Baeckeins F–I, four novel C-methylated biflavonoids from the roots of Baeckea frutescens and their anti-inflammatory activities

Baeckeins J and K, Two Novel C‐Methylated Biflavonoids from the Roots of Baeckea frutescens and Their Cytoprotective Activities

“…It was interesting that the optimal connections of C(2)–C(8*) and C(3)–O–C(7*) between the two segments formed a furan ring D . And the unusual furan ring D was verified by comparison of the experimental NMR data with the values simulated by the ACD Labs software and the related NMR data of known compounds baeckeins F – I . As a result, the planar structure for 1 was determined.…”

“…Previous studies on this plant indicated the presence of essential oil , sesquiterpenes , phloroglucinols , chromones , flavonoids , and their derivatives. Preliminary phytochemical investigations of this plant in our laboratory have reported eleven C ‐methylated flavonoids and biflavonoids . It is known that C ‐methylated flavonoids are not widely distributed, but have occurred in multiple genera of the Myrtaceae family .…”

Identification and quantification of flavonoids and chromes inBaeckea frutescensby using HPLC coupled with diode-array detection and quadruple time-of-flight mass spectrometry

“…Comparing the retention times, UV profiles, MS fragmentation patterns, co-injection experiments with the standards and previous reference reports (Wu et al 2012), peaks 1, 3, 5, 6, 8 and 14 were unambiguously assigned as myricetin-3-O-a-L-rhamnopyranoside, myricetin, 6-C-methylquercetin-4 0 -O-b-D-glucopyranoside, quercetin, 6-C-methylquercetin and 5-hydroxy-7-methoxy-2-isopropylchromone, respectively. In view of isomeric compounds sharing the same molecular formula, almost identical MS fragment ions and very similar retention behaviours, peak 11 producing molecular ion peak at m/z 451.0660 [M þ H] þ corresponding to the formula of C 23 H 14 O 10 was tentatively identified as a pair of isomers, baeckeins A and B (Jia et al 2014). Also isomers were involved in peaks 16 and 17 referring to 5-hydroxy-7-methoxy-2-isopropyl-6-methylchromone (5-hydroxy-7-methoxy-2-isopropyl-8-methylchromone) and 5-hydroxy-6-methyl-7-methoxyflavanone (5-hydroxy-7-methoxy-8-methylflavanone), respectively (Tsui and Brown 1996a;Chen et al 2008).…”

“…Phytochemical investigations of this plant revealed that chromones (Tsui & Brown 1996a;Satake et al 1999) and flavonoids (Tsui & Brown 1996b;Makino & Fujimoto 1999;Chen et al 2008;Lu et al 2008;Quang et al 2008;Kamiya & Satake 2010;Jia, Zhou, et al 2011;Jia et al 2013Jia et al , 2014 were the main components that might be responsible for the overall efficacy. Recently, we have reported nine unusual flavonoids Jia, Zhou, et al 2011;Jia et al 2013Jia et al , 2014 and obtained a number of reference substances from B. frutescens. As a consecutive work, the HPLC method coupled with DAD and Q-TOF/MS techniques was developed for the identification and quantification of main bioactive components in this plant for the first time.…”

Chromones: A Promising Ring System for New Anti‐inflammatory Drugs

“…( Figure16), were studied for their anti-inflammatory effects through inhibition of CNO production. [52] The resultsr evealed that the 2R,3R isomerso ft hese compoundsh ave higher CNO inhibitory activity than the 2S,3S-configured isomers. Moreover,f or these compounds it became clear that the presence of as ugar residue improves inhibitory activity,a sc ompounds with a b-d-glucose moiety were found to be more active than those without.…”