Silk, A Commercially Exploited Textile Material Is Generally Produced By The Silkworms Under The Order Lepidoptera. Mulberry Silk Is Produced Mainly By The Domesticated Silkworm Bombyx Mori Under Family Bombycidae While Non-Mulberry Silk (Tasar) Is Produced By The Wild Silkworm Antheraea Mylitta Under Family Saturniidae And Is Endemic To India. The Cocoon Of All Silkworms Is Composed Of Two Major Proteins: Fibroin, The Major Structural Hydrophobic Protein, Which Is Secreted From Posterior Silk Gland; And Sericin, A Hydrophilic Glycoprotein, Biosynthesized In Middle Silk Gland Of The Mature Silkworm Larva. The Sericin Glues The Fibroin Fibers Together To Form The Fibroin Fiber-Sericin Composite (Cocoons). Sericin Is Composed Of 18 Different Amino Acids, Most Of Which Have Strongly Polar Hydroxyl Side Groups, Which Impart Valuable Antioxidant Potential To It. In The Commercial Textile Industry, Sericin Is Mostly Removed As A Byproduct And Hence, Remains Underutilized. The Utilization Of Sericin Might Be Able To Pave The Way For The Development Of A Valuable Material For Cosmetic, Food And/Or Medicine Industry. The Cocoon Of A. Mylitta Is Composed Of Three Major Sericin Fractions (70 Kda, ~200 Kda And > 200 Kda) With The Lowest Around 70 Kda. Purification And Partial Molecular Characterization Revealed The 70 Kda Protein To Be Enriched In Serine And Glycine Amino Acids. The Polyclonal Antibody Raised Against The 70 Kda Sericin Shows No Cross Reaction With Sericin Isolated From Mulberry Silkworm B. Mori, Thereby Suggesting It As An Unusual Family Of Serine-Rich Proteins. Immunoblot Analysis With Proteins Isolated From Middle Silk Gland Of A. Mylitta At Different Developmental Stages Of Larva Showed That The 70 Kda Sericin Is Developmentally Regulated. The Secondary Structure Of Sericin Includes Β-Sheet And Urea Denaturation Studies Indicate It Is Resistant To Urea . To Evaluate The Antioxidant Potential, Anti-Apoptotic Effect Of A. Mylitta Sericin On Ultraviolet (UVB) Irradiated Human Keratinocytes (Hacat) Has Been Studied. Flow Cytometry And DNA Fragmentation Studies Have Shown That The Pretreatment Of Sericin Protects The UVB Induced (30 And 40 Mj/Cm2) Apoptosis. Immunoblotting Reveals That Sericin Pre-Treatment Suppresses Bax Expression, Up-Regulates The Expression Of Bcl-2, Prevents Both The Activation Of Caspase-3 And Cleavage Of PARP In UVB Induced Hacat. Treatment Of Sericin Also Decreases The Intracellular Hydrogen Peroxide Production In UVB Damaged Keratinocytes, Suggesting That Sericin Probably Inhibits The UVB Induced Apoptosis By Preventing Mitochondrial Damage. Upon Pretreatment With Sericin, Hydrogen Peroxide Challenged Fibroblasts Released Significantly Lower Levels Of Catalase, Lactate Dehydrogenase And Malondialdehyde Activity When Compared To Untreated Ones. In Conclusion, Sericin From Cocoon Of A. Mylitta Is Biochemically And Immunochemically Distinct From That Of The Mulberry Silkworm B. Mori. Sericin Has Been Found To Significantly Inhibit UVB And Hydrogen Peroxide Induced Cell Death In Keratinocytes And Fibroblasts Respectively.