Sesterterpenoid compounds and extract l01 of leucosceptrum canum, and use thereof in treatment of psoriasis

A Leucosceptrum canum extract L01 prepared by a method comprising the following steps:

• (1) mixing a crushed Leucosceptrum canum with an organic solvent to allow an ultrasonic treatment, and collecting a resulted extract solution;
• wherein the organic solvent is one or more selected from the group consisting of methanol, ethanol, acetone, chloroform, DCM, and petroleum ether;
• a solid-liquid ratio of an overground part of the crushed Leucosceptrum canum and the organic solvent is 1:3 to 1:8;
• and a time for the ultrasonic treatment is 10 min to 40 min;
• (2) subjecting the extract solution to concentration to obtain a crude extract;
• wherein the concentration is conducted by rotary evaporation at 30° C. to 60° C.;
• and
• (3) subjecting the crude extract to elution by silica gel column chromatography, collecting a resulting acetone elution phase, and conducting concentration to obtain the Leucosceptrum canum extract L01;
• wherein eluents for the elution by silica gel column chromatography are petroleum ether and acetone in sequence;
• and the concentration is conducted by rotary evaporation at 30° C. to 60° C.