Study on preparation of tricin reference substance by semi-preparative HPLC in Bambusae Caulis in Taenias Preparation of five phenylethanoid glycoside components by semi preparative HPLC Two novel polyketides from Peperomia dindygulensis Two novel polyketides from Peperomia dindygulensis Study on preparation of tricin reference substance by semi-preparative HPLC in Bambusae Caulis in Taenias