Many　Guanine-rich　DNA　sequences　are　capable　of　forming　G-quadruplex,　such　as　the　telomeric　chromosomal　terminals　and　the　promoters　of　several　genes　including　c-myc,　c-kit　and　bcl-2　oncogenes.　G-quadruplex　structure　have　conspicuous　biological　significance　and　hence　the　ligands　which　can　promote　the　formation　and　stabilize　G-quadruplex　have　attracted　much　attention.　In　this　paper,　we　have　evaluated　the　abilities　of　Jatrorrhizine　and　Chelerythrine　in　inducing　the　formation　of　G-quadruplex　employing　Circular　Dichroism　spectroscopy.　Our　results　indicate　that　Jatrorrhizine　can　induce　Pu18　and　c-kit87up　to　form　mixed-type　and　parallel　G-quadruplex　respectively.　Chelerythrine　can　induce　Pu18　and　ckit87up　to　form　parallel　and　antiparallel　G-quadruplex　respectively.　Jatrorrhizine　and　Chelerythrine　can　induce　the　switch　of　Pu18　G-quadruplex　in　the　presence　of　K+　from　mixed-type　to　antiparallel　and　parallel　respectively.　However,　Jatrorrhizine　and　Chelerythrine　can　not　change　the　conformation　of　c-kit87up　G-quadruplex　in　the　presence　of　K+.　From　experimental　results　it　is　clear　that　Jatrorrhizine　and　Chelerythrine　may　have　the　potential　to　inhibit　the　growth　of　tumour　cell　and　also　can　be　useful　guidelines　for　the　design　of　anticancer　agents.