Browsing by Author "Shibnath Ghosal"

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1,2,3-Trioxygenated glucosyloxyxanthones from Polygala triphylla
(1981) Shibnath Ghosal; Prasad C. Basumatari; Shanta Banerjee
Four B-ring oxygen-free trioxygenated xanthones, viz. 1-OH-2,3-(OMe)2-, 1,2,3-(OMe)3-, 1-OH-2,3- (OCH2O)-, 1-OMe-2,3-(OCH2O)-xanthone, two B-ring oxygen-free glucosyloxyxanthones, viz. 1-O-gl.-2-OH-3-OMe- and 1-O-gl.-2,3-(OCH20)-xanthone, and a pentaoxygenated xanthone, 1-OMe-2,3,6,7-(OCH2O)2-xanthone, have been isolated from the flowering top of Polygala triphylla. The xanthones have been characterized on the basis of chemical transformation, comprehensive spectral evidence, and by direct comparison where possible. This is the first report of occurrence of the glucosyloxyxanthones in nature. The biochemical significance of these chemical characters in higher plants is appraised. © 1981.
A plausible chemical mechanism of the bioactivities of mangiferin
(1996) Shibnath Ghosal; Gangadhara Rao; V. Saravanan; Nira Misra; Dipak Rana
A plausible chemical mechanism of the observed bioactivities of mangiferin, a naturally occurring C-glucosylxanthone (1), is depicted. The mechanism focuses its capacity to provide cellular protection as an antioxidant and a radical captodative agent. Mangiferin performs its antioxidant function at different levels of systemic oxidation sequence. As far as membrane lipid peroxidation and consequent immunomodulations are concerned, it acts by (i) decreasing localized O2 concentration there-by generating, in concert, mangiferin phenoxy radicals (2); (ii) by binding metal ions (Fe2+/3+) in forms 3 and 4 that will not allow the generation of such tissue damaging species as hydroxyl and highly reactive oxo-ferryl radicals; (iii) regulating polymer chain lengthening (membrane lipids) by interacting with the reactive oxygen species; (iv) chain breaking (by 2), i.e. scavanging intermediate radicals (such as lipid peroxy and alkoxy radicals) to prevent continued H abstraction from cellular lipid molecules; and (v) maintaining systemic oxidant-antioxidant balance (by 1 and 2). Chemical evidence in support of the above postulate has been sought and obtained in the form of a complex polymer (5) through the intermediates 2 to 4.
Active constituents of Emblica officinalis : Part 1 - The chemistry and antioxidative effects of two new hydrolysable tannins, Emblicanin A and B
(1996) Shibnath Ghosal; Virendra K. Tripathi; Satish Chauhan
The absence of L-ascorbic acid, in free or conjugated form, in the fruits of Emblica officinalis Gaertn. (Hindi : amla) has been established by comprehensive chromatographic (column, TLC, HPLC, HPTLC), spectroscopic (1H and 13C NMR, MS) and crucial chemical analyses of its fresh juice and solvent extractives. The long-lived belief that the therapeutic effects of amla is due to its rich vitamin C (L-ascorbic acid) content has thus been dispelled. The potent vitamin C-like activity (antioxidative effect against reactive oxygen species, ROS) of amla fruits has now been located in the low Mr (Mol. wt < 1000) hydrolysable tannins. Four such compounds, emblicanin-A (1), emblicanin-B (2), punigluconin and pedunculagin, have been isolated from the fresh pericarp and their structures established by spectroscopic analyses and chemical transformation. The first two compounds are new naturally occurring galloellagi-tannins, while the other two similar compounds have been reported earlier in other plant species. The mechanism of antioxidative action of 1 and 2 is appraised.
Alkaloids of Crinum latifolium
(1983) Shibnath Ghosal; Kulwant S. Saini; August W. Frahm
From the bulbs of Crinum latifolium, collected at flowering, two new pyrrolophenanthridone alkaloids, pratorimine and pratosine, have been isolated and characterized on the basis of comprehensive spectral analyses, chemical transformation and synthesis. Additionally, four known alkaloids, hippadine, pratorinine, ambelline and lycorine, encountered before in other Amaryllidaceous species, have now been isolated and characterized from C. latifolium. © 1983.
Alkaloids of Crinum pratense
(1981) Shibnath Ghosal; Potharaju H. Rao; Dinesh K. Jaiswal; Yatendra Kumar; August W. Frahm
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. © 1981.
