A series of flavanols were synthesized to assess their biological activity against human non-small cell lung cancer cells (A549). Among the sixteen synthesized compounds, it was observed that compounds 6k (3.14 ± 0.29 µM) and 6l (0.46 ± 0.02 µM) exhibited higher potency compared to 5-fluorouracil (5-Fu, 4.98 ± 0.41 µM), a clinical anticancer drug which was used as a positive control. Moreover, compound 6l (4’-bromoflavonol) markedly induced apoptosis of A549 cells through the mitochondrial- and caspase-3-dependent pathways. Consequently, compound 6l might be developed as a candidate for treating or preventing lung cancer.

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 (IC₅₀ = 161.86 ± 16.45 μM) and dendrophenol (IC₅₀ = 165.19 ± 13.25 μM) displayed more potent anti-AChE activity than chlorogenic acid (IC₅₀ = 236.24 ± 15.85 μM, positive control). Dendrophenol (IC₅₀ = 14.31 ± 3.17 μM) revealed more efficient anti-NO activity than quercetin (positive control, IC₅₀ = 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.

COVID-19 is a global pandemic infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The herbal formula, Ping An Fang Yu Yin (PAFYY), has been used to prevent respiratory viral infections for many years. This study aims to evaluate the effect of PAFYY on SARS-CoV-2 infection, oxidative stress, and inflammation via in vitro, investigate the chemical composition by full constituent quantitative analysis, and verify its anti-viral potential against SARS-CoV-2 using in silico. In this study, a total of eleven compounds, twenty amino acids, saccharide compositions, and trace elements were found and quantitatively determined by chromatographic techniques. PAFYY displayed free radical scavenging activity (DPPH, SC₅₀: 1.24 ± 0.09 mg/mL), SOD activity (68.71 ± 1.28%), inhibition of lipoxygenase activity (75.96 ± 7.64 mg/mL) and interfered the interaction of SARS-CoV-2 spike protein and angiotensin-converting enzyme 2 (48.04 ± 3.18%). Furthermore, in-silico analysis results supported that liquiritin, 3,5-dicaffeoylquinic acid, and luteolin-7-O-glucoside with the highest affinity between SARS-CoV-2 RBD and human angiotensin-converting enzyme II (hACE2) receptor. Our findings suggest that PAFYY has the potential for anti-SARS-CoV-2 infection, anti-oxidation stress, and anti-inflammation, and may be used as supplements for amelioration or prevention of COVID-19 symptoms, as well as the representative compounds can be used for quality control of PAFYY in the future.