This study includes a physiochemical and a spectrocpical characterization to some alkaloid compounds in the (ANAB AL- THEAB) plant (Solanum nigrun L.). It’s the most important medicinal herb belonging to the family (Solanaceae). Acid  hydrolysis was performed by using limited conc. of  Hcl and H2SO4, to obtain the aglycon  part of previously separated steroidal componants as (A, B and C).   The characterization of the(A,B and C) compounds indicates that they varied between them as the separated steroidal like-alkaloids, carried by using melting  point (m.p.), thin layer chromatography (TLC), Infra -Red  spectroscopy (IR) and Ultra violet-Visible  spectroscopy (UV - Visible).High performance liquid chromatography (HPLC) indicated the presence of single characteristic intense peak belonging to (A) component  which  confirms the  purity of  components. The Mass- spectra   (MS) of this compound gave (397m/z) molecular weight peak related to (Solanidine)  alkaloid, when the chararacteristic to compound (C) showed that same as solasodine alkaloid .      .