A novel acyclic diterpenic alcohol isolated from antioxidant active ethanol extract of leaves of <i>Centaurothamnus maximus</i> grown in Saudi Arabia

Abstract

Background: Isolation and characterization of a new compound from the antioxidant active ethanol extract of leaves of an endemic plant Centaurothamnus maximus. Methods: The air dried powdered leaves of the plant was extracted successively with n-hexane, dichloromethane, ethyl acetate and ethanol. The obtained extracts were concentrated under reduced pressure using rotary evaporator. The antioxidant activity was carried out on various concentrations (1000, 500, 100, 50 and 10 µg/ml) of all the extracts by DPPH free radical scavenging method. After screening for antioxidant potential the ethanol fraction was selected for the isolation of phytoconstituents by column chromatography using LiChroprep RP-18 as stationary phase and water, MeOH and CHCl 3 in different combinations as eluent. The chemical structures of the isolated compounds were elucidated by 1D and 2D NMR spectroscopic techniques (DEPT, COSY, HMBC and HSQC) aided by EIMS mass and IR spectra. Results: The antioxidant activity of ethanol extract was highly comparable with standard ascorbic acid as compared to other extracts. A new compound along with two known compounds has been isolated from antioxidant active ethanol extract. The chemical structure of unknown compound was established as 2, 6, 10, 14-tetramethyl hexadec-12-cis-en-5α, 7α, 9α, 14α-tetraol (CM1) while the known compound isolated Luteolin-7-O-β-glucopyranosyl-6''-O-(6''→1''')-β-D-rhamno-pyranoside (CM-2) and stigmast-5,22-dien-3β -ol (CM3). Conclusion: On the basis of interpretation of different spectroscopy data we concluded that the compound CM1 is an acyclic diterpenic alcohol. The authors are reporting the isolation of CM1 from plant source for the first time but CM2 and CM3 are known compounds. Ethanol extract of leaves can be recommended as potent antioxidant for ethno-medical purposes. The antioxidant properties might be due to some well-known antioxidants like (CM-2) and other falvonoidal compounds.

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“…Some of the anticancer drugs that have been directly derived from herbs and natural plants are vinblastine, camptothecin, and paclitaxel [6]. Centaurothamnus maximus is an plant, native to the Arabian Peninsula; it is a leafy shrub and belongs to the Asteraceae family [7]. Previous phytochemical studies on C. maximus have revealed the presence of numerous phytoconstituents such as sesquiterpene lactones, elemanolides, germacranolides, and guaianolides [8].…”

The transcription factor MebHLH18 in cassava functions in decreasing low temperature-induced leaf abscission to promote low-temperature tolerance

“…When subjected to stress, stress-sensitive plants have high ROS levels and low enzyme activity to eliminate them, ultimately leading to serious cell membrane damage. The ROS level of stress-resistant plants is lower than that of sensitive plants, and the enzyme activity of scavenging ROS is increased, which makes the degradation of the growth phenotype of stress-resistant genotypes lower under stress ( Siddiqui et al., 2015 ; Ren et al., 2016 ). Under adverse conditions, the stress-resistant materials have high antioxidant activity, low ROS content, and lipid peroxidation, as well as higher growth potential, yield, and yield components.…”