In vitro and in vivo activity of Artemisia sieberi against Trichomonas gallinae

Abstract

In Iranian folk medicine Artemisia sieberi has been used for treatment of parasite infections in human and animals. The present study was designed to evaluate the in vitro and in vivo effects of A. sieberi essential oil (EO) against Trichomonas gallinae. Trichomonas gallinae were recovered by wet mount method from infected native pigeons. The in vitro assays were accomplished in multi-well plates containing metronidazole (MTZ) as a standard antitrichomonal and EO in final concentrations of 2.5, 5, 10, 20, 50, and 100 μg/ml of culture medium containing 10⁴ parasites. The in vivo assay was performed on 40 experimentally infected pigeons receiving 25 and 50 mg/kg of MTZ and EO for 7 successive days. Gas chromatographic (GC) analysis was performed to reveal chemical constituents of the EO. At 20 µg/ml, MTZ resulted in no viable trophozoite in culture medium after 24 h incubation period. While the 24 h MIC of EO was 10 µg/ml. Treatment with EO at dose of 50 mg/kg after 4 days led to full recovery of infected pigeons but for MTZ at the same dose 5 days were spent. Major constituents of EO were α-thujone (31.5%) and β-thujone (11.92%). Data of the present study introduced A. sieberi as a natural potent antitrichomonal agent effective against T. gallinae.

Introduction

Internal parasites of human and animals have been treated with a wide variety of herbal products in traditional medicine. One of these plants used to treat helminthosis in Iranian folk medicine is Artemisia sieberi Besser (Artemisia herba alba Asso Var. laxifolia Boiss) (Mahboubi and Farzin, 2009 ▶). Artemisia sieberi (Asteraceae) is a classic dry land plant mainly dominated in south west and central Asia (Podlech, 1986). Artemisia sieberi is locally named “dermaneh” and is widely distributed in the semi-desert and desert areas of Iran (Mahboubi and Farzin, 2009 ▶).

Trichomonas gallinae, the causative agent of avian trichomoniasis is a flagellate belonging to the order of Trichomonadida. The parasite is located in the upper digestive and occasionally in the respiratory tracts of a large variety of birds, mainly in the order Columbiformes and Falconiformes (Boal et al., 1998 ▶; Rouffaer et al., 2014 ▶). Avian trichomoniasis is generally manifested as a caseous lesion within the anterior digestive tract of affected birds. The lesions range from mild, often subclinical infections, to severe inflammation which can be acute and fatal and may lead to death by starvation due to the obstruction of the lumen of the esophagus (Gerhold et al., 2008 ▶). Outbreaks of trichomoniasis have resulted in wide-ranging mortality, mainly in breeding populations (Robinson et al., 2010 ▶; Lawson et al., 2011 ▶). Trichomonas gallinae has significant health and economic impacts on the poultry industry, especially pigeons and game birds rearing and breeding (Stockdale et al., 2015 ▶) and is considered as a major factor for regulation and even decline of avian populations (Robinson et al., 2010 ▶). The drugs of choice for treatment of trichomoniasis are nitroimidazoles. Sub-therapeutic doses and preventive use of these drugs against trichomoniasis, have resulted in emergence of resistant strains of T. gallinae (Lumeij and Zwijnenberg, 1990 ▶). Artemisia sieberi has also been screened for antimicrobial, antifungal, anticoccidial and insecticidal activities (Khosravi et al., 2003 ▶; Arab et al., 2006 ▶; Negahban et al., 2007 ▶; Mahboubi and Farzin, 2009 ▶).

Taken together, the present study was designed to evaluate the in vitro and in vivo effects of A. sieberi essential oil (EO) against T. gallinae.

Materials and Methods

Essential oil

At full-flowering stage aerial parts of A. sieberi were collected from Arak (Markazi Province, Iran) in September 2014. The voucher specimens of the plant were confirmed by Arak Agricultural Sciences University (Arak, Iran). The plant was dried in shadow at room temperature, then by using a Clevenger type apparatus hydrodistilled to extract its EO. Extraction was done according to the method described by (Negahban et al., 2007 ▶). Gas chromatographic (GC) analysis was performed using a Shimadzu GC-9A with helium as a carrier gas on a DB-5 column (30 m × 0.25 mm i.d, film thickness 0.25 mm). GC-MS analysis was carried out on a Varian 3400 GC-MS system equipped with a DB-5 column (30 m × 0.25 mm i.d, film thickness 0.25 mm), oven temperature was 40-250°C at a rate of 4°C; transfer line temperature, 260°C; carrier gas, helium with a linear velocity of 31.5 cm/s; split ratio, 1/60; ionization energy, 70 eV; scan time, 1 s: mass range, 40-300 amu.

