Microalgae and cyanobacteria are groups of organisms with many important
applications. In this study, samples were collected from five locations in
Thai Nguyen province, followed by isolation, classification, identification,
and biomass cultivation. Methanolic extracts of the isolated microalgal and
cyanobacterial strains were evaluated for in vitro anticancer activity against
HepG2 and SK-LU-1 cell lines. The results showed that ten strains
belonging to seven genera were successfully isolated and identified. Among
them, three out of ten strains exhibited inhibitory effects on cancer cell
growth. Notably, Nostoc calcicola (M-TN07) showed the strongest activity
against both cancer cell lines, with IC₅₀ values of 8.97 ± 1.60 µg/mL
(HepG2) and 9.79 ± 1.10 µg/mL (SK-LU-1). Two other strains, Nostoc
muscorum (M-TN08) and Tolypothrix sp. (M-TN09), exhibited weak
activity, with IC₅₀ values ranging from 62 to 77 µg/mL compared with the
positive control ellipticine. This study not only enriches the data on the
diversity of microalgae and cyanobacteria in Thai Nguyen Province but also
provides an important scientific basis for the exploration and development of
anticancer compounds from indigenous microbial resources