| dc.description.abstract | Part I
Section A: The preparation, purification and properties of morellin, the active principle of Garcinia morella, have been described. By chromatographic technique on silica gel columns three distinct pigments viz., morellin-T, morellin-M and morellin-L have been obtained. It appears morellin gets partly hydrated during this procedure, as the analytical figures for morellin-M agree somewhat closely with the formula C??H??O?. Mixed and individual melting points (of morellin-M and morellin) remain unaltered and so it is possible that morellin-M is dehydrated back to morellin above 120°. However, the close resemblance of morellin-M to the well-crystallised pigment, morellin, has been indicated. A few derivatives of morellin have been prepared with a view to testing their antibiotic activity.
Section B: In view of the meagre yield of iso-morellin, an isomer of morellin, by the method of B.S. Rao, comparative experiments to improve its yield have been conducted. A method is described wherein an optimum yield of only 6% of pure iso-morellin is obtained. Its properties and a few of its derivatives have been recorded.
Section C: The absorption spectra (visible region) of morellin, morellin-T, morellin-M, morellin-L, iso-morellin and tetra-acetyliso-morellin have been given. The close resemblance of morellin-M to morellin is further indicated.
Section D: Catalytic hydrogenations of morellin and its derivatives have been carried out. Octohydro derivatives of morellin, dimethoxymorellin and iso-morellin have thus been prepared. It is shown that octohydromorellin and octohydroiso-morellin differ only in their optical rotations but are otherwise identical. This fact gave the first indication of the relationship of iso-morellin to morellin. By methylation of octohydromorellin a dimethoxy compound identical with octohydrodimethoxymorellin obtained by reduction of dimethoxymorellin is produced.
Section E: All the available evidence has been discussed on the basis of which the following structure for morellin is proposed:
CH? OH O CH?—CO-C-CH=CH-CH=C<.ON
CH?-CO-CI—CH-CH?-CH=C<CH?
(This structure explains every known fact about morellin.)
Part II:
The antibacterial properties of allicin, the active principle of Allium sativum (garlic) and the evidence leading to its constitution proposed by Cavallito and co-workers have been reviewed. Attempts to confirm the diallylthiolsulphinate structure have not been fruitful. The evidence presented by Cavallito and Bailey has been re-examined and a diallyl disulphide oxide type of structure for allicin is suggested as being in conformity with its physico-chemical properties. This structure explains satisfactorily all the properties known of allicin and moreover indicates in a clear way its reaction with cysteine.
The aromatic analogue of allicin viz., diphenyl disulphide oxide has been prepared for the first time. It may be pointed out that this is the first compound of this group to be obtained in a crystalline state. A few synthetic substances containing sulphur have also been described in order to test their antibacterial activity.
Part III:
The antibacterial activity of morellins T, M and L, crystalline pigment morellin, dimethoxymorellin, tetra-acetylmorellin, octohydromorellin, octohydrodimethoxymorellin, iso-morellin, octohydroiso-morellin, tetra-acetyliso-morellin and a soluble derivative obtained by the reaction of morellin with chloroacetic acid, on Micrococcus pyogenes var. aureus and some other organisms of the enteric group has been given.
The results indicate the importance of the double bonds and of the phenolic groups in the morellin molecule.
The antibacterial activity of diphenyl disulphide oxide is shown to be less than that of allicin. The few synthetic compounds containing sulphur that were tested do not show any promise for the preparation of new types of compounds from this point of view.
The toxicity of morellin has been studied. Morellin is shown to possess very low toxicity in mice when given subcutaneously in olive oil solution.
The possible use of morellin for topical applications to septic wounds is indicated. | |
