THUJA OCCIDENTALIS L. (CUPRESSACEAE): REVIEW OF BOTANICAL, PHYTO-CHEMICAL, PHARMACOLOGICAL AND TOXICOLOGICAL ASPECTS

Received on 22 November, 2013; received in revised form, 05 February, 2014; accepted, 24 March, 2014; published 01 April, 2014

THUJA OCCIDENTALIS L. (CUPRESSACEAE): REVIEW OF BOTANICAL, PHYTO-CHEMICAL, PHARMACOLOGICAL AND TOXICOLOGICAL ASPECTS

L.D.S. Alves ¹, C.B.M. Figueirêdo ^{1, 2}, C.C.A.R. Silva ¹,G.S. Marques ¹, P.A. Ferreira ¹, M.F.R. Soares ², R.M.F. Silva ¹ and P J. Rolim-Neto*¹

Technology Laboratory of Medicinal ¹, Center for Quality Control of Medicines and Related ², Department of Pharmaceutical Sciences, Federal University of Pernambuco, Recife, Brazil

ABSTRACT: Thuja occidentalis called the tree of life is an endemic plant in eastern North America and cultivated in northern Europe and in Brazil as ornamental tree. According to the popular use of this plant has been used in herbal and homeopathic preparations for acute and chronic infections of the upper respiratory tract, warts, as adjunctive antibiotic, immunostimulant. However, these and other data are old or unavailable, and in view of the therapeutic potential of the species, it was necessary to upgrade the recently published studies and not included in previous reviews about the botanical, pharmacological, toxicological and technological aspects.  In this review article, it was noted that for many years the phytochemistry studies on the species concentrated their efforts around essential oils, highlighting the monoterpene thujone, which is attributed to the pharmacological and toxicological activities. Recently, preclinical studies have identified the presence of polysaccharides, flavonoids, tannins and proteins in the ethanol fraction, which showed antioxidant, hepatoprotective, antitumor, hypolipidemic, antidiabetic and antiulcerative activity. The clinical studies proving its immunostimulant and action against warts, however no need to isolate the constituents responsible for the therapeutic action and to establish of quality parameters for plant drug and its derivatives, capable of ensuring the effectiveness, safety and quality of products from T. occidentalis

Arbor vitae,Methabolits, treatment, Toxicity, Cultivation

INTRODUCTION:The genus Thuja of exotic origin belongs to the Cupressaceae family and covers five species ¹, including Thuja occidentalis L., commonly known as the tree of life. It is endemic in the eastern part of North America and is grown in northern Europe and Brazil as an ornamental shrub ², being especially appreciated by landscape designers ¹.

The mother tincture (MT) diluted or hydro-alcoholic have been widely used in homeopathy and human and veterinary phytotherapy, one of the main uses being the treatment of acute and chronic infections of the upper respiratory tract, and as an adjuvant to antibiotics for severe bacterial infections, such as bronchitis, angina, pharyngitis, otitis media and sinusitis. Its effects are attributed primarily to its immunostimulant and antiviral properties, which increase the proliferation of T lymphocytes and the production of interleukin-2. There are also reports of its association with other plants that modify the immune system, such as Echinacea purpurea, Echinaceae pallida and Baptisia tinctoria ³.

In the form of a tincture, it is used in the lower genital tract for the treatment of warts, papillomas, condylomas, and various types of excrescence, especially those related to Human papillomavirus (HPV) ⁴. There are reports that the cure rate for warts is 84.2% ⁵. Adverse reactions reported in clinical trials are generally mild or moderate and often associated with constituent of essential oil thujone ³. However, there were seen no sign of mutagenesis or synthesis of β-galactosidase in tinctures analyzed ⁶.

The most important of the metabolites present in this medicinal plant are the flavonóides ^3,7, lignans ^2,8, polysaccharides ³ and constituents of the essential oils, characteristic of the Thuja genus ⁹, including diterpenes, monoterpenes (α-thujone, β-thujone, fenchone), and a sequiterpene ². The polysaccharides as well as flavonoids (kercetin, campherol), tannins and proteins were identified by phytochemical investigations in ethanolic fraction of aerial part of T. occidentalis used in several pharmacological studies conducted by Dubey e Batra for hepatoprotective, antidiabetic, anti-ulcerative, antioxidant and hypolipidemic activities ^10-14; addition of flavonoids also are involved with the anti-tumor activity ^{15 ,16}.

According to Naser et al ³, there are various reviews and monographs that describe the botanical aspects, the metabolites, and some pharmacological properties of this plant. However most of these reports are old, written in German and often not available in the data bases. In view of this and given the therapeutic importance of the species under study, it was necessary to update the data with recently published studies and those not included in previous reviews, including the description of the general, botanical and phytochemical aspects of T. occidentalis, beyond its pharmacological properties and data on safety and efficacy, based on clinical and pre-clinical studies, along with the technological aspects involved.

General description, botany and cultivation: Thuja belongs to a small genus of the Cupressaceae family and covers five species, including T. occidentalis¹⁷. The tree has been given various names, including arbor vitae, white cedar of the east, white cedar of the north, the tree of life, white cedar, swamp cedar or yellow cedar. The medicinal parts of this plant are composed of oils extracted from the leaves and extremities of the branches, which must be young, dry and fresh¹⁸.The four main varieties of T. occidentalis cited by Naser et al. ³ are T. occidentalis cv. Aureospica, T.occidentalis cv. Lutea, T.occidentalis cv. Vervaeneana and T. occidentalis cv. Wareana.

This plant is originally from the eastern part of North America, and is found in Europe mainly as an ornamental shrub. The trees are characteristically coniferous and monoecious, measuring 12-21 m in height ^3,18, have a pyramid-shaped summit with monopodial branchings to the trunk, which is erect with a reddish-brown cortex and relatively highly ramifying branches ¹⁹. The branches are flattened, short, horizontals, with an ascending extremity and covered with small rigid leaves, which overlap one another. The leaves are oval-shaped, persistent, greens, with scales crossing from opposite sides and the extremities tapering towards a convex dorsal surface ^{18, 19}.

On the upper branches, the leaves present an angular oval glandular structure containing oil resin with a characteristic intense odor, a sharp taste, which is balsamic and camphoric. On the extremities of the branches there are also small oval cones (6-8 mm in length), which are microsporophyll, greenish yellow in color and covered in yellow leathery foliage ^{18, 19}. These cones are made up of 8 or more scales, with 1-3 ovules each ¹.  The flowers appear in separate (monoecious) cones, composed of male flowers (dark-brown) and female flowers (greenish-yellow), which are almost perfectly star-shaped. The seeds are yellowish-brown, 3-5 mm in length and around 1 mm in width ¹⁸. The fruit is an oblong sub-coni