Phytochemical Content and Related Biological Activities of Rhubarb

Phytochemical Content and Related Biological Activities of Rhubarb Annecie Benatrehina Nicole Eggers Colleen Nackerman Matt Niezgoda 1

Taxonomical Information General name for any species in the Rhuem genus Rhuem australe – Himalayan Rhubarb Rhuem emodi – Ornamental Rhubarb Rhuem nobile – Sikkum Rhubarb Rhuem officinale – Chinese Rhubarb, East Indian Rhubarb Rheum palmatum – Turkey Rhubarb Rheum rhaponticum – Garden Rhubarb Information courtesy rhubarbinfo. com 2

Botanical Information Common growing regions include northern United States, Canada, and Europe Leaves high in oxalic crystals – poisonous to consume Bright red petioles (stalks) used for many culinary applications Rhizome has highest medicinal potential – high phytochemical concentrations Used in ancient times for medicinal purposes Information courtesy rhubarbinfo. com 3

Photos courtesy rhubarbinfo. com 4

Common Phytochemicals Anthraquinones Aloe-emodin, rhein, physcion, danthron, and chrysophanol E. g. Emodin Anthrones 10 -hydroxycascaroside, and cassialoin E. g. Anthrone skeleton Wikipedia 5

Common Phytochemicals Flavon-3 -ols Catechin, epi-catechin, procyanidins, polymeric procyanidins E. g. Catechin Tannins Catechin glucopyranoside, catechin gallate, galloyl glucose, and gallic acid E. g. Galloyl glucose Wikipedia 6

Common Phytochemicals Stilbenes Pterostilbene, piceatannol, rhapontigenin, isorhapontigenin, and desoxyrhapontigenin E. g. Rhapontigenin Wikipedia 7

RHUBARB: ANTICANCER ACTIVITY 8

RHUBARB ANTHRAQUINONES Rhubarb anthraquinones: structures, antioxidants, and prooxidants Chemotherapeutic? Carcinogenic? Genotoxic? 9

CANCER MOLECULAR TARGETS Hsu, S. -C. ; Chung, J. -G. Bio. Medicine 2012, 2, 108– 116. 10

CANCER MOLECULAR TARGETS Huang, Q. ; Lu, G. ; Shen, H. -M. ; Chung, M. C. M. ; Ong, C. N. Med. Res. Rev. 2007, 27, 609– 30. 11

DANTHRON Cancer-causing agent? Case study 18 year old girl – leiomyosarcoma of the small bowel 5 m. L Dorbanex nightly from 14 mo-6 yr (25 mg danthron) Dye factory; oral exposure? In vitro and in vivo studies—unresolved whether truly carcinogenic or genotoxic 1987 FDA “Reasonably anticipated to be a human carcinogen. ” Food matrix & other compounds in rhubarb Patel, P. M. ; Selby, P. J. ; Deacon, J. ; Chilvers, C. ; Mc. Elwain, T. J. Postgrad. Med. J. 1989, 65, 216– 217. National Toxicology Program; Department of Health and Human Services Danthron; Report on Carcinogens, 12 ed. ; 2011; Vol. 12 th ed. , pp. 1– 2. 12

ANTICANCER CONCLUSION Rhubarb, as a whole food, does not exhibit anticancer activity. Rhubarb, as a whole food, does not cause cancer. Rhubarb, as a whole food is safe to consume. More research is necessary to confirm both the cancercausing and cancer-treating characteristics of rhubarb anthraquinones. 13

RHUBARB: LAXATIVE & ANTIDIARRHEAL ANTIBACTERIAL 14

RHUBARB AS A LAXATIVE Traditional medicine: rhubarb “eliminates stagnated food” (Peigen et al. 1984) Active constituents: anthraquinone derivatives (Schulz et al. 1998) Free anthraquinones are the active constituents, but the glycosidic residues are needed for transport to the colon (Feng et al. 2013) Several mechanisms have been speculated, suggesting possible synergistic effect Feng, T. -S. , Yuan, Z. -Y. , Yang, R. -Q. , Zhao, S. , Lei, F. , Xiao, X. -Y. , … Du, L. -J. (2013). Purgative components in rhubarbs: Adrenergic receptor inhibitors linked with glucose carriers. Fitoterapia, 91, 236– 46. doi: 10. 1016/j. fitote. 2013. 09. 020 Peigen, X. , Liyi, H. , & Liwei, W. (1984). Ethnopharmacologic study of Chinese rhubarb. Journal of ethnopharmacology, 10(3), 275– 93. Retrieved from http: //www. ncbi. nlm. nih. gov/pubmed/6748707 Schulz, V. , Hänsel, R. , Tyler, V. E. (1998). Rational Phytotherapy: A physicians’ guide to herbal medicine. (3 rd ed. ). Berlin: Springer, (206 -207). 15

