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Silk peptides
Silk Peptides is a kind of silk proteinic product with smaller molecular weight consisted by a few or ten odd amino acids. Its molecular weight is generally between 300 to 2000 with better water soluble property but not dissolved in the high density ethanol or ether.
The silk peptide in large molecular weight has a good membranate character which gives the hair natural gloss and elasticity to let the hair easy dressing and making up. The silk peptide of low molecular weight is easy to be absorbed by skin, and to be permeated to the inner of hair to provide the necessary nurture for its normal metabolism, as well as to repair the injured hair.
The Benefits of Silk Peptides:
Silk Peptides contains "Fibroin" and "Sericin", "Sericin" provides moisture to skin, antioxidant, cell regeneration, tyrosinase inhibition, prevent formation of melanin. Study shown that amino acid that is contained in Sericin protein is very similar to Natural Moisturising Factor (NMF) content of skin's surface layer (stratum corneum).
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Deep Whitening - Protect against UV rays with melanin block concentration for a radiant, transparent and fair skin.
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Natural Moisturise - Sericin appears to possess anti-lipid peroxidation properties and thus is an anti-oxidant in vitro. It has been used with success as a moisterizser in human volunteers and in rats orally through 1% of the diet.
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Anti-Aging
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Antioxidant effect that strengthens and maintain the skin immune system.
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Promotes cell regeneration and prevents premature cell apoptosis.
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Promotes collagen production that enhances firming effect and reduces wrinkles and pores size.
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Enhances body's immune system.Promotes insulin secretion.
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Improves liver function and liver cleansing function.
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Accelerates wound healing, resistance to bacterial infection.
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Improves blood cholesterol level and fat content.
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Stimulates brain activity and mental alertness.
Silk Amino Acids
Essential Benefits of Silk Amino Acids
Silk Amino Acids are a mixture of amino acids obtained from the cocoon of the Silk Worm Bombix Mori. The mixture of amino acids is very high in the amino acids serine and aspartate, and some versions are rich in tyrosine as well.
The protein can be found in a hydrolysed (pre-digested) form known as Sericin-S, or as a undigestible form known as Sericin-L. The undigestible form appears to exert protective effects on the colon and intestinal tract, whereas the hydrolysed form can beneficially affect systemic (post-intestinal) metabolic functions.
Sericin also appears to beneficially affect the skin, in both a protective sense (anti-oxidation, anti-UV radiation) as well as increasing moisture content. These effects may be seen with both topical application or ingestion.
It looks to be a promising compound, but no human studies on health have been conducted.
1. Sources and Composition
1.1. Sources
Silk Amino Acids are a selection of dietary amino acids from silk. They are arranged in such an order that they form the bioactive peptide 'Sericin'. There are multiple 'Sericin' components, such as Sericin Small (Sericin-S) (5-100kDa in size) which is hydrolyzed and prepared from basic Sericin and Sericin Large (Sericin-L) (50-200kDa) which is non-hydrolyzed. The general idea is that they possess a specific amino acid sequence, which are rich in serine amino acids, at around 30-33% Serine by weight.
Sericin prepared in culture as per this study recorded the sequence of SSTGS SSNTD SNSNS AGSST TYGYS SNSRD GSV. These researchers denoted 'SerD' as a dimer of the above sequence and 'SerT' as a trimer.
They are extracted from the Bombix Moricocoon of the silkworm.
1.2. Other compounds in Silk Amino Acids
Beyond Sericin, components from the cocoon of the silkworm include:
• Fibroin at 70% of cocoon by weight
• Sericin at 25% of the cocoon by weight
• 'Non-Sericin' flavonoids and free amino acids, with potent biological effects.
2. Interactions with Cell proliferation
Sericin has been implicated as having mitogenic properties in vitro on mammalian cells.
It is being explored as being a tool for cell cultures as a replacement for Bovine Serum Albumin. In regards to its ability to feed cell division, the hydrolyzed fragment (Sericin-S) appears to be almost twice as potent (as assessed by viable cells after incubation) as Sericin-L.
In a study on human HepG2 cells, the pathway appears to be through activation of the Erb-b2 receptor and eventual signalling on ERK1/2 via Src and Ras.
These effects on accelerating cell culture growth appear to be dose dependent (as evidenced by doses of 0.01% and 0.1% culture) but showed harm to the medium at higher dosages (0.1%).
Appears to induce cell proliferation and growth when used as a protein medium in vitro, but no evidence suggests this occurs after oral consumption
3. Effects on Performance
One study in mice, with oral dosages of 50,160, and 500mg/kg bodyweight daily, increased performance in the forced swim test in a dose dependent manner over 44 days of treatment. The SAA used in this study was freeze-dried and higher in Alanine (34.36%) with a Serine content of 9.58%. This enhancement of performance was also found in a past study, albeit confounded with supplemental tyrosine.
Only high dose SAA showed benefit in two weeks time, whereas both 160mg and 500mg showed benefits at the end of the study (albeit with a dose-dependent benefit). The numbers were a 35.9% time to exhaustion from 500mg/kg daily at 14 days, and 58.8%/121.4% increased time to exhaustion at day 44 with 160mg and 500mg/kg bodyweight respectively.
