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Background: Spirulina platensis, an edible cyanobacterium, is considered as a valuable and natural resource of novel anticancer agents. This study aimed to investigate the anticancer potential of major bioactive metabolites from Spirulina platensis on hepatocellular carcinoma cells. The total phenolic and alkaloid content of S. platensis were determined using spectrophotometric procedures and thin-layer chromatography. Cellular viability of HepG2 cancer cells and normal fibroblasts was evaluated using MTT assay after 24 h treatment with 0.02-2 mg/ml of alkaloids, phenolic compounds, aqueous, and methanol extracts from Spirulina platensis. Results: Total phenolic and total alkaloid compounds were 150.5 ± 1.18 mg gallic acid equivalents/mg extract and 11.4 ± 0.05 mg atropine equivalents/mg extract, respectively. All tested extracts and compounds demonstrated the inhibitory effect on the viability of HepG2 cells in a dose-dependent manner without cytotoxicity on normal cells. The most potent anticancer activity was induced by alkaloids (2 ± 0.001 mg/ml) with 80% reduction in cell viability and an IC 50 of 0.53 ± 0.08 mg/ml. IC 50 values of the aqueous extract, the methanolic extract, and phenolic compounds were 1.7 ± 0.14, 1.28 ± 0.22, and 0.86 ± 0.14 mg/ml, respectively. Conclusions: This is the first report to demonstrate anticancer effects of alkaloids and phenolic compounds of Spirulina platensis in relation to liver cancer.

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In accordance with the importance of telomerase inhibition as a potential target in cancer therapy, and increasing reports on the association between short telomeres and severe COVID-19 symptoms as well as extensive application of Andrographis paniculata as a remedy for both cancer and SARS-CoV-2, the present study aimed at investigating the impact of the plant’s extracts on telomerase activity (as an important enzyme regulating telomere length). Telomerase inhibition in MCF-7 cells treated with the Dichloromethane, ethanol, water, and methanol extracts of A. paniculata was assessed using Telomerase Repeated Amplification Protocol (TRAP). The above-mentioned extracts inhibited telomerase by 80.3 ± 1.4%, 78.5 ± 1.35%, 77.5 ± 1.81%, and 73.7 ± 1.81%, respectively. Furthermore, the flow cytometry analysis showed that the water and methanol extracts induced higher rates of total apoptosis by 32.8% and 25%, respectively, compared with dichloromethane (10.07%) and ethanol (10.7%) extracts. The inhibitory effect of A. paniculata on telomerase activity can be considered as a potential immunity modulator in cancer therapy; however, telomerase inhibition as a safe approach to SARS-CoV-2 is arguable. Two mechanisms can be considered accordingly; (a) reducing the existing population of short telomeres via telomerase inhibition in cancer cells (arresting proliferation and finally cell death) may decrease the susceptibility against SARS-CoV-2, especially in cancer patients or patients prone to cancer, and (b) increasing the population of short telomeres via telomerase inhibition in normal/somatic cells may increase the susceptibility against SARS-CoV-2. Therefore, the telomerase inhibition of A. paniculata as an immunity modulator in cancer and COVID-19 should be investigated, carefully.

Introduction: Microalgae are known for their bioactive compounds with potential applications as antimicrobial, antiaging, and anticancer activities. Spirulina platensis (S. platensis) is a filamentous and photosynthetic microorganism that has 25 kinds of vitamins and minerals that contain many compounds with biotic activity such as alkaloids, phenolic compounds, terpenoids, and saponins. Saponins are mainly present in plants; while there are few studies about their role in microalgae. This study aims to investigate the anticancer potential of extracted saponins from S. platensis. Methods: Saponins were extracted; using distilled water and n-butanol. The total extracted saponin was dried and weighed. The cellular viability of HepG2, MCF-7, and MDA- MB-123 cell lines was evaluated; using MTT assay after 24 h treatment with 0.02-2 mg/ ml of saponins extracted from S. platensis. Morphology of cell lines was evaluated by invert microscopy. Results: Total saponin extracted from S. platensis was estimated at 28±0.0005 mg/g dry wt. Thin-layer chromatography profiles showed four bands for saponins with Rf values of 0.44, 0.48, 0.50, and 0.55. The cytotoxic activity after 24 h treatment with 0.02-2 mg/ml of saponins was a concentration-dependent manner. The highest toxicity of saponins with IC50=0.22 mg/ml was observed in MDA-MB-123 cells. In HepG2 and MCF-7 cells IC50 value was obtained in 0.35 mg/ml and 0.4 mg/ml, respectively. Conclusions: This is the first report to evaluate the anticancer effects of saponins from S. platensis in liver and breast cancers. The result showed that saponins from Spirulina decrease cancer cellular viability. Therefore, these compounds can be a candidate for anticancer agents.