The bioassay guided fractionation of methanolic extract of Murraya koenigii (L.) Spreng. leaves resulted in the isolation of seven pyranocarbazoles. These were evaluated against four bacterial strains and ten Candida sp. including two matched pair of fluconazole sensitive/resistant clinical isolates. Out of seven, three i.e. Koenine (mk279), Koenigine (mk309) and Mahanine (mk347) exhibited significant antibacterial activity MIC90 3.12-12.5 μg/mL against bacterial strains Streptococcus aureus and Klebsiella pneumonia compared with standard drug Kanamycin MIC90 12.5 μg/mL. However, only mk309 was found active against variety of Candida species MIC90 12.5-100 μg/mL. It was observed that hydroxylation at C-6 and C-7 positions in the studied pyranocarbazoles activate the bioactivity. Simultaneously, decrease in Log P value compares with -H and -O-CH3 substituted derivatives. The study is focused on selective antifungal and antibacterial activity of pyranocarbazoles on bacterial strains S. aureus, K. pneumonia and variety of Candida species with structure activity relationship observations.

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Carbazole alkaloids induce apoptosis in HL-60 cells through activation of the caspase-9/caspase-3 pathway and they are targeted as potential anticancer agents. Thus, the naturally occurring carbazole alkaloids become important as precursors for lead optimization in drug development. A method based on ultra performance liquid chromatography coupled with photodiode-array detection was developed using reverse phase isocratic elution with 85:15 acetonitrile and ammonium acetate buffer (5 mM). Seven samples of Murrya koenigii (L.) Spreng. from north-central India (Uttar Pradesh) were analyzed. All three targeted analytes, koenimbidine (mk1), koenimbine (mk2) and mahanimbine (mk3), were well separated within 4.0 min with linearity of the calibration curves (r 2 > 0.999). The limits of detection and quantification of mk1, mk2 and mk3 were 0.7, 0.4, 0.04 µg/mL and 2.14, 1.21, 0.12 µg/mL, respectively. The natural abundance of mk1, mk2 and mk3 was 0.06-0.20, 0.04-0.69 and 0.13-0.42%, w/w, respectively, in the dried powdered leaves, whereas, the tissue specific distribution of carbazole alkaloids was observed in the order of predominance, mk1 leaf>root>fruit>stem, mk2 fruit>leaf >stem>root, and mk3 fruit>leaf>root>stem. The developed method was validated for limits of detection and quantification, repeatability, accuracy, precision and stability. This is the first report on the natural abundance of the major carbazole alkaloids in M. koenigii and the method developed can be used in HPLC/UPLC systems.

Murraya koenigii (L.) Spreng (Curry leaf) is a commercially important medicinal plant in South Asia, containing therapeutically valuable carbazole alkaloids (CAs). Thus, the quantitative evaluation of these compounds from different climatic zones of India are an important aspect for quality assessment and economic isolation of targeted compounds from the plant. In this study, quantitative estimation of CAs among 34 Indian natural populations of M. koenigii was assessed using UPLC/MS/MS. The collected populations represent the humid subtropical, tropical wet & dry, tropical wet, semi-arid, arid, and montane climatic zones of India. A total of 11 CAs viz. koenine-I, murrayamine A, koenigine, koenimbidine, koenimbine, O-methylmurrayamine A, girinimbine, mahanine, 8,8''-biskoenigine, isomahanimbine, and mahanimbine were quantified using multiple reaction monitoring (MRM) experiments within 5.0 min. The respective range for natural abundance of CAs were observed as 0.