Objective:Isodon is an important genus of the family Lamiaceae which contains diterpenoids of diverse functionalities. The present study attempted with isolation, structure elucidation and bioactivity evaluation of isolated compound from the leaves of Isodon wightii (Bentham) H. Hara. Methods: Petroleum ether extract of powdered leaves was obtained and concentrated in vacuo at 45ºC. Compound was isolated using silica gel column chromatography (60-120 mesh). Antioxidant activity of isolated compound was tested for DPPH free radical and hydroxyl radical scavenging, inhibition of linoleic acid peroxidation and metal ion chelation activities. Antibacterial activity was tested against six pathogenic bacteria by micro broth dilution method and in vitro antiacetyl cholinesterase activity of isolated compound was also studied. Results: Abietane diterpenoid, abietic acid was isolated from the leaves of I. wightii and the structure has been elucidated on the basis of spectroscopic analysis. Abietic acid isolated from petroleum ether extract of leaves showed moderate DPPH free radical, hydroxyl radical scavenging and less inhibition of linoleic acid peroxidation and metal ion chelating activities. Antibacterial activity of abietic acid against Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus mirabilis, Proteus vulgaris and Staphylococcus aureus was found in the range of 340-980 µg/mL. Antiacetylcholinesterase activity of abietic acid was less when compared with positive control. Conclusion: Abietic acid showed concentration dependent antioxidant, antibacterial and antiacetylcholinesterase activities.
The ent kaurene diterpenoid, melissoidesin was isolated from the acetone extract of the leaves of Isodon wightii and the structure was designated as 3beta, 11beta, 15beta-trihydroxy-6alpha-acetoxy-ent-kaur-16-ene based on spectral data and previous reports. Melissoidesin isolated from the acetone extract of leaves showed potent antiacetylcholinesterase activity and the IC(50) value was observed as 215 microg mL(-1). DPPH (1, 1-diphenyl-2-picrylhydrazyl) free radical scavenging activity of melissoidesin was significant and the IC(50) value was 138 microg mL(-1). The significant reducing property of the melissoidesin was stronger in high concentration. IC(50) value of melissoidesin on hydroxyl radicals and metal chelation was observed as 99 and 143 microg mL(-1), respectively. The 50% inhibitory concentration of melissoidesin on lipid peroxidation was calculated as 133 microg mL(-1). These findings indicate that ent kaurene diterpenoid, melissoidesin was promising antiacetylcholinesterase and antioxidant which can be used as food and drug preparations.
Citrus limon (L.) Osbeck cultivated all over the world is a valuable source of aromatic essential oil. To develop tetraploids of C. limon, four different concentration of colchicine (0.025, 0.05, 0.1 and 0.2%; w/v) and three varied exposure time (12, 24 and 48 h) were employed. The ploidy level of diploids (2n = 2x = 18) and tetraploids (2n = 4x = 36) were determined by direct chromosome count and confirmed by flow cytometric analyses. Successful result with maximum tetraploidy frequency was observed in plantlets developed from seeds treated with 0.025% colchicine for 24 h. Morphological and stomatal characteristics indicated that tetraploids were taller with increased leaf and root length. On the other side, the leaves of tetraploids had fewer and larger stomata with a greater number of chloroplasts in guard cells in contrast with diploids. GC-GC/MS analyses showed cyclic monoterpene, limonene had increased significantly in tetraploids and was further confirmed by HPLC quantification. RT-PCR analyses revealed unaltered expression of monoterpene synthase, sesquiterpene synthase and flavone synthase and remarkable upregulation of genes such as limonene synthase, chalcone synthase and phenylalanine ammonia lyase in tetraploids. Antioxidant activity of essential oil of tetraploids was higher than diploids in all the five test systems studied. Overall, the findings of the present study prove that colchicine induced tetraploidy in C. limon could be a greater source of essential oil with improved composition and of economic significance.
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