Alkaloids of Haemanthus kalbreyeri
(1985) Shibnath Ghosal; Rajiv Lochan; Ashutosh Yatendra Kumar; Radhey S. Srivastava
The roots of Haemanthus kalbreyeri contain a new phenanthridone alkaloid, kalbretorine, and a new glucosyloxy alkaloid, kalbreclasine. Additionally, six known alkaloids, viz. haemanthamine, haemanthidine, hippadine, lycorine, narciclasine and pratorimine, previously reported from other Amaryllidaceous plants have now been isolated also from this species. Kalbretorine produced marked inhibition of growth and viability of S-180 tumour cells. Kalbreclasine caused significant mitogenic activation of splenic lymphocytes characteristic of immuno stimulants. © 1985.
Alkaloids of Sida cordifolia
(1975) Shibnath Ghosal; Rama Ballav P.S. Chauhan; Rakesh Mehta
[No abstract available]
Alkaloids of zephyranthes flava
(1986) Shibnath Ghosal; Sushil K. Singh; Radhey S. Srivastava
From fresh, mature seeds of Zephyranthes flava, two new 2-oxyphenanthridinium alkaloids, zefbetaine and zeflabetaine along with 15 known free and glucosyloxy alkaloids have been isolated by gradient solvent extraction, chromatography and derivatization. The new compounds have been characterized by comprehensive spectroscopic analyses, chemical transformations and synthesis. Additionally, changes in the major alkaloids during development of the fruits have been analysed and their biological significance appraised. © 1986.
Anti‐stress activity of sitoindosides VII and VIII, new acylsterylglucosides from Withania somnifera
(1987) Salil K. Bhattacharya; Raj K. Goel; Ravinder Kaur; Shibnath Ghosal
Two new acylsterylglucosides, sitoindoside VII and sitoindoside VIII, were isolated from the roots of Withania somnifera Dun., and were screened for putative anti‐stress activity because the plant is widely regarded as the ‘Indian Ginseng’ by practitioners of the traditional Indian system of medicine. Since an acceptable paradigm of pharmacological tests for anti‐stress screening has yet to be evolved, a battery of tests were employed to delineate the activity of the test compounds. The total MeOH‐H2O (1:1) extractives of the roots of W. somnifera (SG‐1) and equimolecular combination of sitoindosides VII, VIII and withaferin‐A, a common withanolide, (SG‐2), exhibited significant anti‐stress activity in all the test parameters used. The two sitoindosides also produced per se anti‐stress activity, which was potentiated by withaferin‐A. A preliminary acute toxicity study indicated that the compounds have a low order of acute toxicity. The anti‐stress activity of SG‐1 and SG‐2 is consonant with the therapeutic use of W. somnifera in the Ayurveda, the Indian system of medicine. Copyright © 1987 John Wiley & Sons, Ltd.
Anti‐ulcerogenic activity of fulvic acids and 4′‐methoxy‐6‐carbomethoxybiphenyl isolated from shilajit
(1988) Shibnath Ghosal; Sushil K. Singh; Yatendra Kumar; Radheyshyam Srivastava; Raj K. Goel; Radharaman Dey; Salil K. Bhattacharya
Fulvic acids (FA) and 4′‐methoxy‐6‐carbomethoxybiphenyl (MCB, 1), two major organic compounds isolated from Shilajit (a humus product), were screened for anti‐ulcerogenic activity in albino rats. Both FA and MCB showed significant anti‐ulerogenic effects in the battery of tests accepted for this purpose. The mechanism of anti‐ulcerogenic action was studied with MCB on the basis of its effects on mucin content (gastric juice carbohydrates and carbohydrate/protein ratio) and on the concentration of DNA and protein in the gastric juice. The MCB‐induced changes in the mucosa provided resistance against the effect of ulcerogens and also against shedding of mucosal cells. A preliminary acute toxicity study indicated that both FA and MCB had a low order of toxicity. Copyright © 1988 John Wiley & Sons, Ltd.
Antioxidant activity of active tannoid principles of Emblica officinalis (amla)
(1999) Arunabh Bhattacharya; Abhijit Chatterjee; Shibnath Ghosal; Salil K. Bhattacharya
The antioxidant activity of tannoid active principles of E. officinalis consisting of emblicanin A (37%), emblicanin B (33%), punigluconin (12%) and pedunculagin (14%), was investigated on the basis of their effects on rat brain frontal cortical and striatal concentrations of the oxidative free radical scavenging enzymes, superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), and lipid peroxidation, in terms of thiobarbituric acid-reactive products. The results were compared with effects induced by deprenyl, a selective monoamine oxidase (MAO) B inhibitor with well documented antioxidant activity. The active tannoids of E. officinalis (EOT), administered in the doses of 5 and 10 mg/kg, i.p., and deprenyl (2 mg/kg, i.p.), induced an increase in both frontal cortical and striatal SOD, CAT and GPX activity, with concomitant decrease in lipid peroxidation in these brain areas when administered once daily for 7 days. Acute single administration of EOT and deprenyl had insignificant effects. The results also indicate that the antioxidant activity of E. officinalis may reside in the tannoids of the fruits of the plant, which have vitamin C-like properties, rather than vitamin C itself.
