The increasing usage of chemical control agents, as well as fungicides to manage plant diseases, causes human and environmental health problems. Macroalgae represent a reservoir for a tremendous variety of secondary metabolites that display a wide range of biological activities. However, their anti-phytopathogenic properties are still being studied. The current study was conducted to investigate whether or not the macroalgae Ulva fasciata extract exhibits antifungal and antiviral activities. In this regard, the organic extracts of U. fasciata were tested for their capabilities against tobacco mosaic virus (TMV) and three molecularly identified fungal isolates, Fusarium verticillioides, Alternaria tenuissima, and Botrytis cinerea with accession numbers OP363619, OP363620, and OP363621, respectively. Among the three tested extract concentrations, 100 µg/mL had the best biological activity against B. cinerea and TMV, with 69.26%and 81.25% inhibition rates, respectively. The HPLC analysis of chemical profiling of the extract showed the presence of a number of phenolic and flavonoid compounds widely known to display many biological activities. In this line, the 4-Hydroxybenzoic acid was the highest phenolic compound (12.3 µg/mL) present in the extract, followed by ferulic acid (9.05 µg/mL). The 7-hydroxyflavone (12.45 µg/mL) was the highest flavonoid in the organic extract of U. faciata followed by rutin, which recorded a concentration of 7.62 µg/ mL. The results of this study show that the U. fasciata extract has antiviral and antifungal properties, which makes it a possible source of natural antimicrobial agents.

The increasing use of chemical control agents and pesticides to prevent plant disease has resulted in several human and environmental health problems. Seaweeds, e.g., Amphiroa anceps extracts, have significant antimicrobial activities against different human pathogens. However, their anti-phytopathogenic activities are still being investigated. In the present investigation, three fungal isolates were isolated from root rot and grey mold symptomatic strawberry plants and were molecularly identified by ITS primers to Fusarium culmorum, Rhizoctonia solani, and Botrytis cinerea with accession numbers MN398396, MN398398, and MN398400, respectively. In addition, the organic extract of the red alga Amphiroa anceps was assessed for its antifungal activity against the three identified fungal isolates and tobacco mosaic virus (TMV) infection. At 100 µg/mL, the A. anceps extract had the best biological activity against R. solani, B. cinerea, and TMV infection, with inhibition rates of 66.67%, 40.61%, and 81.5%, respectively. Contrarily, the A. anceps extract exhibited lower activity against F. culmorum, causing inhibition in the fungal mycelia by only 4.4% at the same concentration. The extract’s HPLC analysis revealed the presence of numerous phenolic compounds, including ellagic acid and gallic acid, which had the highest concentrations of 19.05 and 18.36 µg/mL, respectively. In this line, the phytochemical analysis also showed the presence of flavonoids, with the highest concentration recorded for catechin at 12.45 µg/mL. The obtained results revealed for the first time the effect of the A. anceps extract against the plant fungal and viral pathogens, making the seaweed extract a promising source for natural antimicrobial agents.

Ulva fasciata, U. lactuca, Amphiroa anceps, Corallina mediterranea, and Sargassum filipendula extract were screened for their in vitro anticancer activity against human breast adenocarcinoma cell line (MCF-7) and colorectal carcinoma cell line (HCT-116). Algal extracts exhibited significantly dose-dependent anticancer activity without significant cytotoxicity against normal human fibroblasts. The maximum inhibitory percentages against MCF-7 and HCT-116 cell lines were recorded by U. lactuca (88.5 ± 1.08 %) and A. anceps (86.1 ± 2.88 %) extracts. Algal extracts showed cytotoxic effect against MCF-7 cell line with fifty percent inhibitory concentration (IC50) values ranging from 3.54 ± 1.2 to 21.2 ± 1.1 µg mL-1. The seaweeds extract has a less cytotoxic effect against HCT-116. FTIR and GC-MS analyses of the extracts indicated that the anticancer potential of the tested seaweeds may be returned to the presence of various anticancer compounds such as palmitic acid, oleic acid, retinoic acid, dihydroactinidiolide, thiosemicarbazide, diisobutyl phthalate, and phytol. Thus, seaweed extracts may be a promising natural source of safe anticancer agents against human breast and colon cancers.