Lobelia Chinensis: Chemical Constituents and Anticancer Activity Perspective
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Chinese Journal of Natural Chinese Journal of Natural Medicines 2014, 12(2): 0103−0107 Medicines doi: 10.3724/SP.J.1009.2014.00103 Lobelia chinensis: chemical constituents and anticancer activity perspective CHEN Mei-Wan1#, CHEN Wen-Rong2#, ZHANG Jin-Ming1, LONG Xiao-Ying2, WANG Yi-Tao1 * 1 State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macau 999078, China; 2 School of Traditional Chinese Medicine, Guangdong Pharmaceutical University, Guangzhou 510006, China Available online 20 Feb. 2014 [ABSTRACT] Research has demonstrated that many chemical constituents dominated by piperidine alkaloids and flavonoids, such as lo- belanidine, lobeline, and lobelanine, have been obtained from Lobelia chinensis Lour. Experimental studies and clinical applica- tions have also indicated that L. chinensis possesses a number of pharmacological activities (e.g., diuretic, choleretic, breathing ex- citement, anti-venom, anti-bacterial, and anticancer). This paper focuses on the properties, chemical constituents, and anticancer activity of L. chinensis to clarify the connection among them, and identify the active anticancer compounds. This work serves as the foundation for further research and development of L. chinensis. [KEY WORDS] Lobelia chinensis; Chemical constituents; Anticancer activity [CLC Number] R284; R285 [Document code] A [Article ID] 2095-6975 (2014)02-0103-05 stituents, L. chinensis exhibits various biological properties, Introduction including anti-bacterial, anti-venom, and anticancer properties. Lobelia chinensis Lour. (L. chinensis) is a plant of the Furthermore, it has been reported to have potential anti-viral [3] Campanulaceae family that is commonly known as ji-jie-suo, and anti-inflammatory activity . In this article, the recent xi-mi-cao, and she-she-cao. It has been widely used as an studies on the metabolites and the anticancer activity profiles antidote, diuretic, and hemostat in traditional Chinese medi- of L. chinensis are summarized to expand its use in clinical cine for decades [1-2]. This plant is dispersed widely through- applications. As far as is known, L. chinensis has been mainly out East Asia, including China, Korea, and Japan [1]. The used to treat liver, gastric, intestinal, and breast tumors. increasing research interests have afforded a variety of Character of L. chinensis chemical compounds from this plant, including piperidine alkaloids, such as lobeline, norlobelanine, and lobelanine; L. chinensis twines around itself when growing. It has coumarins, such as 6, 7-dimethoxycoumarin, 5-hydroxy- yellow roots that are 1−2 mm in diameter, and a light yel- 7-methoxycoumarin, and 5,7-dimethoxy-6-hydroxy-coumarin; low-brown surface. The stem is grey-green with branches and and terpenoids, including phytol, phytenal, cycloeucalenol, joints; the brown-green leaves grow toward one another. The and 24-methylene-cycloartanol. Based on these chemical con- shape of the plant is long and narrow, wrinkling and showing sparse and short teeth on the edge. It has small, light pur- ple-red flowers with a single, tiny, long peduncle growing [Received on] 30-Nov.-2012 under the axillary, five cracks on the bottom of the corolla, [Research funding] This project was supported by the Macao Sci- and white hair within. The smell of L. chinensis is weak, but ence and Technology Development Fund (No. 102/2012/A3) and the special, which is irritating, a little sweet and hot [4]. Research Fund of the University of Macau (No. MYRG 208 (Y3-L4)-ICMS11- WYT). Chemical Ingredients of L. chinensis [*Corresponding author] WANG Yi-Tao: Prof., Tel/Fax: 853-839746 91, 853-28841358; E-mail: [email protected] The main constituents of L. chinensis are piperidine al- #Co-first authors kaloids and flavonoids; other components include terpenes, These authors have no conflict of interest to declare. alkynes, coumarins, and amino acids [2]. The main piperidine – 103 – CHEN Mei-Wan, et al. / Chin J Nat Med, 2014, 12(2): 103−107 alkaloids contributing to the anticancer effects are dominated laceae (Fig. 3) [9-10]. In addition, coumarins can be found in by norlobelanine (1), lobeline (2), lobelanidine (3), lobela- L. chinensis, such as 6, 7-dimethoxycoumarin (14), 5, 7-di- nine (4), radicamine A (5), and radicamine B (6) [1], which are methoxy-6-hydroxycoumarin (15), 5-hydroxy-7-methoxy- shown in Fig. 1. In addition, the flavonoids are comprised of coumarin (16), and 5-hydroxy-6, 7-methoxycoumarin (17) apigenin (7), luteolin (8), quercetin (9), linarin (Fig. 4). (10), and luteolin 3’, 4’-dimethylether-7-O-β-D-gluco- Piperidine alkaloids isolated from L. chinensis side (11) (Fig. 2) [5-6]. Among the flavonoids, apigenin Given the physicochemical properties of alkaloids, sev- and luteolin have been demonstrated as antitumor effective eral useful methods can be used to extract alkaloids from L. compounds by Cai et al [7] and Zhang et al [8]. The terpenoids chinensis, such as solvent extraction and direct extraction. in it mainly include cycloeucalenol, 24-methylene- Kuang et al [5] chose