3,4-DHSA is an organic compound which is the

intermediate product Intermediate goods, producer goods or semi-finished products are goods, such as partly finished goods, used as inputs in the production of other goods including final goods. A firm may make and then use intermediate goods, or make and then sell, o ...

of the

metabolism Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run c ...

cholesterol Cholesterol is any of a class of certain organic molecules called lipids. It is a sterol (or modified steroid), a type of lipid. Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell membr ...

, by the bacteria most commonly responsible for

tuberculosis Tuberculosis (TB) is an infectious disease usually caused by ''Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can also affect other parts of the body. Most infections show no symptoms, in w ...

('' Mycobacterium tuberculosis'').; 3,4-DHSA is an acronym for 3,4-dihydroxy-9,10-seco-androst-1,3,5(10)-triene-9,17-dione, the official name of this substance. It is classified as a

secosteroid A secosteroid () is a type of steroid with a "broken" ring. The word ''secosteroid ''derives from the Latin verb ''secare'' meaning "to cut", and 'steroid'. Secosteroids are alternatively described as a subclass of steroids; ; or derived from s ...

, since one of the four rings of cholesterol from which it is derived is broken. 3,4-DHSA is a

catechol Catechol ( or ), also known as pyrocatechol or 1,2-dihydroxybenzene, is a toxic organic compound with the molecular formula . It is the ''ortho'' isomer of the three isomeric benzenediols. This colorless compound occurs naturally in trace amoun ...

ic intermediate (a compound containing an

aromatic ring In chemistry, aromaticity is a chemical property of cyclic (ring-shaped), ''typically'' planar (flat) molecular structures with pi bonds in resonance (those containing delocalized electrons) that gives increased stability compared to satu ...

with two adjacent

hydroxyl In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydrox ...

groups) produced by ''M. tuberculosis'' during the breakdown of

. 3,4-DHSA is also produced by other bacteria such as '' Comamonas testosteroni''. A particular type of

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecule ...

known as extradiol dioxygenase is responsible for the

oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a ...

and ring opening of 3,4-DHSA to 4,9-DSHA (see metabolic scheme below). ''M. tuberculosis'' bacteria that are deficient in this enzyme are less lethal than wild-type bacteria. 3,4-DHSA itself appears to be toxic to the bacteria while the breakdown products of 3,4-DHSA can be used as energy source by the bacteria. Hence blocking the oxidation of 3,4-DHSA by the extradiol dioxygenase enzyme may be useful in the treatment of tuberculosis. A crystal structure of DHSA in complex with ''M. tuberculosis'' iron-dependent extradiol dioxygenase has been determined.

References

{{DEFAULTSORT:Dhsa Secosteroids