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Phytochemical Constituents of Bitter Melon (Momordica charantia)
Phytochemical Constituents of Bitter Melon (Momordica charantia)
Natural Product Sciences. 2013. Dec, 19(4): 286-289
Copyright © 2013, The Korean Society of Pharmacognosy
  • Received : July 15, 2013
  • Accepted : October 04, 2013
  • Published : December 31, 2013
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About the Authors
Hyun Young Kim
Department of Food Science, Gyeongnam National University of Science and Technology, Jinju 660-758, Korea
So-Youn Mok
Department of Integrative Plant Science, Chung-Ang University, Anseong 456-756, Korea
Su Hyeong Kwon
Department of Integrative Plant Science, Chung-Ang University, Anseong 456-756, Korea
Dong Gu Lee
Department of Integrative Plant Science, Chung-Ang University, Anseong 456-756, Korea
Eun Ju Cho
Department of Food Science and Nutrition, Pusan National University, Busan 609-735, Korea
Sanghyun Lee
Department of Integrative Plant Science, Chung-Ang University, Anseong 456-756, Korea
slee@cau.ac.kr

Abstract
Phytochemical constituents were isolated from bitter melon (the fruits of Momordica charantia ) through open column chromatography. Their structures were identified as β-sitosterol ( 1 ), (23 E )-5β,19-epoxycucurbita-6,23-diene-3β,25-diol ( 2 ), daucosterol ( 3 ), uracil ( 4 ), and allantoin ( 5 ) by interpretation of spectroscopic analysis including MS and 1 H- & 13 C-NMR. Among them, allantoin ( 5 ) was isolated from this plant for the first time.
Keywords
Introduction
Momordica charantia , belonging to the family of Cucurbitaceae, is an indigenous medicinal and vegetable plant found in the tropical and subtropical regions of the world and is commonly known as bitter gourd or bitter melon (Lee ., 2009) . It is distributed in Asian countries and widely cultivated as a vegetable crop. The fruits, vines, leaves, and roots of M. charantia have been used to treat toothache, diarrhea, furuncle, and diabetes in China. All parts of the plant including the fruit taste bitter. The fruit looks usually rectangle and resembles a cucumber (Basch ., 2003 ; Krawinkel and Keding, 2006 ). Bitter melon contains biologically active chemicals such as essential oil, flavonoids, phenolic acids, glycosides, triterpenes, and alkaloids. The immature fruits are a good source of vitamin C and also provide vitamin A (Xie ., 1998 ; Braca ., 2008 ; Chen ., 2008 ; Parichat and Artiwan, 2009 ; Zhang ., 2009 ; Choi ., 2012) .
A number of studies have reported the effects of bitter melon unrelated to diabetes. Bitter melon has some interesting biological and pharmacological activities, e.g. anti-cancer, anti-viral, anti-bacterial, analgesic, antiinflammatory, hypotensive, anti-fertility, and anti-oxidant (Zafar and Neerja, 1991 ; Ng ., 1992 ; Scartezzini and Speroni, 2000 ; Grover and Yadav, 2004 ; Beloin ., 2005 ; Sin ., 2011 ; Cho ., 2012a ; Choi ., 2012 ; Mahmood ., 2012 ; Sin ., 2012) . Bitter melon has been used for the treatment of diabetes mellitus due to their effective constituents such as charantin and peptides which are similar to insulin and several alkaloids (Lee ., 2009) . This paper describes the procedure for the isolation of phytochemical constituents from bitter melon by repeated column chromatography, and structure determination by spectral analyses such as NMR and MS.
Experimental
Plant materials − Bitter melon ( Momodica charantia fruits) was grown and collected at the Experimental Field of Farming Cooperation Hamyang (Hamyang, Korea) in October, 2009.
General experimental procedures −Mass spectrometry (MS) was measured using a Jeol JMS-600W (Tokyo, Japan) mass spectrometer. Nuclear magnetic resonance (NMR) spectra were recorded with a Bruker Avance 300, 400, or 500 NMR (Germany) spectrometer in CDCl 3 , pyridine, or DMSO using TMS as an internal standard. Chemical shifts were reported in parts per million (δ), and coupling constants ( J ) were expressed in Hertz. TLC analysis was conducted with Kiesel gel 60 F254 (Art. 5715, Merck Co., Germany) plates (silica gel, 0.25 mm layer thickness), with compounds visualized by spraying with 10% H 2 SO 4 followed by charring at 60℃. Open column chromatography was conducted with a silica gel (200 - 400 mesh ASTM; Merck Co., Germany). All other chemicals and reagents were analytical grade.
