The short version of lyophilised powder fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-08-01. Anything still debated is marked as such rather than presented as settled.
Terminology around the compound varies by source. It appears in catalogues and papers as Semax, as the heptapeptide ACTH(4-7)-Pro-Gly-Pro, and under various alphanumeric laboratory codes used by individual suppliers. These names refer to the same sequence but may imply different salt forms, purity grades, or counter-ions. Peptide databases usually list the free base mass, while product descriptions sometimes report acetate or trifluoroacetate salts with a different formula weight. Because naming conventions for research peptides are not standardised across vendors, checking the declared sequence and measured mass is more reliable than relying on a trade name alone.
Semax is a synthetic heptapeptide with the sequence Met-Glu-His-Phe-Pro-Gly-Pro. Its design combines the ACTH(4-7) core fragment with a C-terminal Pro-Gly-Pro extension, a modification intended to improve stability and prolong activity. The molecule is hydrophilic, carries no lipid chains or glycosylation, and has a theoretical mass just over 810 daltons in its free form. All seven residues are proteinogenic amino acids, so no non-natural building blocks appear in the backbone. A free N-terminal methionine and C-terminal proline define the unmodified parent peptide.
The compound was developed during the 1980s at the Institute of Molecular Genetics in Moscow as part of research on fragments of adrenocorticotropic hormone. Early work examined short ACTH-derived sequences that retained neurotrophic effects while lacking the endocrine activity of the full hormone. Semax entered clinical use in Russia during the 1990s, where it received registration for several neurological indications. Outside that region it remained primarily a laboratory research material rather than an approved therapeutic. English-language literature on it grew more slowly and frequently cited the original Russian studies.
Identity and purity are confirmed with reversed-phase high-performance liquid chromatography, typically monitored at 214 nanometres where the peptide bond absorbs. Mass spectrometry, either electrospray or MALDI-TOF, verifies molecular mass against the theoretical value and detects truncation or adduct formation. Amino acid analysis and peptide mapping provide additional confirmation when required. The most frequently reported impurities are deletion sequences from incomplete coupling, methionine sulfoxide from oxidation, and dimeric species formed through non-covalent aggregation. Impurity profiles depend strongly on the synthesis and purification route chosen by the producer.
Published research has focused mainly on neurological and cognitive endpoints in animal models, with proposed mechanisms involving brain-derived neurotrophic factor and related signalling pathways. A substantial share of the human data originates from a limited number of research groups, and independent replication in other countries remains sparse. Regulatory status reflects that distribution: the peptide is registered as a medicine in Russia and appears in some neighbouring markets, while elsewhere it is handled as a research chemical without approved therapeutic labelling. Questions about dose-response relationships, long-term effects, and comparability across studies are still open.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic heptapeptide | ACTH(4-7) analogue |
| Sequence | Met-Glu-His-Phe-Pro-Gly-Pro | Free N terminus, unmodified side chains |
| Molecular weight | 813.9 Da | Free base; salt forms differ |
| Appearance | White to off-white powder | Lyophilised solid |
| Solubility | Freely soluble in water | Hydrophilic; polar solvents preferred |
The compound was developed in the 1980s at the Institute of Molecular Genetics in Moscow, where it emerged from research on short ACTH fragments and their effects on the central nervous system. Russian pharmaceutical listings describe it as a nootropic and neuroprotective agent, most often formulated as nasal drops. It is not a marketed medicine in the United States or the European Union, and no pharmacopoeial monograph covers it. Consequently, most published clinical experience with the substance originates from a small number of research centres, mainly in Russia and neighbouring countries.
Pharmacological accounts link semax to melanocortin signalling and to modulation of neurotrophic factor expression, particularly brain-derived neurotrophic factor and nerve growth factor. Much of this evidence comes from rodent studies using intranasal delivery, a route chosen because it allows peptides to reach the central nervous system with limited systemic exposure. Whether the same mechanisms operate in humans at comparable magnitude remains an open question. The precise receptor or receptors responsible for the reported behavioural and neuroprotective effects have not been conclusively identified.
Purity assessment relies mainly on reversed-phase high-performance liquid chromatography, which separates the target heptapeptide from truncated sequences, deletion analogues, and oxidised forms. Mass spectrometry, usually coupled to liquid chromatography, confirms identity through the expected molecular ion and reveals modifications such as methionine sulfoxide formation. Amino acid analysis can verify composition, and tandem mass spectrometry supports sequence confirmation. Ultraviolet detection near 254 to 280 nanometres is convenient because the phenylalanine and histidine residues absorb in that region. Nuclear magnetic resonance is rarely used for routine release testing.
