2-Chloro-3-methylquinoxaline was selected as a nucleus around which various molecular transformations were performed to obtain new compounds expected to possess optimized antimicrobial activity. As very little work regarding attachment of ether linkages replacing chlorine at C-2 has been reported, it was thought worthwhile to synthesize various quinoxaline derivatives by replacing the C2 chlorine with an ether linkage attached to a benzene ring possessing an aldehyde or a free amino group which can be further reacted with aromatic amines and aromatic aldehydes, respectively, to yield new Schiff bases containing quinoxaline moieties. Thus the compounds 4-(2-methylquinoxalinyloxy) benzaldehyde (4), 2-[4-(substituted-benziminomethyl)-phenoxy]-3-methyl quinoxalines 5a–e, 4-(2-methyl-quinoxaline-3-yloxy)benzamine (6) and 4-(2-methylquinoxalin-3-yloxy)-N-substituted benzylidine benzamines 7a–e were synthesized and tested for their antimicrobial activity. The structures of the compounds were confirmed on the basis of their elemental and spectral data.

2-Chloro-3-methylquinoxaline was selected as nucleus around which the molecular manipulations were carried out to get new compounds expected to possess better anti microbial activity. Various quinoxaline derivatives have been synthesized by replacing the chlorine at C-2 with a thioether linkage, which in turn attached to 2-(N-(substituted phenyl)acetamides. The synthesized compounds (5) were tested for their antimicrobial activity. Compounds 5b, 5c, 5d and 5i were found most active (comparable to the standard antibacterial Ciprofloxacin) amongst them. The structure of the compounds was confirmed on the basis of their spectral data.

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Fritillaria roylei (Kshirakakoli) is the threatened species of “Ashtwarga” group suffers lot of confusion for identification & authentification in Ayurvedic system of medicine. Due to lack of natural sources and insufficient availability of kshirakakoli, chances of adulteration and substitution increases which in turn leads to loss of faith of people in herbal drugs. Thus for identification and differentiation, quality standardization and quality assurance of kshirakakoli containing herbal formulations there is a need to isolate chemical marker compound using advanced analytical techniques. The methanol extract of root samples of plant was prepared and phytochemical screening was performed. Marker compound was isolated from the extract using column chromatography. Single compound having Rf value 0.31 was isolated with TLC by using mobile phase n-hexane: ethyl acetate: formic acid (8:2:0.1 v/v/v) and purified by re-crystallization with methanol. Isolated compound was further characterized by using melting point and spectral analysis. The methanol extract was dark brown in color and showed the presence of steroids, amino acids and flavonoids. The isolated compound was found to be white crystalline powder with melting point range of 167-169°C. Spectral analysis confirmed the presence of Stigmasterol. In present study stigmasterol was isolated for the first time and can be used as chemical marker for identification and differentiation of the plant from its substitutes.

Background: Roscoea purpurea also known as Kakoli is an endangered species of "Ashtawarga" group which faces immense identification and authentication crisis in Ayurvedic literature. Due to less availability and high medicinal value of Kakoli plant, adulteration and substitution was done by drug manufacturers. Objectives: This scientific investigation was carried out to isolate discrete and specific chemical compounds from Kakoli using chromatographic and spectral analysis techniques for quality standardization and identification of Kakoli containing herbal formulations. Materials and Methods: The methanol root extract of plant was used for phytochemical screening and isolation of marker compounds. Two compounds with R f values 0.51 and 0.73 respectively were isolated and purified by using mobile phase ethyl acetate: n-hexane: formic acid (07: 03: 0.1 v/v/v). Characterization of isolated compounds was done with help of melting point and spectral analysis. Results: The blackish brown methanol extract showed the presence of flavonoids, alkaloids, terpenoids, phenolic phytosterols and amino acid. The final isolated compounds were of off white and yellowish white with melting point range of 217-220°C and 239-242°C respectively and molecular ion peak at m/z 329 (M+Na) and at 291 (M+H) being according to the proposed structure of Epigallocatechin and Epicatechin respectively. Conclusion: In present study Epigallocatechin and Epicatechin were isolated for the first time and may prove potential tools for differentiation and accurate identification of the authentic plant from its official substitutes and cheap common adulterants.