Parasite

Trichomonas gallinae were recovered by wet mount method from infected native pigeons as follows: forty native pigeons of about 6 to 8 weeks of age were purchased from local breeders in Babol city (Mazandaran province, Iran). Samples were taken from membranous lesions in oropharyngeal area of suspicious birds using microbiology swabs. Wet smears were prepared and examined under a light microscope at ×100 and ×400 magnifications to confirm the existence of T. gallinae. Parasite culture was prepared by immersing oral swabs in tryptone/yeast extract/maltose (TYM) medium supple-mented with 10% fetal calf serum (Sigma, Germany) and incubated at 37°C (Sansano et al., 2009 ▶). Cultures were observed over five consecutive days to check the growth of T. gallinae. Sub-cultures were done on isolates with 48 h intervals during the logarithmic phase of growth when the parasites showed more than 95% mobility and normal morphology (Seddiek et al., 2014 ▶).

In vitro assay

The method used for the in vitro assay was that described by Munoz et al. (1998) ▶ with some slight modifications. To examine the susceptibilities of T. gallinae to A. sieberi EO and MTZ (Alborzdaru, Tehran, Iran), sterile multi well plates were used to incubate the trophozoites with the corresponding EO and drug dilutions. A volume of 100 µL of culture medium containing 1 × 10⁴ parasites pipetted into each well, as well as prediluted MTZ and A. sieberi EO to give final concentrations of 2.5, 5, 10, 20, 50, and 100 μg/ml. Tween 20 (0.01% of final concentration) was used as solubilization vehicle for in vitro analysis. Control wells received only Tween 20. Subsequently, to generate anaerobic conditions a layer of 50 µL of vaseline was added to wells. All assays were run three times. The wells were examined with an inverted microscope every 24 h for 3 consecutive days. The MIC (the lowest concentration of the drug in the well at which no motile parasite was observed) was also recorded.

The growth inhibition percentage (GI %) was determined as the following equation:

$\mathrm{Growth\; inhibition\; \%}=(\mathrm{A}-\mathrm{B})/\mathrm{A}\times 100$

where,

A: The mean number of trophozoites in the control group

B: The mean number of trophozoites in the test group (Seddiek et al., 2014 ▶)

In vivo assay

Protocol of the in vivo study (No. 0492/16) was in accordance with laboratory animal welfare guide of Pasteur Institute of Iran and has been accepted by the committee. Forty native pigeons up to 6 weeks of age were pre-examined and confirmed to be free of T. gallinae were then experimentally infected by ino-culation of 4 × 10⁴ trophozoites in 1 ml of 48 h culture medium. Seven days post-infection, after the birds were examined by wet mount method and by microscopic examination were confirmed to be infected with T. gallinae, they were randomly allocated into 5 groups as follows: the first group (CON) infected but not medicated, EO 25 and EO 50 were the groups infected with T. gallinae and medicated with the doses of 25 and 50 mg/kg of A. sieberi EO, respectively. MTZ 25 and MTZ 50 were infected with T. gallinae and medicated with 25 and 50 mg/kg of metronidazole (MTZ). All of the treatments were administered orally (Per Os) once a day for 7 successive days. Birds of different groups were located in separate wire cages and fed semisolid mixed grains diet in order to prevent starvation due to difficulty in swallowing because of trichomoniasis infection. The numbers of motile trophozoites recovered from the crop of infected birds were calculated every day for seven consecutive days. Any clinical adverse effects or mortality were recorded during the treatment period.

Statistical analysis

Analysis of variance (ANOVA) was used, followed by Newman Keul’s test as the post hoc comparison to determine the source of significant differences (SPSS v.11). The p-value less than 0.05 was considered as statistically significant difference between groups.

Results

Chemical composition of A. sieberi EO

Major constituents of A. sieberi EO were α-thujone (31.5%), β-thujone (11.92%), camphor (12.3%), and 1,8-cineole (10.09%) as showed in Table 1.

Table 1.

