ABSTRACT
Introduction 466
Hydrolyzable Tannins 466
Gallotannins 467
Ellagitannins 467
Gallo-ellagitannins 467
Condensed Tannins (Proanthocyanidins) 467
Phyllanthus Tannins 467
Occurrence of Tannins 469
Tannins of Phyllanthus emblica 470
Product Description and Standardization 470
Product Stability 472
Antioxidant Activity 472
Hydroxy Radical Quenching 472
Superoxide Anion Radical Quenching 473
Singlet Oxygen Quenching 474
Nitrogen Radical Quenching 474
Boosting of Antioxidant Defense Enzymes 475
Chelating Activity 476
Chelators as Oxidation Enhancer 476
Antioxidants Act as Pro-Oxidants 476
Chelating Property of Emblica Antioxidant 477
Matrix Metalloprotease (MMP) Enzymes 478
Collagenase (MMP-1) Inhibitory Activity of Emblica Antioxidant 479
Stromelysin 1 (MMP-3) Inhibitory Activity of Emblica Antioxidant 480
Extracellular Matrix (ECM) Proteins 480
Stimulation of Noncollagenic Protein Synthesis 481
Skin Lightening/Skin Even-Toning 481 Emblica Antioxidant Lightens the Normal Skin Color 482
Emblica Antioxidant Reduces Freckle Spots 482
Emblica Antioxidant Reduces UV-Induced Erythema 483
Safety Data 483
Acute Oral Toxicity Study in Rats 483
Primary Eye Irritation Study in Rabbits 483
Evaluation of Phototoxicity Potential by UV-A Irradiation on
Human Subjects 483
Repeat Insult Patch Test on Human Subjects/Skin Irritation and Skin Sensitization Evaluation 484
Bacterial Mutagenicity Test 484
Conclusion 484
References 485
INTRODUCTION
Phenolic metabolism in plants is complex, and yields a wide array of compounds
ranging from the familiar flower pigments (anthocyanidins) to the complex phe-
nolics of the plant cell wall (lignin). However, the group of phenolic compounds
known as tannins is clearly distinguished from other plant secondary phenolics in
their structural chemistry and biological activities. The term “tannin” comes from
the ancient Celtic word for oak, a typical source of tannins for leather making.
Tannins are usually subdivided into two groups: hydrolyzable tannins (HT)
and condensed tannins [CT, often-called proanthocyanidins (PA)].
