Phlorotannins from Brown Algae (Fucus vesiculosus) Inhibited the Formation of Advanced Glycation Endproducts by Scavenging Reactive Carbonyls

Abstract

Accumulation of advanced glycation end products (AGEs) in vivo is associated with aging, diabetes, Alzheimer's disease, renal failure, etc. The objective of this study was to investigate the inhibitory effects of brown algae Fucus vesiculosus phlorotannins on the formation of AGEs. F. vesiculosus phlorotannins were extracted using 70% acetone. The resultant extract was fractionated into dichloromethane, ethyl acetate, butanol, and water fractions. The ethyl acetate fraction was further fractionated into four subfractions (Ethyl-F1 to -F4) using a Sephadex LH-20 column. F. vesiculosus acetone extract or fractions significantly inhibited the formation of AGEs mediated by glucose and methylglyoxal in a concentration-dependent manner. The concentrations of F. vesiculosus extracts required to inhibit 50% of albumin glycation (EC(50)) in the bovine serum albumin (BSA)-methylglyoxal assay were lower than those of aminoguanidine (a drug candidate for diabetic complication), except for F. vesiculosus acetone extract and dichloromethane fraction. In the BSA-glucose assay, F. vesiculosus extracts inhibited BSA glycation more than or as effectively as aminoguanidine, except for Ethyl-F3 and -F4. The ethyl acetate fraction and its four subfractions scavenged more than 50% of methylglyoxal in two hours. The hypothesis whether F. vesiculosus phlorotannins scavenged reactive carbonyls by forming adducts was tested. Phloroglucinol, the constituent unit of phlorotannins, reacted with glyoxal and methylglyoxal. Five phloroglucinol-carbonyl adducts were detected and tentatively identified using HPLC-ESI-MS(n).

Phloroglucinol protects retinal pigment epithelium and photoreceptor against all‐trans‐retinal–induced toxicity and inhibits A2E formation

“…This result could explain that despite depletion of atRAL in primary cells treated with phloroglucinol, the chromene derivative was not detected, suggesting the formation of different adducts in the cellular context (dimeric chromene compounds or reversible adducts). To support this hypothesis, it has been shown that a molar excess of phloroglucinol can form various adducts with glyoxal and methylglyoxal [25].…”

Pre-column incubation followed by fast liquid chromatography analysis for rapid screening of natural methylglyoxal scavengers directly from herbal medicines: Case study of Polygonum cuspidatum

“…Considering MGO co-eluted with the mobile phase, this dicarbonyl was allowed to react with o-phenylenediamine to form stable 2-methylquinoxaline for reliable quantification by UHPLC [24,26]. Briefly, MGO (1 mM) was incubated with PBS (control), or test samples (1 mM) in PBS (100 mM, pH 7.4) at 37 • C and shaken at 70 rpm for 0-24 h, respectively.…”

“…This assay was adopted from the literatures with some modifications and used to evaluate inhibitory effects of compounds on protein glycation induced by MGO [24,26]. Briefly, HSA (10 mg/mL) was incubated with MGO (5 mM) in the absence or presence of test compounds (0.2, 0.5, 1 mM) in PBS (100 mM, pH 7.4) at 37 • C for 7 days.…”

“…The conventional approach was isolating of chemical compounds from herbal medicines and testing them one by one. Although this strategy has been successful in the discovery of some bioactive compounds [25][26][27], the procedure is time-consuming, arduous and low efficient. Moreover, herbal medicines usually contain up to hundreds of various components, which makes the purification and screening of bioactive components extremely difficult.…”

Bioactive Compounds from Macroalgae in the New Millennium: Implications for Neurodegenerative Diseases

“…A number of phlorotannin oligomers, including fucophlorethol A, tetrafucol A and trifucodiphlorethol A, isolated from Fucus vesiculosus Linnaeus (obtained from Maine Seaweed Co. (Steuben, ME, USA)), was able to scavenge reactive carbonyls, inhibiting the formation of AGEs (Figure 4) [66]. …”