Plants 2012, 1(2), 74-81; doi:10.3390/plants1020074

Communication
Antibacterial and COX-1 Inhibitory Effect of Medicinal Plants from the Pamir Mountains, Afghanistan
Anne S. Jeppesen 1, Jens Soelberg 2 and Anna K. Jäger 1,2,*
1
Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2 Universitetsparken, 2100 Copenhagen, Denmark; Email: annesjeppesen@gmail.com
2
NaturMedicinsk Museum, Faculty of Health and Medical Sciences, University of Copenhagen, 2 Universitetsparken, 2100 Copenhagen, Denmark; Email: jenssoelberg@gmail.com
*
Author to whom correspondence should be addressed; Email: anna.jager@sund.ku.dk; Tel.: +45-3533-6339; Fax: +45-3533-6041.
Received: 27 September 2012; in revised form: 15 October 2012 / Accepted: 17 October 2012 /
Published: 24 October 2012

Abstract

: Plants used to treat inflammatory ailments, pain, fever and infections in the Pamir Mountains in northeastern Afghanistan, were tested for antibacterial and COX-1 inhibitory activity. Water and ethanol extracts of 20 species were tested for antibacterial activity against two gram positive and two gram negative bacteria. The ethanol extract of Arnebia guttata inhibited Staphylococcus aureus with a MIC of 6 µg/mL. Water and ethanol extracts of Ephedra intermedia and the ethanol extracts of Lagochilus cabulicus and Peganum harmala inhibited Staphylococcus aureus at 0.5 mg/mL,and the P. harmala extract further inhibited the growth of Bacillus subtilis and E. coli, also with MICs of 0.5 mg/mL. Ethanol extracts of Artemisia persica (IC50: 0.5 µg/mL), Dragocephalum paulsenii (IC50: 0.5 µg/mL), Ephedra intermedia (IC50: 3.8 µg/mL), Hyoscyamus pusillus, Nepeta parmiriensis (IC50: 0.7 µg/mL) and Rumex patientia subsp. pamiricus (IC50: 3.5 µg/mL) exhibited COX-1 inhibitory activity. The observed in vitro activities support the use of some of the plant species in the traditional medicine systems of the Pamir Mountains.
Keywords:
Afghanistan; antibacterial; COX; medicinal plants; Pamir

1. Introduction

The Wakhan Corridor, in the Pamir Mountains of North-eastern Afghanistan is populated by the Wakhi and Kyrgyz peoples. This area is one of the most remote and isolated areas in the world and the populations rely almost solely on their local herbal medicine. The Third Danish Pamir Expedition documented plant use by both people. A number of plants used to treat infectious diseases, fever and pain was recorded.

The flora of the Pamir/Hindukush Mountains is in general related to the Tibetan and Central Asian floras [1]. Some of the species, however, have a fairly broad distribution through alpine Eurasia, and are well described. Others are endemic to the Pamir/Hindukush and the investigation of these plants has been neglected. All species considered in this study are adapted to a dry high-altitude steppe-environment or associated with man-made irrigation in Wakhi villages, and are all reasonably common within the Wakhan Corridor.

The present study investigated antibacterial and cyclooxygenase-1 (COX-1) inhibitory activity of plants from the Pamir Mountains.

2. Results and Discussion

2.1. Testing for Antibacterial Activity

Water and ethanol extracts of 20 species used in the Pamir Mountains for ailments which could be caused by bacterial infections, were investigated for antibacterial activity against two gram positive and two gram negative bacteria. Most of the tested extracts did not inhibit the test bacteria.

Water and ethanol extracts of Ephedra intermedia and the ethanol extracts of Lagochilus cabulicus and Peganum harmala inhibited Staphylococcus aureus at 0.5 mg/mL,and the P. harmala extract further inhibited the growth of Bacillus subtilis and E. coli, also with MICs of 0.5 mg/mL (Table 1). Antibacterial activity of P. harmala has been demonstrated previously [2], the activity is due to harmane-type alkaloids [3]. The best antibacterial activity was obtained with the ethanol extract of Arnebia guttata, with an exceptional low MIC of 6 µg/mL against S. aureus, very close to the value of 2 µg/mL obtained with streptomycin (Table 1). The water extract of A. guttata did not show activity. When used in the Pamir Mountains, the root material is finely chopped and then fried in oil, and the oil is then applied to cotton wool and inserted in the outer ear against earache. This preparation makes sense as it seems the active compounds are not extracted with water. Arnebia species have been used from Turkey to China to treat various bacterial infections [4,5]. The antibacterial activity of Arnebia species is due to alkannin and derivatives thereof [5]. A. guttata had a strong red color, indicating the presence of alkannin-derivatives, and previously several of such compounds have been shown to be present in the species [6,7].