reflux extraction to obtain the constitu- cycloartanol and β -amyrin. Some ingredi- ents of L. chinensis after comparing the extraction efficiencies ents like lobetyolin (12) and lobetyolinin (13) are considered of ultrasonic extraction, soaking, percolation, and reflux ex- to be typical polyacetylene constituents of the Campanu- traction. The results were obtained through an orthogonal Fig. 1 Structures of the alkaloids isolated from L. chinensis: norlobelanine (1), lobeline (2), lobelanidine (3), lobelanine (4), radicamine A (5) and radicamine B (6) Fig. 2 Structures of the flavonoids isolated from Lobelia chinensis: apigenin (7), luteolin (8), quercetin (9), linarin (10) and lute- olin 3’, 4’-dimethylether-7-O-β-D-glucoside (11) – 104 – CHEN Mei-Wan, et al. / Chin J Nat Med, 2014, 12(2): 103−107 experimental design. The best conditions for extraction in- Terpenes and coumarins extracted from L. chinensis volved using 90% ethanol, eight times the volume of whole Isolation and purification of L. chinensis were carried out herb with refluxing for 1 h twice. In this way, the amount of by Deng et al [14] using silica gel, Sephadex LH-20, and prepa- −1 17.10 mg·g total alkaloids could be extracted. rative HPLC. Four terpenes including phytol, cycloeucalenolⅠ, Flavonoids extracted from L. chinensis cycloeucalenol Ⅱ,24-methylenecycloartanol were obtained. Several methods have been applied to extract flavonoids Han et al [10] obtained three coumarin compounds (Fig. 4) from [11] of L. chinensis. Huang et al optimized the extraction pa- 80% ethanol extract of L. chinensis by column chromate. Addi- rameters of flavonoid glycosides from L. chinensis by ul- tionally, Chen et al [15] also isolated these three coumarins from trosonic-assisted extraction. The optimum extraction condi- 95% ethanol extract of full plant of L. chinensis. tions were as follows: ethanol concentration of 50% , extraction duration of 35 min,extraction temperature of 50 Antitumor Activity −1 °C, and solid to liquid ratio of 1 : 50, obtaining 4.21 mg·g Contemporary studies have revealed that a decoction of flavonoid glycosides under these conditions.Subsequently, L. chinensis provides diuretic, choleretic, excited breathing, Huang et al [12] studied the ultrasonic-assisted semi-bionic anti-central nervous system effects, improved hyperlipidemia extraction method for the flavonoid glycosides from Herba L. and vascular endothelial protection, anti-proliferation of arte- chinensis. This method combines holistic medicine and mo- rial smooth muscle cells, anti-venom, anti-bacterial, and lecular medicine to simulate the progress and circumstances anticancer properties. The decoction is also used to treat ab- in which oral medicines are taken and absorbed in the gas- dominal edema, various swellings, snakebites, for athero- trointestinal tract, whose aim is to extract and reserve active sclerosis, for vascular disease from renal hypertension, and ingredients of raw materials as far as possible. The content of for tumors, where it shows particular therapeutic effects. 4.70 mg·g−1 flavonoid glycosides was found by orthogonal Both the decoction and the alkaloids of L. chinensis show design under the optimal conditions as follows: 70% (V/V) of antitumor activity, creating an area for pharmaceutical re- ethanol-water as the extracting solvent, 1 : 40 g·mL−1 of solid search. to liquid ratio,70w of ultrasonic power, and 25 min of ultra- Antitumor activity of L. chinensis decoction sonic time. Jiang et al [13] used 70% ethanol (12 × V/W herbal The decoction of L. chinensis can efficiently restrain liver weight) to extract for three times, 1 h per time, and combined cancer growth, enhance the immunity of mice, and modulate various chromatographic techniques, including (silica gel, the expression of P53 and C-erbB-2 in the liver cancer or- polyamide, Sephadex LH-20, ODS, and MCI) and ganization, all of which contribute to preventing tumors in re-crystallization methods to separate nine flavonoids, in- the body, as well as curing them [16]. Liu et al. investigated cluding apigenin, luteolin, diosmetin, chrysoeriol, hesperidin, the anti-cancer effects of L. chinensis on H22 hepatocellar loteolin-7-O-β-D-glucoside, apigenin-7-O-β-D-glucoside, linarin, carcinoma-bearing mice, by adjusting P27 and survivin ex- and diosmin. pression [17]. Similar to 5-fluorouracil, the positive control, the L. chinensis decoction exhibited stronger P27 and weaker surviving expression. Compared with the control group, the decoction group had significantly different results (P < 0.05), however, when comparing the decoction and 5-fluorouracil groups, the difference was insignificant (P > 0.05). The L. chinensis decoction reduced the size of the H22 liver tumors, achieving an anti-tumor rate of 33.98%, notably lower than Fig. 3 Structures of polyacetylenes isolated from L. chinen- the control group (P < 0.05) [17]. Based on its efficacy, L. sis: lobetyolin (12) and lobetyolinin (13) chinensis shows activity related to the mechanism of the ex- pression of P27 and survivin. Moreover, Liu et al [17] evalu- ated the anticancer effects on tumor size and anti-tumor rate of L.