Chemical Constituents of Saxifraga umbellulata

Two olean-27-carboxylic acid-type triterpenoids as chemical markers isolated from Saxifraga umbellulata

Two olean-27-carboxylic acid-type triterpenoids ( 1  and 2 ) were isolated from Saxifraga   umbellulata (Saxifragaceae), representing the first case in the chemical discoveries of genus Saxifraga . Compound 1  was determined to be a new compound named 'Saxifragic acid' based on the comprehensive spectroscopic and X-ray crystallographic analyses. Compound  2  (deacetylated saxifragic acid) is a known compound reported before, but its absolute configuration through X-ray crystallographic analyses was first described here. In addition, their cytotoxicity against five digestive human cancer cell lines (BGC-823, GBC-SD, CCC-9810, HT-29, and HepG2) and hepatoprotective activity against CCl 4 -induced L-o2 cell injury in vitro were evaluated. Interestingly, UPLC-QTOFMS analysis showed that these two compounds could be used as chemical markers to discriminate between S . umbellulata  and S. tangutica , both of which are used for the treatment of hepatobiliary diseases in traditional Tibetan medicine.

Caffeoylquinic acids: chemistry, biosynthesis, occurrence, analytical challenges, and bioactivity

Caffeoylquinic acids (CQAs) are specialized plant metabolites we encounter in our daily life. Humans consume CQAs in mg-to-gram quantities through dietary consumption of plant products. CQAs are considered beneficial for human health, mainly due to their anti-inflammatory and antioxidant properties. Recently, new biosynthetic pathways via a peroxidase-type p-coumaric acid 3-hydroxylase enzyme were discovered. More recently, a new GDSL lipase-like enzyme able to transform monoCQAs into diCQA was identified in Ipomoea batatas. CQAs were recently linked to memory improvement; they seem to be strong indirect antioxidants via Nrf2 activation. However, there is a prevalent confusion in the designation and nomenclature of different CQA isomers. Such inconsistencies are critical and complicate bioactivity assessment since different isomers differ in bioactivity and potency. A detailed explanation regarding the origin of such confusion is provided, and a recommendation to unify nomenclature is suggested. Furthermore, for studies on CQA bioactivity, plant-based laboratory animal diets contain CQAs, which makes it difficult to include proper control groups for comparison. Therefore, a synthetic diet free of CQAs is advised to avoid interferences since some CQAs may produce bioactivity even at nanomolar levels. Biotransformation of CQAs by gut microbiota, the discovery of new enzymatic biosynthetic and metabolic pathways, dietary assessment, and assessment of biological properties with potential for drug development are areas of active, ongoing research. This review is focused on the chemistry, biosynthesis, occurrence, analytical challenges, and bioactivity recently reported for mono-, di-, tri-, and tetraCQAs.