2.2. Testing for COX-1 Inhibition

A number of the recorded uses of the plants indicated that the plants might inhibit the prostaglandin biosynthesis, and thereby act as anti-inflammatories, pain killers or febrifuges. Ten plant species were tested for COX-1 inhibitory activity. Ethanol extracts of Artemisia persica (IC50: 0.5 µg/mL), Dragocephalum paulsenii (IC50: 0.5 µg/mL), Ephedra intermedia (IC50: 3.8 µg/mL), Hyoscyamus pusillus, Nepeta parmiriensis (IC50: 0.7 µg/mL)and Rumex patientia subsp. pamiricus (IC50: 3.5 µg/mL) exhibited the best COX-1 inhibitory effect (Table 2).

Table 1. Antibacterial activity of plant species used in the Pamir Mountains to treat ailments related to bacterial infections.

Click here to display table

Table 1. Antibacterial activity of plant species used in the Pamir Mountains to treat ailments related to bacterial infections.
Plant speciesFamilyVoucher No. (J. Soelberg)Reported useUsed partMIC (µg/mL)
S. aureusE. coliB. subtilisP. aeriginosa
Anaphalis virgata Thoms.Asteraceae135Fever, breathing problems, blistersHerba----
Arnebia guttata Bge.Boraginaceae145Ear-acheRadix6 (E)---
Artemisia persica Boiss.Asteraceae154Non-descript stomach problemsHerba1000 (E)---
Artemisia sieversiana Willd.Asteraceae152Treatment for maggot infected wounds (in animals)Herba----
Betula chitralica BrowichBetulaceae36Boils/blisters, decoction drunk for various diseasesCortex----
Carum carvi L.Apiaceae17Fever, throat painSemen500 (E)---
Delphinium brunonianum Royle.Ranunculaceae113Antibacterial, applied to woundsHerba----
Descurainia sophia (L.) Webb & BerthBrassicaceae151Antibacterial decoction, powder blown into hurting throats, blistersSemen----
Ephedra intermedia Schrenk & Mey.Ephedraceae163Mouthwash for toothache/periodontitisHerba500 (E)500 (W)---
Epilobium latifolium L.Onagraceae136BlistersHerba1000 (E)---
Hyoscyamus pusillus L. Solanaceae30ToothacheSemen----
Lagochilus cabulicus Rech, f & Edelb s.l.Lamiaceae141For animal with lung troublesHerba500 (E)
Mentha longifolia (L.) HudsonLamiaceae175Fever, decoction drunk for various unwellnessHerba----
Nepeta parmiriensis Franch.Lamiaceae125Fever, nauseaHerba----
S. aureusE. coliB. subtilisP. aeriginosa
Onobrychis echidna LipskyFabaceae32ToothbrushRadix----
Peganum harmala L.Zygophyllaceae1Childrens ear-ache, powder applied to blistersSemen500 (E)500 (E)500 (E)-
Plantago gentianoides subsp. Griffithii (Dechne.) Reich.Plantaginaceae16Blisters (with pus), absesses and woundsSemen----
Rosa webbiana Wallich.Rosaceae160Fever, non-descript stomach problems. Decoction for bloody coughing, ashes for ear-acheFructus----
Rumex patientia subsp. pamiricus RechPolygonaceae161Antibacterial, feverRadix1000 (E)1000 (E)750 (E)1000 (E)
Ziziphora clinopodioides LamLamiaceae107FeverHerba----
Streptomycin 2666

(-): MIC values > 1,000 µg. (E): Ethanol extract, (W): water extract.

Table 2. COX-1 inhibitory effect of plant species used in the Pamir Mountains to treat ailments related to pain, fever and inflammation.

Click here to display table

Table 2. COX-1 inhibitory effect of plant species used in the Pamir Mountains to treat ailments related to pain, fever and inflammation.
Plant speciesFamilyVoucher No.Reported useUsed partCOX-1 inhibition (%)
Total assay concentration (µg/mL)
0.050.5550500
Artemisia persica Boiss.Asteraceae154Non-descript stomach problems, headache, applied warm to swollen body parts, applied to chest for common coldFolium + Flos145857591
Dragocephalum paulsenii Briq.Lamiaceae51FeverHerba−648967688
Elsholtzia densa BenthLamiaceae147Headache, joint pain, non-descript stomach problemsHerba0134198100
Ephedra intermedia Schrenk & Mey.Ephedraceae163Bath for broken body-parts, poultice, swollen stomach, backache, bath for aching feet, mouthwash for toothache/periodontitisHerba−3−97896103
Hyoscyamus pusillus L. Solanaceae30ToothacheSemen543611587104
Mentha longifolia (L.) HudsonLamiaceae175Fever, backache, decoction drunk for various unwellnessHerba30−4-98105
Nepeta parmiriensis Franch.Lamiaceae125FeverHerba23389783106
Primula macrophylla DonPrimulaceae114Eye painDust from flowers3742101108
Rumex patientia subsp. pamiricus RechPolygonaceae161Anti-inflammatory, feverRadix511527386
Ziziphora clinopodioides LamLamiaceae107Fever, headacheHerba−25−22492767

An in vivo study on Ephedra intermedia has shown that a methanol extract inhibited swelling in the carrageenan-induced paw edema assay [8]. Bioassay-guided isolation identified ephedroxane as the anti-inflammatory compound [9]. Water extracts of Rumex patientia have in previous studies shown anti-inflammatory activity in several paw-oedema models [10], and also exhibited analgesic effect in formaldehyde–induced pain [11]. Previous analysis of the essential oil of Nepeta pamiriensis collected in this study, showed that the oil contains 98% 1,8-cineole [12]. 1,8-Cineole has in several studies been shown to possess anti-inflammatory activity, including activity mediated via inhibition of the prostaglandin synthesis [13].