Common degradation pathways include oxidation of the methionine side chain, hydrolysis of the peptide backbone, and aggregation under unfavourable pH or concentration. Stability studies typically monitor the main peak by chromatography and report total related substances as a percentage. Because no official monograph exists, acceptance criteria vary between laboratories, and reported purity values are not directly comparable across suppliers. Analysts therefore document the method, column, and detection wavelength alongside each result, and open questions remain about how much biological activity the oxidised forms retain.
molecular genetics - proving compound heterozygous or homozygous disease causing variants in the DDC gene CSF examination - low levels of 5-HIAA, HVA, and MHPG, increased levels of 3-OMD, L-DOPA and 5-HTP, and normal levels of pterins serum examination - decreased AADC enzyme activity To establish the diagnosis of AADCD, patient must have positive genetic testing (1st criterion) while also fulfilling either one of the other two criteria. Elevated 3-OMD levels in serum can be used as a simple and sensitive screening test, positive result of which must be confirmed by the diagnostic criteria above.
In 1686, when the area was still a wilderness, New York's colonial governor, Thomas Dongan, designated the area now known as Bryant Park as a public space. George Washington's troops crossed the area while retreating from the Battle of Long Island in 1776. The road upon which Washington's troops retreated traversed the park site diagonally. The city acquired the land in 1822. Beginning in 1823, Bryant Park was designated a potter's field (a graveyard for the poor) and remained so until 1840, when thousands of bodies were moved to Wards Island. The first park at this site opened in 1847, though that park was never legally named. It was called "Reservoir Square" after the Croton Distributing Reservoir, which was erected on the eastern side of the park site due to its elevated location. In 1853, the Exhibition of the Industry of All Nations with the New York Crystal Palace, featuring thousands of exhibitors, took place in the park. The Crystal Palace, also known as the Great Exhibition Hall, burned down in 1858. The Latting Observatory was also constructed in the park as part of the 1853 Exhibition, and was also burned down in 1856. The square was used for military drills during the American Civil War, and was the site of some of the New York City draft riots of July 1863, when the Colored Orphan Asylum at Fifth Avenue and 43rd Street was burned down. Reservoir Square was renovated in 1870–1871, during which the modern-day park had been laid out. Several additional structures were planned for Reservoir Square, but never built.
== In-vitro methods == The tandem affinity purification (TAP) method allows the high-throughput identification of proteins interactions. In contrast with the Y2H approach, the accuracy of the method can be compared to those of small-scale experiments (Collins et al., 2007) and the interactions are detected within the correct cellular environment as by co-immunoprecipitation. However, the TAP tag method requires two successive steps of protein purification, and thus can not readily detect transient protein–protein interactions. Recent genome-wide TAP experiments were performed by Krogan et al., 2006, and Gavin et al., 2006, providing updated protein interaction data for yeast organisms. Chemical crosslinking is often used to "fix" protein interactions in place before trying to isolate/identify interacting proteins. Common crosslinkers for this application include the non-cleavable [NHS-ester] crosslinker, [bis-sulfosuccinimidyl suberate] (BS3); a cleavable version of BS3, [dithiobis(sulfosuccinimidyl propionate)](DTSSP); and the [imidoester] crosslinker [dimethyl dithiobispropionimidate] (DTBP) that is popular for fixing interactions in ChIP assays.
The main advantages with respect to solvent gradient batch chromatography are high yields also for difficult separations, less solvent consumption, higher productivity, usage of countercurrent solid movement, which increases the separation efficiency. The process is continuous. Once a steady state is reached, it delivers continuously purified product in constant quality and quantity. Automatic cleaning in place is integrated. A pure empirical design of the operating conditions from a single solvent gradient batch chromatogram is possible.
Sources: en.wikipedia.org
== See also == Methane Isotope Carbon isotopes Hydrogen isotopes Isotopic signature Isotope geochemistry Isotopologue Isotopomer Clumped isotopes Isotope-ratio mass spectrometry Hydrogen isotope geochemistry of natural gas Methanogenesis Kinetic isotope effect
=== Detection === Modafinil is considered a stimulant doping agent and as such is prohibited by World Anti-Doping Agency in sports competitions. Modafinil enantiomers can be separately quantified in biological samples.
They are used in many dietary probiotic supplements. Theralac contains the strains Bifidobacterium lactis BI-07 and Bifidobacterium lactis BL-34 (also called BI-04) in its probiotic capsule. Bifidobacterium animalis lactis HN019 (DR10) is a strain from Fonterra licensed to DuPont, which markets it as HOWARU Bifido. It is sold in a variety of commercial probiotics, among them Tropicana Products Essentials Probiotics, Attune Wellness Bars and NOW Foods Clinical GI Probiotic. Fonterra has a yogurt that is sold in New Zealand called Symbio Probalance, where the strain is labelled as DR10.
