Identification of Anticandidal Cyclic Trisaccharide from Alhagi pseudalhagi Plant

Abstract

Background: Alhagi pseudoalhagi (Camel thorn) is a herbaceous perennial plant. Recently, several investigations have been conducted for its medical and pharmaceutical applications. Methods: The aerial part of the plant was air dried and extracted by different solvents with increasing polarity. The residue from each extract was in-vitro tested against C. albicans that has been previously isolated from vaginal candidiasis patients. The ethyl acetate extract showed anti-candidial activity and showed presence of two compounds on the TLC plate eluted with methanol. This extract was further purified by silica gel column eluted with methanol. The obtained two compounds were tested against C. albiacns and the purity of the active compound was confirmed by reversed phase HPLC with methanol as a mobile phase and detected at 240nm. The chemical structure of the active pure compound was elucidated by mass spectrometry, 1D and 2D-NMR and IR analysis. Result: The NMR analyses characterized three sugar molecules cross-linked in a cyclic structure. These three building units are: (4,6-dideoxy,6-methyne, α,D,glucopyranose), (β, D,1-deoxy, 1-methyne, fructofuranose), and (2-deoxy, 3-methyne, 4,6-epoxy, fructofuran). The three units are cross-linked through the methyne group that bind with C6 of 4,6-dideoxy, 6-methyne, α,D-glucopyranose, C1 of 1-deoxy, 1- methyne, fructofuranose and with C3 of 2-deoxy, 4,6-epoxy, 3-methyne, fructofuran moieties. The COSY, HSQC, HMBC and TOCSY analyses confirmed the elucidated structure with a molecular formula C19H26C11 and MW = 430.4. Conclusion: The result from this research identified for the first time the cyclic trisaccharide glycoside from Alhagi pseudoalhagi with antifungal activity against C. albicans. Keywords: Alhagi pseudoalhagi, anticandidal, glycoside, C. albicans, mass spectrometry, NMR.