Extraction and isolation − The dried and finely powdered bitter melon (1,150.1 g) was extracted with methanol (MeOH) for 3 hr (6 L × 5) under reflux at 65 - 75℃ and solvent was evaporated in vacuo to give brown residue (351.4 g). The residue was suspended in H 2 O and partitioned with n -hexane (12.4 g), CH 2 Cl 2 (MC) (11.2 g), ethyl acetate (EtOAc) (5.6 g), and n -butanol ( n -BuOH) (10.3 g), successively. A portion of the n -hexane fraction (10.1 g) was chromatographed on a Si gel (6 × 80 cm, No. 7734) column, packed in n -hexane, eluting with a step gradient of n -hexane/EtOAc followed by EtOAc, all fractions being monitored by TLC. Elution of the Si gel column with n -hexane/EtOAc (9 : 1) and n -hexane/EtOAc (8 : 2) afforded compounds 1 and 2 , respectively. A portion of the MC fraction (9.5 g) was chromatographed on a Si gel (6 × 80 cm, No. 7734) column, packed in nhexane, eluting with a step gradient of n -hexane/EtOAc followed by EtOAc, all fractions being monitored by TLC. Elution of the Si gel column with EtOAc afforded compound 3 . A portion of the n -BuOH fraction (9.5 g) was chromatographed on a Si gel (6 × 80 cm, No. 7734) column, packed in CH 2 Cl 2 , eluting with a step gradient of MC/MeOH followed by MeOH, all fractions being monitored by TLC. Elution of the Si gel column with MC/MeOH (1 : 9) and MC/MeOH (2 : 8) afforded compounds 4 and 5 , respectively.
Compound 1 − White powder; EI-MS m/z : 414 [M] + (100.0), 396 (53.1), 381 (25.8), 329 (28.3), 303 (31.0), 289 (11.8), 273 (20.8), 255 (26.3), 231 (15.8), 213 (23.2), 159 (17.0), 145 (21.4); 1 H-NMR (300 MHz, CDCl 3 ): δ 3.52 (1H, m, H-3), 2.27 (2H, m, H-4), 5.35 (1H, m, H-6), 1.99 (2H, m, H-11), 0.68 (3H, s, H-18), 1.01 (3H, s, H-19), 0.96 (3H, d, J = 6.3 Hz, H-21), 0.83 (3H, d, J = 6.3 Hz, H-26), 0.80 (3H, d, J = 3.3 Hz, H-27), 0.91(3H, t, J = 6.3 Hz, H-29); 13 C-NMR (75 MHz, CDCl 3 ): δ 37.4 (C-1), 29.8 (C-2), 72.0 (C-3), 39.9 (C-4), 141.1 (C-5), 122.2 (C-6), 32.0 (C-7), 31.8 (C-8), 50.3 (C-9), 36.6 (C-10), 21.2 (C-11), 40.7 (C-12), 42.4 (C-13), 56.9 (C-14), 24.4 (C-15), 28.4 (C-16), 56.2 (C-17), 11.9 (C-18), 19.1 (C-19), 36.3 (C-20), 18,9 (C-21), 34.1 (C-22), 26.2 (C-23), 46.0 (C-24), 29.3 (C-25), 19.9 (C-26), 19.5 (C-27), 23.2 (C-28), 12.1 (C-29).