Cellulose has no taste, is odorless, is hydrophilic with the contact angle of 20–30 degrees, is insoluble in water and most organic solvents, is chiral and is biodegradable. It was shown to melt at 467 °C (873 °F) in pulse tests in 2016. It can be broken down chemically into its glucose units by treating it with concentrated mineral acids at high temperature. Cellulose is derived from D-glucose units, which condense through β(1→4)-glycosidic bonds. This linkage motif contrasts with that for α(1→4)-glycosidic bonds present in starch and glycogen. Cellulose is a straight chain polymer. Unlike starch, no coiling or branching occurs and the molecule adopts an extended and rather stiff rod-like conformation, aided by the equatorial conformation of the glucose residues. The multiple hydroxyl groups on the glucose from one chain form hydrogen bonds with oxygen atoms on the same or on a neighbour chain, holding the chains firmly together side-by-side and forming microfibrils with high tensile strength. This confers tensile strength in cell walls where cellulose microfibrils are meshed into a polysaccharide matrix. The high tensile strength of plant stems and of the tree wood also arises from the arrangement of cellulose fibers intimately distributed into the lignin matrix. The mechanical role of cellulose fibers in the wood matrix responsible for its strong structural resistance, can somewhat be compared to that of the reinforcement bars in concrete, lignin playing here the role of the hardened cement paste acting as the "glue" in between the cellulose fibres.
This is indicated by swelling (edema) of the eyes and lips; asthma; bronchial irritation; dry, sore throat; congestion; skin redness (erythema); skin blisters (vesication); wheezing; itchy, watery eyes; chest tightness; and skin irritation.
Sources: en.wikipedia.org
=== Gag order === Syngenta sued to stop communication by Swiss health authorities with the Swiss public regarding the "relevance" of specific metabolites of chlorothalonil that Swiss authorities detected in high concentrations in the groundwater from which hundreds of thousands of Swiss people obtain drinking water. The court banned Swiss health authorities from communicating with the public about the dangers posed by some of the metabolites.
12 September 1946 the minister for external affairs in India, Jawaharlal Nehru demanded in a letter to the Commander in Chief and Defence Secretary, that a large-scale reform should be implemented to improve the Indian Army. Calcutta had been ravaged by large communal riots, but the British Indian Army was able to restore order. Nehru demanded with urgency, that the Indian Army should safeguard India's new democracy. Nehru was a nationalist and opposed India's "divide and rule" policy.
=== Developmental plasticity === Biotic and abiotic factors experienced during development will affect developmental resource allocation leading to phenotypic variation, also referred to as developmental plasticity. As in all insects, environmental factors can influence several aspects of development in Drosophila melanogaster. Fruit flies reared under a hypoxia treatment experience decreased thorax length, while hyperoxia produces smaller flight muscles, suggesting negative developmental effects of extreme oxygen levels. Circadian rhythms are also subject to developmental plasticity. Light conditions during development affect daily activity patterns in Drosophila melanogaster, where flies raised under constant dark or light are less active as adults than those raised under a 12-hour light/dark cycle. Temperature is one of the most pervasive factors influencing arthropod development. In Drosophila melanogaster temperature-induced developmental plasticity can be beneficial and/or detrimental. Most often lower developmental temperatures reduce growth rates which influence many other physiological factors. For example, development at 25 °C increases walking speed, thermal performance breadth, and territorial success, while development at 18 °C increases body mass, wing size, all of which are tied to fitness. Moreover, developing at certain low temperatures produces proportionally large wings which improve flight and reproductive performance at similarly low temperatures (See acclimation).
=== Isomers === 3-CMC is a chloromethcathinone, which has two other positional isomers, namely 2-CMC and 4-CMC. These differ in the position of the chlorine atom on the phenyl ring. As well as 3-CMC, these molecules are both known designer drugs. Since 3-CMC contains a chiral center, there are two enantiomers, namely (S)-3-CMC and (R)-3-CMC. The products are most likely on the market as a racemic mixture of the two enantiomers, since separation would result in very high costs.
== Scope == Physical organic chemistry is the study of the relationship between structure and reactivity of organic molecules. More specifically, physical organic chemistry applies the experimental tools of physical chemistry to the study of the structure of organic molecules and provides a theoretical framework that interprets how structure influences both mechanisms and rates of organic reactions. It can be thought of as a subfield that bridges organic chemistry with physical chemistry. Physical organic chemists use both experimental and theoretical disciplines such as spectroscopy, spectrometry, crystallography, computational chemistry, and quantum theory to study both the rates of organic reactions and the relative chemical stability of the starting materials, transition states, and products. Chemists in this field work to understand the physical underpinnings of modern organic chemistry, and therefore physical organic chemistry has applications in specialized areas including polymer chemistry, supramolecular chemistry, electrochemistry, and photochemistry.
Sources: en.wikipedia.org
It is a synthetic seven-amino-acid peptide built from the ACTH(4-7) sequence plus a Pro-Gly-Pro tail. It belongs to the family of short ACTH fragments studied for nervous-system effects. Its backbone contains only standard amino acids.
It contains the 4-7 fragment of adrenocorticotropic hormone extended at the C terminus. That truncation removes the region associated with steroidogenic activity. The design intent was to keep neurotrophic properties while avoiding full hormonal effects.
No natural source of the intact heptapeptide is known. It is produced by solid-phase peptide synthesis. Some related ACTH fragments arise as hormone processing products, but the Pro-Gly-Pro extension is a designed addition rather than a natural sequence.
Reversed-phase HPLC gives the main purity figure, most often with UV detection near 214 nanometres. Mass spectrometry then confirms the molecular mass. Together the two methods distinguish a correct sequence from a closely related impurity.