Preliminary Investigation of the Antioxidant, Anti-Diabetic, and Anti-Inflammatory Activity of Enteromorpha intestinalis Extracts

Biswajita Pradhan,Bimal Prasad Jit,Srimanta Patra,Mrutyunjay Jena,Chhandashree Behera,Andrea Ragusa,Rabindra Nayak

doi:10.3390/molecules26041171

Abstract

Marine algae are a promising source of potent bioactive agents against oxidative stress, diabetes, and inflammation. However, the possible therapeutic effects of many algal metabolites have not been exploited yet. In this regard, we explored the therapeutic potential of Enteromorpha intestinalis extracts obtained from methanol, ethanol, and hexane, in contrasting oxidative stress. The total phenolic (TPC) and flavonoids (TFC) content were quantified in all extracts, with ethanol yielding the best values (about 60 and 625 mg of gallic acid and rutin equivalents per gram of extract, respectively). Their antioxidant potential was also assessed through DPPH•, hydroxyl radical, hydrogen peroxide, and superoxide anion scavenging assays, showing a concentration-dependent activity which was greater in the extracts from protic and more polar solvents. The α-amylase and α-glucosidase activities were estimated for checking the antidiabetic capacity, with IC50 values of about 3.8 µg/mL for the methanolic extract, almost as low as those obtained with acarbose (about 2.8 and 3.3 µg/mL, respectively). The same extract also showed remarkable anti-inflammatory effect, as determined by hemolysis, protein denaturation, proteinase and lipoxygenase activity assays, with respectable IC50 values (about 11, 4, 6, and 5 µg/mL, respectively), also in comparison to commercially used drugs, such as acetylsalicylic acid.

Highlights

Three different solvents were tested for the extraction of the secondary metabolites from E. intestinalis, namely methanol, ethanol, and hexane, yielding the corresponding
The present study revealed potent inhibition of H2 O2 radicals by the extracts in a concentration-dependent manner, with lower IC50 values obtained from the alcoholic extracts compared to that from the apolar one
Marine algae represent a huge resource of secondary metabolites, more studies are still needed to investigate their properties

Summary

Introduction

Secondary metabolites, such as polyphenols, carotenoids, terpenes, and alkaloids are gaining an ever-increasing attention because of their antioxidant capacity and the consequent beneficial effect on the human body [1,2]. These bioactive compounds have been widely investigated in plants and fruits, but they still represent a largely unexplored source of phenolic and flavonoid compounds in marine algae. Their extraction is usually accomplished in organic solvents, such as petroleum ether, hexane, chloroform, ethyl acetate, acetone, and methanol. Because of their well-known beneficial health effects, as well as their positive influence on several pathologies, such as cancer, diabetes, cardiovascular, neurodegenerative, and inflammatory diseases, and in order to improve their pharmacokinetics, secondary metabolites are being exploited in more technological formulations [4,5]

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