A　protein　designated　Hypotin,　with　both　antifungal　and　antibacterial　activity,　was　isolated　from　peanut　(Arachis　hypogaea)　seeds.　The　isolation　procedure　included　extraction,　ammonium　sulfate　precipitation,　affinity　chromatography　on　Affi-gel　blue　gel,　ion　chromatography,　and　gel　filtration.　The　protein　exhibited　a　molecular　mass　of　30.4　kDa　in　SDS-polyacrylamide　gel　electrophoresis　under　both　reducing　and　nonreducing　conditions,　indicating　that　it　is　a　monomeric　protein.　Its　N-terminal　sequence　was　highly　homologous　to　those　of　chitinases　and　chitinase　precursors　from　plants.　It　exerted　potent　antifungal　action　toward　a　variety　of　fungal　species,　including　Pythium　aphanidermatum,　Fusarium　solani,　Physalospora　piricola,　Alternaria　alternata,　Botrytis　cinerea,　and　Fusarium　oxysporum.　In　addition,　this　novel　protein　exhibited　antiproliferative　activity　against　tumor　cells.　These　findings　further　the　progress　in　the　research　of　leguminous　plants.　©　2007　American　Chemical　Society.