This is a working overview of RP-HPLC, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2025-11-29. Anything still debated is marked as such rather than presented as settled.
Identity and purity of semax are established with reversed-phase high-performance liquid chromatography coupled to ultraviolet detection, usually at 214 nanometres. Mass spectrometry, most often electrospray ionisation in positive mode, confirms the molecular mass and reveals truncated sequences. Amino acid analysis and peptide mapping after enzymatic digestion provide additional structural confirmation. Laboratories typically report purity as the percentage area of the main peak, a figure that does not capture isomeric or oxidised variants unless the method resolves them.
The peptide is prone to several degradation pathways. Oxidation of the methionine residue produces a sulfoxide that elutes close to the parent peak in many chromatographic systems. Hydrolysis of peptide bonds and deamidation of susceptible residues in related sequences also reduce purity over time. Lyophilised material kept dry at minus twenty degrees Celsius and shielded from light is the most stable form commonly described in laboratory practice.
Semax is a synthetic heptapeptide developed in the Soviet Union during the 1980s by researchers at the Institute of Molecular Genetics in Moscow. It was designed as a truncated analog of adrenocorticotropic hormone, retaining only the fragment spanning residues four through ten. Investigators sought a peptide that would preserve the cognitive effects associated with ACTH while eliminating the hormonal stimulation of the adrenal cortex. The compound entered clinical use in Russia during the following decade.
Russian regulatory authorities approved the peptide for nasal administration, and it remains listed in the national pharmacopoeia under several trade names. Documented indications include acute ischemic stroke, transient ischemic attacks, traumatic brain injury, and certain ophthalmological and neurological conditions. Physicians also prescribe it for cognitive complaints in older patients, although the evidence base for that use is thinner. Outside Russia and a few neighboring states, the substance is not an approved medicine and is sold instead as a research chemical.
| Property | Value | Notes |
|---|---|---|
| Appearance | White to off-white powder | Lyophilised solid |
| Solubility class | Freely soluble in water | Also dissolves in aqueous buffers |
| Typical storage temperature | -20 °C | Dry, desiccated, protected from light |
| Typical analytical method | RP-HPLC with UV detection | Often paired with LC-MS |
| Water content | Reported as Karl Fischer value | Freeze-dried material is hygroscopic |
Published studies examine a fairly narrow set of endpoints. Rodent experiments commonly measure maze learning, infarct volume after induced ischemia, and tissue levels of neurotrophic factors. Clinical reports from Russian centres describe attention, memory and recovery scores in patients after stroke or transient ischemic attack. Most of those human studies are small and few have been repeated by independent groups. Outcome measures differ between studies, which limits direct comparison.
Circulation time for the peptide is short because peptidases cleave it readily. The Pro-Gly-Pro tail is thought to slow breakdown compared with the bare ACTH fragment, but the gain appears modest. Absorption after intranasal dosing is limited, and only a fraction of a dose is expected to reach the central nervous system. Laboratory concentrations therefore sit well above levels achieved systemically, a gap that complicates translation from bench findings to clinical claims.
各国监管态度分化明显。俄罗斯按处方药管理，部分东欧国家留有使用记录；欧盟与美国未批准其作为药物上市，市面流通品通常标注为研究用化学品。身份差异意味着标示含量、纯度与无菌性缺少统一核查。体育领域还牵涉反兴奋剂名录，跨境携带则受目的地药品法规约束。
Semax 是人工设计的七肽，序列为 Met-Glu-His-Phe-Pro-Gly-Pro，骨架取自促肾上腺皮质激素片段 ACTH(4-10)。它于二十世纪八十年代在苏联的分子遗传学研究机构内合成。设计目标是保留该片段与注意力和记忆相关的活性，同时剔除促皮质激素释放等内分泌作用。此后俄罗斯将其登记为药品并进入临床使用。
当时的短肽研究普遍关注能否穿越血脑屏障、在低剂量下产生中枢效应，Semax 属于这一路线。鼻内给药是其主要使用方式，俄语文献报道的适应症涵盖缺血性卒中、短暂性脑缺血发作、认知功能减退以及视神经病变。这些研究大多发表在当地期刊上，样本规模与终点设置同西方试验惯例存在差异，国际同行对其临床证据的强度看法不一。
Records of attempts at pregnancy testing have been found as far back as the ancient Greek and ancient Egyptian cultures. The ancient Egyptians watered bags of wheat and barley with the urine of a possibly pregnant woman. Germination indicated pregnancy. The type of grain that sprouted was taken as an indicator of the fetus's sex. Hippocrates suggested that a woman who had missed her period should drink a solution of honey in water at bedtime: resulting abdominal distention and cramps would indicate the presence of a pregnancy. Avicenna and many physicians after him in the Middle Ages performed uroscopy, a nonscientific method to evaluate urine. Selmar Aschheim and Bernhard Zondek introduced testing based on the presence of human chorionic gonadotropin (hCG) in 1928. Early studies of hCG had concluded that it was produced by the pituitary gland. In the 1930s, Doctor Georgeanna Jones discovered that hCG was produced not by the pituitary gland, but by the placenta. This discovery was important in relying on hCG as an early marker of pregnancy. In the Aschheim and Zondek test, an infantile female mouse was injected subcutaneously with urine of the woman to be tested, and the mouse later was killed and dissected. Presence of ovulation indicated that the urine contained hCG and meant that the subject was pregnant. A similar test was developed using immature rabbits.
