The effect of the method and duration of extraction on the content of biologically active compounds in herbal teas/Ekstraktsiooni meetodi ja kestuse moju bioloogiliselt aktiivsete ainete sisaldusele ravimtaimede vesitommistes.
Abstract:
The extraction of some most important biologically active compound classes and constituents (water-soluble extractive, polyphenols, tannins, flavonoids, coumarins, anthraquinones, hypercin, pigments, and saponins) into herbal teas, depending on the method and duration of the extraction, was studied. Five herbal teas were prepared of each crude drug studied (n = 11). Most constituents extract in the same amount in infusions and decoctions. The best results were achieved from the extraction during 12 h in a Thermos bottle.

Key words: herbal teas, infusion, decoction, extraction, biologically active compounds.

On uuritud olulisemate toimeainegruppide ja koostisainete (ekstraktiivained, polufenoolid, tanniinid, flavonoidid, kumariinid, antratseenid, huperitsiin, karotenoidid ja saponiinid) ekstraheeruvust vesitommistesse soltuvalt ekstraktsiooni meetodist ja kestusest. Uuritavatest droogidest (n = 11) on valmistatud viis erinevat vesitommist. Enamik analuusitud koostisainetest ekstraheerub leotistesse ja keedistesse vordsel maaral. Ekstraktsiooni korral saadakse parimad tulemused 12 tunni jooksul termoses.

Authors:
Raal, Ain
Kuznetsova, Irina
Pub Date:
03/01/2007
Publication:
Name: Estonian Academy of Sciences: Chemistry Publisher: Estonian Academy Publishers Audience: Academic Format: Magazine/Journal Subject: Chemistry Copyright: COPYRIGHT 2007 Estonian Academy Publishers ISSN: 1406-0124
Issue:
Date: March, 2007 Source Volume: 56 Source Issue: 1
Accession Number:
198809236
Full Text:
INTRODUCTION

Crude drugs are used for preparing herbal teas at home. Earlier, infusions and decoctions were also prepared in pharmacies according to the pharmacopoeia standards. By the Soviet Pharmacopoeia the extraction time of infusions is 15 min and for decoctions 30 min. Decoctions were cooled for 10 min and infusions for at least 45 min [1]. In a very popular book Health Through God's Pharmacy by German housewife Maria Treben it is recommended that the drug should be poured over with boiling water and allowed to stand only for 10-30 s before straining [2]. More academic publications recommend a longer extraction time. According to Weiss & Fintelmann the herbs should be allowed to steep for 5-10 or 10-15 min [3]. The literature written in the Russian language is in most cases influenced by the Soviet pharmacopoeias and recommends a longer extraction time for preparing infusions (45-60 min) [4]. It is rather often recommended that herbal teas be prepared in a Thermos bottle [2, 4, 5].

The purpose of the present work was to study the extraction of some major biologically active compound classes and constituents into herbal teas, depending on the method and duration of the extraction.

MATERIALS AND METHODS

As the research material, the following crude drugs were used: Crataegi fructus (hawthorn berries, Crataegus monogyna Jacq. em. Lindm.), Valerianae radix (valerian roots, Valeriana officinalis L.), Uvae-ursi folia (bearberry leaves, Arctostaphylos uva-ursi (L.) Spreng.), Hyperici herba (St.-John's-wort herbs, Hypericum perforatum L.), Quercus cortex (oak bark, Quercus robur L.), Calendulae flos (marigold flowers, Calendula officinalis L.), Matricariae flos (pineapple weed flowers, Chamomilla suaveolens (Pursh) Rydb.), Chamomillae flos (wild chamomile flowers, Chamomilla recutita (L.) Rauschert), Frangulae cortex (alder buckthorn bark, Rhamnus frangula L.), Primula radix (primrose roots, Primula veris L.), Liquiritiae radix (liquorice roots, Glycyrrhiza glabra L.).

