Carbamic

Summary: Silica gel column chromatography of the ethyl acetate fraction of methanol extract of Vincetoxicum stocksii resulted in the separation of three new rarely occurring natural products; [4-(4-(methoxycarbonyl)benzyl)phenyl] carbamic acid (1), bis[di-p-phenylmethane]ethyl carbamate (2), methyl 2-hydroxy-3-(2-hydroxy-5-(3-methylbut-2-enyl)phenyl)-2-(4-hydroxyphenyl) propanoate, stocksiloate(3), along with five known compounds; 1-(4-hydroxy-3-methoxyphenyl)-1,2,3,-propanetriol (4), feruloyl-6-O-[beta]-D-glucopyranoside (5), 4-hydroxy-3,5-dimethoxybenzoic acid (6), apocynin (7) and vincetomine (8).

Carbamates another important AChE inhibiting class are derived from carbamic acid.

Various pathogenic microbes are able to utilize urea as a nitrogen source through the activity of the enzyme urease that converts urea into ammonia and carbamic acid, with the spontaneous hydrolysis of carbamic acid to carbonic acid generating a further ammonia molecule [40].

When carrying out an EBUI or EBUII reaction at 6-molar excess of PC, a product containing free hydroxyl groups of hydrogenborate and carbamic groups is formed, since signals at 7.4 and 8.2 ppm are observed in [sup.1]H-NMR spectrum of the products (Figure 5(a)) that disappear after addition of D2O (Figure 5(b)).

The residue was purified by silica gel column chromatography using light petroleum/diethyl ether 7 : 3 v/v (compounds 1c and 1e were purified using light petroleum/EtOAc 7 : 3 and 9 : 1 v/v, resp.) to give carbamic compounds 1 with yields generally >95%.

Carbamates are esters of carbamic acid and classified as methyl or dimethyl carbamates and inhibit acetylcholinesterase.

Briefly, sections of abdominal aorta (3 mm long) were preincubated for 45 min at 37[degrees]C in Krebs-HEPES buffer (composition (mM): NaCl 99.9, KCl 4.7, K[H.sub.2]P[O.sub.4] 1.0, MgS[O.sub.4]-7[H.sub.2]01.2, D-glucose 11.0, NaHC[O.sub.3] 25.0, Ca[Cl.sub.2]-2[H.sub.2]O 2.5, Na HEPES 20.0, and pH 7.4) containing diethyldithio carbamic acid (1 mM) to inactivate superoxide dismutase and NADPH (100 [micro]M) as a substrate for NADPH oxidase.

A similar decrease of [T.sub.m] was also observed in [2-(alkyloxy)-phenyl]-2-(l-piperidinyl)ethyl esters of carbamic acids [20].

In the case of PUR foam production, water reacts with isocyanate, forming carbamic acid which decomposes to an amine and carbon dioxide which acts as the foam blowing agent.

On the tear-off of young abalone from the attachment site by four anaesthetics (ethyl carbamic acid, magnesium sulphate, chloral hydrate and sodium diethylbarbituric acid).