A practical reference on thymic extract: what it is, how it behaves, what the literature reports, and where the honest uncertainties sit.
This page was last updated on 2026-06-28 and is reviewed periodically as new material appears.
胸腺素α1（thymosin alpha 1，Tα1）是一种由28个氨基酸组成的酸性肽，N端被乙酰化，分子量约为3108道尔顿。该肽最早从牛胸腺组织提取物中分离，属于胸腺素组分5的一个成分。其序列在不同哺乳动物中高度保守，提示其具有基本的生物学功能。名称中的“α1”指其在电泳中的迁移位置，并非表示亚型编号。它既存在于胸腺，也存在于脾脏和淋巴结等免疫组织。
20世纪70年代，研究者从胸腺提取物中纯化出多种小肽，Tα1是其中被较早表征的一种。最初的制备依赖组织匀浆和层析步骤，产量低且成分复杂。随着固相肽合成技术成熟，实验室和工业界能够生产与天然序列一致的合成版本。合成肽的纯度可达95%以上，并可通过反相高效液相色谱和质谱进行鉴定。这一转变使研究不再依赖动物胸腺来源。
Several names appear in the literature for this peptide, including thymalfasin and the abbreviation T-alpha-1. Naming conventions differ among research articles, regulatory documents, and supplier catalogs, which complicates literature searches. Both synthetic and recombinant production routes yield a peptide with the same 28-residue sequence as the thymic isolate. Because the thymosin label also covers unrelated peptides, sources should be compared by sequence rather than by name alone.
The peptide occurs naturally in thymic tissue and has been detected in serum and other biological fluids. Reported concentrations are low, and reliable measurement generally requires immunoassay or mass spectrometry with an enrichment step. It is released from a larger precursor, prothymosin alpha, by proteolytic cleavage, although the enzymes involved are not fully characterized. Whether circulating levels reflect thymic output specifically remains an open question.
| Property | Value | Notes |
|---|---|---|
| 化学分类 | 线性肽 | 由28个氨基酸组成 |
| 分子量 | 约3108 Da | 合成版本一致 |
| 外观 | 白色至类白色粉末 | 冻干品 |
| 溶解度 | 易溶于水 | 微溶于有机溶剂 |
| 储存温度 | -20°C（冻干） | 溶解后2-8°C |
Thymosin beta-4 is a separate 43-residue peptide that binds actin and participates in cell migration; it shares no sequence similarity with thymosin alpha-1 despite the common family name. Other preparative materials, such as thymosin fraction 5 and thymopoietin, contain distinct mixtures or peptides. The shared thymosin label reflects the tissue of origin used in early purification, not a common structural core. Treating these molecules as interchangeable is a frequent source of confusion in laboratory reports and in popular summaries alike.
Thymosin alpha-1 is a synthetic peptide of 28 amino acid residues that corresponds to a naturally occurring fragment first isolated from thymus tissue. Its chain is acetylated at the amino terminus, a modification that shields the peptide from rapid cleavage by aminopeptidases. The molecule carries a net negative charge at physiological pH and dissolves freely in water. Researchers classify it as an immune-modulating agent rather than a classical hormone, because it acts on several cell types of both the innate and the adaptive immune system.
The peptide was identified during work in the 1970s on thymosin fraction 5, a partially purified extract of calf thymus. Investigators separated that mixture and characterized individual components, one of which they named thymosin alpha-1. The same compound later received the international nonproprietary name thymalfasin. Commercial material is produced by solid-phase peptide synthesis rather than by extraction, so synthetic and natural forms share an identical sequence. Naming conventions vary across the literature, and readers should distinguish the alpha-1 peptide from other thymosins that have unrelated sequences and functions.
Identity and purity testing for thymosin alpha 1 relies mainly on reversed-phase high-performance liquid chromatography and mass spectrometry. Chromatography separates the parent peptide from truncated or modified variants, while mass spectrometry confirms the expected molecular mass. Amino acid analysis and peptide mapping provide additional sequence confirmation. Counterion content, water content, and residual solvents are measured separately as part of specification testing. No single method captures every attribute, so laboratories combine several techniques.
The peptide lacks cysteine, methionine, and tryptophan, so disulfide scrambling and sulfur oxidation are not major degradation routes. Instead, aspartate residues can undergo isomerization or cyclization to succinimide intermediates, generating isoaspartate variants. Hydrolysis of peptide bonds also occurs slowly in solution. These changes may reduce biological activity even when the main peak remains detectable. Stability studies therefore track both potency and the appearance of related substances.
