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Halymenia durvillei (HD), a marine red alga, is believed to have potentials for pharmacological, nutritional and cosmetic applications. However, such potentials are acceptable only when their extracts are devoid of any adverse effects on human health. No previous research has been conducted the toxicity and anti-oxidation capacity of HD. Thus, the aim of this work was to investigate toxicity and anti-oxidation activities of HD extracts. In this study, the toxicity and anti-oxidation capacity of 5 fractions of HD solvent extracts, i.e., ethanol (HDET), hexane (HDHE), ethyl acetate (HDEA), butanol (HDBU), and aqueous (HDAQ) were evaluated. The cytotoxicity was evaluated by MTT and LDH assays on 4 cell types, i.e., fibroblast, macrophage, hepatocyte and keratinocyte. The genotoxicity was evaluated by comet assay and micronucleus test using TK6 lymphoblastoid cell line. The anti-oxidation capacity was investigated by DPPH and ABTS assays. The toxicity studies showed that HDET, HDBU, HDAQ had very low to no toxicity as indicated by cytotoxicity and genotoxicity tests while HDEA, HDHE have some toxicity at high concentrations. HDAQ showed low antioxidant activity while HDET, HDEA, HDHE and HDBU possess relatively high antioxidant activity. Overall, our results indicated that HDET and HDAQ could be consumed as they are not toxic and HDHE, HDEA, and HDBU could be safely consumed at doses lower than 100 μg/mL. Further investigation using in vivo assays are needed to ensure the safety of HD extracts for animal and human consumptions. HIGHLIGHTS Effect of HD extracts on the cytotoxicity and genotoxicity were assessed HDET and HDAQ showed no toxic effects HDET, HDEA, HDHE, and HDBU exhibited antioxidant properties GRAPHICAL ABSTRACT

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Glutathione peroxidase (GPx) is a key member of the family of antioxidant enzymes in trematode parasites including Fasciola spp. Because of its abundance and central role as an anti-oxidant that helps to protect parasites from damage by free radicals released from the host immune cells, it has both diagnostic as well as vaccine potential against fasciolosis. In this study, we have cloned, characterized, and detected the expression of the GPx protein in Fasciola gigantica (Fg). FgGPx (582 bp) was cloned by polymerase chain reaction (PCR) from complementary DNA (cDNA) from an adult fluke. Its putative peptide has no signal sequence and is composed of 168 amino acids, with a molecular weight of 19.1 kDa, and conserved sequences at NVACKUG, FPCNQFGGQ, and WNF. Phylogenetic analysis showed that GPx is present from protozoa to mammals and FgGPx was closely related to Fasciola hepatica GPx. A recombinant FgGPx (rFgGPx) was expressed in Escherichia coli BL21 (DE3) and used for immunizing mice to obtain polyclonal antibodies (anti-rFgGPx) for immunoblotting and immunolocalization. In immunoblotting analysis, the FgGPx was expressed in all stages of F. gigantica (eggs, metacercariae, newly excysted juveniles (NEJ), 4-week-old juveniles, and adults). This mouse anti-rFgGPx reacted with the native FgGPx at a molecular weight of 19.1 kDa in adult whole body (WB) and tegumental antigens (TA) as detected by immunoblotting. The FgGPx protein was expressed at a high level in the tegument, vitelline glands, and eggs of the parasite. Anti-rFgGPx exhibited no cross-reactivity with the other parasite antigens, including Eurytrema pancreaticum, Cotylophoron cotylophorum, Fischoederius cobboldi, Gastrothylax crumenifer, Paramphistomum cervi, and Setaria labiato papillosa. The possibility of using rFgGPx for immunodiagnosis and/or as a vaccine for fasciolosis in animals of economic importance will be explored in the future.

Caulerpa lentillifera (sea grape) has been widely used in pharmaceutical industry and health-care products in Thailand. In this study, we attempted to evaluate the toxicity and antioxidant capacity of sea grape extracts in five fractions (ethanol- CLET, hexane- CLHE, ethyl acetate- CLEA, butanol-CLBU, and aqueous-CLAQ). The extracts were evaluated for cytotoxicity by MTT and LDH assays on four cell lines, fibroblast (L929), macrophages (RAW 264.7), hepatocytes (FL83B), and keratinocytes (HaCaT). Genotoxicity was tested by comet assay and micronucleus assay on human lymphoblast cells (TK6). The antioxidant capacity was measured by DPPH and ABTS scavenging assays. Our results demonstrated low cytotoxicity and genotoxicity of CLET, CLBU and CLAQ. When tested by DPPH and ABTS assays, CLET, CLEA, and CLHE showed high antioxidant activity. In conclusion, CLET, CLBU, and CLAQ demonstrated no toxic effects, and CLET, CLEA, and CLHE exhibited high antioxidant capacity. Therefore, our results indicated that CLET, CLEA, and CLHE could be consumed safely at doses lower than 500 and 200 μg/ml for CLHE and CLEA, respectively. Keywords: Anti-oxidation, Caulerpa lentillifera, Cytotoxicity, Genotoxicity