Periodontitis is currently understood as a chronic inflammatory disease, resulting from dysbiotic biofilms affecting tissues surrounding teeth, leading to periodontal attachment loss (Van Dyke et al., 2020). Lipopolysaccharides and other bacterial products elicit the host response, i.e. a response that involves several mechanisms of the immune-inflammatory system that, in the first stages is protective, however, when an imbalance between the dysbiotic biofilm and the immune system, it can also generate destruction of tissues, such as the periodontal apparatus (Curtis et al., 2020, Loos and Van Dyke, 2020). This process can be modified by certain factors e.g smoking, diabetes, obesity, etc. that also increase the severity of the tissue destruction (Zhang et al., 2020). Clinical management of periodontal diseases is based on control of oral biofilms protocols (Sanz et al., 2020). Additionally, host-modulation strategies have been proposed to promote balanced response to microbial challenge (Donos et al., 2020).

Desmarestia anceps Montagne (D. anceps) is an endemic brown macroalgae widely distributed in the region of the Antarctic Peninsula and its adjacent islands, where dominates benthic communities between 10 and 30 m deep. It is strongly adapted to cold, with a low maximum survival temperature (11 ° C) and a very small light demand for growth and photosynthesis (Huovinen & Gómez, 2013). Chemical characterization of D. anceps extracts has identified the presence of compounds with relevant biologic activity, such as fucoxanthin, violaxanthin, with special highlight to fucosterol (Frassini et al., 2019). This typical algae sterol compound has several well documented biologic activities, e.g., anti-inflammatory and antioxidant properties (Abdul et al., 2016, Ji et al., 2014). Hexadecanoic acid, a saturated fatty acid with anti-inflammatory properties was identified as well (Frassini et al., 2019).

Antarctica is characterized by extreme climatic conditions, habitats, and a unique biogeographic context (Oliveira et al., 2020). Large variations in temperature and salinity can occur in the Antarctic habitat, with a high incidence of ultraviolet radiation alternating with long periods of absence of light, in addition to freezing and thawing cycles (Convey et al., 2014). The seasonality of the radiation and photoperiod levels, as well as the ice cover have a strong effect on the supratidal, intertidal and subtidal communities. Annual ice cycles alternation impacts the physical and chemical environment in several ways and, consequently, the local biota as a whole (Oliveira et al., 2020). Ice formation, as well as melting in the summer, significantly changes the salinity and the penetration of light, exposing the benthic organisms to extreme values of these parameters. Even under these conditions, the Southern Ocean is known to offer space for a large abundance of benthic organisms compared to other regions of the world (Chown et al., 2015, Gómez and Huovinen, 2020a).

These extreme conditions related to temperature, humidity and winds lead to the development of defense strategies in the organisms that inhabit this region (Flores-Molina et al., 2016). Synthesis and accumulation of bioactive compounds are results of a long and complex evolutionary and ecological process. Some of these substances, such as phlorotannins, fucoidan and fucoxanthin may have pharmaceutical applications (Imbs et al., 2018). One of the most striking characteristics of these compounds, due to a series of hydroxyl groups, is their antioxidant potential, which opens up promising prospects for biotechnological use (Gómez & Huovinen, 2020b).

The range of biological activities justifies potential application of D. anceps for studies on the development of preventive and therapeutic strategies in human health. Based on these properties, the hypothesis is that D. anceps crude extracts can positively modulate pathogenesis of periodontitis, leading to more controlled inflammatory response and less tissue destruction. Therefore, the aim of the present study was to evaluate the effect of D. anceps systemic administration on the pathogenesis of ligature-induced experimental periodontitis in rats.