The former study also found that the weight gain (from diet) was attenuated with exercise and further attenuated with SAA. Muscle glycogen depletion from exercise was also attenuated in a dose dependent manner with SAA.
Decent preliminary results, but needs replication
4. Interactions with Hormones
Silk Amino Acid supplementation was able to prevent the decline in testosterone associated with excessive exercise in rats subject to a weighted swim test.
5. Interactions with Fat and Glucose Metabolism
After high dose feeding in rats, Sericin (4% of diet by weight) appears to reduce serum levels of free fatty acids and LDL/vLDL lipoproteins.
Liver triglyerides and lipogenic enzymes (malate dehydrogenase, G6P dehydrogenase) were also reduced at this dose.
6. Intestinal Interactions
6.1. Minerals
In rats fed with 3% of their diet as sericin, intestinal absorption of minerals (Zn, Fe, Mg, Ca) increased by 41%, 41%, 21% and 17% respectively. However, this study did not note elevated serum levels. Final body weight was also unaffected by the supplementation.
The 'apparent increase in absorption' was noted due to decreased fecal mineral levels, which was thought to be due to enhanced solubilization of the elements in the GI tract through serine and aspartate's hydroxyl and carboxyl groups (respectively); a mechanism of action only currently known to be attributed to caseinphosphopeptides.
In the digestive tract, it has been noted to be resistant to 'several proteases' as noted by these authors in their previous, but unpublished, work. Specific proteases were not mentioned.
6.2. Other effects
One study in rats showed that sericin had the potential to increase fecal immunogluboulin A, mucins, and cecal acids in vivoat a high dose; suggesting that it can interact with the intestinal barrier and immune status and possibly fermantation. A similar dose has also been found to reduce serum triglycerides and glucose during high-fat feeding (the former of which the previous study also found).
Although it is noted to be a 'resistant protein' and thus exert some biological effects in the intestine pre-absorption, at least one study noted that systemic effects were attenuated after injection of glucose (suggesting sericin can affect systemic metabolism).
In regards to its effects as a resistant protein (undigestible), it can protect against colonic tumor growth when it reaches the colon, and shows benefit in rats at 3% of feed (which replaced casein) due to its anti-oxidative properties. This appears to be attributable to Sericin-L, as the preparation method used by Zhaoirgetu et al. was without hydrolysis.
Colonic anti-oxidative effects may be mediated through chelation of copper ions in the intestines, which are normally pro-oxidative.
7. Cosmetic Usages
Sericin appears to possess anti-lipid peroxidation properties and thus is an anti-oxidant in vitro. It has been used with success as a moisterizer in human volunteers and in rats orallythrough 1% of the diet.
Sericin also appears to be UV resistant although this has not been studied in relation to skin damage.
Scientific Support & Reference Citations:
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Terada S, et al. Preparation of silk protein sericin as mitogenic factor for better mammalian cell culture. J Biosci Bioeng. (2005)
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Kato N, et al. Silk protein, sericin, inhibits lipid peroxidation and tyrosinase activity. Biosci Biotechnol Biochem. (1998)
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Terada S, et al. Sericin, a protein derived from silkworms, accelerates the proliferation of several mammalian cell lines including a hybridoma. Cytotechnology. (2002)
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Tsujimoto K, et al. Cryoprotective effect of the serine-rich repetitive sequence in silk protein sericin. J Biochem. (2001)
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Wang HY, et al. Isolation and bioactivities of a non-sericin component from cocoon shell silk sericin of the silkworm Bombyx mori. Food Funct. (2012)
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Sato W, et al. Mitogenic effect of sericin on mammalian cells. BMC Proc. (2011)
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Even MS, Sandusky CB, Barnard ND. Serum-free hybridoma culture: ethical, scientific and safety considerations. Trends Biotechnol. (2006)
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Yanagihara K, et al. Effect of the silk protein sericin on the production of adenovirus-based gene-therapy vectors. Biotechnol Appl Biochem. (2006)
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Shin S, et al. Silk amino acids improve physical stamina and male reproductive function of mice. Biol Pharm Bull. (2010)
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Tyrosine-fortified silk amino acids improve physical function of Parkinson’s disease rats
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Okazaki Y, et al. Consumption of sericin reduces serum lipids, ameliorates glucose tolerance and elevates serum adiponectin in rats fed a high-fat diet. Biosci Biotechnol Biochem. (2010)
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Consumption of silk protein, sericin elevates intestinal absorption of zinc, iron, magnesium and calcium in rats
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Okazaki Y, et al. Consumption of a resistant protein, sericin, elevates fecal immunoglobulin A, mucins, and cecal organic acids in rats fed a high-fat diet. J Nutr. (2011)
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Zhang YQ. Applications of natural silk protein sericin in biomaterials. Biotechnol Adv. (2002)
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Zhaorigetu S, Sasaki M, Kato N. Consumption of sericin suppresses colon oxidative stress and aberrant crypt foci in 1,2-dimethylhydrazine-treated rats by colon undigested sericin. J Nutr Sci Vitaminol (Tokyo). (2007)
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Padamwar MN, et al.Silk sericin as a moisturiser: an in vivo study. J Cosmet Dermatol. (2005)
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Kim H, et al. Dietary silk protein, sericin, improves epidermal hydration with increased levels of filaggrins and free amino acids in NC/Nga mice. Br J Nutr. (2012)
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