ABSTRACT
Plant natural products remain a good resource for the discovery of novel pharmaceuticals. A mouse macrophage-based quantitative, reverse transcription polymerase chain reaction (qRT-PCR) system was optimized to screen plant extracts for antiinflammatory activities using three well known genetic markers of inflammation. Plants used for extraction were taxonomically identified and vouchered species from two Central Asian countries, Uzbekistan and Kyrgyzstan, collected through the International Cooperative Biodiversity Groups (ICBG) program. The mRNA expression of cyclooxygenase-2, interleukin 1beta and inducible nitric oxide synthase genes in RAW macrophages was determined quantitatively in response to treatment with plant extracts applied at 100 microg/mL. The screening of 1000 extracts from 449 plant species belonging to 68 plant families resulted in 75 extracts (7.5%) showing strong (75% or higher inhibition) activity against at least one target gene. Many extracts showed qualitative and quantitative differences in the levels of activities against each target gene. Extracts identified from this screen were able to reduce inflammatory symptoms in vivo, thereby validating the screening approach.
Subject(s)
Anti-Inflammatory Agents/pharmacology , Gene Expression Profiling , Gene Expression/drug effects , Macrophages/drug effects , Plant Extracts/pharmacology , Plants, Medicinal/chemistry , Animals , Asia, Central , Cell Survival/drug effects , Cyclooxygenase 2/genetics , Cyclooxygenase 2/metabolism , Dose-Response Relationship, Drug , Inhibitory Concentration 50 , Interleukin-1beta/genetics , Interleukin-1beta/metabolism , Macrophages/metabolism , Medicine, East Asian Traditional , Mice , Nitric Oxide Synthase Type II/genetics , Nitric Oxide Synthase Type II/metabolism , Phytotherapy , RNA, Messenger/metabolism , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
The extract of Tripterygium wilfordii Hook F. (TwHF), which showed anti-inflammatory and immunosuppressive activities in human clinical trials for rheumatoid arthritis, was subjected to the activity-guided fractionation and spectroscopic characterization of bioactives. A tetrahydrofuran lignan, tripterygiol (1), and eight known compounds, all capable of suppressing pro-inflammatory gene expression were identified. Most of the pharmacological activity of the extract can be attributed to triptolide, its most abundant and active component, with some contribution from tripdiolide.
Subject(s)
Anti-Inflammatory Agents/pharmacology , Diterpenes/pharmacology , Immunosuppressive Agents/pharmacology , Phenanthrenes/pharmacology , Tripterygium/chemistry , Animals , Anti-Inflammatory Agents/chemistry , Anti-Inflammatory Agents/isolation & purification , Cell Line , Chemical Fractionation , Diterpenes/chemistry , Diterpenes/isolation & purification , Epoxy Compounds/chemistry , Epoxy Compounds/isolation & purification , Epoxy Compounds/pharmacology , Immunosuppressive Agents/chemistry , Immunosuppressive Agents/isolation & purification , Mice , Nuclear Magnetic Resonance, Biomolecular , Phenanthrenes/chemistry , Phenanthrenes/isolation & purification , Plant Extracts/chemistryABSTRACT
Plant extracts collected from the wild are important sources for drug discovery. However, these extracts suffer from a lack of reproducible bioactivity and chemical composition caused by the highly inducible, variable, and transitory nature of plant secondary metabolism. Here, we demonstrate that exposing roots of hydroponically grown plants to chemical elicitors selectively and reproducibly induced the production of bioactive compounds, dramatically increased the hit rate, and more than doubled the number of plant species showing in vitro activity against bacteria, fungi, or cancer. Elicitation performed under controlled conditions dramatically improves reliability and efficiency of plant extracts in drug discovery while preserving wild species and their habitats.