An Update on Natural Occurrence and Biological Activity of Chromones

Abstract

The chemistry of chromones is very well known. This system is widely used in organic chemistry as an intermediate compound for the synthesis of numerous hetrocycles. On the other hand, chromones were extensively studied as bioactive compounds. They possess remarkable biological activities, such as antimicrobial, antiviral, anticancer, anti-inflammatory, antioxidant, etc. This comprehensive review describes the current status and knowledge of natural occurrence, and biological activities of chromones. Recent advances made over the last decade i.e. January 1999 to December 2009 are critically discussed and we have covered about 176 references and more than 350 compounds reported during this period.

An Overview of 2‐Styrylchromones: Natural Occurrence, Synthesis, Reactivity and Biological Properties

“…However, studies conducted by Letcher and Yue in 1992 on the reactivity of 2-SCs with maleic anhydride and with N-phenylmaleimide and extensive spectroscopic characterization established that the adduct structures were those of the isomeric 1,2,3,4-tetrahydro-9H-xanthen-9-ones 57 (Scheme 15). [95,96] The formation of these compounds 57 was the result of a [1,3] proton shift in the formed adducts 56, with the driving force of this isomerization being the stability of the reformed chromone moiety.…”

“…the A component in structure 1, Figure 1), a well-known class of oxygenated heterocyclic compounds, play an important role in nature due to their recognized biological, pharmacological and biocidal activities. [1][2][3] These effects of these naturally occurring compounds, associated with the large variety of substituents and positions in their skeleton, have resulted in strong demand over the years for their isolation in large amounts, for the development of efficient and eco-friendly routes for their synthesis, as cyclic systems and important intermediates in the search for bioactive compounds. It is our intention in this review to give a general overview on the natural occurrence, synthesis, reactivity and biological properties of 2-styrylchromones, which were published up until 2016.…”

Synthesis and Transformation of Halochromones

“…In fact, this is the only new improvement in the synthesis of 2-halochromones since 1997 [124]. The reaction of unsubstituted chromone 97 with TMP 2 Zn•2MgCl 2 •2LiCl led to regioselective metalation at C-2 which, by subsequent iodolysis, gave 2-iodochromone 98 (Scheme 32). The reversal of regioselective zincation by using TMPZnCl•LiCl (used in the lithiation of C-3 as already mentioned) upon addition of Lewis acids MgCl 2 or BF 3 •OEt 2 also provided, after iodolysis, 2-iodochromone 98.…”

“…The significance of these widely spread and highly diverse compounds is far beyond the important biological functions they assume in nature [1,2].…”

Tandem Claisen Rearrangement/6‐endo Cyclization Approach to Allylated and Pren­ylated Chromones

“…[5] This reaction sequence is complementary to an alternative biosynthetic mechanism that involves the formation of carbenium ions from prenyl diphosphate and a Friedel-Crafts-type alkylation of the aromatic core. [6] Among aromatic secondary metabolites, flavonoids [7,8] often occur as prenyl conjugates. [9] Interestingly, prenylation has been found on several occasions to modulate the bioactivity of natural products.…”