A Journal of the Bangladesh Pharmacological Society (BDPS)
Bangladesh J Pharmacol 2015; 10: 639-644
Journal homepage: www.banglajol.info
Abstracted/indexed in Academic Search Complete, Agroforestry Abstracts, Asia Journals Online, Bangladesh Journals Online, Biological Abstracts,
BIOSIS Previews, CAB Abstracts, Current Abstracts, Directory of Open Access Journals, EMBASE/Excerpta Medica, Google Scholar, HINARI (WHO),
International Pharmaceutical Abstracts, Open J-gate, Science Citation Index Expanded, SCOPUS and Social Sciences Citation Index; ISSN: 1991-0088
Phytochemical characterization of phenolics by LC-MS/MS and
biological evaluation of Ajuga orientalis from Turkey
Fatih Göger1, Yavuz Bülent Köse2, Gamze Göger1,3 and Fatih Demirci1,4
1Department
3Graduate
of Pharmacognosy, Faculty of Pharmacy; 2Department of Pharmaceutical Botany, Faculty of Pharmacy;
School of Health Sciences; 4Faculty of Health Sciences, Anadolu University, Eskişehir 26470, Turkey.
Article Info
Received:
Accepted:
Available Online:
Abstract
27 May 2015
29 June 2015
15 July 2015
DOI: 10.3329/bjp.v10i3.23500
Cite this article:
Göger F, Köse YB, Göger G, Demirci
F. Phytochemical characterization of
phenolics by LC-MS/MS and biological evaluation of Ajuga orientalis from
Turkey. Bangladesh J Pharmacol. 2015;
10: 639-44.
The aim of this study was to reveal the phytochemical constituents,
antioxidant and antimicrobial activity of Ajuga orientalis. According to the
antimicrobial results, the methanol extract of A. orientalis showed a MIC value
of 312.5 µg/mL against the tested pathogenic bacterial strains. Anticandidal
activity of extract was found as 156.3 µg/mL both against Candida albicans and
C. parapsilosis strains. Whereas the extract was more effective against C.
tropicalis with the MIC value of 78.1 µg/mL. The in vitro DPPH radical
scavenging activity of the extract was determined as IC50=0.4 ± 0.02 mg/mL
whereas the standard BHT IC50 was 0.01 ± 0.00 mg/mL. Trolox Equivalent
Antioxidant Capacity (TEAC) of extract was determined 1.3 mM TEAC, while
BHT, 1.9 mM TEAC.
Introduction
Ajuga L. is one of the largest genera of the Lamiaceae
family with 301 species all over the world. In flora of
Turkey, Ajuga is represented by 13 species and 23 taxa
(Güner et al., 2012). Ajuga has some traditional therapeutic uses such as diuretic, antipyretic, tonic, diaphoretic and astringent in Turkey (Baytop, 1984). Ajuga
species are used in traditional medicine all over the
world against some illness such as gout, rheumatism,
malaria, asthma and gastrointestinal diseases and have
antibacterial, antitumor (Ben Jannet et al., 2006; Chen et
al., 1996; Israili and Lyoussi, 2009, Setif, 2011), neuroprotective effects (Guo et al., 2011), anti-inflammatory
(Marc et al., 2008) and antioxidant (Makni et al., 2013;
Turkoglu et al., 2010) activities among others biological
effects.
Ajuga genus contains many important bioactive compounds like anthocyanins, diterpenoids, sterols, ionones, iridoids, phenylethanol and flavonoid glycosides
(Maria et al, 1997, Chen et al., 1996; Shimomura et al.,
1987; Terahara et al., 2001; Akbay et al., 2003).
Essential oil composition of A. orientalis was investiga-
ted and main compounds were germacren D (24.7%), β
-cubaben (18.3%) and β-caryophyllene (16.9%) (Sajjadi
and Ghanadi, 2004).
Even though several bioactive compounds have been
well studied on some Ajuga species, there is not enough
data on phytochemical and biological activities for A.
orientalis. To the best of our knowledge, this is the first
report on determination of the major phenolic compounds, antioxidant activity and antimicrobial properties of the methanol extract of A. orientalis.
Materials and Methods
Chemicals
All antimicrobial agents, Mueller Hinton II broth and
RPMI medium were purchased from Sigma-Aldrich
Chemical Co (St. Louis, MO). Solvents were used
analytical grade.
