What does chlorin mean?
A chlorin is an organic compound belonging to the family of macrocyclic molecules known as porphyrins. Structurally, it consists of four pyrrole rings linked into a large ring system, distinguished from a true porphyrin by having one of its pyrrole rings partially saturated — a subtle chemical difference with major biological consequences. Chlorins are best known as the parent framework of the chlorophylls, the green pigments that allow plants, algae, and cyanobacteria to capture sunlight and drive photosynthesis. Beyond plant biology, chemists have developed synthetic chlorin derivatives for medicine: because these compounds absorb red light efficiently and accumulate in certain tissues, they serve as photosensitizers in photodynamic therapy, where light activation destroys targeted cells such as tumors. The term appears almost exclusively in chemistry, biochemistry, and medical research, and it should not be confused with chlorine, the element.
nounA reduced porphyrin — a large heterocyclic organic compound with a macrocyclic ring containing four pyrrole units and one more saturated (dihydro) pyrrole ring than a porphyrin. Chlorins form the parent framework of the chlorophylls, the pigments responsible for photosynthesis in plants.
- (chemistry) A dihydroporphyrin macrocyclic compound, characterized by one reduced pyrrole ring, serving as the core structure of chlorophyll pigments.
- (biochemistry/medicine) Any of various derivatives of this compound used as photosensitizers in photodynamic therapy.
"The chemist synthesized a novel chlorin derivative to test as a photosensitizer for cancer therapy."
"The chlorin e6 molecule accumulated preferentially in tumor tissue before being activated by red laser light."
"Replacing the central magnesium atom altered the absorption spectrum of the synthetic chlorin."
Regular English plural; typically used when referring to multiple members or derivatives of the chlorin class.
"Several chlorins were screened for their ability to generate singlet oxygen under illumination."
Strip the magnesium from chlorophyll's molecular cousin, the chlorin, and you have the scaffold behind some of modern medicine's most promising light-activated cancer therapies.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of chlorin
The word 'chlorin' derives from the Greek 'chlōros', meaning pale green, the same root that gives us 'chlorine', 'chlorophyll', and 'chloroplast'. It was coined in the nineteenth and early twentieth centuries as chemists elucidated the structures of the green plant pigments, naming the compound after its connection to the color of chlorophyll. The suffix '-in' reflects its status as an organic substance, following the convention seen in words like 'protein' and 'albumin'. Its cognates thus cluster around the Greek color term rather than around other languages' independent coinages.
How chlorin is actually used
A technical term confined chiefly to chemistry and biochemistry literature; rarely encountered outside scientific contexts. In medicinal chemistry, specific derivatives such as 'chlorin e6' are frequently cited by name.
Easily confused with chlorin
Chlorine is the greenish-yellow chemical element (Cl) used as a disinfectant, whereas chlorin is an organic macrocyclic compound structurally related to chlorophyll.
Choline is a nutrient and neurotransmitter precursor, while chlorin is a porphyrin-related pigment compound involved in photosynthesis.