Antioxidant and Antiglycating Constituents from Leaves of Ziziphus oxyphylla and Cedrela serrata

Ziziphus oxyphylla and Cedrela Serrata plants have a folkloric use in Pakistan for treatments of different ailments, i.e., Jaundice, Hepatitis, Diabetes, and antimicrobial. Until now, none of the research studies have reported any phytochemical work on leaves of these two plants. This study aimed to isolate and perform phytochemical analysis in order to search for the constituent having the active role in treatment of the aforementioned ailments. A bioassay-guided fractionation and isolation procedure was used to isolate the concerned phytochemicals present in leaf extracts of Z. oxyphylla and C. serrata. The process involved the hyphenated techniques, i.e., Flash Chromatography, Semi-Preparative HPLC/DAD, UPLC/MS, and NMR in order to isolate and elucidate the structure of the phytochemicals. Seven compounds (1–7) were isolated and identified as flavonoids, more in particular glycosides of quercetin and kaempferol. They showed DPPH scavenging activity, compound 3 (isoquercitrin) being the most active one with an IC50 of 10.8 µg/mL (positive control quercetin; IC50 3.6 µg/mL). The superoxide-radical scavenging and total antioxidant (ABTS) assays indicated IC50 values ranging from 200 to 910 µg/mL and 170 to 320 µg/mL, respectively (positive control quercetin: 374 and 180 µg/mL, respectively). Furthermore, these compounds had low IC50 values for inhibition of protein glycation (AGEs inhibition), ranging from 530 to 818 µg/mL, comparable to aminoguanidine (510 µg/mL) used as a positive control. This study resulted in the identification of seven flavonoid glycosides for the first time from the leaves of Z. oxyphylla and C. serrata with antioxidative and antiglycating activities.