Coptisine

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 270,000(SRC), determined from a structure estimation method(2), indicates that coptisine is expected to be immobile in soil(SRC). Volatilization of coptisine from moist soil surfaces is not expected to be an important fate process(SRC) given an estimated Henry's Law constant of 7.4X10-19 atm-cu m/mole(SRC), using a fragment constant estimation method(2). Coptisine is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 1.1X10-9 Hg at 25 °C(SRC), determined from a fragment constant method(2). Biodegradation data in soil were not available(SRC, 2016).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 270,000(SRC), determined from a structure estimation method(2), indicates that coptisine is expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is not expected(3) based upon an estimated Henry's Law constant of 7.4X10-19 atm-cu m/mole(SRC), developed using a fragment constant estimation method(2). Coptisine is not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions(3). According to a classification scheme(4), an estimated BCF of 3(SRC), from an estimated log Kow of 2.5(2) and a regression-derived equation(2), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Biodegradation data in water were not available(SRC, 2016).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), coptisine, which has an estimated vapor pressure of 1.1X10-9 mm Hg at 25 °C(SRC), determined from a fragment constant method(2), is expected to exist solely in the particulate phase in the ambient atmosphere. Particulate-phase coptisine may be removed from the air by wet and dry deposition(SRC). Coptisine contains chromophores that absorb at wavelengths >290 nm(3) and, therefore, may be susceptible to direct photolysis by sunlight(SRC).

IDENTIFICATION AND USE: Coptisine, a cytotoxic alkaloid found in Chinese goldthread, is related to berberine. It is used in biochemical studies and has been tested as experimental therapy. HUMAN EXPOSURE AND TOXICITY: Cytotoxicity evaluation of coptisine was conducted on a panel of human and murine cell lines in comparison with the established antitumor drugs mitoxantrone, doxorubicin (Dx), and cisplatin (CDDP). Coptisine was cytotoxic on LoVo and HT-29 and less potent on L-1210, and it was partially crossresistant on the human tumor colon cell line resistant to Dx, LoVo/Dx, whereas it was not significantly crossresistant on the murine leukemia cell line resistant to CDDP, L-1210/CDDP. Coptisine prevents vascular smooth muscle cell proliferation selectively at lower concentrations compared with various cells or other structurally related alkaloids. Coptisine has potential pharmacological activity for reducing cholesterol, and may reduce cholesterol by regulating mRNA and protein expressions of key genes involved in cholesterol metabolism, such as LDLR, CYP7A1, and HMGCR. ANIMAL STUDIES: Coptisine is a potent reversible inhibitor of type A monoamine oxidase. Coptisine inhibits proliferation of vascular smooth muscle cells. In the sub-chronic toxicity study, no mortality and morbidity were observed which could be related to coptisine treatment. Besides, there was no abnormality in clinical signs, body weights, organ weights, urinalysis, hematological parameters, gross necropsy, and histopathology in any of the animals after the oral administration of coptisine.

Using a structure estimation method based on molecular connectivity indices(1), the Koc of coptisine can be estimated to be 270,000(SRC). According to a classification scheme(2), this estimated Koc value suggests that coptisine is expected to be immobile in soil.

/ALTERNATIVE and IN VITRO TESTS/ The crude extract (80% MeOH in water) of Chelidonii herba exhibited very interesting cytotoxicity against brine shrimp (Artemia salina Leach) nauplii and cultured human tumor cell in vitro, the colon carcinoma HT 29 (144 hr treatment). Fractionation of the crude extract and bioassay-guided procedures showed that the cytotoxic and the antitumor activities were concentrated in the basic extract. On the basis of IR, MS, and (1)H NMR the compound responsible of the cytotoxic activity was determined to be coptisine. Cytotoxicity evaluation of coptisine was next extended to a panel of human and murine cell lines in comparison with the established antitumor drugs mitoxantrone, doxorubicin (Dx) and cisplatin (CDDP). Coptisine was cytotoxic on LoVo and HT-29 and less potent on L-1210, and it was partially crossresistant on the human tumor colon cell line resistant to Dx, LoVo/Dx, whereas it was not significantly crossresistant on the murine leukemia cell line resistant to CDDP, L-1210/CDDP. Coptisine alkaloid was then synthesized in gram amount from commercial berberine. A four-step synthetic route was elaborated. The overall yield was about 8-10%. The structural identity of synthetic coptisine was verified by IR and NMR methods. A comparison of the cytotoxic effects on the human tumor colon cell line LoVo and on the murine leukemia L-1210 showed, for both natural and synthetic coptisines, a comparable cytotoxic activity more evident against HT-29 cell line and LoVo cell line, while the activity was lower against the L-1210 cell line.

/ALTERNATIVE and IN VITRO TESTS/ Acceleration of vascular smooth muscle cell (VSMC) proliferation is closely linked to the pathogenesis of vascular diseases. We, therefore, focused on traditional Japanese herbal medicines (Kampo medicines) used to ameliorate the impairment of microcirculation or blood stasis and screened them for their ability to inhibit rat VSMC proliferation. Among them, Unsei-in was found to effectively suppress VSMC proliferation, and Coptis rhizome was the responsible constituent crude drug. The extract of Coptis rhizome inhibited VSMC proliferation with the GI(50) value of 4.4 ug/mL, which was much lower than those against the proliferation of 3Y1, dRLh-84, B16, and HeLa cells. The Coptis rhizome extract inhibited the progression of VSMC arrested at G(0)/G(1) phase from G(0)/G(1) to S phase, but not that of 3Y1 cells. Biological assay-guided fractionation revealed that an alkaloid of Coptis rhizome, coptisine, was the active ingredient in selectively preventing VSMC proliferation with GI(50) of 3.3 uM (1.2 ug/mL). When the structurally-related isoquinoline alkaloids of protoberberine class were studied for their inhibitory activities, berberine decreased the VSMC proliferation with GI(50) of 95.1 microM (35.4 ug/mL), about 30 times higher concentration than coptisine, while palmatine failed to show any activity. This study provides evidence that coptisine, an ingredient of Unsei-in, prevents VSMC proliferation selectively at lower concentrations compared with various cells or other structurally related alkaloids.