== Alternative pathway == Plants, most bacteria, and some protozoa such as malaria parasites have the ability to produce isoprenoids using an alternative pathway called the methylerythritol phosphate (MEP) or non-mevalonate pathway. The output of both the mevalonate pathway and the MEP pathway are the same, IPP and DMAPP; however, the enzymatic reactions to convert acetyl-CoA into IPP are entirely different. Interaction between the two metabolic pathways can be studied by using 13C-glucose isotopomers. In higher plants, the MEP pathway operates in plastids while the mevalonate pathway operates in the cytosol. Examples of bacteria that contain the MEP pathway include Escherichia coli and pathogens such as Mycobacterium tuberculosis.
Symptoms of the disease only appear at an advanced stage, when more than two-thirds of the original kidney function has already been lost. This is due to the body's own compensatory mechanisms and the kidney's reserve capacity, which can compensate for the reduced kidney function for a long time and maintain the excretion of urine-requiring substances. With the loss of functioning nephrons—the functional structural unit of the kidney—the filtering capacity of the renal corpuscles (glomerular filtration rate) decreases and with it the excretory capacity for urinary substances. Acute damage to the tubules can regenerate again if the basement membrane is preserved. However, if a section of the nephron is irreversibly damaged, the entire nephron dies. The increased urea levels in the blood (uremia) lead to nausea and vomiting for various reasons. Firstly, they directly irritate chemoreceptors in the chemoreceptor trigger zone in the brain. Secondly, they increase gastrinsecretion and thus lead to an increase in gastric acid production and thus to hyperacidity of the stomach. Finally, they cause vascular inflammation (uraemic vasculitis), which leads to further damage to the digestive tract. As a result of the accumulation of phosphate in the blood (hyperphosphatemia) and the reduced formation of calcitriol in the remaining main parts, there is a drop in the calcium blood level (hypocalcemia) and increased parathyroid hormone is released from the parathyroid gland. Chronic kidney disease leads to hyperparathyroidism in 84% of cases (secondary renal hyperparathyroidism).
=== Approval history === On 22 December 2009, a New Drug Application (NDA) was submitted to the Food and Drug Administration (FDA) in the United States. On 16 September 2010, an FDA advisory panel voted 9–5 against approval of the drug based on concerns over both efficacy and safety, particularly the findings of mammary gland tumors of female rats. On 23 October 2010, the FDA decided not to approve the drug based on the available data. This was not only because cancer promoting properties could not be ruled out, but also because the weight loss efficacy was considered "marginal". On 10 May 2012, after a new round of studies submitted by Arena, an FDA panel voted to recommend lorcaserin with certain restrictions and patient monitoring. The restrictions include patients with a BMI of over 30, or with a BMI over 27 and a comorbidity such as high blood pressure or type 2 diabetes. On 27 June 2012, the FDA approved lorcaserin for use in adults with a body mass index (BMI) of 30 or greater (obese), or adults with a BMI of 27 or greater (overweight) and who had at least one weight-related condition such as high blood pressure (hypertension), type 2 diabetes, or high cholesterol (dyslipidemia). On 15 July 2016, the FDA approved the extended release version of lorcaserin for weight management with once-daily dosing instead of twice daily dosing. On 17 September 2020, the FDA withdrew approval for lorcaserin and for extended-release lorcaserin tablets.
The public expected Jonas Salk or Albert Sabin to receive the prize for their development of the polio vaccines, but instead the award went to John Enders, Thomas Weller, and Frederick Robbins whose basic discovery that the polio virus could reproduce in monkey cells in laboratory preparations made the vaccines possible. Through the 1930s, there were frequent prize laureates in classical physiology, but after that, the field began fragmenting into specialities. The last classical physiology laureates were John Eccles, Alan Hodgkin, and Andrew Huxley in 1963 for their findings regarding "unitary electrical events in the central and peripheral nervous system."