Compound 2 − Amorphous white powder; EI-MS m/z : 456 [M] + (8), 438 (45), 390 (80), 309 (100), 281 (65); 1 H-NMR (500 MHz, CDCl 3 ): δ 1.45 (1H, m, H-1), 1.83 m (1H, m, H-2), 3.40 (1H, m, H-3), 6.04 (1H, dd, J = 2.0, 10.0 Hz, H-6), 5.63 (1H, dd, J = 10.0, 3.5 Hz, H-7), 2.34 (1H, br s, H-8), 2.27 (1H, dd, J = 2.8 Hz, H-10), 1.46, 1.80 (1H, m, H-11), 1.64 (1H, m, H-12), 1.35 (1H, m, H-15), 1.42, 2.00 (1H, m, H-16), 1.48 (1H, m, H-17), 0.86 (3H, s, H-18), 3.67 (1H, d, J = 8.5 Hz, H-19), 3.52 (1H, d, J = 8.5 Hz, H-19), 1.45 (1H, m, H-20), 0.89 (3H, s, J = 6.5 Hz, H-21), 1.80, 2.14 (1H, m, H-22), 5.58 (1H, m, H-23) 5.58 (1H, m, H-24), 1.31 (3H, s, H-26), 1.31 (3H, s, H-27), 1.20 (3H, s, H-28), 0.89 (3H, s, H-29), 0.86 (3H, s, H-30), 4.01 (1H, d, J = 10.0 Hz, OH); 13 C-NMR (125 MHz, CDCl 3 ): δ 17.8 (C-1), 27.6 (C-2), 76.4 (C-3), 37.4 (C-4), 87.8 (C-5), 132.0 (C-6), 131.7 (C-7), 52.3 (C-8), 45.7 (C-9), 39.1 (C-10), 23.8 (C-11), 31.0 (C-12), 45.5 (C-13), 48.8 (C-14), 33.4 (C-15), 28.2 (C-16), 50.3 (C-17), 15.1 (C-18), 80.1 (C-19), 36.4 (C-20), 18.8 (C-21), 39.3 (C-22), 125.4 (C-23), 139.9 (C-24), 70.9 (C-25), 30.1 (C-26), 30.2 (C-27), 20.7 (C-28), 24.8 (C-29), 20.3 (C-30).
Compound 3 − Amorphous white powder; FAB-MS m/z : 599 [M+Na] + ; 1 H-NMR (400 MHz, pyridine): δ 4.03 (1H, m, H-3), 5.38 (1H, br d, J = 4.8 Hz, H-6), 0.69 (3H, s, H-18), 1.03 (3H, s, H-19), 0.92 (3H, d, J = 0.68 Hz, H-21), 0.86 (3H, d, J = 6.3 Hz, H-26), 0.89 (3H, d, J = 6.6 Hz, H-27), 0.88 (3H, t, J = 7.8Hz, H-29), 4.91 (1H, d, J =7.2 Hz, H-1'), 4.12 (1H, t, J =8.7 Hz, H-2'), 4.33 (1H, J =8.7 Hz, H-3'), 4.36 (1H, t, J =8.4 Hz, H-4'), 4.48 (1H, dd, J = 5.7, 11.7 Hz, H-6'a), 4.84 (1H, dd, J =2.4, 11.7 Hz, H-6'b); 13 C-NMR (100 MHz, pyridine): δ 37.4 (C-1), 30.8 (C-2), 72.2 (C-3), 40.5 (C-4), 141.4 (C-5), 123.5 (C-6), 32.6 (C-7), 32.7 (C-8), 50.8 (C-9), 37.98 (C-10), 21.8 (C-11), 39.8 (C-12), 43.0 (C-13), 25.0 (C-15), 57.3 (C-14), 29.0 (C-16), 56.7 (C-17), 12.5 (C-18), 19.9 (C-19), 36.3 (C-20), 19.4 (C-21), 34.5 (C-22), 27.3 (C-23), 50.3 (C-24), 30.5 (C-25), 18.3 (C-26), 20.5 (C-27), 23.4 (C-28), 12.8 (C-29), 103.1 (C-1'), 78.6 (C-2'), 79.1 (C-3'), 75.9 (C-4'), 79.0 (C-5'), 63.3 (C-6').
Compound 4 − Amorphous white powder; EI-MS m/z : 112 [M] + (100.0), 69 (47); 1 H-NMR (500 MHz, pyridine): δ 5.80 (1H, d, J = 7.5 Hz, H-5), 7.51 (1H, d, J = 7.5 Hz, H-6).
Compound 5 − White crystal; EI-MS m/z : 158 [M] + (9.8), 141 (10.9), 130 (100.0), 115 (31.4), 87 (80.8), 70 (10.8) 60 (22.4); 1 H-NMR (500 MHz, DMSO): δ 10.53 (1H, s, H-1), 8.04 (1H, s, H-3), 6.89 (1H, d, J = 8.2 Hz, N H CONH 2 ), 5.77 (2H, s, NHCON H2 ), 5.24 (1H, d, J = 8.2 Hz, H-4).
Results and Discussion
An open column chromatography of the MeOH extract of bitter melon led to the isolation of compounds 1 - 5 .
