Small molecule detection and localization method based on MALDI imaging mass spectrometry

A method for determining distribution of a small molecule drug relative to a target protein in angiogenesis inhibition using MALDI mass spectrometry and immunofluorescence, the method comprising:

• obtaining a sample;
• treating the sample with a small molecule drug;
• performing MALDI mass spectrometry on the sample treated with the small molecule drug;
• detecting a target protein for the small molecule drug in the sample by immunofluorescence;
• comparing a result of the MALDI mass spectrometry with a result of immunofluorescence for the target protein;
• and
• determining whether angiogenesis is inhibited in a portion of the sample overlapping with both (i) a portion where the small molecules are present after the MALDI mass spectrometry and (ii) a portion where the target protein is present after immunofluorescence,
• wherein the small molecule drug is voacangine given in Formula 1 as follows,
• and wherein the target protein is VEGFR2,
• wherein the MALDI mass spectrometry for the voacangine-treated sample shows peaks in the ranges 360 to 380 m/z, 330 to 340 m/z, and 300 to 310 m/z,
• so as to thereby determine distribution and concentration of the small molecule drug relative to target protein in angiogenesis inhibition.