P L MAJUMDER

E SABZABADI

University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Agrostophyllin, a naturally occurring phenanthropyran derivative from Agrostophyllum khasiyanum

Phytochemistry

Agrostophyllinol and agrostophyllinone, two new triterpenoids, were isolated from the orchid Agrostophyllum brevipes. Agrostophyllinone was also isolated from another orchid Agrostophyllum callosum. The structures of agrostophyllinol and agrostophyllinone were established as 24-methylene-lanosta-9(11)-en-3β-ol (5a) and 24-methylene-lanosta-9(11)-en-3-one (5c), respectively, from spectral and chemical evidence. The above triterpenoids are of considerable biogenetic importance. © 2002 Elsevier Science Ltd. All rights reserved.

Triterpenoids from the orchids Agrostophyllum brevipes and Agrostophyllum callosum

Coeloginanthridin, a 9,10-dihydrophenanthrene derivative, and coeloginanthrin, the corresponding phenanthrene analogue, were isolated from the orchid Coelogyne cristata which earlier afforded coelogin (1a) and coeloginin (1b). The structures of coeloginanthridin and coeloginanthrin were established as 3,5,7-trihydroxy-1,2-dimethoxy-9,10-dihydrophenanthrene (2a) and 3,5,7-trihydroxy-1,2-dimethoxyphenanthrene (2c), respectively, from spectral and chemical evidence including the conversion of coeloginanthridin triacetate (2b) to coeloginanthrin triacetate (2d) by dehydrogenation with DDQ. In the light of earlier reports on structurally similar compounds, 2a and 2c may have biological activities of phytoalexins and endogenous plant growth regulators. © 2001 Published by Elsevier Science Ltd.

Phenanthrene derivatives from the orchid Coelogyne cristata

Reptanthrin and isoreptanthrin, two new dimeric phenanthrenes, were isolated from the orchid Bulbophyllum reptans which also afforded nine known stilbenoids, viz. gymnopusin (1a) [2,7-dihydroxy-3,4,9- trimethoxyphenanthrene], confusarin (1c) [2,7-dihydroxy-3,4,8- trimethoxyphenanthrene], 2,7-dihydroxy-3,4,6-trimethoxyphenanthrene (1d) and its 9,10-dihydro derivative, flavanthrinin (1e) [2,7-dihydroxy-4- methoxyphenanthrene] and its 9,10-dihydro derivative (coelonin), 3,3'- dihydroxy-5-methoxybibenzyl (batatasin-III), cirrhopetalanthrin (2a) [2,2',7,7'-tetrahydroxy-4,4'-dimethoxy-1,1'-biphenanthryl] and its 9,9',10,10'-tetrahydro derivative (flavanthrin). The structures of reptanthrin and isoreptanthrin were established as 2,2',7,7'-tetrahydroxy- 3,3',4,4',9,9'-hexamethoxy-1,1'-biphenanthryl (2c) and 2,2',7,7'- tetrahydroxy-3,3',4,4',9,9'-hexamethoxy-1,8'-biphenanthryl (3a), respectively, from spectral and chemical evidence including their biomimetic synthesis from the congener 1a with phosphomolybdic acid (PMA) on silica gel.

Dimeric phenanthrenes from the orchid Bulbophyllum reptans

Thunalbene, a new stilbene derivative, was isolated from the orchid Thunia alba which also afforded six known stilbenoids: batatasin-III, lusianthridin, 3,7-dihydroxy-2,4-dimethoxyphenanthrene, 3,7-dihydroxy-2,4,8- trimethoxyphenanthrene, cirrhopetalanthrin and flavanthrin. The structure of thunalbene, the first stilbene derivative isolated so far from an Orchidaceae plant, was established as 3,3'-dihydroxy-5-methoxystilbene from spectral and chemical evidence.

Thunalbene, a stilbene derivative from the orchid Thunia alba

Callosumin, callosuminin and callosumidin, three new stilbenoids, were isolated from the orchid Agrostophyllum callosum which earlier afforded, besides 4-hydroxy-3,5-dimethoxybenzoic acid, 10 other structurally related stilbenoids, viz. orchinol, 6-methoxycoelonin, imbricatin, flaccidin, oxoflaccidin, isooxoflaccidin, flaccidinin, agrostophyllin, callosin and callosinin. The structures of callosumin, callosuminin and callosumidin were established as 2,4,6,7-tetramethoxy-9,10 dihydrophenanthrene, 2,4,6,7- tetramethoxyphenanthrene and 2,7-dihydroxy-5-ethoxy(ax)-6-methoxy-9,10- dihydro-5H-phenanthro[4,5-bcd]pyran, respectively, from spectral and chemical evidence. Although in naming callosumidin the systematic numbering system has been adopted, for ease of comparison of the spectral results the phenanthrene numbering system for the compound and its structural analogues is used.

Three stilbenoids from the orchid Agrostophyllum callosum

Gymnopusin, the first naturally occurring phenanthrene derivative having a hydroxyl group at C-9, was isolated from the orchid Bulbophyllum gymnopus. It was shown to be 7,9-dihydroxy-2,3,4-trimethoxyphenanthrene (1a) mainly from the spectral data of the compound and those of its diacetyl (1b) and dimethyl ether (1c) derivatives. © 1988.

A ring-B oxygenated phenanthrene derivative from the orchid Bulbophyllum gymnopus

Moscatilin, a bibenzyl derivative from the orchid Dendrobium moscatum

From the orchid Eria confusa were isolated two new polyoxygenated phenanthrene derivatives, confusarin and confusaridin, which were shown to be 2,7-dihydroxy-3,4,8-trimethoxyphenanthrene and 2,6-dihydroxy-3,4,7,8-tetramethoxyphenanthrene, respectively. © 1987.

Confusarin and confusaridin two phenanthrene derivatives of the orchid Eria Confusa

Cyclootochilone and otochilone, two novel steroidal ketones of the orchids Otochilus porecta were shown to have the structures 1a and 2, respectively, from spectral and chemical evidence, 1a alone has also been obtained from the taxonomically related orchid Otochilus fusca. The significance of these compounds in the biogenetic transformation of lanosterol to steroids and the biogenetic sequence of the origin of 9,19- cyclopropane ring present in some terpenoids and steroids, as well as the mechanism of incorporation of two methyl groups at C-24 of some of these compounds were discussed. © 1985.

Tetrahedron

Structures of cyclootochilone and otochilone, two novel steroidal ketones of the orchids otochilus porecta and otochilus fusca

An amorphous phenanthrene, named nudol has been isolated from Eulophia nuda, Eria carinata and E. stricta. It was identified as 2,7-dihydroxy-3,4-dimethoxyphenanthrene. Synthesis of nudol and its dimethyl ether is described. © 1985.

Journal	Phytochemistry
Publisher	-
ISSN	0031-9422