Phloroglucinol compounds of natural origin

Eucalmaidins A-E, (+)-oleuropeic acid derivatives from the fresh leaves of Eucalyptus maideni

Five new (+)-oleuropeic acid derivatives, eucalmaidins A-E (1-5), together with 12 known compounds (6-17), were isolated from the fresh leaves of Eucalyptus maideni. Structures of the new compounds were determined on the basis of spectroscopic analyses (HSQC, HMBC, and (1)H-(1)H COSY), chemical degradation, and enzymatic hydrolysis. Of the tested compounds, only quercetin showed slight anti-herpes simplex virus 1 (HSV-1) activity in vitro.

Guttiferones O and P, prenylated benzophenone MAPKAPK-2 inhibitors from Garcinia solomonensis

Two prenylated benzophenones, guttiferones O (1) and P (2), were isolated from the stem bark of the Papua New Guinean plant Garcina solomonensis. The structures of these compounds and their relative configurations were determined by spectroscopic methods. Both compounds inhibited the phosphorylation of the synthetic biotinylated peptide substrate KKLNRTLSVA by the serine/threonine protein kinase MAPKAPK-2 with IC(50) values of 22.0 microM.

Chemical components and its antioxidant properties in vitro: an edible marine brown alga, Ecklonia cava

Seven phlorotannins were isolated and characterized from an edible marine brown alga Ecklonia cava (EC), along with three common sterol derivatives (fucosterol, ergosterol, and cholesterol) according to the comprehensive spectral analysis of MS and NMR data. Compounds 5 (7-phloro eckol) and 7 (6,6'-bieckoll) of phlorotannin derivatives were obtained for the first time with the high yields. No reports of compound 3 (Fucodiphloroethol G) was published up to date. The antioxidant properties of all phlorotannins were assessed by total antioxidant activity in a linoleic acid model, free radicals scavenging assay using electron spin resonance spectrometry (ESR) technique, cellular reactive oxygen species (ROS) assay by DCFH-DA, membrane protein oxidation assay; measurement of cellular glutathione (GSH) level in RAW264.7 cell line, and myeloperoxidase (MPO) assay in HL-60 cell line. The results revealed that all phlorotannins had antioxidant properties in vitro, especially, compounds 7 (6,6'-bieckol), 6, and 3 showed the significant activities compared to the other phlorotannins. Furthermore, the structure-activity relationship (SAR) was discussed based on the structural differences of the tested phlorotannins which have polymeriged phloroglucinal units with diverse skeletons and linkages. It could be suggested that phlorotaninns from this genus would be more potential candidates for the development of unique natural antioxidants for further industrial applications as functional foods, cosmetics and pharmaceuticals. As well as our results makes it clear to understand the reason behind the use of EC as traditional folk herb for a long history.

Discovery of diacylphloroglucinols as a new class of GPR40 (FFAR1) agonists

In this letter, we report discovery of diacylphloroglucinol compounds as a new class of GPR40 (FFAR1) agonists. Several diacylphloroglucinols with varying length of acyl functionality and substitution on aromatic hydroxyls were synthesized and evaluated for GPR40 agonism using functional calcium-flux assay. Out of 17 compounds evaluated, 14, 17, 19 and 25 exhibited good GPR40 agonistic activity with EC(50) values ranging from 0.07 to 8 microM (pEC(50) 7.12-5.09), respectively, with maximal agonistic response of 84-102%.

Anti-HIV-1 activity of phloroglucinol derivative, 6,6'-bieckol, from Ecklonia cava

Ecklonia cava (EC), which is an edible marine brown alga with a broad range of bioactivities, belongs to the family of Laminariaceae. The bioactive 6,6'-bieckol, one of the main phloroglucinol derivatives naturally occurred from this genus, was isolated and characterized by NMR techniques. For the first time, human immunodeficiency virus type-1 (HIV-1) inhibitory activity of 6,6'-bieckol showed wild inhibition against HIV-1 induced syncytia formation (EC(50) 1.72 microM), lytic effects (EC(50) 1.23 microM), and viral p24 antigen production (EC(50) 1.26 microM), respectively. This result was strongly and clearly supported by the further investigation also, which 6,6'-bieckol selectively inhibited the activity of HIV-1 reverse transcriptase (RT) enzyme with EC(50) of 1.07 microM, as well as HIV-1 entry. Moreover, unlike most of other tannins, 6,6'-bieckol exhibited no cytotoxicity at concentrations which inhibited HIV-1 replication almost completely. Thus, it can be suggested that the potentially effective 6,6'-bieckol might be employed as a drug candidate for development of new generation therapeutic agents against HIV.

Characterizing the metabolic fingerprint and anti-inflammatory activity of Hypericum gentianoides

In this paper we characterize the metabolic fingerprint and first reported anti-inflammatory activity of Hypericum gentianoides. H. gentianoides has a history of medical use by Native Americans, but it has been studied very little for biological activity. High-performance liquid chromatography (HPLC) and liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) analyses of a methanol extract show that H. gentianoides contains a family of over nine related compounds that have retention times, mass spectra, and a distinctive UV absorption spectra characteristic of certain acyl-phloroglucinols. These metabolites are abundant relative to other secondary products present in H. gentianoides, accounting for approximately 0.2 g per gram of dry plant tissue. H. gentianoides methanol extracts and a specific semipreparative HPLC fraction from these extracts containing the putative acyl-phloroglucinols reduce prostaglandin E 2 synthesis in mammalian macrophages.