Two ent-labdane diterpenoids from Andrographis paniculata

Plant species are the principle ingredients of traditional medicine and their use dates back to the beginning of human civilization. In recent years an extensive screening of ethno-medicinal plants is preformed in order to develop new and effective drugs for human illnesses. The plant Andrographis paniculata Nees, collected from Indian Himalaya, is a known Indian medicinal plant used in multiple clinical applications. Infusion of fresh leaves is used to relieve abdominal pain, irregular bowel syndromes and loss of appetite. Leaves and roots are used as treatment of infectious diseases due to their antibacterial, antifungal and antiviral properties and creams are prepared from leaves for the treatment of skin eruptions, scabies, ulcers and wounds. The crude extract of A. paniculata was found to inhibit the bacterial growth of Methicillin sensitive Stphylococcs aureus (MSSA) and Methicillin resistant Stphylococcs aureu (MRSA) with respect to the commercial antibiotic Oxacillin. While searching for the antibacterial principals we isolated two new ent-labdane ditrepenoids. Here we report the isolation and structure elucidation of the two new ent-labdane ditrepenoids: 21-methoxy-3,19-dihydroxy-8(17),11,13-ent-labdatrine-16-oic acid and symmetric bis 16,19-(15-O-β-glucose-3-hydroxy-19-oxy-8(17),13-ent-labdadiene-16-oate) dilactone along with 12 known ent-labdane derivatives from the active crude extract. The structure, including absolute stereochemistry, of the pure compounds was determined by 1D and 2D NMR techniques, high resolution mass spectrometry measurements, and application of Mosher method. The structure elucidation of the two new compounds will be presented.