A Study of Topical Indigo Naturalis Treatment in Patients With Mild to Moderate Plaque-type Psoriasis

Inclusion Criteria: * men or women at ages between 20 - 65 years old with at least 6 months diagnosis of moderate to mild plaque-type psoriasis who have a screening and at time of study agent treatment Psoriasis Global Assessment (PGA)=2-3, and have under 20% of their total body surface area (BSA) involved. , with a target plaque for at least 4 sq cm * In good general health, as evidenced by physical examination, and hematology and blood chemistry tests within normal ranges with the exception of liver function test value \<=1.5ULN * If of childbearing age, agreement to continue using birth control measures for the duration of the study * Patients who agreed to participate and signed the consent form * Patients who agreed to return for follow-up visits and provide all required biopsies. Exclusion Criteria: * Currently have non-plaque forms of psoriasis (e.g., erythrodermic, guttate, or pustular psoriasis), or rebound or flare of chronic plaque psoriasis * Currently or had history of psoriatic arthritis * Have current drug-induced psoriasis (e.g., a new onset of psoriasis or an exacerbation of psoriasis from beta blockers, calcium channel blockers, or lithium). * Are pregnant, nursing, or planning pregnancy (both men and women) while enrolled in the study. * Have used any biologic within the previous 3 months or 5 times the half-life of the biologic, whichever is longer * Have received phototherapy or any systemic treatment that could affect psoriasis (including, but not limited to, (eg, retinoids, methotrexate, cyclosporine, psoralens, sulfasalazine, hydroxyurea, fumaric acid derivatives, herbal treatment or traditional Chinese medicine) within 4 weeks of receiving study treatment * Have used topical treatment that could affect psoriasis (eg. corticosteroid tazarotene, and tacrolimus, tar, anthralin, calcipotriene, topical vitamin D derivatives, retinoids, tazarotene, methoxsalen, trimethylpsoralens, topical traditional Chinese medicines) within 2 weeks of receiving study treatment * Have used any systemic immunosuppressants (eg, MTX, azathioprine, cyclosporine, 6-thioguanine, mercaptopurine, mycophenolate mofetil, hydroxyurea, and tacrolimus) within 4 weeks of receiving study treatment * Are currently receiving lithium, antimalarials, or intramuscular gold, or have received lithium, antimalarials, or intramuscular gold within 4 weeks of receiving study treatment * Positive screening tests for HIV, hepatitis B surface antigen, or hepatitis C antibody * A history of alcohol or other drug abuse * Clinically significant laboratory abnormality in blood, renal function, or liver function * A history of sensitivity to Chinese herbs, olive oil, yellow wax, or petroleum jelly * Have current signs or symptoms of severe, progressive, or uncontrolled renal, hepatic, hematological, gastrointestinal, endocrine, pulmonary, cardiac, neurologic, cerebral, or psychiatric disease * Be participating in another trial using an investigational agent or procedure. * Any other conditions that in the view of investigator, the subject should not be enrolled.