Cheng-Ta Li

Secondary Metabolites from the Unripe Fruits of Capsicum annuum var. conoides

Red pepper, Capsicum annuum (Solanaceae), is used as a spice all over the world. Red pepper is widely studied because its pungent principal component, capsaicin, has dietary, analgesic, and antioxidant activities [1]. The pungent principal component of red peppers is a group of acid amides of vanillylamine and C8 to C13 fatty acids, which are known generally as capsaicin [2]. More than 16 other capsaicinoids have been found as minor components [3]. Numerous studies have been done on the red pepper fruit, but there are few studies on stems [2–4]. Previously, we isolated 20 compounds, including ten amides, four steroids, and six benzenoids, from the stems of this plant [5]. The chemical constituents of unripe fruits of C. annuum L. var. conoides (Mill.) Irish have not yet been reported. This study has isolated secondary metabolites from the unripe fruits of C. annuum var. conoides. To further understand the chemotaxonomy and to continue searching for biologically and chemically novel agents from Solanaceous plants, the unripe fruits of C. annuum var. conoides were chosen for further phytochemical investigation. The MeOH extract of the unripe fruits of its plants were subjected to solvent partitioning and chromatographic separation to afford 17 pure substances. The chemical constituents in the plants of C. annuum var. conoides were separated by column chromatography. Investigation of the MeOH extract of the plants has led to the isolation of 17 compounds: three chlorophylls: pheophytin-a [6], 132-hydroxyl-(132-S)-pheophytin-a [7], and aristophyll-c [6]; six steroids: -sitosterol [8], stigmasterol [8], -sitostenone [8], stigmasta-4,22-dien-3-one [8], 6 -hydroxy-sitosterone [8], and 6 -hydroxystigmasterone [8]; seven benzenoids: p-hydroxybenzoic acid [9], p-hydroxybenzaldehyde [10], methylparaben [10], vanillin [10], isovanillin [10], ferulic acid [10], and syringic acid [10]; and one ionone: (+)-abscisic acid [11]. These compounds were obtained and characterized by comparison of their physical and spectral data (UV, IR, NMR, and MS) with values obtained in the literature. All of these compounds were found for the first time from this species. The specimen of C. annuum var. conoides was collected from Chiayi County, Taiwan in March, 2011. A voucher specimen was characterized by Dr. Jin-Cherng Huang of the Department of Forest Products Science and Furniture Engineering, National Chiayi University, Chiayi, Taiwan and deposited in the School of Medical and Health Sciences, Fooyin University, Kaohsiung, Taiwan. The air-dried unripe fruits of C. annuum var. conoides (5.7 kg) were extracted with MeOH (10 L 4) at room temperature, and the MeOH extract (56.2 g) was obtained upon concentration under reduced pressure. The MeOH extract was chromatographed over silica gel using CH2Cl2–MeOH as eluent to produce nine fractions. Part of fraction 1 (3.4 g) was subjected to silica gel column chromatography by eluting with n-hexane–acetone (60:1) to furnish 10 fractions (1-1–1-6). Fraction 1-2 (1.4 g) was further purified by another silica gel column using n-hexane–acetone (10:1) to obtain p-hydroxybenzoic acid (4 mg), p-hydroxybenzaldehyde (3 mg), and methylparaben (3 mg). Fraction 1-5 (0.2 g) was further purified by another silica gel column using n-hexane–acetone (15:1) to obtain vanillin (5 mg) and isovanillin (1 mg). Part of fraction 2 (8.6 g) was subjected to silica gel column chromatography by eluting with n-hexane–acetone (80:1) to furnish four fractions (2-1–2-4). Fraction 2-2 (2.7 g) was further purified by another silica gel column using n-hexane–acetone (70:1) to obtain pheophytin-a (14 mg), 132-hydroxyl-(132-S)-pheophytin-a (22 mg), and aristophyll-c (14 mg). Part of fraction 3 (5.6 g) was subjected to

