QUANTITATIVE ANALYSIS ON SOME PHENOLIC COMPOUNDS FROM VIOLA SPECIES

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					440                                                         FARMACIA, 2008, Vol.LVI, 4


          QUANTITATIVE ANALYSIS OF SOME
          PHENOLIC COMPOUNDS FROM VIOLA
          SPECIES TINCTURES
          ANCA TOIU* , L. VLASE, ILIOARA ONIGA, M. TĂMAŞ
          University of Medicine and Pharmacy „Iuliu Hatieganu”, Faculty of
          Pharmacy, 12, Ion Creangă Street, 400023, Cluj-Napoca, Romania,
          *
            corresponding author ancamaria_toiu@yahoo.com

           Abstract
           We analysed the 10% tinctures of air-dried flowering aerial parts from three Viola
species (Violaceae) and we have performed spectrophotometric determinations of flavonoids
and polyphenol carboxylic acids and a HPLC study of salicylic acid derivatives. For V.
tricolor L. we have established the content in flavonoids (2.108%), polyphenol carboxylic
acids (0.921%) and salicylic acid (91.83·10–3 %). For V. arvensis Murray and V. declinata
Waldst. et Kit. results obtained were, respectively: 1.846% and 1.694% flavonoids, 0.632%
and 0.505% polyphenol carboxylic acids, 92.21·10–3 % and 137.24·10–3 % salicylic acid. We
observed small differences in the chemical co mposition of the three Viola species.

           Rezumat
           Am analizat tincturile 10% preparate din părţile aeriene uscate ale unor specii de
Viola (Violaceae) prin determinarea spectrofotometrică a flavonoidelor şi a acizilor
polifenolcarbo xilici, iar derivaţii de acid salicilic printr-o metodă HPLC. Pentru specia
Viola tricolor L. au fost obţinute următoarele rezu ltate: concentraţia de flavonoide este de
2,108%, cea de acizi polifenolcarbo xilici de 0,921%, iar cea de acid salicilic de 91,83·10–3
%. Pentru V. arvensis Murray şi V. declinata Waldst. et Kit. rezultatele obţinute au fost,
respectiv: 1,846% şi 1,694% flavonoide, 0,632% şi 0,505% acizi polifenolcarbo xilici şi
92,21·10–3 % şi 137,24·10–3 % acid salicilic. S-au observat mici diferenţe ale co mpoziţiei
chimice între cele trei specii de Viola analizate.

                  Viola sp.                                         salicylic acid
                  Flavonoids                                        HPLC

          INTRODUCTION
          The most important medicinal plants from Viola genus (Violaceae)
are considerered V. tricolor, V. arvensis and V. odorata. Wild pansy (Viola
tricolor L.) is largely spread in Romania’s spontaneous flora. The aerial
parts are used in traditional medicine for their anti- inflammatory,
expectorant and diuretic properties, for treating skin conditions, bronchitis,
cystitis, rheumatism. These properties are due to the presence of the
following active principles: saponins, flavonoids, mucilages, salicylic acid
derivatives, coumarins, carotenoids [1- 5].
FARMACIA, 2008, Vol.LVI, 4                                               441


         The anti- inflammatory activity is related to depurative and anti-
allergic effects because some of the skin conditions can be caused by
inflammation. Anti- inflammatory properties are ascribed to salicylic
derivatives, rutin and can be enhanced by saponins [6].
         In our previous phytochemical studies we have analysed the
polyphenolic compounds (flavonoids, polyphenol carboxylic acids,
anthocyanins, proanthocyanins) from three Viola species by Thin Layer
Chromatography (TLC), High Performance Liquid Chromatography
(HPLC), High Performance Liquid Chromatography – Mass Spectrometry
(HPLC-MS) and by spectrophotometric methods [7,8]. We continued our
reasearch with the analysis of 10% tinctures of V. tricolor, V. arvensis and
V. declinata by spectrophotometric techniques and by a HPLC method.

        MATERIALS AND METHODS
          We have analysed the aerial parts of Viola tricolor L. and V.
arvensis Murray harvested from Cluj, Romania and V. declinata Waldst. et
Kit. harvested from Alba, Romania in May 2005. The vegetal products were
air dried and then pulverised. The tinctures were prepared as follows: 10g of
vegetal product was extracted with 100g of ethanol 70 C at room
temperature, as described in Romanian Pharmacopoeia Xth Edition [9].
          Spectrophotometric determinations were performed with a UV-
VIS JASCO V-530 spectrophotometer.
          The quantitative analysis of flavonoids was performed using the
method described in the Romanian Pharmacopoeia Xth Edition in the
monography Cynarae folium [9]. This direct method of quantitative
determination needs aluminium thrichloride as reagent and rutoside as
standard. The absorbance was measured at 430 nm. The calibration curve
was linear between 0.1 mg/mL and 0.4 mg/mL rutoside.
          The quantitative analysis of polyphenol carboxylic acids
(caffeic acid derivatives) was performed using the method described in the
Romanian Pharmacopoeia IXth Edition in the monography Cynarae folium
[10]. We used Arnow reagent (sodium nitrite and sodium molibdate) and the
results were expressed in caffeic acid. The calibration curve was linear
between 0.05 mg/mL and 0.25 mg/mL
          HPLC determinations:
          Apparatus and chromatographic conditions: We used an
Agilent 1100 HPLC Series (Agilent, USA) equipped with a degasser
G1322A, HP 1100 Series binary pump, a Zorbax SB-C18 reversed-phase
analytical column 100 mm x 3,0 mm i.d., 3.5 µm particle (Agilent
technologies, USA), and we operated at 45 o C. The mobile phase was a
442                                                                FARMACIA, 2008, Vol.LVI, 4


