Photochemistry and Photocytotoxicity of Alkaloids from Goldenseal (Hydrastis canadensisL.). 2. Palmatine, Hydrastine, Canadine, and Hydrastinine

Abstract

Goldenseal is an herb that is widely used in dietary supplements, eye washes, and skin lotions. The presence of Goldenseal root powder in dietary supplements and the topical application of Goldenseal preparations raise the possibility that an adverse phototoxic reaction may result from an interaction between its constituent alkaloids and light in exposed tissues. We have previously shown that berberine, the major alkaloid in Goldenseal powder, in combination with UVA causes DNA damage and cell death in HaCaT keratinocytes [(2001) Chem. Res. Toxicol. 14, 1529]. We have studied the photochemical and photobiological properties of four minor alkaloids found in Goldenseal, namely, hydrastine, palmatine, canadine, and hydrastinine. UVA radiation of palmatine in aqueous solutions generated no (1)O(2), but in CH(2)Cl(2), copious amounts of (1)O(2) were detected (Phi = 0.2). Palmatine also photogenerated oxygen-centered radicals, (*)OH and O(2)(*)(-) in aerated aqueous buffer and acetonitrile, respectively, as detected by the spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO). In nitrogen-sparged acetonitrile containing DMPO, we observed the neutral palmatine radical formed by one-electron reduction. UVA irradiation (4 J/cm(2)) of HaCaT keratinocytes in the presence of palmatine (50 microM) resulted in a 50% decrease in cell viability but no DNA damage as measured by the comet assay. UVA irradiation of hydrastine, hydrastinine, or canadine (50 microM) did not cause DNA damage or cell death in keratinocytes. Although palmatine is photoactive, it is present in such small amounts in Goldenseal root powder that the phototoxicity of the herb is most likely due to berberine, the major constituent alkaloid.

The Microenvironment of DNA Switches the Activity of Singlet Oxygen Generation Photosensitized by Berberine and Palmatine

“…The S 1 state of these alkaloids immediately returns to the ground state via a nonradiative mechanism (22,23). This rapid deactivation should be the reason for the decreased 1 O 2 generation by photosensitized berberine and palmatine in an aqueous solution (Fig.…”

Activity of phenolic compounds from plant origin against Candida species

“…Alkaloids comprise a diverse group of heterocyclic nitrogen substances, being commonly considered high toxic molecules that play an important defensive role, but reflecting a general biological principle of poisonous plants (Inbaraj et al, 2001(Inbaraj et al, , 2006Sertel et al, 2011). Nevertheless, in some situations, their toxicity is benefic; for example, Sertel et al (2011) reported that vinblastine, vincristine (from Catharanthus roseus, formerly: Vinca rosea) and semisynthetic vindesine and vinorelbine, presented high cytotoxicity against cancer cells, highlighting the potential of these dimeric indole alkaloids for cancer, leukemia and lymphomas treatments.…”

Fluorescence enhancement for alkaloids by anions: Spectroscopic and electrochemical characterizations

“…6). The above cathodic wave is thought to relate to a one-electron transfer process, as described in Scheme 3 [15], in which the quaternary nitrogen is the electrochemical center. Because fluoride ions can interact with the electrochemical center, the incorporation of fluoride ions would therefore interfere with the conversion of palmatine into palmatine radicals in aprotic systems.…”