Doi: 10. 1016/j chroma

3.2. Benzyl glycosides

Recently, Lei reported the isolation and structure elucidation of three new benzyl glycosides, salsasides A–C (35–37, Fig. 2) from C. salsa, which were also benzyl glycosides isolated from Cistanche plants for the first time [47]. The structural features of these benzyl glycosides are similar to those of phenylethanoids isolated from this genus, except that the benzyl alcohol substituted phenethylol in the aglycone.

3.3. Iridoids

Up to now, three iridoid aglycones and fourteen iridoid glycosides have been isolated from Cistanche plants (38–54, Table 5) [102–109]. The structural features of iridoid glycosides from Cistanche plants are summarized as follows: glucose occurs in C₁ position of aglycone, with a configuration in H₅ and H₉; hydroxylation often occurrs in C₈ and C₁₀ positions; sometimes, dehydration may happen between the hydroxyls of C₁₀ with C₁ or C₃ to give an epoxy moiety.

3.4. Lignans

One lignan aglycones and five lignan glycosides have been isolated from C. deserticola and C. tubulosa plants (55–60, Table 6). The basic skeletons of these compounds are of ditetrahydrofuran and benzofuran lignans. The sources of those C. tubulosa from which several lignans have been isolated are mainly from Pakistan, while few lignans have been isolated from C. tubulosa collected in China. This further proved that the chemical differences existed between C. tubulosa from China and Pakistan [27,28].

Table 7

3.5. Saccharides and their derivatives
3.5.1. Chemical study on saccharides and their derivatives
Carbohydrates comprise a high proportion in the dry mass of plants of Cistanche species [110]. Among them, one of the monosaccharides,galactitolhasbeenreportedasthemainactivecomponent with laxative activity in Herba Cistanches [18,19,103,104]. While, the polysaccharides have been regarded as the active constituents with advancing body immunity, anti-aging and anti-cancer activities in Herba Cistanches [20,21,111–113].
In 90s, the studies on polysaccharides of Cistanche species had been focused on the isolation/purification and the analysis of composition of monosaccharides [110,112,114–116]. The exact structures of polysaccharides from Cistanche species have not been clarified until 1997. In Table 7, the elucidated structural properties of polysaccharides isolated from Cistanche species have been listed. Interestingly, all of these have been isolated from C. deserticola, and thepolysaccharidesinother Cistanche plantshavenotbeenstudied.
Except these, some oligosaccharide derivatives, such as cistanoside F, cistanoside I, cistantubuloses A₁/A₂ and cistansinensose A₁/A₂ have also been isolated from Herba Cistanches (Fig. 3), which are actually the residues of PhGs after losing the phenethylol aglycone. Since there are and configurations existing in glucoses in nature, sometimes, these oligosaccharide derivatives also exist as anomers, and this phenomenon could be observed from the paired NMR signals [37,39,40,11,45].