Chemical constituents of Gynostemma pentaphyllum Technology optimization for extracting total favonoids from Gynostemma pentaphyllum by cellulase Research progress in hypoglycemic effect of natural dammarane saponins Protoplast fusion in Dendrobium candidum and Gynostemma pentaphyllum Gene cloning, sequence, and expression analysis of GpSS1 and its regulation by MeJA in Gynostemma pentaphyllum