Plant material and preparation of the extract
A. orientalis was collected during flowering stage from
Bursa, Turkey [A2 (A) Bursa: Bursa, Uludağ,1773 m,
640
Bangladesh J Pharmacol 2015; 10: 639-644
19.6.2008, K 400 06’ 23.3’’ D 290 08’ 11.1’’].
Microbial strains
The antimicrobial activities of the extract were tested
against a panel of microbial strains, including: Escherichia coli NRRL B3008, Staphylococcus aureus ATCC 6538,
Salmonella typhimurium ATCC 13311, Bacillus cereus
NRRL B-3711, Candida albicans ATCC 90028, C. tropicalis
ATCC 1369 and C. parapsilosis ATCC 22019.
Determination of Minimum Inhibitory Concentration
(MIC)
The MIC values of the strains were determined by broth
microdilution methods (CSLI, 2006, 2008). The methanol extract of A. orientalis was examined against a panel
of seven different human pathogenic bacteria and
Candida strains using the microdilution method according to CSLI method compared with standard antimicrobial agents. Methanol extract of A. orientalis was
studied between [1250-2.44 μg/mL] for MIC and the
antimicrobial standard agents ampicillin, tetracycline,
ketoconazole (64-0.125 µg/mL) and oxiconazole (160.03 µg/mL) were prepared in dimethyl sulfoxide
(DMSO) and water.
The extract (100 µL) was added to wells of row A, while
the remaining wells in rows B to H received 50 µL of
cation adjusted Mueller-Hinton Broth-2 (MHB-2).
Bacterial suspensions were grown overnight in double
strength broth and were standardized to 105 cfu/mL for
bacteria. Each bacterial suspension (50 µL) was added
to the appropriate well. All Candida strains were inocula
-ted on Patoto Dextrose Agar (PDA) prior the experiments at 35°C. After incubation grown microorganisms
were inoculated sterile saline %0.85. And then
standardized using a turbitometer (Biosan) (McFarland
No: 0.5) to 5 x 103 cfu per well in RPMI medium under
sterile conditions. Serial dilution series were prepared
in 100 µL RPMI medium with an equal amount of the
test samples. After serial dilution 100 µL each microorganism suspension was pipetted into each well and
incubated at 35°C for 24 hours. Positive growth controls (to assess the presence of turbidity) were performed in wells not containing antimicrobial agents. In addition, negative growth control (medium) was applied in
96-well plate. After incubation at 35°C for 24 hours the
first well without turbidity was determined as the MIC
(µg/mL).
Antioxidant activity (total phenolics)
Total phenols were estimated as gallic acid equivalents
(GAE), expressed as mg gallic acid/g extract (Singleton,
1999).
TEAC assay (Trolox Equivalent Antioxidant Capacity)
This test measures the ability of a compound to scavenge the ABTS (2,2′-azinobis-(3-ethyl-benzothiazoline6-sulfonate) radical in comparison to antioxidant activi-
ty of trolox which is a water-soluble form of vitamin E,
used as a standard. The blue–green ABTS radical was
formed through the reaction of 7 mM ABTS with 2.5
mM sodium persulfate (Na2S2O8) in the dark at room
temperature for 12–16 hours before use. ABTS solution
was diluted with ethanol to a final absorbance of 0.7–0.8
at 734 nm. 10 µL portion of the sample was added to
990 µL of ABTS solution, and the reduction in absorbance was measured 1 min after addition of trolox up to
40 min after addition of the extract. The stock solu-tion
of trolox (2.5 mM) was prepared in ethanol. Absorbance was measured on a UV/spectrophotometer
(Papandreou et al., 2006).
1,1-Diphenyl-2-picrylhydrazyl
scavenging activity
(DPPH)
radical
Serial dilutions were prepared with the stock solutions
(4 mg/mL) of the extract to get the half concentration of
previous one. Diluted solutions were added with
DPPH•(equal amounts). After 30 min UV absorbance
was recorded at 517 nm. The experiment was performed in triplicate for extract and positive standard control,
BHT (butylated hyroxytoluene). The average of the
absorption was noted for each concentration. The
percentage inhibition was calculated using Eq 1. The
IC50 value, which is the concentration of the test
material that inhibits 50% of the free radical concentration, was calculated as mg/mL using Sigma Plot
statistical program (Kumarasamy et al., 2007).
