Mosquito Larvicidal and Antifungal Isoquinoline Alkaloids from Papaveraceae
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Jpn. J. Environ. Entomol. Zool. 30(2):51-61(2019) 環動昆 第 30 巻 第2号:51-61(2019) Original Article Mosquito larvicidal and antifungal isoquinoline alkaloids from Papaveraceae Shingo Ueno1), Park Pyoyun1), Yukio Tosa1), Takashi Maoka2), Naoto Kojima3), Masayuki Yamashita3), Masafumi Inoue4)* and Tamio Ueno5) 1) Graduate School of Agricultural Science, Kobe University, Kobe 657-8501, Japan 2) Research Institute for Production Development, Kyoto 606-0805, Japan 3) Kyoto Pharmaceutical University, Kyoto 607-8412, Japan 4) Research & Development Laboratory, Dainihon Jochugiku Co., Ltd, Toyonaka, Osaka 561-0827, Japan 5) Prof. Emeritus of Kyoto University, Graduate School of Agriculture, Kyoto University, Kyoto, 606-8502, Japan (Received:October 17, 2018;Accepted: Aprli: 24, 2019) Abstract From the extracts of three Papaveraceous plants, i.e., Macleaya cordata (Willd.) R.Br., Corydalis incisa (Thunb.) Pers., and Chelidonium majus L. var. asiaticum (Hara) Ohwi., eight isoquinoline alkaloid compounds, i.e., protopine, allocryptopine, sanguinarine, chelerythrine, coryincine, (±)-corynoline, (+)-chelidonine, and (±)-stylopine, were isolated. Furthermore, their structures were spectroscopically determined. Among them, the absolute structure of coryincine was directly determined by X-ray crystallography for the first time. Seven compounds showed larvicidal activity in the mosquito Culex pipiens pallens Coquillett (1898), with corynoline, chelidonine, and stylopine showing particular activity even at low concentrations (1 ppm). In an antifungal test against rice blast fungus, Pyricularia oryzae Cavara involving six compounds, sanguinarine and chelerythrine exhibited almost the same excellent level of activity as isoprothiolane. The toxicity of the M. cordata extract to the fish Oryzias latipes Temminck & Schlegel (1846) was weaker than that of nicotine, which suggests that the fish toxicity of sanguinarine and chelerythrine are low. We believe that these aromatic quaternary benzo[c]phenanthridine alkaloids, especially sanguinarine and chelerythrine, are potentially highly suited as new treatments against the blast fungi and mosquito larvae in aquatic environments, including paddy fields, because of their efficacy and low fish toxicity. Keywords: antifungal, Chelidonium majus, Corydalis incisa, isoquinoline alkaloids,Macleaya cordata, mosquito larvicidal Introduction killer” and has been used as a folk-remedy insecticide by putting the dried plants into toilets to control house fly larvae. Papaveraceous plants have long been used as private Based on these interesting biological characteristics, the medicinal herbs as their tissues contain various biologically alkaloid components of M. cordata and two other plants in active alkaloids (Yu et al., 2014). Macleaya cordata (Willd.) Papaveraceae, i.e., Corydalis incisa (Thunb.) Pers. and R.Br. (Papaveraceae) is distributed in eastern Asia and North Chelidonium majus L. var. asiaticum (Hara) Ohwi, were America and has been used in traditional Chinese medicine for investigated. its analgesic, antiedemic, carminative, depurative, diuretic, Mosquito-borne infections, malaria, and Japanese anti-inflammatory, and antimicrobial properties (Baek et al., encephalitis have been problematic for many years, but 2013). In Japan, M. cordata has been called the “maggot recently, new infections, such as dengue fever and Zika fever, *Correspondig author:[email protected] - 51 - Inoue et al have also become prevalent (Alshammari et al., 2018). To the following chromatographic procedures. reduce the occurrence of these infectious diseases, it is The alkaloid phase was washed with water, dried over important to reduce the number of adult mosquitoes, by killing sodium sulfate, and evaporated to dryness to afford a both the larvae and the adults using insecticides. Therefore, we reddish-brown solid (5–7 g) containing alkaloids. After focused on the effect of Papaveraceous alkaloids against evaporation of the solvent, the precipitate and solid were mosquito larvae. applied to an aluminum oxide column and eluted with a Paddy fields are a potential habitat for mosquito larvae; benzene-chloroform mixture to produce a stepwise increase in therefore, prior to use of a new insecticide in this environment, polarity (9:1 to 1:9 each 200 mL). Each fraction was monitored it is necessary to ensure that its toxicity to fish is low in by TLC and LC-MS. The fractions containing components with consideration of outflow to rivers and fields and take into the same Rf value on TLC and the same m/z peak account the chemical balance