binary gradient: distillated water with 0.1% (v/v) orthophosphoric acid 85%
and acetonitrile. The linear gradient started at 5% acetonitrile for 2 minutes,
followed by isocratic elution with 25% acetonitrile over the next 3 minutes.
The flow rate was 1 mL/min and the injection volume was 10 μL.
          Samples preparation: The tinctures were centrifuged at 4000 rpm.
The solutions were diluted with distilled water in a 10 mL volumetric flask
and filtered through a 0.45 µm filter before injection.
          Detection: We used the fluorescence detector: 310 nm as
excitation wavelength and 450 nm as emission wavelength. Salicylic acid
was identified by external standard method and by comparing its retention
time to the one of the standard, in the same chromatographic conditions and
quantified by external standard method.
          The wavelengths for fluorescence detection were chosen in order to
give an optimal sensitivity and selectivity to this method.
          Salicylic acid standard (Sigma, Germany) was used in order to
perform quantitative determinations in distilled water solutions with
concentrations between 68 - 21960 ng/mL (Table I).
                                                                            Table I
             The concentrations of salicylic acid (ng/mL) for the calibration curve
 Concentration
                68.625 137.25 274.5 549 1098 2196 5490 10980 21960
   (ng/mL)
     Area        6.48   12.07 22.8 46.21 85.7 156.5 449.7 918.2 2040.1

        The calibration curve for salicylic acid standard was linear between
68.625-21960 ng/mL and it is presented in figure 1.

                      2500




                                                y = 0.0918x - 20.962
                      2000
                                                     R2 = 0.9973




                      1500

                                                                 Series1
                                                                 Linear (Series1)
                      1000




                       500




                        0
                             0   5000   10000   15000        20000         25000



                                     Figure 1
                      The calibration curve of salicylic acid
FARMACIA, 2008, Vol.LVI, 4                                                         443


          The fluorescence spectrum of salicylic acid (obtained at 310 nm as
excitation wavelength and 450 nm as emission wavelength) is presented in
figure 2.
       Norm.

                                                                      Emission
                            Excitation                                wavelength
        1000
                            wavelength

         800




         600




         400




         200




           0


               200   250      300        350     400       450   nm




                                     Figure 2
                     The fluorescence spectrum of salicylic acid


         RESULTS AND DISCUSSION
         The results of quantitative determinations of phenolic compounds
from the three Viola species are shown in table II.

                                                                            Table II
                     Quantitative determinations results for the phenolic compounds
                                Flavonoids        Polyphenol
                                                                          Salicylic
           Species                 g (%         carboxylic acids
                                                                         acid g (%)
                                 rutoside)     g (% caffeic acid)

       V. tricolor L.               2.108              0.921             91.83·10–3

    V. arvensis Murr.               1.846              0.632             92.21·10–3
  V. declinata Waldst. et
                                    1.694              0.505             137.24·10–3
            Kit.
444                                               FARMACIA, 2008, Vol.LVI, 4


          The flavonoids are the major polyphenolic compounds in all the
samples, the richest species being V. tricolor L. Caffeic acid derivatives are
present in small quantities, as well as salicylic acid. The highest level of
salicylic acid was found in Violae declinatae herba.

          CONCLUSIONS
         We have analysed phenolic compounds (flavonoids, caffeic acid
derivatives and salicylic acid) by spectrophotometric methods and by a
HPLC technique from 10% tinctures of dried aerial parts from V. tricolor, V.
arvensis and V. declinata.
         We completed the literature data with qualitative and quantitative
determinations of phenolic compounds from three Viola species. Our
phytochemical study showed small quantitative differences among the three
Viola species.

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      6. Mills S.Y. - The essential book of herbal medicine, Arkana Penguin
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FARMACIA, 2008, Vol.LVI, 4                                      445


   9. xxx - Farmacopeea Română, ed. a X-a, Ed. Medicală, Bucureşti,
       1993
   10. xxx –Farmacopeea Română, ed. a IX-a, Ed. Medicală, Bucureşti,
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