Secondary Metabolites from the Stems of Capsicum annuum var. conoides

Red pepper, Capsicum annuum (Solanaceae), is used as a spice all over the world. Red pepper is studied actively because its pungent principal component, capsaicin, has a dietary effect, analgesic activity, and antioxidant activity [1]. The pungent principal component of red peppers is a group of acid amides of vanillylamine and C8 to C13 fatty acids, which are known generally as capsaicin [2]. More than 16 other capsaicinoids have been found as minor components [3]. Numerous studies have been done on the red pepper fruit, but there are few studies on stems [2–4]. The chemical constituents of stems of C. annuum L. var. conoides Irish have not yet been reported. This study has shown the isolation of secondary metabolites from the stems of C. annuum var. conoides. To further understand the chemotaxonomy and to continue our search for biologically and chemically novel agents from Solanaceous plants, the stems of C. annuum collected from Chiayi County, Taiwan in March, 2011 were chosen for further phytochemical investigation. The MeOH extract of its plants were subjected to solvent partitioning and chromatographic separation to afford 19 pure substances. The chemical constituents in the plant of C. annuum var. conoides were separated by column chromatography. Investigation of the MeOH extract of the plants has led to the isolation of 21 compounds, 10 amides 1–10, four steroids 11–14, one lignan 15, and six benzenoids 16–21. These compounds were obtained and characterized by comparison of their physical and spectral data (UV, IR, NMR, and MS) with values in the literature. All of these compounds were found for the first time from this species. The specimen of C. annuum var. conoides Irish was collected from Chiayi County, Taiwan in March, 2011. A voucher specimen was characterized by Dr. Jin-Cherng Huang of the Department of Forest Products Science and Furniture Engineering, National Chiayi University, Chiayi, Taiwan and deposited in the School of Medical and Health Sciences, Fooyin University, Kaohsiung, Taiwan. The air-dried stems of C. annuum var. conoides (6.2 kg) were extracted with MeOH (10 L 4) at room temperature, and an MeOH extract (64.3 g) was obtained upon concentration under reduced pressure. The MeOH extract was chromatographed over silica gel using CH2Cl2–MeOH as eluent to produce 10 fractions. Part of fraction 2 (6.52 g) was subjected to silica gel column chromatography by eluting with n-hexane–acetone (50:1) to furnish seven fractions (2-1–2-7). Fraction 2-2 (2.52 g) was further purified by another silica gel column using n-hexane–acetone (10:1) to obtain p-hydroxybenzoic acid (16) (2 mg) and p-hydroxybenzaldehyde (17) [5] (5 mg). Fraction 2-3 (1.86 g) was further purified by another silica gel column using n-hexane–acetone (9:1) to obtain vanillic acid (18) [5] (2 mg) and isovanillic acid (19) [5] (3 mg). Part of fraction 3 (5.12 g) was subjected to silica gel column chromatography by eluting with n-hexane–acetone (40:1), then enriched with acetone to furnish eight fractions (3-1–3-8). Fraction 3-1 (1.24 g) eluted with n-hexane–EtOAc (30:1) was further separated using silica gel column chromatography and preparative TLC (n-hexane–EtOAc, 10:1) to give a mixture of -sitosterol (11) [6] and stigmasterol (12) [6] (37 mg). Fraction 3-2 (1.41 g) was further purified on a silica gel column using the CH2Cl2–MeOH system to obtain (+)-syringaresinol (15) [7] (5 mg), ferulic acid (20) [8] (3 mg), and hydroferulic acid (21) [9] (2 mg).

Cinnapine, a New Pyridine Alkaloid from Cinnamomum Philippinense

Cinnapine (1), a new pyridine alkaloid, has been isolated from the roots of Cinnamomum philippinense (Lauraceae). The structure was characterized and identified by spectral analysis.

