In vitro Anti-Leishmanial Activity of Essential Oils Extracted from Plants Growing in Northern Cyprus Against Leishmania tropica

Objective: Natural plant products are considered as a source of novel and effective compounds for the treatment of leishmaniasis. In this study, the in vitro activities of essential oils obtained from Origanum dubium (OD), Origanum majorana (OM), Salvia fruticosa (SF) and Laurus nobilis (LN) plants in Northern Cyprus were investigated against Leishmania tropica. Methods: Leishmania tropica strain (MHOM/TR/2012/CBCL-LT) was obtained. RPMI-1640 was added to 96-well plates in 100 µL aliquots, 100 µg/mL essential oil was added to the first well of each row and serial 2-fold dilutions were performed. A promastigote suspension was pipetted into all wells, and the plates were incubated. The promastigotes were enumerated using a haemocytometer. Results: OD essential oil was effective at killing all promastigotes at a minimum inhibitor height (MIC)=0.2 µg/mL and had high activity at the lowest concentrations. Both SF and LN oils had MIC=1.56 µg/mL and LD50=0.78 µg/mL. SF was observed to impair promastigote morphology at the lowest concentrations, while LN did not exert any effect at concentrations <0.2 µg/mL. OM essential oil was found to have a MIC=3.13 µg/mL and a LD50=1.56 µg/mL. Conclusion: All tested essential oils inhibited promastigotes of Leishmania tropica. OD essential oil demonstrated the highest anti-leishmanial activity. Amaç: Bitkilerden elde edilen dogal ürünlerin leishmaniasis tedavisi için yeni ve etkili bilesiklerin üretilmesine öncülük edecegi düsünülmektedir. Çalismamizda, Kuzey Kibris'ta yetisen Origanum dubium (OD), Origanum majorana (OM), Salvia fruticosa (SF) ve Laurus nobilis (LN) bitkilerinden elde edilen uçucu yaglarin Leishmania tropica'ya karsi in vitro etkinlikleri arastirilmistir. Yöntemler: Çalismamizda, Leishmania tropica susu (MHOM/TR/2012/CBCL-LT) kullanildi. Düz tabanli 96'lik plaklarda, tüm kuyucuklara 100 µL RPMI-1640 ve ilk kuyucuklara 100 µg/mL uçucu yaglar eklenerek, seri dilüsyonlari yapildi. Ardindan tüm kuyucuklara Leishmania tropica promastigot süspansiyonundan pipetlendi ve inkübe edildi. Hemositometre yöntemiyle promastigotlarin sayisi incelendi. Bulgular: OD yaginin minimum inhibitör konsantrasyonu (MIK)=0,2 µg/mL'de tüm promastigotlari öldürürken, en düsük konsantrasyonlarda bile etkili oldugu görülmüstür. SF ve LN uçucu yaglarinin ikisinde de MIK=1,56 µg/mL, LD50=0,78 µg/mL olarak saptanmistir. SF'nin en düsük konsantrasyonlarinin bile promastigot morfolojisini bozdugu görülürken, Laurus nobilis'in ise 0,2 µg/mL'den sonraki konsantrasyonlarda etkisini kaybettigi belirlenmistir. OM uçucu yaginin MIK=3,13 µg/mL, LD50=1,56 µg/mL oldugu görülmüstür. Sonuç: Kullanilan tüm uçucu yaglarin Leishmania tropica promastigotlarini inhibe ettigi görülürken, en yüksek anti-leishmanial etkinlik Origanum dubium uçucu yaginda bulunmustur.

[An Endemic Plant of Cyprus, Origanum majorana: Is It A New Alternative Natural Product for Malaria Treatment?] / Kibris Endemik Bitkisi Origanum majorana: Sitma Tedavisinde Yeni Bir Alternatif Dogal Ürün Olabilir mi?

Malaria still remains to be a public health threat and one of the most important infectious diseases to get attention from World Health Organization. No domestic malaria cases have been reported on the island of Cyprus since 1948, as a result of successful elimination process. All of the malaria cases detected in recent years are imported cases. As known, hundreds of medicines are obtained from plants and traditional medicine are used in endemic places of malaria. The cause of malaria - Plasmodium parasites, are developing resistance to antimalarial drugs. Hence, research on plant extracts and essential oils have gained great interest in recent years to obtain new and safe agents/substances. In our study, it was aimed to investigate the in vivo antimalarial activities of essential oils obtained from Origanum dubium, Origanum majorana, Salvia fruticosa and Laurus nobilis plants which grows in Northern Cyprus against Plasmodium berghei - the rodent malaria agent. Plants were collected in appropriate seasons and were dried to obtain and analyze essential oils via Clevenger Apparatus system. L929 mouse fibroblast cell line and MTT [3-(4.5-dimethylthiazole-2-yl) -2.5-diphenyltetrazolium bromide] kit were used to determine the cytotoxic activities of the essential oils obtained. In our study, total of 36 mice (Balb/c) of 6 groups (6 mice in each group) were formed: chloroquine group (CG) (50 mg/kg) as malaria reference group, untreated control group (UTCG), O.dubium (OD) (20 mg/kg), O.majorana (OM) (20 mg/kg), S.fruticosa (SF) (20 mg/kg) and L.nobilis (LN) (20 mg/kg). The essential oils were given to mice infected with P.berghei strain orally on 0, 1, 2 and 3rd days (4 times in total). Blood was taken from the tail end of each mouse 24 hours after the last treatment and blood collection was continued every two days until the mice died. Withdrawn blood taken from the mice were prepared as a thin smear and stained with Giemsa. Then, parasitemia percentages in each smear were calculated. As a result of the cytotoxicity tests, cytotoxic activity was not found at 100 µg/ml (20 mg/kg) in all oils except OD essential oil. While the mice receiving chloroquine continued their lives with the disappearance of the parasite on the 6thday, the mice in the UTCG died on the 9th day. The parasitemia rate reached 35% in the OM group on the 23rd day, in the OD group on the 21st day and in the other groups (SF and LN) on the 14th day and the mice have died. In our study, the difference between the life span in all groups was found statistically significant (p≤ 0.001). As a result, the essential oils O.majorana (14 days increase according to UTCG) an endemic plant of Cyprus and O.dubium (12 days increase according to UTCG) which had an antimalarial effect, decreased parasitemia and increased the life span of mice more than two times, indicated that they could be a source for the acquisition of new antimalarial molecules.