of the aquatic environment. corresponding to [M+H]+ or [M]+ at the same retention time on Effects of the active components in the extracts on the fish LC-MS were collected, evaporated, and recrystallized to afford were preliminarily examined based on toxicity against the fish the following crystal alkaloid compounds: 1, 2, 3 and 4 from M. Oryzias latipes Temminck & Schlegel (1846). cordata; 1, 5, and 6 from Cor. incisa; and 1 and 7 from Chel. Furthermore, the antifungal activity of some of the extracted majus. alkaloids was examined against rice blast fungus, Pyricularia The basic component of the former hexane phase was oryzae Cavara, one of the most problematic pathogens partitioned into 1.0 L of 2 N L-(+)-tartaric acid and extracted infecting rice in the paddy fields, thus significantly reducing with 0.5 L of chloroform twice under basic conditions (pH rice production. 10.0) by the addition of 2 N sodium carbonate. Evaporation of Here, we report the potential development of a pesticide the chloroform phase of Chel. majus afforded a yellow-brown with unique alkaloid ingredients active against mosquito larvae solid, which yielded yellow crystal needles (compound 8) on and the rice blast fungus, with low fish toxicity and usage in recrystallization from ethanol (Fig. 1). aquatic environments, such as paddy fields. Reverse phase HPLC using a Gemini C6-Phenyl column (4.6 mm ID × 150 mm, Phenomenex Inc.) and eluting with 70% Materials and Methods MeOH-NH4HCO3 at pH 10.7 at a flow rate of 1 mL/min, showed the following retention times: 8.47, 0.68, 2.42, 2.26, 2.00, 2.13, 1.85, and 2.16 min for compound 1–8, respectively. Plant materials Three species of Papaveraceae native to Japan, M. cordata, Elucidation of chemical structure Cor. incisa, and Chel. majus, were harvested in the flowering Compound 1: protopine (1) period in May from the Kyoto and Osaka areas. The whole A colorless prism; mp. 205°C–206°C; TLC (Aluminum plants were dried in the shade for 3 weeks, chopped (1.5 Oxide, 100% CHCl ) R : 0.20; IR (KBr): ν 2891, 2802, kg/plant), and extracted with Methanol (15 L, 3 times, each 10 3 f max 2359, 1640, 1610 cm−1; HR-ESIMS : found [M+H]+ m/z days) at room temperature. The combined Methanol extracts 354.1341, calcd. for C H NO : 354.1328; EIMS m/z (%): 353 were filtered, concentrated, and stored at room temperature. 20 20 5 (M+, 8.0), 281 (6.1), 267 (9.1), 252 (7.6), 190 (12.8), 163 (20.6), 148 (100), 134 (6.8); 1H NMR (400 MHz, CDCl , δ ) Extraction and isolation 3 H 1.98 (3H, s, N-CH ), 2.54 (2H, bm, H-6), 3.00 (2H, bm, H-5), The reserved Methanol extracts were evaporated in vacuo 3 3.58 (2H, bm, H-13), 3.80 (2H, bm, H-8), 5.93 (2H, s, yielding a brown paste (40–50 g), which was suspended in 2.0 -OCH O-), 5.95 (2H, s, -OCH O-), 6.64 (1H, s, H-4), 6.66 (1H, L of water (pH 6.0) and successively extracted with 1.0 L of 2 2 d, J = 5.2 Hz, H-11), 6.72 (1H, d, J = 5.2 Hz, H-12), 6.91 (1H, n-hexane three times to afford a hexane phase and a water s, H-1); 13C NMR (100 MHz, CDCl , δ ): 31.8 (C-5), 41.5 phase. The water phase was extracted with 1.0 L of 3 C (N-CH ), 46.5 (C-13), 50.8 (C-8), 57.8 (C-6), 100.9 (-OCH O-), chloroform three times. The chloroform phase was partitioned 3 2 101.2 (-OCH O-), 106.7 (C-11), 108.2 (C-1), 110.5 (C-4), with 1.0 L of 1 N HCl twice to afford an HCl phase. The HCl 2 117.9 (C-8a), 125.1 (C-12), 129.0 (C-12a), 132.8 (C-4a), 136.2 phase was re-extracted with 1.0 L of chloroform twice under (C-14a), 145.9 (C-2), 146.0 (C-10), 146.3 (C-9), 148.0 (C-3), basic conditions at pH 10.0, adjusted by the addition of sodium 195.0 (C-14). carbonate to afford a chloroform phase, named the alkaloid These data were in agreement with the values of 1 in phase. This phase was used for the fish toxicity bioassay and - 52 - 殺ボウフラ活性型アルカロイド Takahashi et al. (1985). -OCH2O-), 7.76 (1H, s, H-1), 8.26 (1H, d, J = 9.0 Hz, H-9), 8.27 (1H, s, H-4), 8.29 (1H, d, J = 9.0 Hz, H-12), 8.76 (1H, d, Compound 2: allocryptopine (2) J = 9.0 Hz, H-11), 8.80 (1H, d, J = 9.0 Hz, H-10), 10.05 (1H, s, 13 A colorless prism; mp. 161°C–163°C; TLC (Aluminum H-6); C NMR (125 MHz, DMSO-D6, δC) 52.5 (N-CH3), 57.4 Oxide, 100% CHCl3) Rf: 0.12; IR (KBr): νmax 2891, 2802, (C-8 -OCH3), 62.5 (C-7 -OCH3), 103.1 (-OCH2O-), 104.6 2359, 1640, 1610 cm−1; HR-ESIMS : found [M+H]+ m/z (C-4), 106.1 (C-1), 119.0 (C-6a), 119.6 (C-11), 119.6 (C-10), 370.1655, calcd. for C21H24NO5: 370.1654; EIMS m/z (%): 369 120.5 (C-4a), 125.6 (C-14), 126.4 (C-9), 128.3 (C-10a), 131.4 (M+, 100), 352 (20.1), 290 (9.5), 206 (11.5), 188 (40.8); 1H (C-12), 132.0 (C-13), 132.6 (C-12a), 145.8 (C-7), 149.0 (C-3), NMR (400 MHz, CDCl3, δH) 1.86 (3H, s, N-CH3), 2.64 (2H, 149.1 (C-2), 150.9 (C-8), 151.1 (C-6).