Laura N. Cariddi,* Adriana Panero, Mirta S. Demo, Liliana I. Sabini, Ana M. Maldonado, Margarita Grosso and Julio Zygadlo

Abstract: An oil of Minthostachys verticillata (Griseb.) Epling was analyzed by GC. The main constituents identified were pulegone (63.0%) and menthone (16.4%). It was found that the oil inhibited β-hexosaminidase release from basophils. Forty-two percent of the cells present in lymphocyte cultures stimulated by the oil were CD8(+) T cells and showed higher IFN-γ levels than non-stimulated cultures (p < 0.05). According to these results, the oil was considered to be a Th1 deviation inducer, inhibiting the immediate-type allergic reaction.

Minthostachys is a taxonomically complex South American genus represented by twelve species of aromatic herbs and green bushes, which belong to the Labiatae family. They grow widely in Colombia, Venezuela, Brazil, Ecuador, Peru, Bolivia and also in the northwest and central regions of Argentina (1). The species that belong to this genus include: Minthostachys glabrescens Epling.; Minthostachys verticillata (Griseb.) Epling [syn. Minthostachys mollis (Griseb.)); Minthostachys andina (Brett.) and Minthostachys spicata (Benth.) Epling. Minthostachys verticillata, commonly known as ‘peperina’, ‘pipirina’, ‘peperita’ or ‘piperita’, has the widest geographical distribution and is known for its ethno-medicinal properties (2,3). Minthostachys verticillata is an aromatic bush of 0.3 to 2 m in height, with oblong leaves from 1 to 5 cm in length, obtuse or sub-acute, which form 90° angles with the stem. Its white flowers are grouped in the leaves’ axils and the stem has a quadrangular section. It’s a pubescent plant that flowers in summer. The fruits are dry, small capsules with four seeds each. Its fructification period is in March and April and it is harvested in summer (4,5). It is used mainly in infusions to diminish diarrhea and vomiting. It is also used as a digestive, a sedative, an anti-spasmodic and a bronchial dilating agent. It also has insecticidal, fungicidal and anti-parasitic properties (1,6). In the alimentary industry, it is used for the fabrication of liquors, cool drinks and mixed herb preparations (7,8). Previous studies have shown essential oil derived from M. verticillata has antimicrobial activity against some staphylococcal strains and antiviral properties against HSV-1, strain RC/79 of PrV and Herpes Suis Virus (9). In addition, the oil has mitogenic properties on human lymphocytes as PWM (10). For a long time, the corticoids represent the more effective anti-inflammatory therapy in allergy because they block many of the inflammatory routes that abnormally are activated in this type of pathologies as described by Jungsuwadee et al. (11). Nevertheless, an installed problem refers allergic patients who do not respond to the treatment with β-adrenergic steroids which justifies the search of new immunomodulators. It is known that the fourth part of drugs used in the industrialized countries has been obtained from the plant kingdom. Recent studies demonstrate that the homeopathy, acupuncture and the herbal medicine are the types of alternative medicine, but commonly used by patients with allergic diseases, is for that reason that the vegetal products are at the present time object from study at world-wide level (12,13). The purpose of this study is to investigate the properties attributed to the oil derived from M. verticillata. Several objectives were established. First, we obtained the plant’s essential oil and detected main constituents by gas chromatography. Second, we evaluated the modulating ability this has over basophils degranulation by β-hexosaminidase release assay, comparing their inhibitory properties with those of dexamethasone and theophylline. Third, we determined the % of CD8(+) T cells in lymphocyte cultures stimulated by the vegetal derivate and measured the IFN-γ level in the supernatants of these cultures in order to deduce if essential oil, can induce Th1 deviation.