Abs control - Abs sample
x100
Abs control
Percentage Inhibition =
Equation 1
Phenolic compound determination
Experiments were performed with a Shimadzu 20A
HPLC system coupled to an Applied Biosystems 3200 Q
-Trap LC- MS/MS instrument equipped with an ESI ion
source used in the negative ionization mode. Separations were performed on an ODS 150 x 4.6 mm, i.d., 3
µm particle sizes, octadecyl silica gel analytical column
operating at 40ºC at a flow rate of 1 mL/min.
Powdered dried herbal parts of A. orientalis were macerated with methanol 70% at 25°C for 24 hours. After
evaporation of the methanol part, the aqueous part
freeze-dried and the dry extract was used in all experiments.
Results and Discussion
An antioxidant activity generally occurs a hydrogen
donating procedure. Phenolic acids and flavonoids are
well known hydrogen donating agents due to their high
PKa values. Determination of the total phenol com-
Bangladesh J Pharmacol 2015; 10: 639-644
641
Figure 1: Ajuga orientalis LC chromatogram at 320 nm
Figure 2: Mass spectrum of compound 5: verbascoside
pounds provides preliminary information about antioxi
-dant activity results. The more total phenolic compounds means the more antioxidant activity.
According to results, extract of A. orientalis showed
similar amount of gallic acid equivalent total phenol
content in 1 g methanol extract. A. orientalis: 32 mg
GAE/g ext.
According to the identification of phenolic profile by
LC-MS/MS (Table I) 9 compounds were determined
(Figure 1).
Compound 1Rt =2.8 co-eluted with [M-H]-molecular
ions at m/z 195 (galactonic acid or gluconic acid) and
m/z 341 (disaccharide like sucrose). High absorbance at
280 nm must be related to gradient changing of mobile
phase. Product ions of m/z 341 similar with caffeoyl
glucose fragments (m/z 179, m/z 161) but it is not
642
Bangladesh J Pharmacol 2015; 10: 639-644
Table I
Compounds determined with LC-MS/MS
No.
Compound
Rt
(M-H)
Fragments
Reference
1
Galactonic acid
2.8
195
177, 159, 129, 11
Nist 14
2
3
Ascorbic acid
Luteolin glucuronide derivative
9.8
14.6
175
513
115
487, 461, 285, 179, 135
Nist 14
(Cvetkovikj et al., 2013)
4
Echinacoside
15.4
785
623, 461, 161
(Mitreski et al., 2014)
5
Verbascoside
16.2
623
461, 315, 161
(Mitreski et al., 2014)
6
Forsythoside A
16.5
623
461, 315, 161
(Guo et al., 2007; Mitreski et al., 2014)
7
Castanoside A
18.4
799
623, 461
(Mitreski et al., 2014)
8
4"-O-methylisoscutellarein 7-Oallosyl(1-2)glucoside
19.2
623
461, 315, 161, 135
(Petreska et al., 2011)
9
Leucoseptoside A
19.6
637
461, 175
(Mitreski et al., 2014)
possible to determine a caffeoyl glucose molecule at this
retention time. Other fragments of galactonic acid can
be seen in Table I.
Compound 2 was identified as ascorbic acid according
to Nist 14 MS/MS library and comparison with
authentic standard’s fragmentation patterns.
Compound 3Rt = 14.6 displayed [M−H]− ion at m/z 513
and a base peak ion at m/z 461 further fragmentation
showed several ions at m/z 487, 461, 285 (most
probably a luteolin), 179 and 135. Following fragmentation of m/z 461, it was found as similar with luteolin
glucuronide. However, compound 6 was exhibited 26
amu higher than luteolin glucuronide so this compound
was labeled as luteolin glucuronide derivative.
Compound 4Rt = 15.4 displayed [M−H]− ion at m/z 785
yielded a base peak ion at m/z 623 due to the loss of a
hexose (or caffeoyl) moiety, the same loss of base peak
ion was led to form ion at m/z 461. Other fragmentation corresponding with cinnamic acids, m/z 179 and
161, was also observed. The compound was identified
as echinacoside by compression to compound previously reported (Petreska et al., 2011).