Chemical composition of A. sieberi EO

Compounds	Retention index	% Constituents of A. sieberi EO
α-Thujene	922	0.6
α-Pinene	932	1.22
Camphene	945	8.72
Sabinene	969	0.3
β-Pinene	975	0.98
Myrcene	986	0.3
α-Terpinene	1012	0.26
ρ-Cymene	1019	1.03
1,8-Cineole	1028	10.09
γ-Terpinene	1052	0.62
Linalool	1070	0.64
Artemisia alcohol	1080	0.23
α-Thujone	1102	31.5
β-Thujone	1112	11.92
Myrcenol	1123	0.37
Camphor	1140	12.3
cis-Verbenol	1143	0.35
Pinocarvone	1149	1.22
trans-Verbenol	1160	0.89
Borneol	1166	1.2
p-Cymen-8-ol	1176	1.14
Myrtenol	1192	0.3
cis-Piperitol	1196	0.26
trans-Piperitol	1206	0.54
Piperitone	1224	1.8
Thymol	1248	0.3

In vitro results

The results for the in vitro anti-trichomonalmactivitiy of A. sieberi EO and MTZ are shown in Table 2. The results revealed high efficacy of A. sieberi EO against T. gallinae. At dose of 20 µg/ml, MTZ after 24 h incubation period resulted in no viable trophozoite in culture medium. While the 24 h MIC of A. sieberi EO was 10 µg/ml. The 48 h and 72 h MIC of MTZ were 20 and 10 µg/ml but these values for A. sieberi were 10 and 5 µg/ml, respectively. Mortality of trophozoites were confirmed by the lack of resumption of growth in the subsequent 48 h cultures.

Table 2.

In vitro anti-trichomonal activity of metronidazole (MTZ) and Artemisia sieberi EO against T. gallinae. Data are presented as mean±SD

Time (hour)	Control	Number of trophozoites ×104
		MTZ (µg/ml)						A. siberi EO (µg/ml)
		2.5	5	10	20	50	100	2.5	5	10	20	50	100
24	7.93±0.08d	7.38±0.38	5.14±2.06ab	3.24±0.2ac	0a	0a	0a	4.9±0.72ab	3.4±0.24ac	0a	0a	0a	0a
48	9.41±0.56d	5.1±0.56ab	2.29±0.82ac	1.38±0.1ae	0a	0a	0a	2.38±0.7ac	1.03±0.44ad	0a	0a	0a	0a
72	9.2±0.46d	2.4±0.2ab	1.37±0.72ac	0a	0a	0a	0a	1.09±0.34ac	0a	0a	0a	0a	0a

^{a, b, c, d} Means with different letters in the same row indicate statistically significant difference (P<0.05)

Results of GI % in MTZ and A. sieberi treated groups in 24 h intervals are shown in Figs. 1A and B. It showed that there was significant difference between GI % in MTZ and A. sieberi EO treated groups in comparison to control. In dose-GI % graphs, doses of 2.5, 5, 10, and 20 µg/ml MTZ and A. sieberi EO resulted in different responses of GI% (Fig. 1).

Fig. 1.

Growth inhibition percentage (GI %) in Artemisia sieberi (A) and metronidazole (B) treated groups in 24 h, 48 h, and 72 h intervals

In vivo results

The in vivo assay demonstrated the effectiveness of two doses of MTZ and A. sieberi EO against T. gallinae (Table 3). Seven days post inoculation of T. gallinae (day 0), before initiation of treatments, number of trophozoites recovered from crop of birds was measured and no significant difference was seen among different groups. In the second day of experiment, treatment with all doses of MTZ and A. sieberi EO even after administration of only one dose eventuated in significant reduction of trophozoites in comparison to control group (P<0.05). Artemisia sieberi EO at the dose of 50 mg/kg in the 3rd and 4th day of the treatment resulted in significant reduction in number of T. gallinae in comparison to all other groups (P<0.05). In the 4th day, no motile trophozoite was recovered from A. sieberi EO 50 mg/kg treated birds. One day later (the 5th day), A. sieberi EO 25 mg/kg led to full recovery of infected pigeons. For the dose of 25 mg/kg of MTZ treated pigeons, 7 days’ time was spent to reach full recovery. No mortality was recorded for treatment groups and no clinical side effects were observed in treated birds.

Table 3.

