B.A. Knights

Hydrocarbon content and its relationship to physiological state in the green alga Botryococcus braunii

Abstract Three physiological states, characterized by their hydrocarbon content are described for the green alga Botryococcus braunii : (1) Green active state colonies containing a complex mixture of hydrocarbons of the general formula C n H 2 n -2 and C n H 2 n -4 , (2) Brown resting state colonies containing a high concentration of a nearly pure (90 per cent) hydrocarbon botryococcene, (3) Large green cells showing very little synthesis of hydrocarbons.

Hydrocarbons from the green form of the freshwater alga Botryococcus braunii

Abstract Using ozonolysis, followed by analysis of the products by gas chromatography and mass spectrometry, it has been shown that the three principal hydrocarbons of the green, exponential-growth stage of Botryococcus braunii are heptacosa-1,18-diene, nonacosa-1,20-diene and hentriaconta-1,22-diene.

Identification of the sterols of oat seed

Abstract Gas chromatographic, chemical and mass-spectrographic evidence show that the three principal sterols in oat seeds are β-sitosterol, Δ 5,24(28) - and Δ 7,24,(28) -stigmastadienol respectively. Cholesterol, brassicasterol, campesterol, stigmasterol and Δ 7 -stigmastadienol as a minor components of the mixture.

Studies in the cruciferae changes in the composition of the sterol fraction following germination

Abstract It was noted for some genera of the Cruciferae that the composition of the sterol fraction in growing plants was markedly different from that found in seed. Changes in sterol content were studied following germination of seed of Brassica napus L., B. rapa L., B. oleracea L., Raphanus sativus L., Sinapis alba L. and Cheiranthus cheiri L. In the first five cases a rise in the cholesterol proportion and a gradual disappearance of brassicasterol was noted.

Isomers of 24-ethylidenecholesterol: Gas chromatographic and mass spectrometric characterization

Abstract The C-28 isomers of 24-ethylidenecholesterol, Δ 5 -avenasterol and fucosterol, are characterized by gas chromatography and mass spectrometry. Similar results are quoted for one isomer of 24-ethylidenelophenol (citrostadienol) and 24-ethylidene-Δ 7 -cholesten-3β-ol (Δ 7 -avenasterol).

β-Diketones in Rhododendron waxes

Abstract Chromatographic, mass spectrometric and spectroscopic evidence has been obtained for four β-diketones occurring in the leaf waxes of some members of

Studies on lettuce seed germination-I. Coumarin induced dormancy

Abstract A large number of coumarin derivatives and a few isocoumarins were tested with regard to their capacity to induce light sensitive dormancy in seeds of Lactuca sativa L. cv. “Grand Rapids”. Only those derivatives which are more reduced than coumarin showed this biological activity. Hydroxylation resulted in loss of activity as also happened when coumarin was poly substituted. Mono substitution by methoxyl at positions 4 and 8 did not result in marked reduction of activity. 2-Thiocoumarin was weakly active. The 8-hydroxy-isocoumarin, oosponol had some activity. On the basis of the findings it is proposed that the coumarins and isocoumarins which induce light sensitive dormancy in plants may act as anti-gibberellins. Their action is considered to result from the structural similarity to that moiety of gibberellin containing the lactone bridge. It is supposed that there is competition for the same active site in the plant cell. Competitive inhibition with gibberellic acid is implied from the experimental data in the case of dihydro- and hexahydrocoumarin. With coumarin and 4-methoxycoumarin the data obtained do not allow this interpretation but the inability to demonstrate competitive inhibition may arise because factors like diffusion, bonding and metabolic destruction result in the compounds arriving at the active site in disproportionate amounts. A possible model for the action of gibberellins and anti-gibberellins is proposed.

Comparison of the grain sterol fractions of cultivated and wild oat species

Abstract Sterol fractions from grain of cultivated oat ( Avena sativa L.) and two species of wild oat ( A. fatua L. and A. ludoviciana Dur.) have been compared and found very similar.

Studies in the cruciferae: Sterols in pollen of Brassica napus L.

Abstract Using GLC with mass spectrometry the main sterols of pollen from Brassica napus L. f. annua ( cv. Giant English rape) have been shown to be 24-methylenecholesterol and 24-ethylidenecholesterol.

Sterols and triterpenes of Ilex aquifolium

Abstract Sterols of male and female flowers from Ilex aquifolium were found to be mainly 24-ethylcholesterol, with trace amounts of cholesterol, 24-methylcholesterol and 24-ethyl-5,22-cholestadien-3β-ol. Several pentacyclic triterpenes were partially characterized.