Isolation and Biological Characterization of Homoisoflavanoids and the Alkylamide N-p-Coumaroyltyramine from Crinum biflorum Rottb., an Amaryllidaceae Species Collected in Senegal

Crinum biflorum Rottb. (syn. Crinum distichum) is an Amaryllidaceae plant used in African traditional medicine but very few studies have been performed on this species from a chemical and applicative point of view. Bulbs of C. biflorum, collected in Senegal, were extracted with ethanol by Soxhlet and the corresponding organic extract was purified using chromatographic methods. The pure compounds were chemically characterized by spectroscopic techniques (1D and 2D 1H and 13C NMR, HR MS and ECD) and X-ray analysis. Four homoisoflavonoids (1-4) and one alkylamide (5) were isolated and characterized as 5,6,7-trimethoxy-3-(4-hydroxybenzyl)chroman-4-one (1), as 3-hydroxy-5,6,7-trimethoxy-3-(4-hydroxybenzyl)chroman-4-one (2), as 3-hydroxy-5,6,7-trimethoxy-3-(4-methoxybenzyl)chroman-4-one (3) and as 5,6,7-trimethoxy-3-(4-methoxybenzyl)chroman-4-one (4), and the alkylamide as (E)-N-(4-hydroxyphenethyl)-3-(4-hydroxyphenyl)acrylamide (5), commonly named N-p-coumaroyltyramine. The relative configuration of compound 1 was verified thanks to the X-ray analysis which also allowed us to confirm its racemic nature. The absolute configurations of compounds 2 and 3 were assigned by comparing their ECD spectra with those previously reported for urgineanins A and B. Flavanoids 1, 3 and 4 showed promising anticancer properties being cytotoxic at low micromolar concentrations towards HeLa and A431 human cancer cell lines. The N-p-coumaroyltyramine (5) was selectively toxic to A431 and HeLa cancer cells while it protected immortalized HaCaT cells against oxidative stress induced by hydrogen peroxide. Compounds 1-4 also inhibited acetylcholinesterase activity with compound 3 being the most potent. The anti-amylase and the strong anti-glucosidase activity of compound 5 were confirmed. Our results show that C. biflorum produces compounds of therapeutic interest with anti-diabetic, anti-tumoral and anti-acetylcholinesterase properties.

New Homoisoflavanes, a New Alkaloid and Spirostane Steroids from the Roots of Herreria montevidensis Klotzsch ex Griseb. (Herreriaceae)

The roots of the South American vine Herreria montevidensis Klotzsch ex Griseb. (Herreriaceae) are used in traditional medicine by several Amerindian groups of the Paraguayan Chaco. Little is known on the chemistry of the plant, despite its widespread use across the South American Chaco. From the ethyl acetate/methanol 1:1 extract of the roots, four new and one known homoisoflavanoid, two flavan derivatives, a stilbene, a new alkaloid, and three new and four known spirostane steroids were isolated. The corresponding structures were elucidated by spectroscopic and spectrometric means. The homoisoflavonoids of the plant are related to compounds isolated from the Dracaenaceae (formerly Agavaceae) sources of the Chinese crude drug Dragon’s Blood. The new alkaloid is a novel skeleton that can be used as a chemical marker of Herreria. The spirostane steroids suggest chemotaxonomic relations with the Liliales. This is the first comprehensive report on the chemistry of a South American Herreria species.