Phlorotannins derivatives

Examples of other anti-HIV compounds also included four phlorotannin derivatives, eckol, 8,8 -dieckoI, 8,4 -dieckoI and phlorofucofiiro-eckol A, isolated from the brown alga Ecklonia cava [65]. Among these compounds, 8,8 -dieckol and 8,4 -dieckol exhibited an inhibitory effect on HIV-1 RT and protease. An enzyme kinetic assay... 

FIGURE 10.1 Phlorotannins derived from brown seaweeds and their chemical structures. 

Lee, S. H. (2010). Anti-inflammatory Medianisms of Phlorotannins Derived from Eisenia bicycUs and Their Inhibitory Effects on Matrix Metalloproteinases. Pukyong National University, Busan, South Korea. 

FIGURE 18.2 Phlorotannin derivatives from marine brown algae. 

The most important seaweed derived phenolic phytochemicals are phlorotannin polyphenols, which are uniquely found only in brown seaweeds [96], Phlorotannins are polymers which contain phloroglucinol as their monomeric component, and they are termed phlorotaimins since phloroglucinol is a common monomer unit [96]. As most tannins, similarly phlorotannins have the potential for cardiovascular disease management through an increase of HDL cholesterol and prevention of atherosclerosis [136-140], However, many recent reports have indicated more unique potential health benefits of phlorotaimins for a wide variety of diseases. A study by Li et al. [141] revealed that E. cava contains plenty of phlorotannin derivatives with interesting bioactivities. Chemical composition and antioxidant activity studies on E. cava showed that the major phlorotannins present are phloroglucinol, eckol. 

In brown algae, phlorotannins are localized in specialized bodies called physodes (Ragan 1976). Shifting the experimental approach, from chemical assays of total phlorotannin concentration to microscopic methods that describe physode transport and establish the timeframes at which phlorotannins accumulate in response to abiotic or biotic stimuli, has provided new insight into the understanding of phlorotannin production and function. It is known that physodes are derived from the endoplasmic reticulum (ER) and Golgi of the cell (Schoenwaelder and Clayton 2000). It appears that physodes are transferred across the cytosol and incorporated into the cell wall, where the phlorotannins are assumed to have a structural role and thus be involved in primary metabolism (Schoenwaelder and Clayton 2000 Arnold and Targett 2003). 

Several studies have tested hypotheses derived from the CNBM by manipulating the availability of resources (nutrients or light) either in laboratory or in field experiments (Table 7.3). The phlorotannin content in F. vesiculosus at sites with naturally low nitrogen levels was decreased when seaweeds were fertilized in the... 

FIGURE 8.3 Frequency distribution of average phlorotannin concentrations of northeastern Pacific and Australasian rockweeds (Order Fucales) and kelps (Order Laminariales). Data are derived from a compilation of phlorotannin concentrations from the literature.19-24-25-29 31 33 35-37-39-41-42-78-141-150-151... 

Arnold, T.M., In situ rates of phlorotannin synthesis, polymerization, and turnover in marine brown algae an evaluation of terrestrial-derived ecological theories in the marine environment, Ph.D. thesis, University of Delaware, Newark, Delaware, 1998. 

Phlorotannins Phlorotannins are secondary metabolites analogous to the shikimate-derived condensed polyphenolics found in plants and brown algae and absorb strongly from 280 to 320 nm [115]. Exposure to UV-B was found to increase the concentration of phlorotannins in the brown alga Ascophyllum nodosum [116]. That phlorotannins act in photoprotection may be the reason why MAAs are virtually absent in brown algae in comparison to red and green... 

It is a well-understood fact that marine flora harbors a wide range of biologically active compounds that are reported to have an outstanding prospective in the medicinal, nutraceutical, and cosmeceutical applications. Natural metabolites obtained from marine seaweeds prove to be abundant resources with chemical diversity, and among them, phlorotannins are studied most for fheir biological activities. These phlorotannins (Fig. 10.1) are derived from fannins and are composed of several phloroglucinol units linked to each other in different ways and mostly... 

Recent studies have provided evidence that marine algal derived SPs and phlorotannins play a vital role in human health and nutrition. Further, seaweed processing by-products with bioactive SPs and phlorotannins can be easily utilized for producing functional ingredients. The possibilities... 

Tannins are naturally occurring water-soluble polyphenolic compoimds, and it has been reported that they show their anti-HIV activity by inhibiting polymerase and ribonuclease activities of HIV-1 RT. Phlorotannins are tannin derivatives which contain several phloroglucinol imits linked to each other in different ways and formed by the polymerization of phloroglucinol (1,3,5-trihydroxybenzene) monomer units and biosynthesis through the acetate-malonate pathway. So far, phlorotannins mostly have been isolated from red and brown alga. Numerous bioactivities of phlorotannins have been reported up to date such as antioxidant, antiinflammatory, antibacterial, and anti-MMP activities (Kim et al., 2006 Nagayama et al., 2002). 

Acetylation is also useful in the negative-ion mode. Peter-Katalinic et al. [33] have reported the advantages of peracetylation on the FAB target in the analysis of sulfated phlorotannins. In this study, micro scale peracetylation of hydroxy groups on aromatic carbons was performed using the direct addition of 2/acetic anhydride to the analyte. Derivatization on the FAB probe tip facilitates rapid mass spectral analysis and subsequently minimizes the time available for the decomposition of an unstable derivative. 

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