Somepalli Venkateswarlu

Synthesis and Antioxidative Activity of 3′,4′,6,7-Tetrahydroxyaurone, a Metabolite of Bidens frondosa

3′,4′,6,7-Tetrahydroxyaurone (1a), an aurone isolated from Bidens frondosa, and five analogues (1b–1f) were synthesized from pyrogallol in three steps. The antioxidative activity of 1a–1f was determined by the superoxide free radical and 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging methods.

Synthesis and Biological Activity of Isoamoenylin, a Metabolite of Dendrobium amoenum

Isoamoenylin (6), a dihydrostilbene from Dendrobium amoenum, was synthesised from 3,4,5-trimethoxybenzaldehyde (1) in four steps with an overall yield of 60%. The spectral data for synthetic 6 are in good agreement with those of the natural product. Isoamoenylin showed moderate antioxidative and weak antibacterial activities.

Synthesis of Microfolicoumarin, a Constituent of Cedrelopsis microfoliata

Microfolicoumarin (1), a prenylcoumarin from Cedrelopsis microfoliata, was synthesized from 2,4,5-trimethoxybenzaldehyde in five steps. 1 did not show significant antioxidative activity, but the key intermediates, esculetin (3) and 5-prenylesculetin (6), exhibited strong antioxidative activity in both the superoxide-radical and 1,1-diphenyl-2-picrylhydrazyl radical-scavenging models.

Synthesis and Antioxidant Activity of 4-[2-(3,5-Dimethoxyphenyl)ethenyl]-1,2-benzenediol, a Metabolite of Sphaerophysa salsula

4-[2-(3,5-Dimethoxyphenyl)ethenyl]-1,2-benzenediol (7), a stilbene isolated from Sphaerophysa salsula, was synthesized from 3,4-dihydroxybenzaldehyde (1) in five steps in an overall yield of 33%. The spectral data for synthetic 7 are in good agreement with those of the natural product. Hydroxystilbene 7 showed potent antioxidative activity.

Synthesis of 1,7-Bis(4-Hydroxyphenyl)-3-Hydroxy-1,3-Heptadiene-5-One, an Antiplatelet Diarylheptanoid from Alpinia blepharocalyx K. Schum

Abstract A general and straight forward total synthesis of 1,7-bis(4-hydroxyphenyl)-3-hydroxy-1,3-heptadiene-5-one (5) starting from 4-methoxycinnamic acid (6) via ethyl 5-(4-methoxyphenyl)-3-hydroxy-2,4-pentadienoate (14) was accomplished in 19% overall yield.

An unusual product in the condensation of 3- t -butyl-2-hydroxy-5-methoxybenzaldehyde with acetylacetone

The reaction of 3-t-butyl-2-hydroxy-5-methoxybenzaldehyde 6 with acetylacetone resulted in the formation of an unusual product, 1-[8-(t-butyl)-6-methoxy-2H-chromem-2-ylidene] acetone 4.