In vivo anti-trichomonal activity of metronidazole (MTZ) and Artemisia sieberi EO against T. gallinae. Data are presented as mean±SD

Days	Number of trophozoites ×104
	MTZ (25 mg/kg)	MTZ (50 mg/kg)	A. sieberi EO (25 mg/kg)	A. sieberi EO (50 mg/kg)	CON
0	127.28 ± 2.21a	130.56 ± 4.67a	130.8 ± 3.43a	128.56 ± 3.17a	135.44 ± 4.64a
1	84.08 ± 1.50a	41.42 ± 10.28b	36.73 ± 5.04b	20.12 ± 3.35b	140.64 ± 5.55c
2	26.8 ± 1.32a	11.11 ± 0.82b	13.35 ± 1.06b	3.83 ± 1.37c	140 ± 2.33d
3	13.16 ± 0.68a	3.2 ± 0.41b	2.91 ± 0.45b	0c	140.16 ± 4.36d
4	6.41 ± 0.26a	0.36 ± 0.2b	0b	0b	136.16 ± 2.75c
5	3.2 ± 1.56a	0a	0a	0a	126.56 ± 0.68b
6	0a	0a	0a	0a	128.56 ± 0.86b
7	0a	0a	0a	0a	115.68 ± 2.32b

^{a, b, c, d} Means with different letters within the same row indicate statistically significant difference (P<0.05)

Discussion

Preventive treatment with nitroimidazoles could result in isolates of T. gallinae which can serve as serious threat endangering birds’ lives. Nitroimidazole resistant isolates of T. gallinae are reported from different parts of the world including Belgium, Spain and the United States (Munoz et al., 1998 ▶; Rouffaer et al., 2014 ▶; Gerhold et al., 2008 ▶). In spite of the fact that nitro-imidazole resistant strains of T. gallinae are becoming prevalent, very few researches focused on alternative antitrichomonal resources effective against T. gallinae. Antitrichomonal property of the extract of Clausena lansium stem bark was studied by Adebajo et al. (2009) ▶. They concluded that this extract could not fully achieve the efficacy of MTZ against T. gallinae (Adebajo et al., 2009 ▶). Adebajo et al. (2006) ▶ demonstrated the anti-trichomonal activity of Murrayakoenigii (L.) Spreng (Rutaceae), an ancient Indian medicinal herb, and its isolated carbazole alkaloids against T. gallinae. Data obtained in their study showed higher efficacy of MTZ in comparison to isolated carbazole alkaloids. Seddik et al. (2014) ▶ reported that garlic was as effective as MTZ in inhibiting the growth of T. gallinae trophozoites in both in vitro and in vivo assays. They also declared the side effects of cytotoxicity, carcinogenic effects and neurological dysfunction for MTZ and recommended garlic as a safe alternative for prophylactic and therapeutic uses in case of trichomoniasis (Seddiek et al., 2014 ▶). They found that garlic at the dose of 200 mg/kg after 4 days was effective in treatment of infected pigeons while in the present study A. sieberi EO at much lower dose of 25 mg/kg after 4 days resulted in full recovery of infected birds and this period for the dose of 50 mg/kg was as short as just 3 days. Comparison of the results of these two studies reveal higher efficacy of A. sieberi against T. gallinae.

The other evidence for antiprotozoal activity of A. sieberi was in a study done by Arab et al. (2006) ▶ who reported its effectiveness against Eimeriatenella and E. acervulina. They reported protective effect of A. sieberi in broiler coccidiosis (Arab et al., 2006 ▶). Further, it was reported that Iranian flora A. sieberi was effective against Plasmodium berghei. Artemisia sieberi showed anti-malarial effects and also was able to reduce parasitemia in infected mice (Nahrevanian et al., 2012 ▶).

The GC analysis of the A. sieberi used in the present study revealed that α-thujone (31.5%) was the major constituent of the EO. It is reported that this monoterpenoid could be found in many plant species, including Artemesia, sage, and the Thuja tree (Hold et al., 2000 ▶). Artemisia extracts were used for treatment of gastrointestinal helminthes with records back to ancient Egyptian times. One of the toxic monoterpenoids tested against insects was α-thujone (Lee et al., 1997 ▶). It was showed that α-thujone acts as a blocker of the GABA_A (γ-Aminobutyric acid_A) receptor (Hold et al., 2000 ▶). On the other hand, paralyzing effect of some antiparasitic agents on helminthes is thought to be associated with GABA_A receptor (Feng et al., 2002 ▶). So, anthelminthic effect of A. sieberi can be attributed to its α-thujone component. Probably α-thujone is one of the most active components of A. sieberi with parasiticide action. Further studies on active antitrichomonal component of A. sieberi EO and also its activity against T. gallinae are recommended.

Data obtained in this study introduced A. sieberi as a natural potent antitrichomonal agent effective against T. gallinae. Major chemical constituents of A. sieberi can be considered as leading compounds in research and development of novel antitrichomonal agents.

Conflicts of Interest:

The authors declare no conflict of interest.