Two new tropolonic alkaloids from Colchicum speciosum Steven bulbs

Abstract

<strong>Background and objectives:</strong> The genus <em>Colchicum</em> belongs to the family Colchicaceae, which comprises of 19 genera, and 225 species worldwide. They have been recognized for more than 2000 years for their noticeable biological properties. The <em>Colchicum</em> species are well known for presence of tropolonic alkaloids, mainly colchicine. Colchicine, is still the drug of choice for treatment of gout, and is used for the treatment of a number of proinflammatory disorders, such as familial Mediterranean fever, and Behcet's disease. Clinical studies have proved colchicine to posses potent anti-tumor activity. <em>Colchicum speciosum </em>Steven is an indigenous perennial herbaceous plant widely distributed in northern, central and western regions of Iran. <strong>Methods:</strong> In the present study, the phytochemical composition of MeOH extract from bulbs of <em>C. speciosum </em>collected fromSavadkouh region, Iranwas investigated by combination of HPLC-PDA-MS spectrometry and NMR specroscopy. The fractionation of MeOH extract was carried out by partitioning on CH₂Cl₂, EtOAc and water. <strong>Results:</strong> The isolation and purification of CH₂Cl₂ portion by combination of reverse and normal phase chromatography resulted in the isolation, purification and identification of two new tropolonic alkaloids, compounds (<strong>1</strong>) and (<strong>2</strong>), as well as two known compound colchicine (<strong>3</strong>) and demecolcine (<strong>4</strong>). Their structures were established by extensive spectroscopic methods, including 1D (¹H NMR) and 2D-NMR (COSY, HSQC and HMBC). The absolute configurations of isolated compounds were established by aid of circular dichroism. <strong>Conclusion:</strong> Phytochemical investigation of CH₂Cl₂ extract of <em>C. speciosum</em> by combination of HPLC, column chromatography and hyphenated spectroscopic techniques led to identification two new alkaloids with potential as lead compounds.