Sources: en.wikipedia.org
=== EDTA-dependent agglutination === In some individuals, clinically insignificant antibodies may cause in vitro agglutination of platelets. As a result of platelet clumping, platelet counts reported by automated counters may be much lower than the actual count in the blood because these devices cannot differentiate platelet clumps from individual cells. Pseudothrombocytopenia has been reported in association with the use of EDTA as an anticoagulant, with platelet cold agglutinins, and with multiple myeloma. Other risk factors associated with pseudothrombocytopenia are autoimmune diseases, infections, pregnancy and the treatment with some medications such as low-molecular-weight heparin, valproic acid, insulin, antibiotics and chemotherapy medications like sunitinib. The prevalence of pseudothrombocytopenia in K2-EDTA reported in different studies ranges from 0.03 to 0.27 percent in outpatients, which accounts for 15 to 30 percent of all cases of isolated thrombocytopenia. Tests can mistake small clumps of platelets for leukocytes, thus showing a pseudoleukocytosis in blood counts.
== See also == Ergine (lysergic acid amide; LSA; lysergamide) Aztec use of entheogens § Ololiuqui and Tlitliltzin Morning glory § Chemistry and ethnobotany List of entheogens List of psychoactive plants
== Further reading == Griesemer RL (25 July 2008). Index of Central Obesity as a Parameter to Evaluate Metabolic Syndrome for White, Black, and Hispanic Adults in the United States (Master's thesis). Public Health Theses, Georgia State University. doi:10.57709/1062268. Archived from the original on 22 July 2012. Retrieved 4 June 2011. Lee K, Song YM, Sung J (April 2008). "Which obesity indicators are better predictors of metabolic risk?: healthy twin study". Obesity. 16 (4): 834–40. doi:10.1038/oby.2007.109. PMID 18239595. S2CID 1633972. Shao J, Yu L, Shen X, Li D, Wang K (November 2010). "Waist-to-height ratio, an optimal predictor for obesity and metabolic syndrome in Chinese adults". The Journal of Nutrition, Health & Aging. 14 (9): 782–5. doi:10.1007/s12603-010-0106-x. PMID 21085910. S2CID 11187741. Pant S (31 October 2025). "Normal BMI With Abdominal Obesity Associated With Cardiometabolic Risks". JAMA (Medical News in Brief). 334 (16): 1875. doi:10.1001/jama.2025.17532. PMID 41171291.
In 2019, Kennedy called on the Treasury Department to establish a website where citizens could find out whether they had unclaimed Treasury savings bonds. He established a similar website for the state of Louisiana when he was treasurer. On October 22, 2019, the Treasury Department announced that it would launch a website for unclaimed bonds. Kennedy said, "The bond might be lost, the physical bond in the days when we used paper bonds, and the people who loaned the money to the federal government might have forgotten about the bonds. But you know who knows about the bonds? The United States Department of Treasury, because they've got the names and the addresses, and right now they've got the money—$26 billion that they are holding that belongs to the American people, and they won't give it back." On November 25, 2019, Trump signed Kennedy's Recovery for Small Businesses After Disaster Act, a bill allowing small business disaster loans to remain at a limit of $25,000, rather than dropping to $14,000. After Justice Ruth Bader Ginsburg's death in 2020, Kennedy supported Trump's nomination of Amy Coney Barrett to fill the Supreme Court vacancy. Kennedy voted to confirm Barrett, and said in an interview on Tucker Carlson Tonight, "you would have to be barking mad to think that she is not qualified". After her confirmation on October 26, he applauded it as a "victory for our founders". On February 4, 2020, Kennedy voted against Trump's first impeachment.
Janaki Ramachandran of the AIADMK became the first woman to hold the position of the state's chief minister. J. Jayalalithaa of the AIADMK became the youngest Chief Minister of Tamil Nadu at the age of 43 in 1991, and had the second longest tenure, holding the office for more than fourteen years across multiple terms. There have been four instances of President's rule in Tamil Nadu, most recently in 1991. C. Joseph Vijay of the Tamilaga Vettri Kazhagam is the incumbent Chief Minister since 10 May 2026.