Five herbal teas were prepared of each crude drug studied (n = 11). One tablespoonful of cut crude drug was poured over with 200 mL of water. The teas were prepared using five different methods: (1) it was left with boiling water for 10 min at room temperature, (2) it was left with boiling water for 3 h at room temperature, (3) an infusion was prepared, (4) a decoction was prepared (methods (3) and (4) following the Soviet Pharmacopoeia [1]), and (5) it was left with boiling water in a Thermos bottle for 12 h.

The content of water-soluble extractive and tannins was analysed applying the methods suggested in [1]. The amounts of polyphenols ([lambda] = 730 nm), flavonoids ([lambda] = 428 nm), coumarins ([lambda] = 315 nm), anthraquinones ([lambda] = 540 nm), hypericin ([lambda] = 425 nm), and pigments (carotenoids, [lambda] = 455 nm) in herbal teas were determined spectrophotometrically. The foaming index of saponins was analysed according to the International Pharmacopoeia [6]. The content of biologically active compounds (Table 1) was calculated to the dried herbal substance. The standard errors were mostly calculated to four parallel measures of optical density, or four parallel extractions for water-soluble extractive and to four parallel shakings of herbal teas for the determination of the foaming index.

RESULTS

The least water-soluble extractives were received from the 10 min extraction of crude drugs (Table 1). There was also the smallest amount of polyphenols and tannins in the teas that had stood for 10 min. The highest content of flavonoids was ensured by the 12 h extraction in a Thermos bottle. The content of coumarins in teas acted differently from the other constituents. The content of anthraquinones was equal in infusions and decoctions, but hypericine dissolves in water very slowly and more of it was found in decoctions than in infusions. Carotenoids extracted minimally during 10 min and maximally during 12 h. The extraction of saponins showed a similar tendency to the other constituent classes.

Our results showed that in most cases the extraction during 10 min ensured the smallest extraction of the constituents of crude drug into herbal teas. Extraction in a Thermos bottle during 12 h gave the best results.

Received 5 December 2006, in revised form 15 January 2007

REFERENCES

[1.] U.S.S.R. State Pharmacopoeia. 11th edition. Part 1. Meditsina, Moscow, 1987 (in Russian).

[2.] Treben, M. Health Through God's Pharmacy: Advice and Experiences with Medicinal Herbs. 23rd edition. Ennsthaler Gesellschaft GmbH & Co KG, 1994.

[3.] Weiss, R. F. & Fintelmann, V. Herbal Medicine. 2nd edition, revised and expanded. Thieme, Stuttgart, New York, 2000.

[4.] Lavrenov, V. K. & Lavrenova, G. V. 500 Most Important Herbs. AST, Donetsk, 2003 (in Russian).

[5.] Bisset, N. G. & Wichtl, M. Herbal Drugs and Phytopharmaceuticals: A Handbook for Practice on Scientific Basis. Medpharm Scientific Publishers, Stuttgard, 1994.

[6.] Mukherjee, P. K. Quality Control of Herbal Drugs. Business Horizons, New Delhi, 2002.

Ain Raal * and Irina Kuznetsova

Institute of Pharmacy, University of Tartu, Nooruse 1, 50411 Tartu, Estonia

* Corresponding author, ain.raal@ut.ee
Table 1. The content of biologically active compounds in selected
herbal teas depending on the method and duration of extraction

Herbal substance           10 min                    3 h

                            Water-soluble extractive, %
Crataegi fructus      28.3 [+ or -] 1.8       35.8 [+ or -] 1.7
Valerianae radix      10.9 [+ or -] 0.6       23.3 [+ or -] 1.4

                               Polyphenols, %
Uvae-ursi folium     19.6 [+ or -] 0.15      23.0 [+ or -] 0.25
Hyperici herba       19.3 [+ or -] 0.52      23.2 [+ or -] 0.20

                               Tannins, %
Uvae-ursi folium     10.1 [+ or -] 0.13      16.4 [+ or -] 0.22
Quercus cortex        7.9 [+ or -] 0.12       8.8 [+ or -] 0.32

