Considering that the hederagenin have a Log P closer to 5, try to change the solvent, like acetone or add a fraction of this, may be this molecule is slightly soluble in methanol.
thank u for all ,my mobile acetonitrile water 32:68 with ,05%formic acid on C18 column ,wave lenght 210nm, temp 30. conc 1mg/ml.I get early unconstant peaks early.and small peak at RT 4min flow1ml/min. should Ihave to change column and decrease polarity of system