Secondary Metabolites from Nelumbo nucifera cv. Rosa-plena

Nelumbo nucifera Gaertn. cv. Rosa-plena is a perennial aquatic crop grown and consumed throughout Asia. All parts of N. nucifera have been used for various medicinal purposes in oriental medicine. In particular, the leaves are known for diuretic and astringent properties and are used to treat fever, sweating, and strangury, and as a styptic [1]. To further understand the chemotaxonomy of the Nelumbo species [1, 2], Nelumbo nucifera Gaertn. cv. Rosa-plena was chosen for phytochemical investigation. There is only one paper describing the constituents of this plant [3]. Previously, we have isolated seven aporphines, two oxoaporphines, one dioxoaporphine, one dehydroaporphine, two steroids, and two chlorophylls from this plant [3]. As part of our continuing investigation of the phytochemical and bioactive compounds of Nelumbo plants, seven flavonoids, quercetin [4], quercetin 3-O-D-glucopyranoside [5], quercetin 3-O-D-galactopyranoside [6], quercetin 3-O-Dglucopyranosyl-(1 6)-D-glucopyranoside [7], isorhamnetin [8], isorhamnetin 3-O-D-glucopyranoside [8], and isorhamnetin 3-O-D-galactopyranoside [8] were obtained by systematic extraction and isolation from the leaves of Nelumbo nucifera Gaertn. cv. Rosa-plena. All of these compounds were isolated for the first time from this source. The leaves of Nelumbo nucifera Gaertn. cv. Rosa-plena were collected from Tainan County, Taiwan, November 2008. Plant material was identified by Prof. Fu-Yuan Lu (Department of Forestry and Natural Resources College of Agriculture, National Chiayi University). A voucher specimen (Nelumbo nucifera Gaertn. cv. Rosa-plena) was deposited in the Department of Medical Laboratory Science and Biotechnology, School of Medical and Health Sciences, Fooyin University, Kaohsiung, Taiwan. The air-dried leaves of Nelumbo nucifera Gaertn. cv. Rosa-plena (1.5 kg) were extracted with MeOH (5 L 5) at room temperature, and a MeOH extract (108.7 g) was obtained upon concentration under reduced pressure. The MeOH extract, suspended in H2O (1 L), was partitioned with CHCl3 (3 L 4) to give fractions soluble in CHCl3 (57.23 g) and H2O (43.62 g). The CHCl3-soluble fraction was chromatographed over silica gel (1700 g, 70–230 mesh) using n-hexane–EtOAc– MeOH mixtures as eluents to produce six fractions. Part of fraction 5 (5.34 g) was subjected to silica gel chromatography by eluting with CH2Cl2–MeOH (40:1) and enriched with MeOH to furnish two fractions (5-1–5-2). Fraction 5-2 (1.67 g) was eluted with n-hexane–EtOAc mixtures to obtain isorhamnetin (2 mg). Part of fraction 6 (4.21 g) was subjected to silica gel chromatography by eluting with EtOAc–MeOH (20:1) and enriched with MeOH to furnish five further fractions (6-1–6-5). Fraction 6-1 (1.46 g) was subjected to silica gel chromatography by eluting with n-hexane–EtOAc (1:9) and enriched gradually with EtOAc to produce quercetin (5 mg). Fraction 6-2 (0.76 g) was subjected to silica gel chromatography by eluting with EtOAc–MeOH (30:1) and enriched gradually with MeOH to produce isorhamnetin 3-O-D-glucopyranoside (5 mg) and isorhamnetin 3-O-D-galactopyranoside (7 mg). Fraction 6-3 (1.51 g) was further purified on a silica gel column using EtOAc–MeOH mixtures to obtain quercetin 3-O-D-glucopyranoside (5 mg) and quercetin 3-O-D-galactopyranoside (4 mg). Fraction 6-4 (0.76 g) was eluted with EtOAc–MeOH (9:1) and repeatedly subjected to silica gel CC to give quercetin 3-O-D-glucopyranosyl-(1 6)-D-glucopyranoside (6 mg).