Compound 1 was obtained as white powders from the n -hexane fraction and it showed a molecular ion peak at m/z 414 [M] + in the EI-MS. The 1 H-NMR spectrum of 1 showed existence of sterol skeleton. The two angular methyl singlets of 18- and 19-Me at δ 0.68 and 1.01, and the three doublets of 21-, 26-, and 27-Me at δ 0.96, 0.83, and 0.80, and the one triplet of 29-Me at δ 0.91 were observed. The olefinic proton broad doublet one signal at δ 5.35 was showed H-6. The 13 C-NMR spectrum of 1 showed 27 resonances, and C-5 and -6 signals were noticed at δ 141.1 and 122.2, respectively. Accordingly, the structure of 1 was elucidated as β-sitosterol (stigmast-5-en-3-ol) by comparison of the spectral data in the literature (Rubinstein ., 1976 ; Lee ., 2013) .
Compound 2 was obtained as amorphous white powder from the n -hexane fraction and it showed a molecular ion peak at m/z 456 [M] + in the EI-MS. The 1 H- and 13 C-NMR data indicated the presence of six tertiary methyl signals at δ 0.89, 1.20 (3H each, s), 0.86 (3H × 2), and 1.31 (3H × 2), a secondary methyl signal at δ 0.89 (3H, d, J = 6.5 Hz), an oxomethylene signal at δ 3.53 (1H, d, J = 8.5 Hz), 3.67 (1H, d, J = 8.5 Hz), and δ 80.1, and a mutiplet oxymethine (δ 3.40) coupling to hydroxyl group (δ 4.01). In addition, the NMR signals for an allylic ABX system of cis-oriented cyclohexene signal at δ 6.04 (1H, dd, J = 2.0, 10.0 Hz, H-6), 5.63 (1H, dd, J = 10.0, 3.5 Hz, H-7), 2.34 (1H, br s, H-8); δ 132.0, 131.7, 52.3 were also found. Accordingly, the structure of 2 was elucidated as (23 E )-5β,19-epoxycucurbita-6,23-diene-3β,25-diol by comparison of the spectral data in the literature (Chang ., 2006) .
Compound 3 was obtained as white powders from the MC fraction and it showed a molecular ion peak at m/z 599 [M+ Na] + in the FAB-MS. The 1 H-NMR spectrum showed the two angular methyl singlets of 18- and 19-Me at δ 0.69 and 1.03, and the three doublets of 21-, 26-, and 27-Me at δ 0.92, 0.86, and 0.89, respectively. The olefinic proton of a broad doublet signal at δ 5.38 showed H-6. The anomeric proton of 3 produced a peak at δ 5.07 (d, J = 7.2 Hz), and the glucose position was at C-3 (β-linkage) of the aglycon. The 13 C-NMR spectrum of 3 showed C-5 and -6 signals noticed at δ 141.1 and 123.5, respectively. Accordingly, the structure of 3 was daucosterol (β-sitosterol 3- O -glucoside) by comparison of the spectral data in the literature (Huh ., 2011 ; Cho ., 2012b , Lee ., 2013) .
Compound 4 was obtained as white crystals from the n -BuOH fraction and showed a molecular ion peak at m/z 112 [M] + in the EI-MS, which corresponds to a molecular formula of C 4 H 4 N 2 O 2 . In the 1 H-NMR spectrum of 4 , doublets at δ 7.51 ( J = 7.5 Hz) and 5.80 ( J = 7.5 Hz) assigned H-6 and -5 of pyrimidine, respectively. Accordingly, the structure of 4 was elucidated as uracil by comparison of the spectral data in the literature (Ko ., 1992 ; Lee ., 2002) .
PPT Slide
Lager Image
Structures of compounds 1 - 5.
Compound 5 was obtained as white crystals from the n -BuOH fraction. In the EI-MS, molecular peak showed at m/z 158 [M] + corresponding to the molecular formula C 4 H 6 N 4 O 3 . In the 1 H-NMR spectrum, it was obtained relating the peak height of the down-field proton at a 10.53. The broad amino signal at δ 5.77 was detected and a sharp singlet at δ 5.23 was presumably -NHC H NH-. Accordingly, the structure of 5 was elucidated as allantoin (2,5-dioxo-4-imdazolidinylurea) by comparison of the spectral data in the literature (Siegfried and Johannes, 1975 ; Kim ., 2009) .
β-Sitosterol ( 1 ) and daucosterol ( 3 ) showed antiinflammatory, anti-neoplastic, and immune modulating activities (Patrick and Lamprecht, 1999) . Allantoin ( 5 ) has the effect of urease inhibitory activity and prevents inflammation and ulcers in human (Weber ., 1981 ; Leem ., 2005 ; Fu ., 2006) .