Two compound, compound 5 (Figure 2) and 6 were coeluted at Rt = 16.2 and Rt = 16.5 with a same deprotonated molecular ion at m/z 623 which showed same
fragmentation pattern. Both of the spectrums yielded
m/z 461 owing to loss of a caffeoyl moiety (-162) and
m/z 315 due to the loss of a rhamnose unit (-146).
Caffeoyl part of the compounds were also observed at
m/z 179 and further fragmentation at m/z 161 and 135.
Compound 5 at RT 16.2 was determined as verbascoside whereas compound 6 at Rt = 16.5 was identified as
fosythoside A using similar mass spectrum and chromatographic separation of previously reported data
(Guo et al., 2007; Mitreski et al., 2014).
Compound 7Rt = 18.5 showed [M−H]−ion at m/z 799
its MS/MS spectrum yielded two main fragments at m/
z 623 (loss of a feruloyl, -176) and 461 (loss of a caffeoyl
moity). This compound was identified as castanoside A
according to previous data (Mitreski et al., 2014).
Compound 8 showed MS fragmentation characteristic
of verbascoside and forsythoside A. Pseudomolecular
ion at m/z 623 and its MS2 experiment yielded in
several ions at m/z 461, 315, 161 and 135. According to
previously published data (Petreska et al., 2012) the
compound, eluted after verbascoside and forsythoside
A, with the same molecular weight is 4"-O-methylisoscutellarein 7-O-allosyl(1-2)glucoside. These data sugges
-ted that compound could be identified tentative-ly as
4"-O-methylisoscutellarein 7-O-allosyl(1-2)gluco-side.
Compound 9 showed [M−H]− molecular ion at m/z 637
in MS2 spectrum a ferruloyl break at m/z 461 and the
ferruloyl part at m/z 175 was also observed. This
compound was labeled as leucoptoside A according to
literature data (Mitreski et al., 2014; Petreska et al.,
2011).
DPPH•is a radical that gives maximum absorption at
517 nm in alcoholic solutions because of its intense
purple color. The color of radical converts pale yellow if
neutralized via an antioxidant compound. DPPH
radical was used for determination of the radical
scavenging antioxidant potential of A. orientalis extract.
The extract radical scavenging activity was not effective
as a positive control standard BHT. IC50 value of the
extract was 0.4 ± 0.02 mg/mL and the positive control
of BHT 0.01 ± 0.00 mg/mL.
The calibration curve of trolox that is water soluble
analog of vitamin E is used in the quantification. A
radical form of ABTS is used as an indicator for
evaluation of the antioxidant activities. This radical
occurs after treatment of the non-radical ABTS salt with
potassium persulfate after 16 hours. Alcoholic solution
of radical gives maximum absorption at 734 nm owing
to its green color. Green color of the radical converts to
colorless and the absorption reduces if it encounters
with antioxidant compound. In this test high TEAC
643
Bangladesh J Pharmacol 2015; 10: 639-644
Table II
Minimum Inhibitory Concentrations (MIC, µg/mL)
Microorganisms
Ajuga orientalis
extract
Ketoconazole
Oxiconazole
Ampiciline
Tetracycline
Escherichiacoli NRRL B-3008
312.5
-
-
4
4
Staphylococcus aureus ATCC 6538
Salmonella typhimurium ATCC 13311
Bacillus cereus NRRL B-3711
312.5
312.5
312.5
-
-
2
2
0.5
2
2
0.5
Candida albicans ATCC 90028
156.25
1
4
-
-
Candida tropicalis ATCC 1369
78.12
0.5
2
-
-
156.25
2
2
-
-
Candida parapsilosis ATCC 22019
values shows high antioxidant activity results. ABTS ● +
radical scavenging and DPPH radical scavenging effect
showed a high correlation with each other. The extract
at 1% concentration, showed ABTS ● + radical scavenging effect. But the extract was not found as effective as
standard BHT. TEAC values were found 1.3 mM for
extract and 1.9 mM for BHT.
Oxidative attack of free radicals is the reason for many
chronic diseases. Natural antioxidants such as flavonoids and phenolic acids help to protect human body
from free radicals (Koolen et al., 2013). Antioxidant
activity of this plant can be used as natural radical
scavenger but not as good like as synthetic standard
antioxidants. Determined phenolic compounds are the
first reason of the antioxidant activities. Hydroxyl rich
compounds is well known free radical scavengers.
