Shahab Uddin Ahmed
Department of Applied Chemistry and Chemical Engineering, Faculty of Engineering and Technology, University of Dhaka, Dhaka-1000, Bangladesh
Al-Mansur M. A
Analytical Research Division, Bangladesh Council of Scientific and Industrial Research, Dhaka-1205, Bangladesh.
Yunus Ahmed2, ,
Department of Applied Chemistry and Chemical Engineering, Faculty of Engineering and Technology, Islamic University, Kushtia, Bangladesh
M. H. Sohrab
Analytical Research Division, Bangladesh Council of Scientific and Industrial Research, Dhaka-1205, Bangladesh.
A. M. Sarwaruddin Chowdhury*
Department of Applied Chemistry and Chemical Engineering, Faculty of Engineering and Technology, University of Dhaka, Dhaka-1000, Bangladesh
Choudhury M. Hasan
Analytical Research Division, Bangladesh Council of Scientific and Industrial Research, Dhaka-1205, Bangladesh.
Carica papaya, Caricaceae, β-sitosterol, Brine shrimp lethality bioassay, Antimicrobial
Botanical Garden, Dhaka, in the month of February, 2007
Crop-Soil-Water Management
General experimental procedure The 1H NMR spectra were recorded by using a Bruker DPX-400 (400 MHz) instrument. For NMR studies deuterated chloroform was used and the δ values for 1H spectra were referenced to the residual nondeuterated solvent signals. Plant Material The fresh leaves of Carica papaya was collected from Botanical Garden, Dhaka, in the month of February, 2007. It was identified by Boshra Khan, Senior Scientific officer, Bangladesh National Herbarium, Dhaka. A voucher specimen has been deposited in the Bangladesh National Herbarium, Dhaka (DACB Accession No. 32,765), for the collection. The leaves were at first sun dried for five consecutive days. Finally the dried leaves were ground into a coarse powder using a grinding machine. Extraction and Isolation The powdered stem bark (533 g) of C. papaya was soaked in 2.5 L methanol for 15 days and filtered through a cotton plug followed by Whatman filter paper number 1. The extract was then concentrated by using a rotary evaporator. A portion of the concentrated methanol extract was fractionated by the modified Kupchan partitioning method 13 into petroleum ether, carbon tetrachloride and dichloromethane. The petroleum ether soluble fraction(3.5gm) was fractionated by column chromatography (CC) over silica gel (70-230 mesh) using petroleum ether, dichloromethane and methanol mixtures of increasing polarities to give 30 fractions, collecting each 100 ml. Fraction 18 upon washing with petroleum ether gave compounds 1. β-sitosterol: white crystals; 1H NMR (400 MHz, CDCl3): δ 3.51(1H, m,H-3),5.34 (1H, m, H-6), 1.00 (3H, s, 10-CH3), 0.67 (3H,s, 13-CH3), 0.91 (3H, d , J = 6.8, 20-CH3), 0.81 (3H, d , J = 7.6, 25-CH3), 0.82(3H, d , J = 7.6, 25-CH3). Bioassays The antimicrobial activity of the extractives was determined by the disc diffusion method.14,15 The samples were dissolved separately in specific volume of chloroform and applied to sterile discs at a concentration of 500 µg/disc and carefully dried to evaporate the residual solvent. For cytotoxicity screening, DMSO solutions of fractions obtained from the crude extract were applied against Artemia salina in a 1-day in vivo assay.16-18 For the experiment, 4 mg of each of the Kupchan fractions was dissolved in DMSO and solutions of varying concentrations such as 400, 200, 100, 50, 25, 12.50, 6.25, 3.125, 1.563, 0.781 µg/ml were obtained by serial dilution technique. The median lethal concentration (LC50) of the test samples after 24 hours of exposure was obtained by plotting percentage of the shrimps killed against the logarithm of the sample concentration (toxicant concentration). Here vincristine sulphate was used as a standard.
Dhaka Univ. J. Sci. 58(2): 265-268, 2010 (July)
Journal