Malignance‐restriction activity exhibited by bioactive compounds of selected actinobacteria as silver nanoparticles against A549 lung cancer cell lines

This article deals with the antibacterial and anticancer potential of secondary metabolites produced by actinomycetes also reported as actinobacteria, Microbacterium proteolyticum (MN560041), and Streptomycetes rochei, where preliminary studies were done with the well diffusion method. These actinobacteria's silver nanoparticles were synthesized and characterized using transmission electron microscopy (TEM) and UV‐Visible spectroscopy. Anticancer was measured using the MTT test, reactive oxygen species (ROS) generation measured with DCFDA, mitochondrial membrane potential (MMP) measurement, and DAPI fluorescence intensity activity was measured in treated and non‐treated cancerous cells. The IC50 value for 5‐FU (a), LA2(O) (b), LA2(R) (c), LA2(ON) (d), and LA2(RN) (e) was obtained at 3.91 μg/mL (52.73% cell viability), 56.12 μg/mL (52.35% cell viability), 44.90 μg/mL (52.3% cell viability), 3.45 μg/mL (50.25% cell viability), and 8.05 μg/mL (48.72% cell viability), respectively. TEM micrographs revealed discrete, well‐separated AgNPs particles of size 7.88 ± 2 to 12.86 ± 0.24 nm. Gas chromatography‐mass spectrometry was also performed to detect the compounds in bioactive metabolites where n‐hexadecanoic acid was obtained as the most significant one. MTT test showed a substantial decline in A549 cell viability (up to 48.72%), 2.75‐fold increase in ROS generation was noticed in comparison to untreated A549 lung cancer cells when measured with DCFDA. A total of 0.31‐fold decrease in MMP and 1.74‐fold increase in DAPI fluorescence intensity compared to untreated A549 lung cancer cells suggests that the synthesized nanoparticles promote apoptosis in cancerous cells. Our findings suggests that the secondary metabolites of M. proteolyticum and S. rochei in nanoparticle form can be used as a significant compound against lung cancers. Significance statement The current study has shown that these novel and rare actinobacteria Microbacterium proteolyticum and Streptomycetes rochei can produce a wide range of bioactive compounds which could serve as potential sources for future anticancer drug development.