was tested against seven gram-negative or gram-positive bacteria and four fungi. The results of the bioassays showed the interesting antimicrobial activity, in which the gram-positive bacteria, Bacillus subtilis and Staphylococcus aureus, were the most sensitive to the oil. Also, the oil exhibited a remarkable antifungal activity against all the tested fungi.     

Leaf essential oil composition of three species of Myrcianthes from Monteverde, Costa Rica

To examine the chemical diversity of essential oils from Myrcianthes species (Myrtaceae) as well as potential chemotaxonomic relationships between them, the leaf essential oils of M. fragrans (Sw.) McVaugh, M. rhopaloides (Kunth) McVaugh, and an undescribed species, Myrcianthes 'black fruit', from Monteverde, Costa Rica, were isolated by hydrodistillation and analyzed by GC/MS. The most abundant components of the essential oil of M. fragrans were 1,3,5-trimethoxybenzene (15.7%), (Z)-hex-3-en-1-ol (10.0%), alpha-cadinol (10.4%), eudesma-4(15),7-dien-1beta-ol (9.0%), caryophyllene oxide (7.8%), and spathulenol (7.5%). The leaf oils of two different samples of Myrcianthes rhopaloides were quantitatively different with one sample composed mostly of linalool (17.7%), alpha-cadinol (14.4%), spathulenol (11.1%), tau-cadinol (9.6%), and 1-epicubenol (6.9%), and the other was made up largely of (E)-hex-2-enal (46.1%), 1,8-cineole (12.5%), linalool (9.1%), alpha-cadinol (6.7%), and alpha-terpineol (4.4%). The major components in the leaf essential oil of Myrcianthes 'black fruit' were 1,8-cineole (38.3%), alpha-terpineol (21.2%), heptan-2-ol (15.5%), terpinen-4-ol (4.2%), and beta-pinene (3.8%). The leaf oil compositions of Myrcianthes in this study are very different from leaf oils from other members of Myrcianthes reported in the literature. A cluster analysis reveals large chemical variation not only between members of the genus, but also between samples of the same species.     

Essential oil variation and antioxidant capacity of Mentha pulegium populations and their relation to ecological factors

Mentha pulegium L. is an aromatic herb belonging to the Lamiaceae family, a wild plant which is distributed in different areas of Iran. In this research, we evaluated the variability of essential oil content and compositions of 12 M. pulegium populations. Essential oils were analyzed using gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) methods. The essential oils content varied from 0.22 to 1.63% w/w within different populations. Twenty-nine compounds were identified which represent 83.4–98.7% of the total essential oil. The most significant essential oil compounds among the studied population were identified using the principal components analysis (PCA-biplot). According to the PCA-biplot, the major compounds were pulegone (2.5–51.7%), menthone (0.2–25.3%), limonene (0.0–35.4%), 1,8-cineol (0.0–33.4%), piperitenone oxide (0.2–55.2%), and trans-piperitone epoxide (0.0–28.5%). Besides, hierarchical cluster analysis indicated that the studied populations were classified into two main clusters based on the essential oil components. The canonical correspondence analysis (CCA) indicated that some environmental factors could influence the phytochemical constituents as well as the antioxidant activity. The temperature and altitude were effective environmental factors with regards to 1–8 cineol, limonene and menthone content, while average rainfall was the most effective factor with respect to trans-piperitone epoxide, piperitenone oxide, and pulegone content. Our results consequently showed that environmental factors had a significant effect on the essential oil content and its antioxidant activity in M. pulegium populations.     

Activity of essential oils and individual components against acetyl- and butyrylcholinesterase

We have tested acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities of nineteen essential oils obtained from cultivated plants, namely one from Anethum graveolens L. (organic fertilizer), two from Foeniculum vulgare Mill. collected at fully-mature and flowering stages (organic fertilizer), two from Melissa officinalis L. (cultivated using organic and chemical fertilizers), two from Mentha piperita L. and M. spicata L. (organic fertilizer), two from Lavandula officinalis Chaix ex Villars (cultivated using organic and chemical fertilizers), two from Ocimum basilicum L. (green and purple-leaf varieties cultivated using only organic fertilizer), four from Origanum onites L., O. vulgare L., O. munitiflorum Hausskn., and O. majorana L. (cultivated using organic fertilizer), two from Salvia sclarea L. (organic and chemical fertilizers), one from S. officinalis L. (organic fertilizer), and one from Satureja cuneifolia Ten. (organic fertilizer) by a spectrophotometric method of Ellman using ELISA microplate-reader at 1 mg/ml concentration. In addition, a number of single components widely encountered in most of the essential oils [gamma-terpinene, 4-allyl anisole, (-)-carvone, dihydrocarvone, (-)-phencone, cuminyl alcohol, cumol, 4-isopropyl benzaldehyde, trans-anethole, camphene, iso-borneol, (-)-borneol, L-bornyl acetate, 2-decanol, 2-heptanol, methyl-heptanol, farnesol, nerol, iso-pulegol, 1,8-cineole, citral, citronellal, citronellol, geraniol, linalool, alpha-pinene, beta-pinene, piperitone, iso-menthone, menthofurane, linalyl oxide, linalyl ester, geranyl ester, carvacrol, thymol, menthol, vanilline, and eugenol] was also screened for the same activity in the same manner. Almost all of the essential oils showed a very high inhibitory activity (over 80%) against both enzymes, whereas the single components were not as active as the essential oils.