Poly-Electrophilic Sesquiterpene Lactones fromVernonia amygdalina: New Members and Differences in Their Mechanism of Thiol Trapping and in Bioactivity

Abstract

In addition to known compounds, the leaves of Vernonia amygdalina afforded the new sesquiterpene lactones 14-O-methylvernolide (2), 3'-deoxyvernodalol (6), and vernomygdalin (8). These and related compounds were evaluated for modulation of a series of thiol trapping-sensitive transcription factors (NF-κB, STAT3, and Nrf2), involved in the maintenance of the chronic inflammatory condition typical of human degenerative diseases. Vernolide (1) emerged as a potent inhibitor of STAT3 and NF-κB and showed cytostatic activity toward the prostate cancer cell line DU45, arresting the cell cycle at the S phase. The exomethylene lactones are characterized by multiple Michael acceptor sites, as exemplified by vernolide (1) and vernodalol (5). By using the nuclear magnetic resonance-based cysteamine assay, the most reactive thiophilic site could be identified in both compounds, and competitive experiments qualified vernolide (1) as being more thiophilic than vernodalol (5), in agreement with the results of the pharmacological assays.

Comparison extraction methods for evaluating antioxidant and antibacterial properties of Vernonia amygdalina leaves extract

“…Biological activity of V. amygdalina species has been reported as antimicrobial 5 , antitumor 6,7 , anticancer 8,9 , anti-inflammatory 10 , and antidiabetic 11 . Extracts of the leaves of V. amygdalina contain flavonoid compounds, which are secondary metabolites to act as antioxidant 12 .…”

Steroidal Saponins from Vernonia amygdalina Del. and Their Biological Activity

“…It has received considerable scientific interest due to the observation that adult chimpanzees with malaria returned to normal activity after chewing the extract of the bitter juice of this species [ 1 ]. Over the years, several studies on the chemical components of this species, including flavonoids [ 2 ], sesquiterpene lactones [ 3 ], steroidal saponins [ 4 , 5 , 6 ], and fatty acids [ 7 ], have been performed. Previous studies have indicated different bioactivities of this species, including anti-inflammation [ 8 ], anti-malaria [ 9 ], anti-obesity [ 10 , 11 ], antioxidant [ 12 , 13 ], anti-tumor [ 14 ], and other activities [ 15 ].…”

Green synthesis and characterization of silver nanoparticles using leaves extracts of neem (<i>Azadirachta indica</i>) and bitter leaf (<i>Vernonia amygdalina</i>)

“…The objective also includes the characterization of the as-synthesized nanoparticles. Both plants are known to be medicinal with various therapeutic benefits (Abay et al, 2015;Asante et al, 2016;Luo et al, 2011;Sinisi et al, 2016;Subarpriya, 2005). The synthesized silver nanoparticles were characterized by UV-Vis spectroscopy, FTIR and powder X-ray diffraction (PXRD).…”