Antiviral Components from Cleome droserifolia and Lotus creticus

摘要

Objectives: Searching for new antiviral compounds is important due to continuous appearance of new viral strains that resist the commonly used drugs and due to toxic side effects of some of these drugs. This current study was designed to investigate some herbs to discover new natural antiviral agents. Methods: Eight herbal extracts were screened for antiviral activities against Hepatitis A, Herpes Simplex-1 and Coxsackie viruses. Bio guided fractionation of the active extracts using different solvents and further investigation of the bioactive one using various chromatographic techniques including normal phase column chromatography, poly amide column and preparative TLC led to isolation and identification of twelve compounds. Structural elucidation of these compounds was done using different spectroscopic techniques including IR, HR-MS, 1D and 2D-NMR. The antiviral activities of the isolated compounds were assessed by MTT assay that depends on mixed treatment assay which test inactivation of virus particles in the virus suspension by samples. The concentration of samples which inactivate virus particles in virus suspension by 50% compared with untreated control was determined for each sample and was compared with IC50 of positive control, Acyclovir. Findings: Twelve known compounds were isolated from the bioactive fractions of Cleome droserifolia and Lotus creticus. Nine compounds (1-9) from methylene chloride and ethyl acetate fractions of Cleome droserifolia and four compounds (10-13) from ethyl acetate and butanol fractions of Lotus creticus. Teuclatriol (4) was the most potent, with IC50 value of 4.89 0.061mM against HSV-1 and a selective index (SI) value of 4.8. Moreover, the pentamethoxyflavone (3) was the most active against HAV with IC50 value of 9.52 0.329 mM and SI of 3.4. The potent activity against Cox. B4 virus with IC50 of 13.054 0.348 mM and SI of 3.4 exhibited by b -sitosterol 3-O-b -D-glucoside(6, 12). Novelty: The results highlight that these compounds are candidates for the development of new lead antiviral compounds. This is the first report for proving antiviral activities of these compounds.