Five decades in the study of natural products

This paper describes the five-decade long fascinating journey taken by Prof. T R Govindachari towards the study of the natural products of India. A variety of Indian plants were investigated by him for the study of their constituent alkaloids and terpenoids. The concluding part of the paper summarizes the isolation and identification of the constituents of the neem kernel, which eventually led to the first X-ray structure determination of azadirachtin A

Insect antifeedant and growth regulating activities of neem seed oil- the role of major tetranortriterpenoids

An attempt was made to correlate insect antifeedant and growth regulatory activities of neem (Azadirachta indica) seed oil with the major tetranortriterpenoids. Selective elimination of triterpenoids by preparative high-performance liquid chromatography, incorporation of the eliminated compounds in defined concentrations and bioassaying the resultant fractions against Spodoptera litura indicated the necessity to quantify major triterpenoids for correlation of bioactivity of neem oil

Chemical examination of Cardanthera uliginosa

This article does not have an abstract

Studies in the isoquinoline series Part III. synthesis of some 5:6- and 5: 8-dimethoxyisoquinolines

A series of 3:4-dihydro-5:6-dimethoxy and 3:4-dihydro-5:8-di-methoxyisoquinolines are repoited. These have been dehydro genated to the corresponding isoquinoline derivatives

Insect antifeedant and growth-regulating activities of salannin and other c-seco limonoids from neem oil in relation to azadirachtin

The antifeedant and insect growth-regulating activities of salannin, nimbin, and 6-deacetylnimbin, in comparison with azadirachtin-A, have been studied against Spodoptera litura, Pericallia ricini, and Oxya fuscovittata. Salannin deterred feeding, delayed molt by increasing larval duration, caused larval and pupal mortalities, and decreased pupal weights in the two lepidopterans. Salannin also caused molt delays and nymphal mortalities in Oxya fuscovittata. The role of salannin and other compounds in conferring bioactivity, along with azadirachtin-A, to neem oil/neem seed extracts is emphasized

Addition of dinitrogentrioxide to Δ<SUP>1</SUP>-arylcyclohexenes

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Structure of tylophorine

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Studies in protoberberine alkaloids: Part III. Stereochemistry of 13-Methylprotoberberines

NMR spectral analysis has been used to deduce conformational structure la for thalic-tricavine and Vic for meso-thalictricavine

Chemical investigation of some Indian plants. Part VI

Several known compounds belonging to the class of acids, alcohols, alkaloids, anthraquinones, carbohydrates, coumarins, isocoumarins, steroids, triterpenoids and xanthones have been isolated from a number of Indian plants

Synthesis, Biological Evaluation and Mechanism Studies of Deoxytylophorinine and Its Derivatives as Potential Anticancer Agents

Previous studies indicated that (+)-13a-(S)-Deoxytylophorinine (1) showed profound anti-cancer activities both in vitro and in vivo and could penetrate the blood brain barrier to distribute well in brain tissues. CNS toxicity, one of the main factors to hinder the development of phenanthroindolizidines, was not obviously found in 1. Based on its fascinating activities, thirty-four derivatives were designed, synthesized; their cytotoxic activities in vitro were tested to discover more excellent anticancer agents. Considering the distinctive mechanism of 1 and interesting SAR of deoxytylophorinine and its derivatives, the specific impacts of these compounds on cellular progress as cell signaling transduction pathways and cell cycle were proceeded with seven representative compounds. 1 as well as three most potent compounds, 9, 32, 33, and three less active compounds, 12, 16, 35, were selected to proform this study to have a relatively deep view of cancer cell growth-inhibitory characteristics. It was found that the expressions of phospho-Akt, Akt, phospho-ERK, and ERK in A549 cells were greater down-regulated by the potent compounds than by the less active compounds in the Western blot analysis. To the best of our knowledge, this is the first report describing phenanthroindolizidines alkaloids display influence on the crucial cell signaling proteins, ERK. Moreover, the expressions of cyclin A, cyclin D1 and CDK2 proteins depressed more dramatically when the cells were treated with 1, 9, 32, and 33. Then, these four excellent compounds were subjected to flow cytometric analysis, and an increase in S-phase was observed in A549 cells. Since the molecular level assay results of Western blot for phospho-Akt, Akt, phospho-ERK, ERK, and cyclins were relevant to the potency of compounds in cellular level, we speculated that this series of compounds exhibit anticancer activities through blocking PI3K and MAPK signaling transduction pathways and interfering with the cell cycle progression