                                Flavonoids, mg%
Crataegi fructus     162.4 [+ or -] 0.89     201.4 [+ or -] 1.61
Calendulae flos      112.3 [+ or -] 0.82     158.7 [+ or -] 1.93

                                Coumarins, mg%
Matricariae flos     164.3 [+ or -] 1.03     163.8 [+ or -] 0.56
Chamomillae flos     184.2 [+ or -] 0.56     462.3 [+ or -] 1.15

                                Anthraquinones, mg%
Frangulae cortex     281.0 [+ or -] 7.43     359.0 [+ or -] 4.31
Hyperici herba      1414.3 [+ or -] 33.65   2048.3 [+ or -] 8.10

                                Hypericin, mg%
Hyperici herba       139.5 [+ or -] 8.93     323.7 [+ or -] 2.08

                               Pigments, mg%
Calendulae flos      82.8 [+ or -] 0.58      124.3 [+ or -] 0.25

                             Saponins, foaming index
Primulae radix              < 100                   153.9
Liquiritiae radix           < 100                   111.1

Herbal substance          Infusion                Decoction

                              Water-soluble extractive, %
Crataegi fructus      39.3 [+ or -] 1.9       36.6 [+ or -] 1.3
Valerianae radix      21.0 [+ or -] 1.3       23.9 [+ or -] 1.7

                               Polyphenols, %
Uvae-ursi folium     22.1 [+ or -] 0.65      22.5 [+ or -] 0.23
Hyperici herba       20.7 [+ or -] 0.06      20.5 [+ or -] 0.16

                               Tannins, %
Uvae-ursi folium     18.9 [+ or -] 0.25      19.7 [+ or -] 0.74
Quercus cortex        9.3 [+ or -] 0.43      11.3 [+ or -] 0.25

                                Flavonoids, mg%
Crataegi fructus     228.7 [+ or -] 1.15     248.7 [+ or -] 0.28
Calendulae flos      186.6 [+ or -] 2.40     184.3 [+ or -] 0.18

                                Coumarins, mg%
Matricariae flos     207.7 [+ or -] 0.68     300.2 [+ or -] 1.43
Chamomillae flos     406.1 [+ or -] 0.94     510.1 [+ or -] 0.38

                               Anthraquinones, mg%
Frangulae cortex    271.4 [+ or -] 35.56     317.6 [+ or -] 2.88
Hyperici herba      2366.7 [+ or -] 18.68   2474.1 [+ or -] 18.67

                                Hypericin, mg%
Hyperici herba       283.9 [+ or -] 2.81     425.0 [+ or -] 4.67

                               Pigments, mg%
Calendulae flos      131.0 [+ or -] 1.58     139.2 [+ or -] 0.96

                            Saponins, foaming index
Primulae radix              173                      200
Liquiritiae radix           208.3                    250

Herbal substance           12 h in
                           Thermos
                           bottle

                    Water-soluble extractive, %
Crataegi fructus      36.4 [+ or -] 1.7
Valerianae radix      30.0 [+ or -] 1.9

                       Polyphenols, %
Uvae-ursi folium     25.3 [+ or -] 0.19
Hyperici herba       26.3 [+ or -] 0.12

                         Tannins, %
Uvae-ursi folium     24.5 [+ or -] 0.15
Quercus cortex       15.1 [+ or -] 0.21

                       Flavonoids, mg%
Crataegi fructus     272.9 [+ or -] 1.05
Calendulae flos      223.8 [+ or -] 0.63

                       Coumarins, mg%
Matricariae flos     216.2 [+ or -] 0.42
Chamomillae flos     268.9 [+ or -] 0.67

                     Anthraquinones, mg%
Frangulae cortex     388.0 [+ or -] 5.49
Hyperici herba      2811.9 [+ or -] 16.32

                       Hypericin, mg%
Hyperici herba       536.1 [+ or -] 5.76

                        Pigments, mg%
Calendulae flos      210.7 [+ or -] 0.50

                    Saponins, foaming index
Primulae radix              285.7
Liquiritiae radix           429.2
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