Revista de Biología Marina y Oceanografía Vol. 55, N°2: 119-127, 2020 DOI: https://doi.org/10.22370/rbmo.2020.55.2.2497 Article Toxicological and therapeutic evaluation of the algae Macrocystis pyrifera (Phaeophyceae) in rodents Evaluación toxicológica y terapéutica del alga Macrocystis pyrifera (Phaeophyceae) en roedores Jorge Tapia-Martínez1, Edgar Cano-Europa1, Margarita Casas-Valdez3, Vanessa Blas-Valdivia2 and Margarita Franco-Colin1* 1Laboratorio de Metabolismo I, Departamento de Fisiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Ciudad de México, México 2Laboratorio de Neurobiología, Departamento de Fisiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Ciudad de México, México 3Laboratorio de Macroalgas, Centro Interdisciplinario de Ciencias Marinas, Instituto Politécnico Nacional, La Paz, Baja California Sur, México *Corresponding author: [email protected] Resumen.- Macrocystis pyrifera es un alga parda gigante con alto contenido nutricional, utilizada como suplemento dietético en algunos animales de granja. Contiene fucoidan, el cual posee efecto farmacológico sobre el metabolismo de lípidos y glucosa. Algunas algas pardas pueden bioacumular tóxicos en su pared celular, representando un problema si no se realizan los ensayos de toxicidad que garanticen la seguridad de su consumo.M. pyrifera, no presenta estudios toxicológicos que garanticen su inocuidad. El objetivo del trabajo fue realizar la evaluación toxicológica aguda y subcrónica de M. pyrifera en roedores, así como, determinar su posible efecto terapéutico. Frondas deM. pyrifera fueron recolectadas en Baja California Sur, México, para su secado y obtención de la harina del alga. El ensayo de toxicidad aguda LD50 se realizó en ratones macho C57BL/6 (25 ± 3 g) durante 7 días, encontrando una LD50 superior a 10 g kg-1. La toxicidad subcrónica se determinó durante 121 días en ratas Sprague Dawley macho adulta con peso (98 ± 2 g), en este periodo los animales de experimentación no mostraron signos de toxicidad, ni cambios en los parámetros hematológicos, bioquímicos ni histopatológicos de sus órganos. En el balance óxido-reducción, las especies reactivas de oxígeno, la peroxidación lipídica y la proporción de glutatión no fueron diferentes al grupo testigo. Se encontró un efecto terapéutico sobre la regulación del peso corporal y un efecto hipolipidémico (triglicéridos: 82,27 ± 5,55 mg dL-1, colesterol: 98,61 ± 6,48 mg dL-1). Se concluye que, bajo las condiciones en que se desarrolló este estudio, el consumo de M. pyrifera como ingrediente funcional es seguro. Palabras clave: Toxicidad sub-crónica, Macrocystis pyrifera,ingesta segura, antiobesogénico, hipolipidémico Abstract.- Macrocystis pyrifera is a giant brown seaweed with high nutritional content, used as a dietary supplement in some farm animals. It contains fucoidan which has a pharmacological effect on lipids and glucose metabolism. Some brown seaweeds can bioaccumulate toxic elements in their cell wall, representing a problem if toxicity tests that guarantee the safety of their consumption are not done. M. pyrifera, does not present toxicological studies that guarantee its safety. This work aimed to perform the acute and subchronic toxicological evaluation of M. pyrifera in rodents as well as to determine its possible therapeutic effect. Fronds of M. pyrifera were collected in Baja California Sur, Mexico, for drying and obtaining algae flour. The acute toxicity test LD50 was performed in C57BL / 6 male mice (25 ± 3 g) for 7 days, finding an LD50 greater than 10 g kg-1. Subchronic toxicity was determined for 121 days in adult male Sprague Dawley rats (98 ± 2 g), during which the experimental animals showed no signs of toxicity, or changes in the hematological, biochemical and histopathological parameters of the organs. The reactive oxygen species, lipid peroxidation or glutathione ratio were not different from the control group. A therapeutic effect on the regulation of body weight and a hypolipidemic effect (triacylglycerides: 82.27 ± 5.55 mg dL-1, cholesterol: 98.61 ± 6.48 mg dL-1) were found. It is concluded that, under the conditions in which this study was developed, the consumption of M. pyrifera as a functional ingredient is safe. Key words: Subchronic toxicity, Macrocystis pyrifera, safe intake, antiobesogenic, hypolipidemic Introduction forests. The thallus can grow up to 45 m in length and last Brown algae represent an important food resource for from 4 to 8 years attached to a substrate using a conical human population. Hence, it is very important to evaluate support (Hernández-Carmona et al. 1991). This alga is toxicity to ensure the safety of its consumption and take found in America, mainly in northern Mexico from Baja advantage of its beneficial effects and therapeutic properties California to Alaska, Perú and Chile (Carrillo-Domínguez (Rajapakse & Kim 2011, Makkar et al. 2016). Macrocystis et al. 2002). M. pyrifera is also distributed in