Obtained total phenolic compounds amount can be low
for this plant material using this extraction procedure.
However, high amount of hydroxyl groups of molecules that we determined showed moderate activity.
Discovering new antimicrobial agents are also important because of antimicrobial resistance of some
microorganism. Synthetic antimicrobial agents are used
in several years and today some of them are ineffective
and researchers are focused on to investigate new
natural antimicrobial agents.
Additionally phytochemical studies of the extract, in
vitro antimicrobial activity was evaluated seven
different strains in this study (Table II) using microdilution methods. A. orientalis extract exhibited antimicrobial action against all tested microorganisms,
being more effective against yeasts than bacteria. The
MIC was found at 312.5 µg/mL for Escherichia coli,
Staphylococcus aureus, Salmonella typhimurium and
Bacillus cereus. MIC value of 156 µg/mL for C. albicans
and C. parapsilosis for the extract. Our results showed
that C. tropicalis was the most sensitive strain for the
extract (MIC=78.12 µg/mL).
There have been some reports for antimicrobial
activities belong to A. orientalis. Ali-Shtayeh et al (2013)
found that extract of A. orientalis inhibited the growth of
some against acne-inducing bacteria and aerobic
bacteria (Ali-Shtayeh et al 2013). A. orientalis was also
evaluated antifungal activity against Phytophthora
capsici which is a pathogen fungus (Kıran et al, 2010).
As a result, the antimicrobial activity was determined
the first time for A. orientalis extract, especially against
Candida species. The extract can be used as an
alternative natural prevention of Candida infections and
candidal resistance.
Acknowledgement
This work was supported by the Anadolu University Research
Funding (Project No.: BAP: 080307).
References
Akbay P, Calış I, Heilmann J, Sticher O. Ionone, iridoid and
phenylethanoid glycosides from Ajuga salicifolia. Z
Naturforsch. 2003; 58C: 177-80.
Ali-Shtayeh, MS, Al-Assali AA, Jamous RM. Antimicrobial
activity of Palestinian medicinal plants against acne-inducing bacteria. Afr J Microbiol Res. 2013; 7: 2560-73.
Baytop T. Türkiyede bitkiler ile tedavi geçmişte ve bugün;
İstanbul Üniversitesi. 1984.
Chen H, Tan RX, Liu ZL, Zhang Y, YangL. Antibacterial
neoclerodane diterpenoids from Ajuga lupulina. J Nat Prod.
1996; 597: 668-70.
Clinical and Laboratory Standarts Institue (CLSI) 2006.
Methods for dilution antimicrobial susceptibility tests for
bacteria that grow aerobically, CLSI M7-A7, Clinical and
Laboratory Standards Institute, 940 West Valley Road,
Wayne, Pennsylvania, USA.
Clinical and Laboratory Standards Institute (CLSI). Reference
method for broth dilution antifungal susceptibility testing of
yeast, Approved standard. CLSI 27-A3. 3rd ed. PA, USA,
2008.
Cvetkovikj I, Stefkov G, Acevska J, Stanoeva JP, Karapandzova
M, Stefova M, Kulevanova S. Polyphenolic characterization
and chromatographic methods for fast assessment of
culinary Salvia species from South East Europe. J
Chromatogr A. 2013; 1282: 38-45.
Güner A, Aslan S, Ekim T, Vural M, Babaç M.Türkiye Bitkileri
644
Bangladesh J Pharmacol 2015; 10: 639-644
Listesi Damarlı Bitkiler. Nezahat Gökyiğit Botanik Bahçesi
ve Flora Araştırmaları Derneği Yayını. İstanbul. 2012.
R. Macedonia: LC/DAD/ESI-MS; profile and content. Nat
Prod Commun. 2014; 92: 175-80.
Guo H, Liu AH, Ye M, Yang M, Guo DA. Characterization of
phenolic compounds in the fruits of Forsythia suspensa by
high-performance liquid chromatography coupled with
electrospray ionization tandem mass spectrometry. Rapid
Commun Mass Spectrom. 2007; 215: 715-29.
