What is Hortensin?

Hase, Ohtani, Kasai, Yamasaki and Chayan, Phytochemistry, 40, 287-289 (1995) <PDF file>.

A flavonoid we isolated from Thai medicinal plant, Millingtonia hortensis (Bignoniaceae) was identical with hortensin isolated from the same plant, as far as physicochemical constants are concerned. And the structure proposed for this compound is 1 (Figure).
Bunyapraphatsara et al, Phytochemistry, 28, 1555 (1989).

The other group isolated the same compound from the same plant in 1992, and they synthesized "hortensin" (1) for confirmation. However, the synthesized compound was not identical with natural one. So, they proposed the different structure (2) for "hortensin". The compound 2 was a known flavonoid [circimaritin] already isolated from Flourensia ceruna (Compositae).
Nair et al, Phytochemistry, 31, 671 (1992).

We also isolated "hortensin" from the same plant. The all physico-chemical data were identical with those of the two previous paper. Hoever, by reading NMR spectra, especially NOE, the structure was readily determined as 3.

The Compound 3 is also known compound [pectolinarigenin*] previously isolated from Digitalis schischkinii.@So, the name of "Hortensin" should be withdrawn.

*Imre et al, Phytochemistry, 16, 799 (1977)

Even in these days (1990s) where modern NMR measurements are available, this sort of mistake may happen for such a simple structure. Young students should stick to their work diligently and in detail, then they might make one paper as we did.

Don't call us SCAVENGER !!

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