A new bioactive monoterpene–flavonoid from Satureja khuzistanica

Abstract

A new monoterpene–flavonoid, saturejin (3′-(2,5-dihydroxy-p-cymene) 5,7,4′-trihydroxy flavone) (4), together with twelve known flavonoids consist of two flavanonols (aromadendrin (8) and taxifolin (12)), two flavanones (naringenin (3) and 5,7,3′,5′-tetrahydroxy flavanone (9)) and eight flavones (xanthomicrol (1), acacetin (2), cirsimaritin (5), 7-methoxy luteolin (6), apigenin (7), cirsilineol (10), diosmetin (11) and 6-hydroxyluteolin 7,3′-dimethyl ether (13)), were isolated from an ethyl acetate extract and identified for the first time in the dried aerial parts of Satureja khuzistanica Jamzad, an endemic medicinal plant traditionally used as dental anesthetic, oral antiseptic and anti-inflammatory among the nomadic inhabitants of southwestern Iran. The structures of these compounds were determined using the usual spectroscopic methods including 2D-NMR and MS analyses.

Saturejin showed a significant β-glucosidase inhibitory activity at concentration of 10 μg as well as positive antioxidant activity at the amount of 1 μg. These results could be correlated with the in vitro and in vivo anti-inflammatory, anti-oxidant and anti-diabetic properties reported from this medicinal plant. Similar activities were also described for some of the other isolated compounds.

Introduction

Herbs and shrubs belonging to the genus Satureja L. (savory), a worldwide genus of the family Lamiaceae, are often aromatic and widely distributed in the Mediterranean area, Asia and boreal America [1].

They have been used in traditional medicine as antimicrobial, spasmolytic, cicatrisant and diuretic agents since antiquity [2]. However, as many other species of the family, especially endemics, they are used locally by indigenous people in different parts of Iran and few information or documented references about their uses were founded.

The genus Satureja represents sixteen species in the flora of Iran which nine of them (Satureja atropatana Bunge, Satureja sahendica Bornmüller, Satureja bachtiarica Bunge, Satureja isophylla Rechinger, Satureja edmondi Briquet, Satureja kallarica Jamzad, Satureja khuzistanica Jamzad, Satureja rechingeri Jamzad and Satureja kermanshahensis Jamzad) are endemic, appear in small populations in mountainous habitats of north, west and central parts of the country [1], [3], [4]. Members of this genus are called Marzeh in Persian, and they are important commercial and medicinal plants, widely used in pharmaceutical, food, cosmetics and perfumery industries due to their high content of essential oils [5].

S. khuzistanica, “Marzeh khuzestani” in Persian, is an endemic traditional herbal medicine among the nomadic inhabitants of southwestern Iran used as herbal tea for its analgesic, antiseptic and anti-inflammatory properties, especially in toothache problems [6], [7]. Several studies have been carried out on the chemical composition of the essential oil of S. khuzistanica and carvacrol together with p-cymene, thymol, myrcene, γ-terpinene and terpinene-4-ol were identified as its main components [6], [8], [9]. Various biological activities such as antibacterial [10], antifungal [11], anti-parasitic [12], [13], antioxidant [14], anti-diabetic [15], anti-inflammatory [16], anti-coagulant as well as triglyceride-lowering potential [17] have been recently investigated using the essential oils and extracts.

Considering the reported valuable pharmacological properties of S. khuzistanica aerial parts, dental anesthetic and oral antiseptic drops of its essential oils as well as capsules containing dried leaf powder, for their antioxidant and triglyceride-lowering activities are used in pharmaceutical and food industries [6].

Previously phytochemical analysis of Satureja species revealed the presence of phenolic acids, anthocyanins, flavones, diterpenes, triterpenes and sterols [18], [19], [20], [21], [22].

Although the essential oil composition of S. khuzistanica aerial parts has been widely investigated, the chemical analyses of the extract marker compounds are still scarce. So far, only one flavonoid (6-hydroxyluteolin 7,3′-dimethyl ether) together with three terpenoids were reported from this medicinal plant [19].

In the present study we aimed to report the isolation and structural elucidation of the flavonoids from the aerial parts of S. khuzistanica which has not been previously reported.