Papandreou MA, Kanakis CD, Polissiou MG, Efthimiopoulos
S, Cordopatis P, Margarity M, Lamari FN. Inhibitory activity
on amyloid-β aggregation and antioxidant properties of
Crocus sativus stigmas extract and its crocin constituents. J
Agr Food Chem. 2006; 5423: 8762-68.
Guo P, Li Y, Xu J, Liu C, Ma Y, Guo Y. Bioactive neo-clerodane
diterpenoids from the whole plants of Ajugaciliata Bunge. J
Nat Prod. 2011; 747: 1575-83.
Petreska J, Stefova M, Ferreres F, Moreno DA, Tomas-Barberan
FA, Stefkov G, Gil-Izquierdo A. Potential bioactive phenolics
of Macedonian Sideritis species used for medicinal mountain
tea. Food Chem. 2011; 1251: 13-20.
Israili ZH, Lyoussi B. Ethnopharmacology of the plants of
genus Ajuga. Pakistan J Pharm. 2009; 224: 425-62.
Ben Jannet H, Chaari A, Bakhrouf A, Mighri Z. Structure–
antibacterial activity relationship of secondary metabolites
from Ajuga pseudoiva Rob. leaves. Nat Prod Res. 2006; 203:
299-304.
Kıran ÖE, İlçim A, Dığrak, M. Antifungal activity against
Phytophthora capsici leon which causes root neck burn in
pepper around Kahramanmaras. Asian J Chem. 2010; 22:1;
468-74.
Koolen HHF, Da Silva FMA, Gozzo FC, De Souza AQL, De
Souza ADL. Antioxidant, antimicrobial activities and
characterization of phenolic compounds from buriti Mauritia
flexuosa L. by UPLC–ESI-MS/MS. Food Res Int. 2013; 512:
467-73.
Kumarasamy Y, Byres M, Cox PJ, Jaspars M, Nahar L, Sarker
SD. Screening seeds of some Scottish plants for free radical
scavenging activity. Phytother Res. 2007; 217: 615-21.
Makni M, Haddar A, Kriaa W, Zeghal N. Antioxidant, free
radical scavenging, and antimicrobial activities of Ajuga iva
leaf extract. Int J Food Prop. 2013; 164: 756-65.
Maria C, Rodriguez, B, Bruno, M, Piozzi, F, Vassallo, N,
Bondi, Maria L, Servettaz, O. Neo-clerodane diterpenoids
from Ajuga australis and A. orientalis. Phytochemistry 1997;
45: 121-23.
Mitreski I, Stanoeva JP, Stefova M, Stefkov G, Kulevanova S.
Polyphenols in representative Teucrium species in the flora of
Author Info
Yavuz Bülent Köse (Principal contact)
e-mail: ybkose@anadolu.edu.tr
Petreska Stanoeva J, Bagashovska D, Stefova, M. Characterization of urinary bioactive phenolic metabolites excreted
after consumption of a cup of mountain tea Sideritis scardica
using liquid chromatography–tandem mass spectrometry.
Maced J Chem Chem Eng. 2012; 31: 2229-43.
Sajjadi SE, Ghannadi A. Volatileoilcomposition of the aerial
parts of Ajugaorientalis L. from Iran. Z Naturforsh. 2004; 59c:
166-68.
Setif A. Antibacterial activity of extract of Ajuga iva and
Teucrium polium. Adv Environ Bio. 2011; 52: 491-95.
Shimomura H, Sashida Y, Ogawa K. Iridoid glucosides and
phenylpropanoid glycosides in Ajuga species of Japan.
Phytochemistry 1987; 26: 1981-83.
Singleton Vernon L, Orthofer R, Lamuela-Raventos RM.
Analysis of total phenols and other oxidation substrates and
antioxidants by means of folin-ciocalteu reagent. Methods
Enzymol. 1999; 299C: 152-78.
Terahara N, Callebaut A, Ohba R, Nagata T, Ohnish
Kameyama M, Suzuki M. Acylated an thocyanidins 3sophoroside-5-glucosides from Ajuga reptans flowers and the
corresponding cell cultures Phytochemistry 2001; 58: 493500.
Turkoglu S, Turkoglu I, Kahyaoglu M, Celik S. Determination
of antimicrobial and antioxidant activities of Turkish
endemic Ajuga chamaepitys L. Schreber subsp. euphratica PH
Davis Lamiaceae. J Med Plant Res. 2010; 413: 1260-68.