Analysis of Two New Flavonoid Glycosides From Zanha golungensis Hiern With COX Inhibition Activity: Structural...

Zanha golungensis is used as herbal medicine for a variety of ailments. In this study, flavonoids, including two new kaempferide polyglycosides, namely, kaempferide-3-O-[α-l-rhamnopyranosyl-(1 $\to 2$ )-α-l-rhamnopyranosyl-(1 $\to 6$ )]-β-d-glucopiranoside-7-O-α-l-rhamnopiranoside (1) and kaempferide-3-O-[4-O-acetyl-α-l-rhamnopyranosyl-(1 $\to 2$ )-α-l-rhamnopyranosyl-(1 $\to 6$ )]-β-d-glucopiranoside-7-O-α-l-rhamnopiranoside (2) alongside known compounds (-)-epicathecin (3), procyanidin A2 (4) and procyanidin B2 (5), were isolated and characterized using ESI-TOF-MS and NMR. The compounds exhibited good cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) inhibitions with high percentage inhibitions at 20 µg/mL. Compound was most active with percentage inhibitions of 74.3 ± 1.2 and 78.6 ± 1.5 on COX-1 and COX-2, respectively, compared to Cy-3-coumSamb-5-Glc (standard) with percentage inhibitions of 68.3 ± 1.1 and 70.0 ± 1.4 on COX-1 and COX-2, respectively. Density functional theory (DFT) calculations were used in predicting the electronic and molecular properties of isolated compounds, notably optimized geometries and molecular electrostatic potentials, which all correlated with highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energies. Molecular docking predictions indicated favourable and thermodynamically stable complexes between the compounds and COX-2 receptor sites revealed by binding affinities and negative binding energies. The results show the potential anti-inflammatory, antipyretic and anticancer potential drug design of the isolated compounds.