Phloroglucinol compounds of natural origin

In the last years, tannase has been the subject of a lot of studies due to its commercial importance and complexity as catalytic molecule. Tannases are capable of hydrolyzing complex tannins, which represent the main chemical group of natural anti-microbials occurring in the plants. The general outline of this work includes information of the substrates, the enzyme, and the applications. This review considers in its introduction the concepts and history of tannase and explores scientific and technological aspects. The "advances" trace the route from the general, molecular, catalytic, and functional information obtained under close to optimal conditions for microbial production through purification, description of the enzyme properties, and the commercial applications to the "perspectives" including expression studies, regulation, and potential uses; aspects related to the progress in our understanding of tannin biodegradation are also included.

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Microbial tannases: advances and perspectives

Identification of phenolics in the fruit of emblica (Phyllanthus emblica L.) and their antioxidant activities.

Eighteen main compounds, including four norsesquiterpenoids (1-4) and 14 phenolic compounds (5-18) isolated previously from Phyllanthus emblica, together with a main constituent, proanthocyanidin polymers (19) identified at this time from the roots, were estimated for their antiproliferative activities against MK-1 (human gastric adenocarcinoma), HeLa (human uterine carcinoma), and B16F10 (murine melanoma) cells using an MTT method. All of the phenolic compounds including the major components 5-8 from the fruit juice, 8, 9, and 12 from the branches and leaves, and 19 from the roots showed stronger inhibition against B16F10 cell growth than against HeLa and MK-1 cell growth. Norsesquiterpenoid glycosides 3 and 4 from the roots exhibited significant antiproliferative activities, although their aglycon 1 and monoglucoside 2 showed no inhibitory activity against these tumor cells.

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Antiproliferative Activity of the Main Constituents from Phyllanthus emblica

Nowadays, many researches have been made on gallotannin biodegradation and have gained great success in further utilization. Some of industrial applications of these findings are in the production of tannase, the biotransformation of tannic acid to gallic acid or pyrogallol and detannification of food and fodder. Although ellagitannins have the typical C–C bound which is more difficult to be degraded than gallotannins, concerted efforts are still in progress to improve ellagitannin degradation and utilization. Currently, more attention is mainly focused on intestinal microflora biodegradation of tannins especially ellagitannins which can contribute to the definition of their bioavailability for both human beings and ruminants. Also there have been endeavours to utilize the tannin-degrading activity of different fungi for ellagitannin-rich biomass, which will facilitate application of tannin-degrading enzymes in strategies for improving industrial and livestock production. Due to the complicated structures of complex tannins and condensed tannins, the biodegradation of them is much more difficult and there are fewer researches on them. Therefore, the researches on the mechanisms of gallotannin and ellagitannin biodegradation can result in the overall understanding to the biodegradation of complex tannins and condensed tannins. Biodegradation of tannins is in an incipient stage and further studies have to be carried out to exploit the potential of various tannins for largescale applications in food, fodder, medicine and tannery effluent treatment. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Biodegradation of gallotannins and ellagitannins

Six new ellagitannins, phyllanemblinins A-F (1-6), were isolated from Phyllanthus emblica, along with 30 known tannins and related compounds. Their structures were determined by spectral and chemical methods. Phyllanemblinins A (1) and B (2) were confirmed to be ellagitannins having a tetrahydroxybenzofuran dicarboxyl group and a hexahydroxydiphenoyl group, respectively, by chemical synthesis from furosin (8). Phyllanemblinin C (3) has a new acyl group at the glucose 2,4-positions and is structurally related to chebulagic acid. Phyllanemblinins D (4), E (5), and F 6) were found to be positional isomers of neochebuloyl 1(beta)-O-galloylglucose.

Phyllanemblinins A-F, new ellagitannins from Phyllanthus emblica.

Phyllanthus emblica L. (Euphorbiaceae) is a shrub or tree native to subtropical and tropical areas of China, India, Indonesia and the Malay Peninsula. The fruit has been widely used for antiinflammatory and antipyretic treatment. The root, leaves and bark are also used for the treatment of indigestion, diarrhea or dysentery, eczema and wart. As a continuation of investigation on the constituents of this plant, 1—5) we chemically examined its leaves and branches, and two new acylated flavanone glycosides, a new phenolic glycoside, and 22 known compounds were isolated. This paper describes the isolation and structural elucidation of these com

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Tomomi Abe

Papers

Phyllanemblinins A-F, new ellagitannins from Phyllanthus emblica.

Two New Acylated Flavanone Glycosides from the Leaves and Branches of Phyllanthus emblica