3. Experimental Section

3.1. Plant Material

Plants were collected during the summer season of 2010 in the Wakhan valley, Big and Small Pamir. Plant material was air dried out of sunlight and kept in paper bags. Voucher specimens were identified by Jens Soelberg and deposited at the Herbarium of The Botanical Museum of Copenhagen University (C) and Kabul University Faculty of Science Herbarium (KUFS). See Table 1 and Table 2 for voucher numbers.

3.2. Extraction for Antibacterial Assay

Dried, powdered material (1 g) of plant material was extracted with 3 mL of water or ethanol for 30 min in an ultrasound bath. The extract was filtered through a filter paper. The extraction procedure was repeated. After filtration the combined ethanol extract was evaporated to dryness under nitrogen, whereas the water extracts were freeze-dried. The extracts were redissolved in DMSO to 100 mg/mL and diluted with Mueller-Hinton broth to a final concentration of 8 mg/mL.

3.3. Extraction for COX-Assay

Dried, powdered material (100 mg) of plant material was extracted with 1 mL ethanol for 30 min in an ultrasound bath and filtered through a filter paper. The extraction procedure was repeated. After filtration the extract was evaporated to dryness under nitrogen and redissolved in ethanol to a final concentration of 40 mg/mL.

3.4. Antibacterial Assay

The antibacterial assay was performed in 96-well microplates. Bacteria (Staphylococcus aureus ATCC 6538; Eschericia coli ATCC 11229; Bacillus subtilis ATCC 6633; Pseudomonas aeriginosa ATCC 9027) were cultured overnight in Mueller-Hinton broth at 37 °C. 100 µL overnight culture was added to 9.9 mL Mueller-Hinton broth. Each well contained 50 µL test solution (plant extract, streptomycin or broth), 50 µL broth and 100 µL bacterial suspension. The plates were incubated overnight at 37 °C. After incubation, 40 µL MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) was added to each well and the plate was incubated for 30 min before observation for blue color formation.

3.5. Cyclooxygenase-1 Assay

The COX-1 assay was performed according to [14] with minor modifications. Fifty µL of COX-1 (Sigma) (75 unit per sample) and 1,250 µL co-factor solution (0.003 g l-adrenaline, 0.003 g reduced gluthatione) and 200 µL Tris-buffer per sample were preincubated for 15 min on ice. Sixty µL of this solution was added to the test solution consisting of 2.5 µL plant extract and 17.5 µL water and preincubated for 10 min at room temperature. 14C-Arachidonic acid (20 µL) was added to this enzyme-extract mixture and incubated for exactly 10 min in a water bath at 37 °C. The reaction was terminated with 10 µL 2 N HCl. In each test, two types of controls were run (2.5 µL ethanol and 17.5 µL water): backgrounds in which the enzyme was inactivated with HCl before the addition of 14C-arachidonic acid; and solvent blanks. The COX-1 inhibitor indomethacin was used as a positive control.

Unlabeled prostaglandin carrier solution (4 µL per sample) was added to the reaction mixture. 14C-prostaglandins synthesized in the assay were separated from unmetabolized arachidonic acid by column chromatography using silica columns. The assay mixture was applied to the column with 1 mL eluent 1 (hexane:1,4-dioxane:acetic acid (350:150:1 v/v/v)) followed by an additional 4 mL eluent 1 to elute the unreacted arachidonic acid. The prostaglandins were eluted into scintillation vials using 3 mL eluent 2 (ethyl acetate:methanol (85:15 v/v)). Four milliliters scintillation fluid (Pico-Flour 15, Perkin Elmer) was added to the vials and the radioactivity was counted after 1 h in the dark in a TriCarb scintillation counter. The percentage inhibition of the extracts was obtained by measuring the amount of radioactivity in the solutions relative to the solvent blank.

The assay was performed in triplicate. Data were fitted into Grafit5 software for estimation of IC50-values.

4. Conclusions

Ephedra intermedia, Lagochilus cabulicus, Peganum harmala and especially Arnebia guttata inhibited Staphylococcus aureus, and the P. harmala extract further inhibited the growth of E. coli and Bacillus subtilis. Artemisia persica, Dragocephalum paulsenii, Ephedra intermedia, Hyoscyamus pusillus, Nepeta parmiriensis and Rumex patientia subsp. pamiricus exhibited COX-1 inhibitory activity.

The results indicate that some of the plant species used in traditional medicine in the Pamir Mountains have in vitro activities that support their use.

Acknowledgments

The plants were collected during “The Third Danish Pamir Expedition,” funded by the Carlsberg Foundation, Denmark.

References

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