Chemical Composition, Antioxidant Capacity, and Anticancerous Effects against Human Lung Cancer Cells of a Terpenoid-Rich Fraction of Inula viscosa.

Simple Summary: Inula viscosa (synonymous of Dittrichia viscosa) is a plant used in traditional Mediterranean and Middle Eastern medicine to manage various illnesses. While it has shown anticancer effects against various cancer cell lines, its impact on lung cancer has not been under extensive study. This research explored the potential of the methanolic and aqueous extracts and a terpenoid-rich fraction of I. viscosa leaves and stems against human lung cancer cells. We found that the methanolic extract of I. viscosa leaves was particularly effective in reducing the viability of lung cancer cells in vitro, and other cancer cell types, without affecting normal cells. The terpenoid-rich fraction demonstrated anticancer properties by attenuating the levels of proliferation marker proteins, activating the intrinsic apoptosis pathway, and inhibiting cell migration. GC/MS analysis revealed that the terpenoid-rich fraction encompasses several metabolites that can substantiate its biological activities. Inula viscosa is a widely used plant in traditional Mediterranean and Middle Eastern medicine for various illnesses. I. viscosa has been shown to have anticancer effects against various cancers, but its effects against lung cancer have been under limited investigation. At the same time, I. viscosa is rich in terpenoids whose anti-lung cancer effects have been poorly investigated. This study aimed to examine the potential anticancer properties of methanolic and aqueous extracts of stems and leaves of I. viscosa and its terpenoid-rich fraction against human lung cancer A549 cells. Results showed that the methanolic extracts of I. viscosa had significantly higher polyphenol and flavonoid content and radical scavenging capacity than the aqueous extracts. In addition, leaves methanolic extracts (IVLM) caused the highest reduction in viability of A549 cells among all the extracts. IVLM also reduced the viability of human ovarian SK-OV-3, breast MCF-7, liver HepG2, and colorectal HCT116 cancer cells. A terpenoid-rich I. viscosa fraction (IVL DCM), prepared by liquid-liquid separation of IVLM in dichloromethane (DCM), displayed a substantial reduction in the viability of A549 cells (IC₅₀ = 27.8 ± 1.5 µg/mL at 48 h) and the panel of tested cancerous cell lines but was not cytotoxic to normal human embryonic fibroblasts (HDFn). The assessment of IVL DCM phytochemical constituents using GC-MS analysis revealed 21 metabolites, highlighting an enrichment in terpenoids, such as lupeol and its derivatives, caryophyllene oxide, betulin, and isopulegol, known to exhibit proapoptotic and antimetastatic functions. IVL DCM also showed robust antioxidant capacity and decent polyphenol and flavonoid contents. Furthermore, Western blotting analysis indicated that IVL DCM reduced proliferation (reduction of proliferation marker Ki67 and induction of proliferation inhibitor proteins P21 and P27), contaminant with P38 MAP kinase activation, and induced the intrinsic apoptotic pathway (P53/BCL2/BAX/Caspase3/PARP) in A549 cells. IVL DCM also reduced the migration of A549 cells, potentially by reducing FAK activation. Future identification of anticancer metabolites of IVL DCM, especially terpenoids, is recommended. These data place I. viscosa as a new resource of herbal anticancer agents. [ABSTRACT FROM AUTHOR]