One new alkyl benzoquinone, paphionone (1), one new trans-stilbenoid, (E)-6,5'-dihydroxy-2,3'-dimethoxystilbene (2), and eight known stilbenoids and flavonoids (3-10) were isolated from the leaves and roots of Paphiopedilum exul (Orchidaceae). Their chemical structures were determined based on IR, ECD, MS and NMR analyses. Cytotoxicity of all isolated compounds towards human hepatocellular carcinoma (HepG2) cell line was examined in vitro by MTT assay. The para-hydroxybenzyl substituted stilbene 10 was potently cytotoxic to the cancer cells, with an IC₅₀ value of 4.80 ± 1.10 μM (selectivity index = 20.83). All compounds were non-toxic to normal human embryo fibroblast (OUMS-36) cell line.

A new trans-stilbene, (E)-2,4-bis(4-hydroxybenzyl)-3,5-dihydroxystilbene (1), and ten known compounds including stilbenoids (2, 7, 8, 10), coumaric acid ester (3), flavonoids (4-6), aromatic aldehyde (9) and triterpenoid glycoside (11) were isolated from the leaves and roots of the lady slipper's orchid Paphiopedilum hirsutissimum (Lindl. ex Hook.) Stein. The structures of these chemical constituents were determined based on their spectroscopic data and comparison with literature. In vitro cytotoxicity of all isolated compounds towards human hepatic cancer (HepG2) cell line was examined by MTT assay. Izalpinin (6) was potently cytotoxic to the cancer cells, with an IC₅₀ value of 4.62 ± 1.50 μM. Stilbenoids 2, 7 and 8 also exhibited notable activity in the range of 6.31-6.68 μM. All compounds, except the new stilbene 1, were non-toxic to normal fibroblast (OUMS-36) cell line.

Lung cancer remains a major clinical challenge, with therapy resistance in non-small-cell lung cancer (NSCLC) driving the search for novel selective agents. This study demonstrates that 2,3′-dihydroxy-5′-methoxystilbene exhibits significant anticancer activity in NSCLC cell lines (A549, H23, and H460) while displaying substantially lower toxicity toward normal NIH/3T3 fibroblasts. The compound reduced the viability of H23 and H460 cells after 48 h. (IC50: 23.39 ± 3.27 μM and 24.20 ± 2.61 μM, respectively), with NIH/3T3 cells remaining comparatively resistant (IC50 > 100 μM). At 25 μM, it suppressed proliferation by approximately 40% in H23, 30% in H460, and 20% in A549 cells, and dose-dependently impaired colony formation and migration, leading to near-complete migration arrest in H460 cells. Apoptosis induction peaked at 19% in H23, 17% in H460, and 8% in A549 cells at 25 μM. Mechanistic studies and molecular modeling revealed AKT-dependent activity, with decreased p-AKT and p-GSK3β levels (0.70 and 0.75 in H23; 0.65 and 0.70 in H460 at 25 μM), without changes in total protein expression. Combination treatment with cisplatin yielded synergistic effects in A549 (CI = 0.83) and H460 (CI = 0.94) cells, but antagonistic effects in H23 cells (CI = 1.32). These findings identify 2,3′-dihydroxy-5′-methoxystilbene as a selective AKT-targeting stilbene with promising anticancer potential and context-dependent chemosensitizing activity in NSCLC cells.

Lung cancer is a leading cause of cancer-related deaths globally, with current treatments having significant limitations, including drug resistance, metastasis, and tumor heterogeneity. This study investigated the anticancer potential of isalpinin, a flavonoid isolated from Paphiopedilum dianthum, against non-small cell lung cancer (NSCLC) cell lines A549, H23, and H460. Isalpinin significantly inhibited NSCLC cell viability in a dose- and time-dependent manner; H23 and H460 cells showed greater sensitivity (IC₅₀ a ~ 44 μM at 48 h) compared to A549 cells (IC₅₀ 82 μM). Isalpinin suppressed proliferation, migration, and anchorage-independent growth, particularly in H23/H460 cells. Mechanistically, it induced apoptosis via increased ROS production and Bcl-2 downregulation, particularly in H23 and H460 cells. In a molecular docking analysis, isalpinin was found to directly bind to the ATP-binding pocket of AKT1, as confirmed by reduced Akt/GSK3β phosphorylation. These results suggest that isalpinin showed a potent multi-target natural compound against NSCLC that disrupts the key hallmarks of malignancy and pro-survival signaling. However, its subtype-specific efficacy warrants further in vivo studies and an investigation of combinatorial therapeutic approaches to elucidate its clinical potential.