Cytotoxic and antiproliferative effects of Streblus asper from northeastern Thailand on A549 lung cancer cells

Thailand's second-leading cause of death is lung cancer. Thai indigenous herbal plants are sought after as an alternative treatment against lung cancer. This work aimed to examine cytotoxic, antiproliferative and antimigratory capacities of different parts of Streblus asper (SA) from northeastern Thailand on A549 lung cancer cells. Plant leaves, twigs, bark and wood were used for ethanolic extraction by maceration. The highest cytotoxicity of 85.46% was found in twig extract (IC50 57.46 µg/mL) assessed by an MTT assay. The lowest IC50 (18.42 µg/mL) was also found in twig extract using a clonogenic assay indicating its most antiproliferative activity in a long-term therapy. In addition, all SA extracts displayed antimigratory activity against A549 cells in a dose-dependent fashion, especially twig extract. Apoptotic characteristics were noticeable in SA extract treated cells. The maximum DPPH-scavenging activity, FRAP value, total phenolic and flavonoid content were found in twig extract. GC-MS analysis revealed that twig extract contained four prominent components namely ethyl-α-D-glucopyranoside, hexadecanoic acid, ethyl ester, lupeol and γ-sitosterol. Real-time PCR results showed that genes (Bcl-2, Bax, p21, and cytochrome c) linked to apoptosis were significantly affected by all SA extracts. The various SA components' ethanolic extracts exhibited moderate-to-high cytotoxic action towards A549 cells. This work will significantly advance the utilization of the plant as an alternative source of medicine for rural Thais, and it paves the way for future research to determine the active compound(s) and anticipate new drug candidates