Antioxidant activity of glycowithanolides from Withania somnifera
(1997) Salil K. Bhattacharya; Kalkunte S. Satyan; Shibnath Ghosal
Antioxidant activity of active principles of Withania somnifera, consisting of equimolar concentrations of sitoindosides VII-X and withaferin A, was investigated for their effects on rat brain frontal cortical and striatal concentrations of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX). Results were compared with affects induced by deprenyl, an agent with well documented antioxidant activity. Active glycowithanolides of W. somnifera (WSG) (10 and 20 mg/kg,ip), administered once daily for 21 days, induced a dose-related increase in SOD, CAT and GPX activity in frontal cortex and striatum, which was statistically significant on days 14 and 21, except with the lower dose of WSG on GPX activity, where the effect was evident only on day 21. The data were comparable to those induced by deprenyl (2 mg/kg/day, ip) with respect to SOD, CAT and GPX activities, which were evident by day 14. These findings are consistent with the therapeutic use of W. somnifera as an Ayurvedic rasayana and medhyarasayana. Antioxidant effect of active principles of W. somnifera may explain, at least in part, the reported antistress, immunomodulatory, cognition-facilitating, anti-inflammatory and anti-aging effects produced by them in experimental animals, and in clinical situations.
Antioxidant defense by native and processed shilajit - A comparative study
(1996) Shibnath Ghosal; Salil K. Bhattacharya
Antioxidant defense provided by three native shilajit (Sh-N) and a processed shilajit (SJP) samples have been evaluated. A typical redox-activating system, consisting of 2,6-dichlorophenol-indophenol (DCPI, oxidised form), ascorbic acid (AA) and each shilajit (Sh) sample, has been developed. This system prevents, albeit in different degrees (depending on the quality of Sh), the reoxidation of DCPIH2, by dissolved oxygen, by recycling AA from the intermediate semidehydroascorbate (SDHA). In another set of experiment, Sh scavanges singlet oxygen (1O2), in a competitive manner, in the presence of a readily oxidizable arylamine substrate (L-DOPA) and thereby prevents the formation of dopachrome. The mechanisms envisaged for these antioxidant reactions in vitro, appear to operate also in vivo. While SJP is found to provide significant antioxidant defense in these parameters, that of Sh-N is considerably weak. The findings reinforce our earlier report that purification of native shilajit, from several undesirable contaminants, is an imperative necessity to ensure its beneficent effects in living systems.
Anxiogenic activity of methylenedioxymethamphetamine (Ecstasy) : An experimental study
(1998) Salil K. Bhattacharya; Arunabh Bhattacharya; Shibnath Ghosal
Methylenedioxymethamphetamine (MDMA), commonly known as Ecstasy, is widely abused as a recreational agent. Reports of death following MDMA intake has aroused serious concern. Although some of the clinical symptoms of MDMA toxicity include severe anxiety, panic, excitation and agitation, behavioural studies on the drug are sparse and incomplete. The present study investigated the anxiogenic activity of MDMA in rats, using yohimbine (2 mg/kg, i.p.) as the standard anxiogenic agent for comparison. The experimental methods used were the open-field, elevated plus-maze, social interaction and novelty-suppressed feeding latency tests, all the tests being experimentally validated as rodent models of clinical anxiety. In addition, the effect of MDMA was assessed on rat brain tribulin activity in terms of endogenous monoamine oxidase (MAO) A and B inhibition. Tribulin has been postulated to function as an endogenous marker of anxiety. MDMA (5 and 10 mg/kg i.p.) reduced ambulation and rears, and increased immobility and defaecation, in the open-field test. These doses of MDMA produced a dose-related decrease in the number of entries and time spent on the open arms of the elevated plus maze, reduced social interaction in paired rats and increased the feeding latency time in an unfamiliar environment in food deprived rats. A qualitatively similar response was induced by yohimbine in all these test parameters. Both MDMA (5 and 10 mg/kg, i.p.) and yohimbine (2 mg/kg, i.p.) increased rat brain tribulin activity, the increase in the MAO A inhibitor component being more than that on the MAO B inhibitor component. Several anxiogenic agents induce a similar response, as does anxiety associated with addictive drug withdrawal. The anxiogenic effects of MDMA and yohimbine on the elevated plus maze were inhibited by the benzodiazepine anxiolytic lorazepam (0.25 mg/kg, i.p.). However, the 5-HT(1A) receptor agonist-antagonist, buspirone (2.5 mg/kg, i.p.), selectively inhibited the anxiogenic effect of MDMA. Earlier studies have indicated that MDMA has significant effect on rat brain 5-HT(1A) receptors and induces an increase in serotonergic activity in this species. The results of the present study indicate that MDMA induces significant anxiogenic response in rats which may involve the serotonergic neurotransmitter system.
