Although free porphyrins occur in nature in small quantities, no known function has been assigned to them. In contrast, heme and cobalamin, which are Fe and Co chelates of porphyrins or porphyrin derivatives, respectively, carry out crucial biological functions. Heme is the prosthetic group for a number of hemoproteins. These include myoglobin and hemoglobin, which carry out oxygen binding or transport; mitochondrial cytochromes aa3, b, c, and c3, which are important in transferring electrons; microsomal cytochrome P-450, which catalyzes mixed-function oxidations; catalase, which decomposes H2O2; peroxidase, which activates H2O2; and tryptophan pyrrolase, which catalyzes the oxidation of tryptophan. Recently, heme has also been shown to be the prosthetic group of prostaglandin and peroxide synthetase and indoleamine dioxygenase. The elegant studies of the biochemical pathway for the formation of heme demonstrated the arrangement in the porphyrin macrocycle of the carbon and nitrogen atoms originating from the eight glycine and the succinic acid molecule that are the precursors of porphyrins. There are eight enzymes involved in the synthesis of heme. The first and last three of these enzymes are localized in mitochondria, while the intermediate enzymes are localized in cytosol. The catalytic site of HMOX recognizes metalloporphyrins with central metal atoms other than iron; it favors some of these metalloporphyrins over heme as a potential substrate, sometimes by a large factor, permitting the synthetic heme analogue to serve as a potent competitive inhibitor of HMOX reaction. Since these synthetic metalloporphyrins do not bind molecular oxygen, they are not metabolically degraded by ring rupture and do not add to the body pool of bile pigment. One possible consequence of this competitive inhibition of heme degradation is suppression of bile pigment formation to such a degree that excessive plasma levels of bilirubin may be diminished. The studies of Drummond and Kappas (1981) and later studies in rats, mice, monkeys, and man, and also our studies have proved the latter phenomenon. The compound does not appear to affect the metabolic disposition of preformed bilirubin but inhibits biliary bilirubin excretion derived from the metabolism of endogenous or exogenous heme. Whether some of the effect of Sn-PP on naturally occurring or experimentally induced jaundice in animals reflects diversion of heme to nonheme to oxygenase-dependent pathways of heme metabolism, or whether a pathway which is normally latent becomes activated concurrent with HMOX inhibition is not known.(ABSTRACT TRUNCATED AT 400 WORDS)

A waxlike substance extracted from the needles of black spruce by means of petroleum ether gives, upon saponification, capric, lauric, myristic, pentadecanoic, palmitic, stearic, oleic, linoleic, linolenic, arachidic, behenic, lignoceric acids, and one acid not identified. Acids of the C-20 to C-24 series constitute approximately 38 % of the total acids. The unsaturated acids present are mostly of the C-18 series. The acids were identified by the gas-liquid chromatography (g.1.c.) of their methyl esters.The constituent acids of the waxlike substance from balsam fir needles are capric, lauric, myristic, pentadecanoic, palmitic, palmitoleic, heptadecanoic, stearic, oleic, linoleic, linolenic, arachidic, behenic, lignoceric, and about 7 more, not identified. The acids of the C-20 to C-24 series are presenl to the extent of ca. 20%. About 55 % of the acids are of the C-18 series, which is mostly unsaturated. There are present certain unsaturated acids, ca. 5 %, of the C-20 to C-22 series.10-Nonacosanol has been isolated from the unsaponifiable matter remaining after saponification of the waxlike substances from black spruce and balsam fir foliage. Its identity has been established by infrared, nuclear magnetic resonance, and mass spectrometry.

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IN continuation of the work in progress in these laboratories on plant mucilages, the exalrfination of the tubers of Curculigo orchioides Gaertn. has been undertaken. Curculigo orchioides is a small herbaceous plant growing in the hotter regions of India and Ceylon. The tuberous root of this plant, which is called Kalimusli in Hindi, is largely used in the Ayurvcdic and Unani systems of medicine as, a tonic and for piles and diarrhoea.