An estimated BCF of 3 was calculated in fish for coptisine(SRC), using an estimated log Kow of 2.5(1) and a regression-derived equation(1). According to a classification scheme(2), this BCF suggests the potential for bioconcentration in aquatic organisms is low(SRC).

The Henry's Law constant for coptisine is estimated as 7.4X10-19 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that coptisine is expected to be essentially nonvolatile from water and moist soil surfaces(2). Coptisine is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 1.1X10-9 mm Hg(SRC), determined from a fragment constant method(1).

/LABORATORY ANIMALS: Acute Exposure/ The present study was conducted to investigate the antinephritic effects of berberine and coptisine, which are contained in Coptidis rhizoma, on original-type anti-GBM nephritis in rats. Berberine and coptisine at the doses of 0.5, 1.0, and 5.0 mg/kg/day, ip were effective in inhibiting urinary protein excretion, elevation of serum cholesterol and creatinine contents as well as glomerular histopathological changes. In addition, berberine at 20 mg/kg/day, po also inhibited urinary protein excretion throughout the experimental periods. Berberine and coptisine inhibited platelet aggregation in both in vitro and in vivo assays, and berberine inhibited the decline of renal blood flow. Although berberine inhibited an increase in thromboxane B2 formation, it increased the formation of 6-keto-prostaglandin F1 alpha in platelets and isolated glomeruli. These results indicate that the antinephritic effects of berberine and coptisine may be partly due to antiplatelet action and improved renal hemodynamics via changing prostanoid synthesis.

/LABORATORY ANIMALS: Neurotoxicity/ The inhibitory effects of coptisine, a protoberberine isoquinoline alkaloid, on type A and type B monoamine oxidase (MAO-A and MAO-B) activities in mouse brain were investigated. Coptisine showed an inhibitory effect on MAO-A activity in a concentration-dependent manner using a substrate kynuramine, but coptisine did not inhibit MAO-B activity. Coptisine exhibited 54.3% inhibition of MAO-A activity at 2 uM. The values of Km and Vmax of MAO-A were 151.9 +/- 0.6 uM and 0.40 +/- 0.03 nmol/min/mg protein, respectively (n=5). Coptisine competitively inhibited MAO-A activity with kynuramine. The Ki value of coptisine was 3.3 uM. The inhibition of MAO-A by coptisine was found to be reversible by dialysis of the incubation mixture. These results suggest that coptisine is a potent reversible inhibitor of MAO-A, and that coptisine functions to regulate the catecholamine content.

/ALTERNATIVE and IN VITRO TESTS/ Coptisine, an isoquinoline alkaloid isolated from rhizome of Coptis japonica, inhibits proliferation of vascular smooth muscle cells (VSMCs). The aim of this study was to evaluate the action of coptisine, along with berberine (a structurally similar isoquinoline alkaloid), on progression of the cell cycle in VSMCs. Coptisine displayed antiproliferative action against VSMCs by blocking the cell cycle at G(1) and G(2)/M phases. The G(1) block was shown by inhibition of [(3)H]thymidine incorporation into VSMCs at coptisine concentrations higher than 15 uM. The mechanism underlying the G(1) arrest involved a decrease in cyclin D1 protein, although cyclin E, A, and B were not affected by coptisine treatment. The selective reduction in cyclin D1 protein was mainly attributable to accelerated proteolysis via proteasome-dependent pathway, since it was inhibited by a proteasome inhibitor, N-carbobenzoxy-L-leucinyl-L-leucinyl-L-norleucinal (MG132) and further the mRNA level of cyclin D1, protein synthesis, and mitogen-activated protein kinase (MAPK) activity remained unaltered. The mechanism underlying the G(2)/M arrest involved partial inhibition of tubulin polymerization, which was apparent at coptisine concentration of 3 uM. Berberine arrested the cell cycle at G(1) phase via a mechanism identical with coptisine, but did not cause block at G(2)/M phase. The results demonstrate that a small difference in the structure between isoquinoline alkaloids produces a big difference in activity, and that coptisine has a unique double action in arresting the cell cycle of VSMCs.

Coptisine is not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions(1). Coptisine contains chromophores that absorb at wavelengths >290 nm(1) and, therefore, may be susceptible to direct photolysis by sunlight(SRC).

Occupational exposure to coptisine may occur through dermal contact with this compound at workplaces where coptisine is extracted or used. Use data indicate that the general population may be exposed to coptisine via its medicinal use. (SRC)

Traditional medicine

MEDICATION

A poison

Coptisine, a cytotoxic alkaloid found in Chinese goldthread, is related to berberine. It has been analyzed as a cytotoxic agent in heptoma and leukemic cells and is reported to block cell cycle progression.