# Advances in the Biosynthesis and Molecular Evolution of Steroidal Saponins in Plants
## 5 Distribution of Steroidal Saponins in Plants
### Asparagales Species  
In contrast, Asparagales plants contain relatively more steroidal saponins, including the Amaryllidaceae, Agavaceae, Lomandroideae, Nolinioideae, Asparagoideae, and Asphodelaceae [75; 76; 77; 78]. In addition, the type and distribution of steroidal saponins in these plants are also different.  
At present, the main plant species containing steroidal saponins in the Amaryllidaceae include the Allioideae, _Allium_ species. According to the structure of aglyclone, steroidal saponins isolated from the flowers, bulbs, seeds, and underground parts of _Allium_ plants can be divided into three types: spirostand saponins with diosogenin or agigenin as aglycones, fuorstand saponins with sugar chains at the C-3 and C-26 positions, and cholestane saponins with C-5 (C-6) unsaturated double bonds [79; 80; 81; 82] (Figure 1, Supplementary Table S1). The sugar residues linked to steroidal saponins in _Allium_ plants are mainly monosaccharides or disaccharides, but there are a few trisaccharides [10].  
Compared with the Amaryllidaceae, _Agave_ species are the main plants containing steroidal saponins in the Agavaceae, and a small number of steroidal saponins have also been identified from a few Agavaceae plants, such as _Camascia_ and _Yucca_ species [83; 84; 85]. The types of steroidal saponins isolated from Agavaceae plants are mainly fuorstand saponins and spiro sterol saponins. Meanwhile, steroidal saponins are mainly distributed in the leaves, fruits, flowers, and rhizomes of Agavaceae plants [75; 86; 87; 88] (Supplementary Table S1). Spirostanol saponins can be divided into monosaccharides, disaccharides, and polysaccharides according to the linked glycosyl units, while fuorstand saponins are mainly disaccharides and a few trisaccharides [75; 86; 87; 88].  
As for Lomandroideae plants, only five steroidal saponins have been identified in _Cordyline stricta_[89]. Among the Nolinioideae plants, the plants containing steroidal saponins are mainly _Polygonatum_, _Dracena_, and _Sanseveria_ species [9; 64]. About 180 different saponins were isolated from _Dracena_ and _Sanseveria_ plants, mainly fuorstand saponins and spirostand saponins, as well as a small number of cholestane saponins, pregnane saponins, and \(\beta\)- Sitosterol saponins [9]. In traditional Chinese medicine, the rhizomes of some _Polygonatum_ plants are also known as \"Yuzhu\", which are used to treat osteoporosis, diabetes, and lung disease [64; 77; 78]. Steroidal saponins isolated from the rhizomes of _Polygonatum_ plants can be divided into three types: cholestanol-type (such as polygonatunoside A/B/C), fuorstand-type (such as polygonatunoside G), and spirostand-type (such as polygonoside A/B/C) [77; 90; 91] (Supplementary Table S1).  
Among the Asparagoideae plants, steroidal saponins are mainly distributed in Asparagus species [92]. Not many steroidal saponins have been isolated from the roots and fruits of Asparagus plants, and the most common one is protodioscin [93; 94]. Only a small number of steroidal saponins were isolated from the aerial parts of _Hemerocallis fulva_ var. _kwanso_ in the Asphodelaceae [78] (Supplementary Table S1).