In conclusion, β-sitosterol ( 1 ), (23 E )-5β,19-epoxycucurbita-6,23-diene-3β,25-diol ( 2 ), daucosterol ( 3 ), uracil ( 4 ), and allantoin ( 5 ) were isolated from bitter melon ( Fig. 1 ). Among them, allantoin ( 5 ) was isolated from this plant for the first time.
Acknowledgements
This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2010-0005480). The authors thank the staff and crew of the National Center for Inter-University Research Facilities (Seoul National University) for assistance with the NMR and GC/MS experiments.
References
Basch E. , Gabardi S. , Ulbricht C. (2003) Bitter melon (Momordica charantia): a review of efficacy and safety. Am. J. Health Syst. Pharm. 60 356 - 359
Beloin N. , Gbeassor M. , Akpagana K. , Hudson J. , de Soussa K. , Koumaglo K. , Arnason J.T. (2005) Ethnomedicinal uses of Momordica charantia (Cucurbitaceae) in Togo and relation to its phytochemistry and biological activity. J. Ethnopharmacol. 96 49 - 55    DOI : 10.1016/j.jep.2004.08.009
Braca A. , Siciliano T. , D'Arrigo M. , Germanò M.P. (2008) Chemical composition and antimicrobial activity of Momordica charantia seed essential oil. Fitoterapia 79 123 - 125    DOI : 10.1016/j.fitote.2007.11.002
Chang C.I. , Chen C.R. , Liao Y.W. , Cheng H.L. , Chen Y.C. , Chou C.H. (2006) Cucurbitane-type triterpenoids from Momordica charantia. J. Nat. Prod. 69 1168 - 1171    DOI : 10.1021/np068008v
Chen J. , Tian R. , Qui M. , Lu L. , Zheng Y. , Zhang Z. (2008) Trinorcucurbitane and cucurbitane triterpenoids from the roots of Momordica charantia. Phytochemistry 69 1043 - 1048    DOI : 10.1016/j.phytochem.2007.10.020
Cho E.J. , Choi J.Y. , Lee K.H. , Lee S. (2012b) Isolation of antibacterial compounds from Parasenecio pseudotaimingasa. Hort. Environ. Biotechnol. 53 561 - 564    DOI : 10.1007/s13580-012-0040-4
Cho E.J. , Sin S.M. , Choi J.M. , Lee S. , Cho K.M. , Kim H.Y. (2012a) Protective effects of the active fraction of bitter melon (Momordica charantia) on nitric oxide-induced oxidative stress in LLC-PK1cell. J. Med. Plant Res. 6 4968 - 4973
Choi J.S. , Kim H.Y. , Seo W.T. , Lee J.H. , Cho K.M. (2012) Roasting enhances antioxidant effect of bitter melon (Momordica charantia L.) increasing in flavan-3-ol and phenolic acid contents. Food Sci. Biotechnol. 21 19 - 26    DOI : 10.1007/s10068-012-0003-7
Fu Y.C. , Ferng L.H. , Huang P.Y. (2006) Quantitative analysis of allantoin and allantoic acid in yam tuber, mucilage, skin and bulbil of the Dioscorea species. Food Chem. 94 541 - 549    DOI : 10.1016/j.foodchem.2004.12.006
Grover J.K. , Yadav S.P. (2004) Pharmacological actions and potential uses of Momordica charantia: a review. J. Ethnopharmacol. 93 123 - 132    DOI : 10.1016/j.jep.2004.03.035
Huh G.W. , Park J.H. , Shrestha S. , Lee Y.H. , Ahn E.M. , Kang H.C. , Baek N.I. (2011) Sterols from Lindera glauca Blume stem wood. J. Appl. Biol. Chem. 54 309 - 312    DOI : 10.3839/jabc.2011.050
Kim K.M. , Henderson G.N. , Frye R.F. , Galloway C.D. , Brown N.J. , Segal M.S. , Imaram W. , Angerhofer A. , Johnson R.J. (2009) Simultaneous determination of uric acid metabolites allantoin, 6-aminouracil, and triuret in human urine using liquid chromatographymass spectrometry. J. Chromatogr. 877 65 - 70    DOI : 10.1016/j.jchromb.2008.11.029
