Bioaffinity Ultrafiltration Combined with HPLC-ESI-qTOF-MS/MS for Screening Potential Bioactive Components from the Stems of Dendrobium fimbriatum and In Silico Analysis.

Dendrobium fimbriatum is a perennial herb, and its stems are high-grade tea and nourishing medicinal materials. Various solvent extracts of D. fimbriatum were evaluated for their anti-inflammatory, anti-acetylcholinesterase (AChE), antioxidant, and anti-α-glucosidase properties. Acetone and EtOAc extracts showed significant antioxidant effects. Acetone, n-hexane, and EtOAc extracts revealed potent inhibition against α-glucosidase. EtOAc, n-hexane, and dichloromethane extracts displayed significant anti-AChE activity. Among the isolated constituents, gigantol, moscatin, and dendrophenol showed potent antioxidant activities in FRAP, DPPH, and ABTS radical scavenging tests. Moscatin (IC(50) = 161.86 ± 16.45 μM) and dendrophenol (IC(50) = 165.19 ± 13.25 μM) displayed more potent anti-AChE activity than chlorogenic acid (IC(50) = 236.24 ± 15.85 μM, positive control). Dendrophenol (IC(50) = 14.31 ± 3.17 μM) revealed more efficient anti-NO activity than quercetin (positive control, IC(50) = 23.09 ± 1.43 μM). Analysis of AChE and iNOS inhibitory components was performed using molecular docking and/or the bioaffinity ultrafiltration method. In bioaffinity ultrafiltration, the binding affinity of compounds to the enzyme (acetylcholinesterase and inducible nitric oxide synthase) was determined using the enrichment factor (EF). Among the main components of the EtOAc extract from D. fimbriatum stem, moscatin, dendrophenol, gigantol, and batatasin III with acetylcholinesterase exhibited the highest binding affinities, with affinity values of 66.31%, 59.48%, 54.60%, and 31.87%, respectively. Moreover, the affinity capacity of the identified compounds with inducible nitric oxide synthase can be ranked as moscatin (88.99%) > dendrophenol (65.11%) > gigantol (44.84%) > batatasin III (27.18%). This research suggests that the bioactive extracts and components of D. fimbriatum stem could be studied further as hopeful candidates for the prevention or treatment of hyperglycemia, oxidative stress-related diseases, and nervous disorders.