Chemical constituents of the stems of Michelia figo

Species belonging to the Michelia genus are arboreous plants, growing in temperate zone of oriental India, southern China, Malaysia, and Indonesia. The species more utilized is Michelia champaca: its cortex and seeds are used as febrifuge and tonic-aromatic, its roots are employed as emmenagogue, its leaves as astringent, its gemmae in the treatment of hemorrhage and its flowers and fruits are believed to possess curative properties in enteritis [1]. Less known species, such as Michelia figo, are used as ornamental plants and to obtain essences. [1]. Michelia figo is an evergreen medium shrub, commonly called banana shrub, because of the heavy, sweet fragrance banana scent of its purple flowers. The plant is also known in Indian folk medicine as a remedy against hypertension [2]. To further understand the chemotaxonomy of the Michelia species [3–11], M. figo was chosen for phytochemical investigation. The chemical constituents of this plant have not yet been reported. The compounds derived from the stem include four alkaloids, (6,7-dimethoxyisoquinolinyl)-(4 -methoxyphenyl)-methanone [12], corydaldine [13], N-methylcorydaldine [14], and liriodenine [15]; two steroids, 6 -hydroxystigmast-4-en-3-one [16] and 6 -hydroxystigmast-4,22-dien-3-one [16]; five benzenoids, p-hydroxybenzaldehyde [17], p-hydroxybenzoic acid [18], 3,4,5-trimethoxybenzoic acid [18], vanillin [18], and vanillic acid [18]. All of these compounds were found for the first time from this plant. The stems of M. figo Spreng. were collected from Chiayi County, Taiwan, in May 2011. Plant material was identified by Prof. Fu-Yuan Lu (Department of Forestry and Natural Resources, College of Agriculture, National Chiayi University). A voucher specimen (Michelia 5) was deposited in the School of Medical and Health Sciences, Fooyin University, Kaohsiung City, Taiwan. The air-dried stems of M. figo (2.3 kg) were extracted with MeOH (5 L 3) at room temperature, and a MeOH extract (53.4 g) was obtained upon concentration under reduced pressure. The MeOH extract, suspended in H2O (1 L), was partitioned with CH2Cl2 (3 L 4) to give fractions soluble in CH2Cl2 (40.5 g) and H2O (7.7 g). The CH2Cl2-soluble fraction was chromatographed over silica gel (900 g, 70–230 mesh) using n-hexane–EtOAc–MeOH mixtures as eluents to give five fractions. Part of fraction 2 (7.04 g) was subjected to silica gel chromatography eluting with n-hexane–EtOAc (50:1), enriched gradually with EtOAc, to furnish five fractions (2-1–2-5). Fraction 2-2 (2.51 g) was further purified on a silica gel column using n-hexane–EtOAc mixtures to obtain a mixture of 6 -hydroxystigmast-4-en-3-one and 6 -hydroxystigmast-4,22-dien3-one (14 mg). Part of fraction 3 (5.68 g) was subjected to silica gel chromatography eluting with n-hexane–EtOAc (40:1), enriched with EtOAc, to furnish three further fractions (3-1–3-3). Fraction 3-2 (2.11 g) was further purified on a silica gel column using CH2Cl2–MeOH mixtures to obtain corydaldine (5 mg) and N-methylcorydaldine (4 mg). Fraction 3-3 (2.18 g) was further purified on a silica gel column using CH2Cl2–MeOH mixtures to obtain liriodenine (17 mg) and (6,7-dimethoxyisoquinolinyl)-(4 -methoxyphenyl)-methanone (3 mg). Part of fraction 4 (7.65 g) was subjected to silica gel chromatography eluting with CH2Cl2–MeOH (40:1), enriched with MeOH, to furnish four fractions (4-1–4-4). Fraction 4-2

Chemical Constituents of Fruit Shells of Passiflora edulis

Passiflora edulis is a plant that belongs to the family Passifloraceae. This is a native plant of South America. The fruit of this plant is called passion fruit, and the seeds are often eaten together with the yellow pulp. Previous studies reported that the leaves, vines, seeds, and flowers contain polyphenolic compounds and exhibit a variety of physiological effects, such as antianxiety [1, 2], anti-inflammatory [3, 4], and antioxidant activities [5], vasorelaxing effects [5], and cough-suppressant effects [6]. Moreover, it was reported that the rind of passion fruit has a hypotensive effect [7]. However, the specific compound in passion fruit shells that contributes to these effects remains unknown. These observations provide useful information for potential chemopreventive drug design. The MeOH extract of its fruit shell was subjected to solvent partitioning and chromatographic separation to afford twelve pure substances. The chemical constituents of the fruit shell of P. edulis were separated using column chromatography. Twelve compounds, including four flavonoids, 5-hydroxy-4 ,7-dimethoxyflavonoid (1) [8], luteolin-7,3 ,4 -trimethyl ether (2) [9], 5,3 -dihydroxy-7,4 dimethoxyflavone (3) [10], and persicogenin (4) [11], three benzenoids, vanillic acid (5) [12], p-hydroxybenzoic acid (6) [13], and syringic acid (7) [14], one quinol, 4-acetyl-3,5-dimethoxy-p-quinol (8) [15], two amides, N-trans-feruloyltyramine (9) [16] and N-cis-feruloyltyramine (10) [16], one steroid, -sitostenone (11) [17], and one lignan, (+)-syringaresinol (12) [12], were isolated from the fruit shell of P. edulis. All of these compounds (1–12) were obtained for the first time from this plant.

