Yatendra Kumar

Alkaloids of Crinum pratense

Abstract From the bulbs of Crinum pratense, collected at flowering, lycorine, 1,2-diacetyllycorine, ambelline, narcissidine, and three phenanthridone alkaloids, viz. hippadine, pratorinine and anhydrolycorin-7-one, were isolated and characterized on the basis of comprehensive spectral analyses (UV, IR, 1H NMR, 13C NMR, MS, [α]D) and chemical evidence. Among the phenanthridone alkaloids (1–3, only the natural occurrence of hippadine was previously known. Pratorinine is a new phenanthridone alkaloid and anhydrolycorin-7-one was known before only as a synthetic compound. The physiological significance of hippadine is appraised.

Isocarbostyril alkaloids from Haemanthus kalbreyeri

Abstract Two new isocarbostyril alkaloids, 7-deoxypancratistatine and pancratiside (= pancratistatine-2- O -β- d - glucoside), were isolated from the resting bulbs of Haemanthus kalbreyeri . The structures of the two alkaloids were established by comprehensive spectral analyses and chemical transformations. The plant growth regulatory profile of these two alkaloids and three other isocarbostyril congeners, narciclasine, 7-deoxynareiclasine, and pancratistatine, is appraised. Haemanthus kalbreyeri provides a new source of the anti-tumour alkaloid, pancratistatine.

Glucosyloxy alkaloids from Pancratium biflorum

Abstract From fluids of flower stems and bulbs, and from extracts of roots of Pancratium biflorum , collected at different stages of growth, three new glucosyloxy alkaloids, viz. hordenine-4- O -β- d -glucoside, lycorine-1- O -β- d -glucoside and pseudolycorine-1- O -β- d -glucoside, have been isolated and characterized. Additionally, three proto alkaloids, β-phenethylamine, tyramine and hordenine, together with four true alkaloids, lycorine, pseudolycorine, pretazettine and tazettine, encountered before in other memebrs of the Amaryllidaceae, have now been isolated also from this species. Ontogenic variations of alkaloidal constituents have been observed. The ability of the alkaloidal constituents to complex with divalent metal ions and phytosterols has been examined with a view to evaluating their significance in plant biochemistry.

Parasitism of Imperata cylindrica on Pancratium biflorum and the concomitant chemical changes in the host species

Abstract A rare incidence of phanerogamic parasitism of Imperata cylindrica on Pancratium biflorum and the concomitant changes in the chemical constituents, from the hypersensitive responses in the host species, are reported.

Palmilycorine and lycoriside: acyloxy and acylglucosyloxy alkaloids from crinum asiaticum

Abstract Two new types of alkaloidal conjugates, a C 16 -acyloxy derivative, named palmilycorine, and an acylglucosyloxy derivative, named lycoriside, were isolated from the fruits of Crinum asiaticum . The presence of these compounds was also detected in the fleshy scale leaves and in roots of this species. The structures of the two compounds were established as 1- O -palmitoyllycorine (1) and lycorine-1- O -(6′- O -palmitoyl-β- D -glucopyranoside)(2), respectively, on the basis of chemical transformation and comprehensive spectral evidence. The biological effects of the alkaloids were evaluated.

Three chromones from bulbs of Pancratium biflorum

Abstract Two polyoxygenated chromones, 5,7-dihydroxy-2-methylchromone (1) and 5,6-dihydroxy-7- methoxy-2-methylchromone(2), and a glucosyloxychromone, 7

Biflorin, a chromone-C-glucoside from Pancratium biflorum

Abstract A new polyoxygenated chromone- C -glucoside, named biflorin, was isolated from the roots of Pancratium biflorum collected at flowering time. The

Toxic substances produced byFusarium. X. Concerning the malformation disease of mango

Accumulation of mangiferin and degraded carotenoids, in response toFusarium moniliforme infection, has been suggested to be responsible for the malformation disease ofMangifera indica L. (Anacardiaceae).

Free and glucosyloxy acetophenones from Pancratium biflorum

Abstract Two new dimethoxy-acetophenone- O -glucosides and the known 2,4,6-trimethoxyacetophenone were isolated from the flowering bulbs and pseudo-stem fluid of Pancratium biflorum . The structures of the new compounds were established as 4,6-dimethoxyacetophenone-2- O -β- d -glucoside and 2,6-dimethoxyacetophenone-4- O -β- d -glucoside on the basis of chemical transformation, comprehensive spectroscopic analyses, and synthesis of the aglucones. The biological activity profile of the glucosides and their aglucones is also appraised.

Similarities in the core structures of shilajit and soil humus

Abstract Convincing evidence has been found for the similarities in physical and chemical characteristics of shilajit and soil humus. Structural similarities of building blocks of the humus core of shilajit and two soil samples have been established by acid hydrolysis of the extracted humus (EHs; free from loosely-bound low M r organic compounds), followed by comprehensive Chromatographic (HPTLC) and spectroscopic (u.V., [ 1 H]NMR, GC, MS) analyses of the degradation products. 13 C-isotopic abundane data of the core molecules, as determined from their respective (M + 1) values, in the EI MS, suggest that the origin of these molecules in shilajit, at least in part, predates their biological synthesis (e.g. by plant-microbial interaction). Additional evidence has been found in support of this contention. A memory molecule (1 and its hemiquinone complement, 5a ag 5b ), that exhibited appropriate chemical and biological properties has been encountered in the core of all humus samples.