South Africa, pyrifera (Linnaeus) C.Agardh 1820, commonly known as Australia, New Zealand and Sub Antarctic Islands (Macaya giant kelp or giant bladder kelp, is a species of kelp (large & Zuccarello 2010). brown algae) that can be found forming large aquatic 119 From a nutritional point of view, Macrocystis pyrifera is Rodents experiment a low-calorie product, with a high concentration of minerals All the experimental procedures described in this study +2 +2 +5 + - (Mg , Ca , P , K , I ), vitamins, complex polysaccharides were carried out in accordance with the guidelines of the and low lipids content (Rodríguez-Montesinos 1991, laws and codes approved in the Seventh Title of the General Jiménez-Escrig & Goñi-Cambrodón 1999). In addition, Health Law in matter of Research for the Health (DOF 2014) the species contains molecules with pharmacological and the NOM-062-ZOO-1999, which show the technical activity such as fucoidan, a compound that inhibits lipid specifications for the production, care and use of laboratory accumulation. For this reason, it has been considered that animals. The IPN Internal Bioethics Committee approved its consumption can be a therapeutic alternative to improve this protocol. the metabolism of lipid and glucose (Kim et al. 2009, Park et al. 2011). The experiments were design as previously reported (Tapia-Martinez et al. 2019). The LD50 acute toxicity test This species has been proven as a nutritional supplement was based in accordance with the method provided by the in shrimp (Farfantepenaeus californiensis) (Casas-Valdez et Organization for Economic Cooperation and Development al. 2006), laying hens (Carrillo et al. 2008) and goats (Mora- (OECD 2008) and Lorke method (Lorke 1983). Twelve Castro et al. 2009). Due to these characteristics, it could be C57BL/6 male mice (20 ± 1 g) were used. The subchronic considered an option as a functional food to improve human toxicity test was based on a WHO guide (WHO 2000) and nutritional status (Mohamed et al. 2012). the OECD Guidelines for Chemical Tests (OECD 1998). On the other hand, toxicological studies are very 16 male Sprague Dawley rats (98 ± 2 g) were used. They important to consider that the consumption of algae is safe were housed in a room with controlled lighting (8:00 a.m. for humans, this because, in the cell walls, kelps contain to 8:00 p.m.), temperature (21 ± 1 °C) and relative humidity structural polysaccharides such as alginates, which can act (40-60%). Food and water intake were ad libitum. as binding sites for the accumulation of toxic substances that are resuspended in marine currents, such as heavy LD50 acute toxicity test metals. This situation is important since if consumed, The acute toxicity LD50 of M. pyrifera was determined it can cause alterations in oxidative stress and in the using 20 male C57BL/6J mice, randomly divided into 4 REDOX environment of the organism, causing functional groups (n= 3). Singly doses were administered by oral and structural changes in tissues (Tapia-Martinez et al. gavage route (o.g.r.): 1) 10 g kg-1 (Purine rat chow® powder 2019). Although M. pyrifera is widely consumed, there are suspended in 0.9% saline solution SS), 2) 1 g kg-1 of M. no toxicological studies to ensure its consumption as an pyrifera (administrated from an 0.008 g mL-1 mixture of the additive in animal diets or for direct human consumption. powder suspended in 0.9% SS), 3) 5 g kg-1 of M. pyrifera Therefore, the objective of this study was to carry out (administrated from a 0.016 g mL-1 mixture of the powder a toxicological study of M. pyrifera to determine acute suspended in 0.9% SS), and 4) 10 g kg-1 of M. pyrifera and subchronic toxicity in rodents as well as its possible (administrated from a 0.16 g mL-1 mixture of the powder therapeutic effect. suspended in 0.9% SS). Doses greater than 10 g kg -1 were not possible to Materials and methods administer, because the high alginate composition in the algae formed a colloid that was not possible to use via Obtaining the seaweed o.g.r. After the administration, the male C57BL/6J mice Macrocystis pyrifera was provided by Laboratorio de were observed every 30 min, during 4 h and then, daily Macroalgas from Centro Interdisciplinario de Ciencias for 7 days. Signs of toxicity were documented according Marinas (CICIMAR), Instituto Politécnico Nacional (I.P.N), to Lorke scale (Lorke 1983), such as piloerection, ocular México. It was collected from Tortugas (27°41’30”N, irritation, salivation, displacement of motor activity, postural 114°53’45”W) and Asunción bay (27°08’18”N, anomalies or death. Animals were euthanized by cervical 114°17’45”W), Baja California Sur, Mexico. M. pyrifera dislocation. fronds were sun dried for 3 days on a cement surface. To obtain the powdered algae, samples were ground in a Hammer Mill (M 20S3, IKA Labortechnik) at 20,000 cycles for 10 min. After that, the powder was passed through a N100 sieve with a mesh size of 150 μm.