A New Chromone from Citrus reticulata

One new chromone, 5,7-dihydroxy-8-methoxychromone (1), was isolated from the peels of Citrus reticulata (Rutaceae), together with two polymethoxyflavones, 5,6,7,8,3′,4′-hexamethoxyflavone (2) and 5,6,7,8,4′-pentamethoxyflavone (3). The structure of 1 was characterized and identified by spectral analysis.

Chemical Constituents of the Wood of Aquilaria agallocha

Aquilaria is a genus in the family Thymelaeaceae and class Magnoliopsida. It is native to southwest Asia. This tree occurs particularly in rain forest of Indonesia, Thailand, Cambodia, Laos, Malaysia, Northern India, Philippines, and Borneo. Studies revealed that agarwood has remarkable anticancer activity [1]. Aquilaria sinensis is the only plant resource in China for agarwood, which is also called Chinese eaglewood, to distinguish it from agarwood of other species, such as A. agallocha. Previous phytochemical investigations on Chinese eaglewood revealed characteristic sesquiterpenes and chromone derivatives [2–7], but little is known about the chemical constituents of the healthy wood. The benzene extracts of the plant have central nervous system antidepression activities [8]. These observations provide useful information for potential chemopreventive drug design. The MeOH extract of its wood was subjected to solvent partitioning and chromatographic separation to afford 12 pure substances. The chemical constituents in the wood of A. agallocha were separated with column chromatography. Twelve compounds, including four flavonoids, 5-hydroxy-7,4 -dimethoxyflavone [9], 5-hydroxy-7,3 ,4 -trimethoxyflavone [10], 5,3 -dihydroxy-7,4 dimethoxyflavone [11], and 5,4 -dihydroxy-7,3 -dimethoxyflavone [12], three benzenoids, vanillic acid [13], p-hydroxybenzoic acid [14], and methylparaben [15], one quinol, 4-acetyl-3,5-dimethoxy-p-quinol [16], three steroids, -sitosterol [17], -sitostenone, and stigmastenone [18], and one lignan, (+)-syringaresinol [13], were isolated from the wood of A. agallocha. All of these compounds were obtained for the first time from this plant. The specimen of A. agallocha was collected from Shanshang District, Tainan City, Taiwan in May, 2008. A voucher specimen was identified by Prof. Fu-Yuan Lu (Department of Forestry and Natural Resources, College of Agriculture, National Chiayi University) and was deposited in the School of Medical and Health Sciences, Fooyin University, Kaohsiung, Taiwan. The wood (3.1 kg) of A. agallocha was chipped and air dried and extracted repeatedly with MeOH (5 L 6) at room temperature. The combined MeOH extracts (72.1 g) were then evaporated and further separated into five fractions by column chromatography on silica gel (4.5 kg, 70–230 mesh) with gradients of n-hexane–CH2Cl2–acetone–MeOH. Part of fraction 1 (20.3 g) was subjected to silica gel chromatography by eluting with n-hexane–acetone (80:1), enriched with acetone, to furnish three further fractions (1-1–1-3). Fraction 1-2 (7.1 g) was further purified on a silica gel column using n-hexane–acetone mixtures to obtain 5-hydroxy-7,4 -dimethoxyflavone (15.2 mg). Part of fraction 1-3 (15.3 g) was subjected to silica gel chromatography by eluting with n-hexane–acetone (60:1), enriched gradually with acetone, to furnish two fractions (1-3-1–1-3-5). Fraction 1-3-1 (2.7 g) was further purified on a silica gel column using n-hexane–acetone mixtures to yielded 5-hydroxy-7,3 ,4 trimethoxyflavone (6.8 mg) and 5,3 -dihydroxy-7,4 -dimethoxyflavone (5.1 mg). Fraction 1-3-3 (1.8 g) was further purified on a silica gel column using n-hexane–acetone mixtures to yield a mixture of -sitostenone and stigmastenone (22.3 mg). Part of fraction 2 (21.8 g) was subjected to silica gel chromatography by eluting with n-hexane–acetone (50:1), enriched with acetone, to furnish three further fractions (2-1–2-3). Fraction 2-2 (6.1 g) was further purified on a silica gel column using