Overview on the Antihypertensive and Anti-Obesity Effects of Secondary Metabolites from Seaweeds

Abstract

Hypertension and obesity are two significant factors that contribute to the onset and exacerbation of a cascade of mechanisms including activation of the sympathetic and renin-angiotensin systems, oxidative stress, release of inflammatory mediators, increase of adipogenesis and thus promotion of systemic dysfunction that leads to clinical manifestations of cardiovascular diseases. Seaweeds, in addition to their use as food, are now unanimously acknowledged as an invaluable source of new natural products that may hold noteworthy leads for future drug discovery and development, including in the prevention and/or treatment of the cardiovascular risk factors. Several compounds including peptides, phlorotannins, polysaccharides, carotenoids, and sterols, isolated from brown, red and green macroalgae exhibit significant anti-hypertensive and anti-obesity properties. This review will provide a comprehensive overview of the recent advances on bioactive pure compounds isolated from different seaweed sources focusing on their potential use as drugs to treat or prevent hypertension and obesity. On the other hand, although it is obvious that macroalgae represent promising sources of antihypertensive and anti-obesity compounds, it is also clear that further efforts are required to fully understand their cellular mechanisms of action, to establish structure-inhibition relationships and mainly to evaluate them in pre-clinical and clinical trials.

Seaweed Secondary Metabolites with Beneficial Health Effects: An Overview of Successes in In Vivo Studies and Clinical Trials

“…The search for angiotensin-converting enzyme (ACE) inhibitors is of great biological value due to their inherent hypotensive effects and subsequent applications. Macroalgae were proven to be an especially rich source of compounds with ACE inhibition activity [18,[99][100][101][102][103][104]. Regarding seaweed ACE or renin inhibitors, this review chooses to focus on the IRLIIVLMPILMA tridecapeptide 13 and the Phe-Tyr dipeptide 14 (Figure 3) shown in Table 2, mainly due to their potent hypotensive activity compared to a current pharmaceutical option (captopril), as well as being of more recent relevance and interest.…”

“…Concerning algal lipids, fucoxanthin 22 ( Figure 5), a xanthophyll-like carotenoid, is one of the most studied metabolites because of its beneficial health effects [18,103,132]. Indeed, there are many published reviews and research articles demonstrating and extolling, among others, the nutraceutical, antioxidant, anticancer, anti-obesity, antidiabetic, antimicrobial, and cardiovascular protective effects of fucoxanthin 22 [103,[132][133][134][135][136][137][138][139].…”

“…Regarding clinical trials, studies with pure algal metabolites are scarce, limited to those carried out with kahalalide F and fucoxanthin. The majority of clinical trials currently aim to ascertain the effect of algae consumption, as extracts or fractions, on obesity and diabetes.Studies focusing on the preparation of macroalgae extracts and their chemical characterization revealed a large range of seaweed compounds with very interesting biological activities including antitumor, anti-inflammatory, antimicrobial, antidiabetic, antivirus, antihypertensive, fat-lowering, and neuroprotective activities [12][13][14][15].The large volume of studies proving the seaweed compound activities in in vitro systems [16][17][18][19] hints the need for further advancements in the knowledge about macroalgae compound efficiency in living systems (in vivo) and their use in the development of pharmaceuticals. In vitro studies are very relevant and yield very important information, but they only represent the first step of a long process, and the results obtained rarely reveal anything about the effects of a compound in vivo, because the responses observed in vitro can be magnified, diminished, or totally different in a more complex and integrated system.…”

“…The large volume of studies proving the seaweed compound activities in in vitro systems [16][17][18][19] hints the need for further advancements in the knowledge about macroalgae compound efficiency in living systems (in vivo) and their use in the development of pharmaceuticals. In vitro studies are very relevant and yield very important information, but they only represent the first step of a long process, and the results obtained rarely reveal anything about the effects of a compound in vivo, because the responses observed in vitro can be magnified, diminished, or totally different in a more complex and integrated system.…”

Aqueous–ethanol extracts of some South African seaweeds inhibit beta‐amyloid aggregation, cholinesterases, and beta‐secretase activities in vitro

“…Apart from the nutritional importance of some seaweeds, their functional properties have been investigated which include immunomodulatory (Palstra, Kals, Blanco Garcia, & Dirks, . ), anticancer (Moussavou et al, ), antihypertensive (Seca & Pinto, ), antidiabetic, and anti‐HIV activities (Thomas & Kim, ). Previous reports have also revealed the neuroprotective effects of some seaweeds such as Ecklonia cava (Alghazwi et al, ), Ecklonia bicyclis (Jung, Oh, & Choi, ) Caulerpa racemose (Yang et al, ), and Ecklonia kurome (Hu et al, ) against some neurodegenerative diseases.…”