Sources: en.wikipedia.org
2 SeO3 → 2 SeO2 + O2 (ΔH = −54 kJ/mol) Selenium trioxide is produced in the laboratory by the reaction of anhydrous potassium selenate (K2SeO4) and sulfur trioxide (SO3). Salts of selenous acid are called selenites. These include silver selenite (Ag2SeO3) and sodium selenite (Na2SeO3). Hydrogen sulfide reacts with aqueous selenous acid to produce selenium disulfide:
==== Absorption ==== With oral administration of a single dose, THC is almost completely absorbed by the gastrointestinal tract. However, due to first-pass metabolism in the liver and the high lipid solubility of THC, only about 5 to 20% reaches circulation. Following oral administration, concentrations of THC and its major active metabolite 11-hydroxy-THC (11-OH-THC) peak after 0.5 to 4 hours, with median time to peak of 1.0 to 2.5 hours at different doses. In some cases, peak levels may not occur for as long as 6 hours. Concentrations of THC and 11-hydroxy-THC in the circulation are approximately equal with oral administration. There is a slight increase in dose proportionality in terms of peak and area-under-the-curve levels of THC with increasing oral doses over a range of 2.5 to 10 mg. A high-fat meal delays time to peak concentrations of oral THC by 4 hours on average and increases area-under-the-curve exposure by 2.9-fold, but peak concentrations are not significantly altered. A high-fat meal additionally increases absorption of THC via the lymphatic system and allows it to bypass first-pass metabolism. Consequently, a high-fat meal increases levels of 11-hydroxy-THC by only 25% and most of the increase in bioavailability is due to increased levels of THC. The bioavailability of THC when smoking or inhaling is approximately 25%, with a range of 2% to 56% (although most commonly between 10–35%).
==== Agrochemicals ==== Agrochemical companies are the second largest users of fine chemicals. Most products have a "pharmaceutical heritage". As a consequence of an intensive M&A activity (Mergers and Acquisitions) over the past 10–20 years, the industry now is more consolidated than the pharmaceutical industry. The top 10 companies, led by Syngenta, Switzerland; Bayer Cropsciences, Germany: Monsanto, USA; BASF Crop Protection, Germany, and Dow Agrosciences, USA have a share of almost 95% of the total 2,000,000 tons / $48.5 billion pesticide output in 2010. Since the 1990s, the R&D effort has been focused mainly on gene modified (GM) seeds. At both Monsanto and DuPont's seed subsidiary, Pioneer Hi-Bred, the GM seed businesses already account for more than 50% of total sales. 100 new LMW agrochemicals were launched between 2000–2009. However, only 8 products achieved sales in excess of $100 million per year. Generics play a bigger role in the agro than in the pharma industry. They represent some 70% of the global market. China National Chemical Corp is the world's largest supplier of generic farm chemicals. Mahkteshim Agan, Israel, and Cheminova, Denmark, rank second and third. Apart from these multibillion-dollar companies, there are hundreds of smaller firms with sales of less than $50 million per year, mainly in India and China. The incidence of the cost of the active ingredient is about 33%, much higher than in drugs.
=== Air quality analysis === In Fig. 3 a mass spectrum of air inside a laboratory (obtained with a time-of-flight (TOF) based PTR-MS instrument), is shown. The peaks on m/z 19, 37 and 55 (and their isotopes) represent the reagent ions (H3O+) and their clusters. On m/z 30 and 32 NO+ and O2+, which are both impurities originating from the ion source, appear. All other peaks correspond to compounds present in typical laboratory air (e.g. high intensity of protonated acetone on m/z 59). If one takes into account that virtually all peaks visible in Fig. 3 are in fact double, triple or multiple peaks (isobaric compounds) it becomes obvious that for PTR-MS instruments selectivity is at least as important as sensitivity, especially when complex samples / compositions are analyzed. One methods for improving the selectivity is high mass resolution. When the PTR source is coupled to a high resolution mass spectrometer isobaric compounds can be distinguished and substances can be identified via their exact mass. Some PTR-MS instruments are, despite the lack of a mass filter between the ion source and the drift tube, capable of switching the reagent ions (e.g. to NO+ or O2+). With the additional information obtained by using different reagent ions a much higher level of selectivity can be reached, e.g. some isomeric molecules can be distinguished.
Sources: en.wikipedia.org
它不是经典的内分泌激素，而是一种免疫调节肽。其作用主要通过局部免疫细胞间的信号传递实现，而非经血液循环作用于远隔器官。
天然胸腺素α1主要从胸腺组织提取，也可在脾脏和淋巴结中检出。目前研究和临床使用的多为化学合成版本，不再依赖动物组织。
胸腺素组分5是牛胸腺提取物的粗组分，包含多种肽。胸腺素α1是其中一种被纯化和表征的单一肽，具有明确的28个氨基酸序列。
It is a 28-amino-acid peptide originally purified from a bovine thymic extract and later produced synthetically. It is studied mainly for its effects on immune cell function.