Ideally that the enlargement of the cyclic chain minimizes the ring strain [86, 178], although the energy of -5.0 Kcal x [mol.sup.-1] for the p-[[pi].sup....]H hydrogen bond in the cyclopropane is twice the amount of - 2.5 Kcal x [mol.sup.-1] which is higher than -1.9 Kcal x [mol.sup.-1] in comparison with the respective complexes of cyclobutane
and cyclopentane whose interaction is [C.sup....]H rather than p-[[pi].sup....]H.
Sex pheromone of the cotton mealybug, Phenacoccus solenopsis, with an unusual cyclobutane
Formation of cyclobutane
pyrimidine dimers at dipyrimidines containing 5-hydroxymethylcytosine.
Compounds that show these effects include cyclobutane
acrylics, benzocyclobutenes and atropisomeric biaryls.
In fact, it is the first cosmetic ingredient proven to reduce the UV-induced formation of both immediate (iCPDs) and delayed cyclobutane
pyrimidine dimers (dCPDs).Thus, it virtually stops aging before it happens, effectively providing 24/7 skin defense..
It can render DNA non-amplifiable through the formation of cyclobutane
pyrimidine dimers and, to a lesser extent, what's known as the "6-4 photoproduct"; in either case, it's the creation of covalent bonds between adjacent bases on a DNA strand that disrupts their ability to hydrogenbond as needed to serve as a replication template.
Specifically, niacinamide is known to enhance DNA excision repair and repair of UVB-induced cyclobutane
pyrimidine dimers and UVA-induced 8-oxo-7,8-dihydro-2'-deoxyguanosine.
Stojanovic, "[sup.1]H NMR chemical shifts of cyclopropane and cyclobutane
: a theoretical study," Journal of Organic Chemistry, vol.
UV light is one of the powerful agents that can induce a variety of mutagenic and cytotoxic DNA lesions, such as cyclobutane
pyrimidine dimers (CPDs), 6-4 photoproducts (6-4PPs), and their Dewar valence isomers as well as DNA strand breaks (most of them single-strand breaks) by interfering the genome integrity .
After UVA exposure bind with pyrimidine base to form cyclobutane
The addition of tetrachloromethane to [beta]-pinene 1a and [alpha]-pinene 1b led to the formation of the adduct 2a in excellent yields (86% and 85%, resp.) after opening the cyclobutane