**2.11.** *Smilax glycyphylla*

*S*. *glycyphylla* is a plant endemic to Australia and its leaves and fruits have a sweet taste like honey grass. The sweet principle of *S*. *glycyphylla* is called glycyphyllin A (**71**) and identified as a phenol compound with a structure of dihydrochalcone, phloretin2′αLrhamnose [48]. Cox *et al*. evaluated aqueous extracts of leaves and stems of *S. glyciphylla* [49]. The methods used to evaluate antioxidant activity were lipid peroxidation using thiobarbituric acid reactive substances (TBARS), superoxide quenching by coupling superoxide generation to the reduction of nitroblue tetrazolium (NBT), inhibition of deoxyribose-driven fenton degradation and total radical-antioxidant potential (TRAP) using free radicals derived from ABTS (2,2′azinobis(3ethylbenzothiazoline 6sulphonate). The results showed that *S*. *glycyphylla* extract inhibited deoxyribose degradation. The total radical-antioxidant potential was seven times that the trolox a water-soluble analog of vitamin E with a high antioxidant activity.

Huang *et al*. performed a study of phenolic profile and antioxidant activity of *S*. *glycyphylla* leaves [50]. The leaves of *S*. *glycyphylla* previously dried and blended were extracted with 80% aqueous ethanol. Then, the extract was concentrated and partitioned with hexane and butanol, consecutively. The butanol fraction was subjected to chromatographic separation. The separation produced eight phenolic compounds such as the glycyphyllin A previously mentioned, two new dihydrochalcones (glycyphyllin B (**72**) and C (**73**)) and five flavonoids (catechin (**26**), (2*R*,3*R*)-dihydrokaempferol-3-*O*-*β*-D-glucopyranoside (**57**), kaempferol-3-*Oβ*-D-glucopyranoside (**74**), quercetin-3-*O*-*β*-D-glucopyranoside (**75**) and kaempferol-3-*O*-*β*neohesperidoside (**76**), **Figures 14** and **15**). The antioxidant activity of pure compounds was evaluated using ferric reducing ability of plasma (FRAP) and DPPH• radical scavenging. The flavonoids showed a good antioxidant activity; contrary to this, the dihydrochalcones showed weak antioxidant activity [50].
