Mechanism exploration on synthesis of secondary metabolites in Sorbus aucuparia cell cultures treated with yeast extract Biotransformation of Gastrodin by Cell Suspension Cultures of Catharanthus roseus Biotransformation of furannoljgularenone by cell suspension cultures of Nicotiana tabacum Biotransformation of 3b-Hydroxyandrost-5-en-17-one by Cell Suspension Cultures of Catharanthus roseus Chemical constituents from cell suspension cultures of Cudrania tricuspidata