Asymmetric Synthesis of Scillascillin-Type Homoisoflavonoid

The first asymmetric synthesis of a scillascillin-type homoisoflavonoid was reported. Key reactions for the asymmetric synthesis of benzocyclobutene include catalytic reductive desymmetrization of malonic ester and an intramolecular C-H activation of the methyl group.

Synthesis of proposed structure of ledebourin A

Naturally occurring homoisoflavonoids have attracted significant attention in the field of medicinal chemistry due to their potential health benefits and diverse range of biological properties. Recently, C-prenylated homoisoflavonoids, namely ledebourin A, B, and C, were isolated from the bulbs of Ledebouria floribunda and have exhibited potent antioxidant activity. In this study, we successfully synthesized ledebourin A and its regioisomer, compounds 1 and 9. By comparing the NMR spectra of the synthesized compounds with those of reported ledebourin A, we observed discrepancies. Nonetheless, our synthesis and subsequent findings offer valuable insights into the structural revision and biological activities of these unique prenylated homoisoflavonoids. Both synthesized compounds 1 and 9 exhibited no toxicity towards Hep-G2 cells and displayed the ability to recover glyceraldehyde-induced cell death, suggesting their potential as protective agents against liver damage.

A Comprehensive Review on Chemotaxonomic and Phytochemical Aspects of Homoisoflavonoids, as Rare Flavonoid Derivatives

Homoisoflavonoids (3-benzylidene-4-chromanones) are considered as an infrequent flavonoid class, possessing multi-beneficial bioactivities. The present study gives an overview on phytochemical aspects of homoisoflavonoids, including utilized plant species, parts, extracts, and separation techniques. Overall, these compounds have mainly been isolated and identified from bulbs and rhizomes of the plants belonging to Asparagaceae and Fabaceae families, particularly the genera of Ophiopogon, Dracaena, Scilla, Polygonatum, and Caesalpinia.

Antimicrobial Homoisoflavonoids from the Rhizomes of Polygonatum verticillatum

Three homoisoflavonoids, including a new compound, 5,7-dihydroxy-3-(4-methoxybenzyl)-8-methyl chroman-4-one (1), together with two known compounds, 5,7-dihydroxy-3-(2-hydroxy-4-methoxybenzyl)-8-methylchroman-4-one (2) and 5,7-dihydroxy-3-(2-hydroxy-4-methoxybenzyl)-chroman-4-one (3), were isolated from the rhizomes of Polygonatum verticillatum (L.) All. (P. verticillatum). Isolated compounds were characterized on the basis of UV, FT-IR, ESI-MS, and 1D-, 2D-NMR data. Further, different extract fractions and pure compounds from Polygonatum verticillatum were screened for their antimicrobial potential. Among three pure compounds, compound 2 was found most potent with good zone of microbial growth inhibition as compared to the standards.

Constituents of the Rhizomes of Sansevieria cylindrica

A new sappanin-type 3-benzyl chroman-4-one (homoisoflavanone), (3 S)-3-(4'-methoxybenzyl)-3,5-dihydroxy-7-methoxy-6-methyl chroman-4-one (1), together with known congeners (3 S)-3-(4'-methoxybenzyl)-3,5-dihydroxy-7-methoxy chroman-4-one (2), (3 S)-3-(4'-hydroxybenzyl)-3,5-dihydroxy-7-methoxy-6-methyl chroman-4-one (3), (3 S)-3-(4'-hydroxybenzyl)-3,5-dihydroxy-7-methoxy chroman-4-one (4), 3-(3’,4'-methyledioxybenzyl)-7-hydroxy-8-methoxy chroman-4-one (5), and stigmasterol and ergosterol peroxide have been isolated from the rhizomes of Sansevieria cylindrica, collected in Myanmar. Moreover, the first isolation of the (-)-enantiomer of the dihydrochalcone trifasciatine C (7) from nature is described. The structures of the compounds have been established by extensive spectroscopic analysis. Compounds 4 and 7 showed no significant cytotoxicity against HeLa cells. Compounds 1–4 and 7 exhibited weak radical scavenging activity (DPPH). A new biosynthetic pathway has been proposed for the formation of homoisoflavanone 5 and dihydrochalcone 7.

HPLC Analysis and NMR Identification of Homoisoflavonoids and Stilbenoids from the Inter-bulb Surfaces of Scilla nervosa

The yellow inter-bulb deposits from Scilla nervosa were analyzed by HPLC and found to contain 19 major components. Twelve of the 19 were identified by comparison of Rt values with those of authentic homoisoflavonoids and stilbenoids, co-elution and by preparative isolation followed by NMR and MS analyses. Of these, two homoisoflavonoids, 3-(4-hydroxyoxybenzyl)-5,7-dimethoxy-6-hydroxychroman-4-one and 3-(4-methoxybenzyl)-6,7-dimethoxy-5-hydroxychroman-4-one are new.

Isoquinoline Alkaloids and Homoisoflavonoids from Drimiopsis barteri Bak and D. burkei Bak

The powdered bulbs and leaves of Drimiopsis barteri yielded two novel isoquinoline alkaloids: 5-hydroxy-7,2′,3′,4′-tetramethoxy{2H-1-}benzopyran [4,3-c]isoquinoline and 6-hydroxy-7,2′,3′,4′-tetramethoxy{2H-1-}benzopyran [4,3-c]isoquinoline, three new scillascillins: 5,7-dihydroxy-2′,3′,4′-trimethoxyspiro-{2H-1-benzopyran-7′-bicyclo [4.2.0]octa[1,3,5]-triene}-4-one, 5-hydroxy-7,2′,3′,4′-tetramethoxyspiro{2H-1-benzopyran-7′-bicyclo [4.2.0]octa[1,3,5]-triene}-4-one and 5,2′,4′-trihydroxy-7,3′-dimethoxyspiro{2H-1-benzopyran-7′-bicyclo [4.2.0]octa[1,3,5]-triene}-4-one, and a tetrahydroxyhomo-isoflavanone: 5,6,7-trihydroxy-3-(4-hydroxybenzyl)chroman-4-one. The bulbs of Drimiopsis burkei gave three new metabolites: the first scillascillin, mentioned above, and two xanthones: 1,6-dihydroxy-2,3-dimethoxy-8-methylxanthone and 1,4-dihydroxy-2,3,6-trimethoxy-8-methylxanthone. Seventeen known compounds were isolated from both plants. Structures were elucidated based on detailed 1-, and 2D-NMR spectroscopic and MS analyses.