Ethnopharmacological evaluation of the anticonvulsant, sedative and antispasmodic activities of Lavandula stoechas L

Abstract

Lavandula stoechas L. (Lamiaceae) has been used for a long time in traditional medicine as an anticonvulsant and antispasmodic. The aqueous-methanolic extract of L. stoechas flowers (LS) was studied for its possible anticonvulsant and antispasmodic activities. When tested in mice, LS (600 mg/kg) significantly reduced the severity and increased the latency of convulsions induced by pentylene tetrazole (PTZ). LS likewise reduced PTZ's lethality. LS up to a dose of 600 mg/kg was found devoid of any hypnotic effect in mice, however, animals were found to be dull, calm and relaxed. The sedative effect of the plant extract was confirmed, as it prolonged the pentobarbital sleeping time in mice similar to that of diazepam. In isolated rabbit jejunum preparations, LS caused a dose-dependent (0.1–1.0 mg/ml) relaxation of spontaneous contractions. LS also inhibited K⁺-induced contractions in a similar dose range, thereby suggesting calcium channel blockade. This effect was confirmed when pretreatment of the jejunum preparation with LS produced a dose-dependent shift of the Ca²⁺ dose-response curve to the right, similar to the effect of verapamil, a standard calcium channel blocker. These data indicate that the plant extract exhibits anticonvulsant and antispasmodic activities. Its calcium channel blocking property may be mechanistically related to these activities. Its usefulness in folk medicine appears thus to be based on a sound mechanistic background.

Introduction

Lavandula stoechas L. (Lamiaceae), locally known on the Subcontinent as ‘Ustu khuddoos’, is indigenous from the Arabic and Mediterranean Coasts to Asia Minor (Nadkarni, 1982). It is an imported product in Pakistan and used by traditional healers for various diseases of the central nervous system, like epilepsy and migraine. It is called broom of the brain (Nadkarni, 1982, Hakeem et al., 1991). It is also being used in folk medicine, as antispasmodic in colic pain (Nadkarni, 1982, Usmanghani et al., 1997). Lavandula species are used for the extraction of oil (known as lavender oil) employed in perfumery and cosmetics. For medicinal purposes, its aerial parts are used.

L. stoechas has been extensively studied phytochemically, with limited work on pharmacological aspects. The oil content of L. stoechas varies from 0.77–1.2% (Sharma, et al. 1983). The aerial parts contain oleanolic acid, ursolic acid, vergatic acid, β-sitosterol, α-amyrin, α-amyrin acetate, lupeol, erythrodiol and flavonoids, luteolin, acacetin and vitexin (Ulubelen and Olcay, 1989) and two longipinane derivatives, longipin-2-ene, 7β, 9α-diol-1one and longipin-2-ene, 7β, 9α-diol-1one,-monoacetate (Ulubelen et al., 1988). It also contains 7-methoxy coumarin (which is a smooth muscle relaxant) and lavanol (Manzoor-I-Khuda and Khan, 1969). In the essential oil, 51 compounds have been described, the major ones being fenchone, pinocarvyl acetate, camphor, eucalyptol and myrthenol constituting 63.4% of the oil (Kokkalou, 1988).

L. stoechas has been shown to reduce blood sugar levels (Gamez et al., 1987). The oil has been found useful as nocturnal sedative in elderly patients in the form of an air freshener (Hardy, 1991, Hudson, 1996), and has also beneficial effects in cancer care (Horrigan, 1992) and in stress (Tisserand, 1992). Inhaling the lavender oil vapors shows anticonvulsive action (Yamada et al., 1994). However, there is no report available for antispasmodic and/or anticonvulsive activities of the flower extract, which usually contains non-volatile components. The aim of this investigation was to provide a scientific basis for the traditional use of L. stoechas flowers (LS) in epilepsy and colic pain.