It is very important to quickly cool the wort to a level where yeast can be added safely as yeast is unable to grow in very high temperatures, and will start to die in temperatures above 60 °C (140 °F). After the wort goes through the heat exchanger, the cooled wort goes into a fermentation tank. A type of yeast is selected and added, or "pitched", to the fermentation tank. When the yeast is added to the wort, the fermenting process begins, where the sugars turn into alcohol, carbon dioxide and other components. When the fermentation is complete the brewer may rack the beer into a new tank, called a conditioning tank. Conditioning of the beer is the process in which the beer ages, the flavour becomes smoother, and flavours that are unwanted dissipate. After conditioning for a week to several months, the beer may be filtered and force carbonated for bottling, or fined in the cask.
Additionally, Professor Marie-Christine Renard of Rural Sociology of Chapingo University in Mexico wrote a case study of Starbucks's, Conservation International's, and Agro-industries United of Mexico (AMSA)'s joint conservation effort in Chiapas, Mexico in which she concluded that "[w]hile the CI-Starbucks-AMSA Alliance paid better prices, it did not allow the producers to appropriate the knowledge that was necessary for the organizations to improve the quality of their coffee".
Sources: en.wikipedia.org
== Biosynthesis and regulation == Calcitonin is formed by the proteolytic cleavage of a larger prepropeptide, which is the product of the CALC1 gene (CALCA). It is functionally an antagonist with PTH and Vitamin D3. The CALC1 gene belongs to a superfamily of related protein hormone precursors including islet amyloid precursor protein, calcitonin gene-related peptide, and the precursor of adrenomedullin. Secretion of calcitonin is stimulated by:
Tetrapeptide-21 (GEKG peptide) is a tetrapeptide that is derived from a sequence found in connective tissue proteins such as collagens and elastin. It stimulates endogenous biosynthesis of collagens, fibronectin and hyaluronic acid, and is used in skincare products for its purported anti-aging effects.
=== Notable incidents of use === DJ Screw, who popularized the codeine-based drink, died of a codeine–promethazine, Valium, and PCP overdose on November 16, 2000, several months after the video of Three 6 Mafia's single debuted. Big Moe, a DJ Screw protégé whose albums City of Syrup and Purple World were based on the drink and who has been described as having "rapped obsessively about the drug", died at age 33 on October 14, 2007, after suffering a heart attack one week earlier that left him in a coma. There was speculation that lean may have contributed to his death. Pimp C, a widely influential rapper from Port Arthur, Texas, and member of the rap duo UGK, was found dead on December 4, 2007, at the Mondrian Hotel in West Hollywood, California. The Los Angeles County Coroner's Office reported that the rapper's death was "due to promethazine-codeine effects and other unestablished factors." Ed Winter, assistant chief of the Coroner's Office, said the levels of the medication were elevated, but not enough to deem the death an overdose. However, Pimp C had a history of sleep apnea, a condition that causes one to stop breathing for short periods during sleep. A spokesman for the coroner's office said that the combination of sleep apnea and cough medication probably suppressed Pimp C's breathing long enough to bring on his death. Fredo Santana, an American rapper who frequently made references to the drink in his music, died of a seizure on January 19, 2018.
Rodrigo Roa Duterte (born March 28, 1945) is a Filipino former politician who served as the 16th president of the Philippines from 2016 to 2022. He served as mayor of Davao City for three non-consecutive terms between 1988 and 2016. Duterte is the first Philippine president from Mindanao, and the oldest person to assume office, beginning his term at age 71. Duterte is the chairman of PDP–Laban, the ruling party during his presidency. Born in Maasin, Leyte (now in Southern Leyte), Duterte moved to Davao as a child where his father, Vicente Duterte, served as provincial governor. He studied political science at the Lyceum of the Philippines University, graduating in 1968, before obtaining a law degree from San Beda College of Law in 1972. He then worked as a lawyer and prosecutor for Davao City, before becoming vice mayor and, subsequently, mayor of the city in the wake of the 1986 People Power Revolution. Duterte won seven terms and served as mayor of Davao for over 22 years, during which the once crime-ridden city became peaceful and investor-friendly. Duterte's 2016 presidential campaign led to his election victory. During his presidency, his domestic policy focused on combating the illegal drug trade by initiating the controversial war on drugs, fighting crime and corruption, and intensified efforts against terrorism and communist insurgency. He launched a massive infrastructure plan, initiated liberal economic reforms, streamlined government processes, and proposed a shift to a federal system of government which was ultimately unsuccessful.
Sources: en.wikipedia.org
Reversed-phase high-performance liquid chromatography is the standard method, with detection in the ultraviolet range. Peak area percentage yields a purity figure for the main component. Mass spectrometry is normally run alongside to confirm molecular identity.
Dry lyophilised powder is generally kept at minus twenty degrees Celsius, protected from light and moisture. Repeated freeze-thaw cycles are avoided because they encourage aggregation and moisture uptake. Solutions are less stable than the solid form and degrade faster at room temperature.
A certificate documents what the supplier measured, not what an independent party confirmed. Methods, instruments and acceptance criteria can differ between suppliers. Third-party testing is the usual way to resolve discrepancies.
It originated at the Institute of Molecular Genetics in Moscow during the 1980s. The work was carried out by a Russian research group that specialized in peptide neuropharmacology.