Bioactive Molecules from Marine Diatoms and Their Value for the Nutraceutical Industry

The search for novel sources of nutrients is among the basic goals for achievement of sustainable progress. In this context, microalgae are relevant organisms, being rich in high-value compounds and able to grow in open ponds or photobioreactors, thus enabling profitable exploitation of aquatic resources. Microalgae, a huge taxon containing photosynthetic microorganisms living in freshwater, as well as in brackish and marine waters, typically unicellular and eukaryotic, include green algae (Chlorophyceae), red algae (Rhodophyceae), brown algae (Phaeophyceae) and diatoms (Bacillariophyceae). In recent decades, diatoms have been considered the most sustainable sources of nutrients for humans with respect to other microalgae. This review focuses on studies exploring their bio-pharmacological activities when relevant for human disease prevention and/or treatment. In addition, we considered diatoms and their extracts (or purified compounds) when relevant for specific nutraceutical applications.

Marine Algae as a Potential Source for Anti-diabetic Compounds - A Brief Review

BACKGROUND

Diabetes Mellitus (DM) is a major chronic metabolic disorder characterized by hyperglycemia that leads to several complications such as retinopathy, atherosclerosis, nephropathy, etc. In 2019, it was estimated that about 463 million people had diabetes, and it may increase up to 700 million in 2045. Marine macroalgae are the rich source of bioactive compounds for the treatment of diabetes mellitus.

OBJECTIVE

This review summarizes the recent epidemiology and possible use of marine macroalgae-derived bioactive compounds for the protection against chronic metabolic disease, diabetes mellitus and marine macroalgae as a nutraceutical supplement.

CONCLUSION

The present therapies available for diabetes treatment are oral medicines and insulin injections. But continuous use of synthetic medicines provides low therapeutic with many side effects. In continuing search of anti-diabetic drugs, marine macroalgae remain as a promising source with potent bioactivity. Among existing marine algae, red and brown algae are reported to show anti-diabetic activity. Hence, the present review focuses on the epidemiology, diabetes biomarkers and different secondary bioactive compounds present in marine macroalgae to treat diabetes mellitus.

Marine natural products

This review covers the literature published in 2011 for marine natural products, with 870 citations (558 for the period January to December 2011) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1152 for 2011), together with the relevant biological activities, source organisms and country of origin. Biosynthetic studies, first syntheses, and syntheses that lead to the revision of structures or stereochemistries, have been included.

A THEORETICAL STUDY OF DACTYLYNE STEREOISOMERS: A MARINE NATURAL PRODUCT FROM APLYSIA DACTYLOMELA

Dactylyne is an acetylenic dibromochloro ether from the Persian Gulf sea hare, Aplysia dactylomela. As a result of its unique structure and nontoxic nature; it has been known as a promising pharmacological substance of marine origin. A theoretical study of dactylyne and its stereoisomers, initiated in the hope of understanding more details of its action, is reported here. In the present research, for the first time, a density functional theory (DFT) calculation has been performed on the stereoisomers of dactylyne to determine the most stable configurations in gas phase. The HOMO–LUMO gap, global softness, chemical potential, and electrophilicity index have been calculated for the most stable stereoisomers at the B3LYP level of theory. These DFT-based global reactivity descriptors have been applied to demonstrate the reactive nature of compounds. Moreover, results from the quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analysis have been employed to support the finding of more reactive stereoisomers. The investigation has indicated that the configuration of stereoisomers has some effects on their electronic and structural properties which control their global reactivity. It is also shown that the most probable interaction sites of dactylyne are in its unsaturated region. In the second part of our study, the effects of some typical substituents on dactylyne reactivity have been investigated theoretically and it has been shown that the strong electron donor groups increase the reactivity of dactylyne more than withdrawing substituent. However, creation of an ionic compound highly influences on reactivity descriptors.