Abstract: Ultra diluted drugs have a statistically significant medicinal effect compare to placebo but it is still unknown how they work. Extract of foxglove plant, Digitalis purpurea, Scrophulariaceae, an effective cardiotropic natural product, is one such compound, which is used by almost all prevalent systems of medicine. As a natural cardiotropic drug it is presumed to have an energy component involved in producing the effect. Since the effect of Digitalis purpurea depends on concentration and dilution, it motivated us to carry out a systematic study to explore an energy entity in less than micro volume, commercially available drug Digitalis purpurea, diluted with aqueous ethanol. The diluent and cleaning agent used was free from any possible contaminant whatsoever. We report a preliminary UV spectroscopy analysis on the effect of serial ultra dilution in the medicinal plant extract Digitalis purpurea. Well-known technique of UV spectroscopy has been used for identification/characterization and analytical evaluation of the medicinally active ingredients of Digitalis purpurea. The experimental results, although preliminary, provide significant and reliable information showing standard UV spectral absorption peak within expected range. It also shows, the diluted out effect on the active component of the drug Digitalis purpurea and provides information to compute energy on serial dilution of drugs. It is found that 4.5 eV is required to dislodge the bond in the group. The eV content of a drug may become important issue for pharmacological and posological considerations.