Ayurvedic Maharasas, the Repository of Primordial Organic Chemistry
(Indian Chemical Society, 1997) Shibnath Ghosal
A fundamental problem of tracing the sequence of primordial organic chemistry is the identification of the primitive organic molecules, from among the currently known millions of possible compounds. The observed intimate association, for ages, of a selected group of organic compounds, e.g. hydroxyacetophenones and oxygenated dibenzo-α-pyrones (DBPs), and of the Ayurvedic maharasas (inorganic minerals), in their natural habitats, is regarded as a strong circumstantial evidence in support of an organized sequence of primordial organic chemistry. These phenolic compounds also occur, selectively and consistently within the core of 'till' and boulders of the Gangotriglacier (1 to 60 million-year-old). Another unique feature of these compounds is that the DBPs are found in the organ deposits of several insects (haemolymph gland), animals (scent-gland, clover-stone), and in man (kidney and gall stone), but rarely so in plants. This phenomenon suggests their non-photosynthetic (abiotic) origin, at least partly, which is also supported from their high δ13C values. These organic compounds seem to bear a link between the primordial and the modern eras of organic chemistry on earth.
Biflorin, a chromone-C-glucoside from Pancratium biflorum
(1983) Shibnath Ghosal; Yatendra Kumar; Shripati Singh; Kamal Ahad
A new polyoxygenated chromone-C-glucoside, named biflorin, was isolated from the roots of Pancratium biflorum collected at flowering time. The. © 1983.
Chemical constituents of gentianaceae. Part 22. Structures of new 1,3,5-tri- and 1,3,5,6,7-penta-oxygenated xanthones of canscora decussata schult
(1977) Shibnath Ghosal; Kanika Biswas; Ratan K. Chaudhuri
Two new xanthone glucosides and two free xanthones, isolated from Canscora decussata, have been identified as 1-glucosyloxy-3-hydroxy-5-methoxy- (1), 7-glucosyloxy-1,6-dihydroxy-3,5-dimethoxy- (2), 1.5.6-trihydroxy-3,7-dimethoxy- (4), and 1.5.7-trihydroxy-3,6-dimethoxy-xanthone (7) on the basis of chemical transformations and spectral evidence. On the basis of reassessment of the spectroscopic data and additional chemical evidence, it has been shown that the pentaoxygenated xanthones previously reported to be 1,3,7-trihydroxy-5,6- dimethoxyxanthone (' Xanthone IV ') and 1,7-dihydroxy-3,5,6-trimethoxyxanthone (' Xanthone XII ') are in fact 1,3,5-trihydroxy-6,7-dimethoxy- (9) and 1,5-dihydroxy-3,6,7-trimethoxy-xanthone (10), respectively. The stucture of 1,6,7-trihydroxy-3,5-dimethoxyxanthone (' Xanthone XIII ') has been confirmed.
Chemical constituents of the gentianaceae. Part XII. Structure of the pentaoxygenated xanthones of Canscora decussata schult
(1974) Shibnath Ghosal; Ratan K. Chaudhuri; Ken R. Markham
The oxygenation pattern of the major pentaoxygenated xanthones of Canscora decussata is shown by synthesis and reassessment of spectrsocopic evidence, to be 1,3,5,6,7- and not 1,3,6,7,8- as previously reported. The structures of three of these xanthones are revised to 1-hydroxy-3,5,6,7-tetramethoxy-1,7-dihydroxy-3,5.6-trimethoxy-, and 1,6,7-trihydroxy-3,5-dimethoxy-xanthone, and that of a new xanthone is shown to be 1,3,7-trihydroxy-5,6-dimethoxyxanthone. The presence of minor amounts of 1,3,6,7,8-oxygenated xanthones has also been established.
Chemistry of shilajit, an immunomodulatory Ayurvedic rasayan
(1990) Shibnath Ghosal
The chemical polemics in the reported literature on shilajit are resolved. This study shows that humification of latex and resin-bearing plants is responsible for the major organic mass (80-85%) of shilajit. The low mol. wt. chemical markers (8-10%), viz. aucuparins, oxygenated dibenzo-α -pyrones and triterpenic acids of the tirucallane type (free and conjugated), occurring in the core structure of shilajit humus, are the major active constituents of Himalayan shilajit. The therapeutic effects of shilajit are the consequences of hormonal control and regulation of immunity. © 1990 IUPAC
Crinum alkaloids: their chemistry and biology
(1985) Shibnath Ghosal; Kulwant S. Saini; Sushma Razdan
The current staus of research of free and glycosylated alkaloids occuring in members of the genus Crinum is reviewed. The distribution, isolation, spectral properties, structural properties, inter conventions and biological acitivities of these alkaloids are presented. © 1985.