Ko S.H. , Do S.H. , Kwon Y.S. , Kim C.M. (1992) A study on the chemical components from the roots of Anthriscus sylvestris. Kor. J. Pharmacogn. 23 225 - 228
Krawinkel M.B. , Keding G.B. (2006) Bitter gourd (Momordica charantia): a dietary approach to hyperglycemia. Nutr. Rev. 64 331 - 337    DOI : 10.1111/j.1753-4887.2006.tb00217.x
Lee J.M. , Lee D.G. , Lee K.H. , Cho S.H. , Nam K.W. , Lee S. (2013) Isolation and identification of phytochemical constituents from the fruits of Acanthopanax senticosus. African J. Pharm. Pharmacol. 7 294 - 301    DOI : 10.5897/AJPP12.898
Lee S. , Kang S.S. , Shin K.H. (2002) Coumarins and a pyrimidine from Angelica gigas roots. Nat. Prod. Sci. 8 58 - 61
Lee S.Y. , Eom S.H. , Kim Y.K. , Park N.I. , Park S.U. (2009) Cucurbitanetype triterpenoids in Momordica charantia Linn. J. Med. Plant Res. 3 1264 - 1269
Leem M.J. , Ryu J.M. , Jang H.B. , Rho Y.K. , Oh S.J. , Lee H.Y. (2005) Isolation of urease inhibitory compounds from Arecae semen. Kor. J. Pharmacogn. 36 56 - 59
Mahmood A. , Raja G.K. , Mahmood T. , Gulfraz M. , Khanum A. (2012) Isolation and characterization of antimicrobial activity conferring component(s) from seeds of bitter gourd (Momordica charantia). J. Med. Plant Res. 6 566 - 573    DOI : 10.5897/JMPR12.703
Ng T.B. , Chan W.Y. , Yeung H.W. (1992) Proteins with abortifacient, ribosome inactivating, immunomodulatory, antitumor and anti-AIDS activities from Cucurbitaceae plants. Gen. Pharmacol. 23 579 - 590    DOI : 10.1016/0306-3623(92)90131-3
Parichat B. , Artiwan S. (2009) Enhanced recovery of phenolic compounds from bitter melon (Momordica charantia) by subcritical water extraction. Sep. Purific. Tech. 66 125 - 129    DOI : 10.1016/j.seppur.2008.11.014
Patrick J.D. , Lamprecht J.H. (1999) Plant sterols and sterolin: a review of their immune-modulating properties. Altern. Med. Rev. 4 170 - 177
Rubinstein I. , Goad L.J. , Clague A.D.H. , Mulheirn L. (1976) The 220 MHz NMR spectra of phytosterols. Phytochemistry 15 195 - 200    DOI : 10.1016/S0031-9422(00)89083-4
Scartezzini P. , Speroni E. (2000) Review on some plants of Indian traditional medicine with antioxidant activity. J. Ethnopharmacol. 71 23 - 43    DOI : 10.1016/S0378-8741(00)00213-0
Siegfried E.D. , Johannes V.S. (1975) Determination of allantoin in Protea seed. Phytochemistry 14 751 - 753    DOI : 10.1016/0031-9422(75)83028-7
Sin S.M. , Mok S.Y. , Lee S. , Cho K.M. , Cho E.J. , Kim H.Y. (2011) Protective effect of bitter melon (Momordica charantia) against oxidative stress. Cancer Prev. Res. 16 86 - 92
Sin S.M. , Mok S.Y. , Lee S. , Cho K.M. , Cho E.J. , Kim H.Y. (2012) Antiinflammatory effect of bitter melon (Momordica charantia) in RAW 264.7 cell. Cancer Prev. Res. 17 56 - 61
Weber J.F. , Fuhrman F.A. , Fuhrman G.J. , Mosher H.S. (1981) Isolation of allantoin and adenosine from the marine sponge Tethya aurantia. Comp. Biochem. Physiol. 70B 799 - 801
Xie H. , Huang S. , Deng H. , Wu Z. , Ji A. (1998) Study on chemical components of Momordica charantia. Zhong Yao Cai 21 458 - 459
Zafar R. (1991) Momordica charantia-a review. Hamdard. Med. 34 49 - 61
Zhang M. , Hettiarachchy N.S. , Horax R. , Chen P. , Over K.F. (2009) Effect of maturity stages and drying methods on the retention of selected nutrients and phytochemicals in bitter melon (Momordica charantia) leaf. J. Food Sci. 74 441 - 448    DOI : 10.1111/j.1750-3841.2009.01222.x