MECHANISM OF ACTION (1) Osmotic: inhibition channels for the absorption into enterocytes (Rauwald, 1998) Upregulation of c. AMP causing activation of ion channel (CFTR) for the reflux of chloride into the lumen (Shi et al. 2006) Na+, Cl- Lumen Adapted from Shi et al. (2006). Chemical Research in Chinese Universities, 22(3), 312– 314 16 Rauwald, H. W. (1998). Herbal Laxatives Influence of Anthrones- Anthraquinones on Energy Metabolism and Ion Transport in a Model System. In L. Lawson & R. Bauer (Eds. ), Phytomedicines of Europe; ACS Symposium Series (Vol. 691, pp. 97– 116). Washington, DC: American Chemical Society. Shi, L. , Xu, L. , Hou, S. , Lin, S. , Yang, H. , & Ma, T. (2006). Activation Effect of Cathartic Natural Compound Rhein to CFTR Chloride Channel. Chemical Research in Chinese Universities, 22(3), 312– 314

MECHANISM OF ACTION (2) Mechanistic: inhibition of human β-adrenergic receptor, blocking adrenaline’s effect, allowing colonic contraction (Feng et al. 2013) • Anthraquinones had a weak affinity compared to the control • Emodin showed activity at a concentration of 100 x more than that of adrenaline Adapted from Feng et al. (2013) Fitoterapia 91, 236– 246 17 Feng, T. -S. , Yuan, Z. -Y. , Yang, R. -Q. , Zhao, S. , Lei, F. , Xiao, X. -Y. , … Du, L. -J. (2013). Purgative components in rhubarbs: Adrenergic receptor inhibitors linked with glucose carriers. Fitoterapia, 91, 236– 46. doi: 10. 1016/j. fitote. 2013. 09. 020

RHUBARB AS ANTIDIARRHEAL Effect due to tannin content Tannins bind proteins causing precipitation Proposed mechanism: § Proteins of intestinal walls precipitate forming coating which prevents water secretion into the lumen Total Tannin extract caused precipitation of bovine serum albumin (1 mg/ml) Adapted from Qin et al. (2011). Journal of Ethnopharmacology. 133 (3). 1096 -1102 Qin, Y. , Wang, J. , Kong, W. , Zhao, Y. , Yang, H. , Dai, C. , … Xiao, X. (2011). The diarrhoeogenic and antidiarrhoeal bidirectional effects of rhubarb and its potential mechanism. Journal of ethnopharmacology, 133(3), 1096– 102. doi: 10. 1016/j. jep. 2010. 11. 041 18

ANTIBACTERIAL EFFECT Rhubarb’s rhein, emodin and aloe-emodin active against several bacterial strains (Peigen et al. 1984) Rheum rhaponticum ethanol extract more active than the aqueous extract (Raudsepp et al. 2013) Bacteria strain R. Rhaponticum (mm) Control (mm) Bacillus subtilis 9 15 Campylobacter jejuni 10 14 Eschericia coli 1 4 Bifidobacterium bifidum 1 5 Lactobacillus acidophilus - 8 Table adapted from Raudsepp et al. (2013) Food Control, 31(1), 129 -135 19 Raudsepp, P. , Anton, D. , Roasto, M. , Meremäe, K. , Pedastsaar, P. , Mäesaar, M. , … Püssa, T. (2013). The antioxidative and antimicrobial properties of the blue honeysuckle (Lonicera caerulea L. ), Siberian rhubarb (Rheum rhaponticum L. ) and some other plants, compared to ascorbic acid and sodium nitrite. Food Control, 31(1), 129– 135. doi: 10. 1016/j. foodcont. 2012. 10. 007

ANTIBACTERIAL MECHANISM Proposed mechanisms: Inhibition of respiration (mitochondria) Inhibition of nucleic acids and proteins syntheses (Peigen et al. 1984) Emodin shown to enter bacterial cell and to cause cytoplasmic leakage in Aeromonas hydrophila Emodin also binds DNA between bases (Lu et al. 2011) Lu, C. , Wang, H. , Lv, W. , Xu, P. , Zhu, J. , Xie, J. , … Lou, Z. (2011). Antibacterial properties of anthraquinones extracted from rhubarb against Aeromonas hydrophila. Fisheries Science, 77(3), 375– 384. doi: 10. 1007/s 12562 -011 -0341 -z Peigen, X. , Liyi, H. , & Liwei, W. (1984). Ethnopharmacologic study of Chinese rhubarb. Journal of ethnopharmacology, 10(3), 275– 93. Retrieved from http: //www. ncbi. nlm. nih. gov/pubmed/6748707 20

RHUBARB: CHOLESTATIC HEPATITIS & RENAL ACTIVITY 21

Cholestatic Hepatitis Cholestasis: liver disease in which bile acid transport is defective; leads to biliary and hepatic disorders Caused by inflammation The anthraquinone emodin can protect against this condition via anti-inflammatory activity (Ding et al. 2008). Anthraquinones rhein, aloe-emodin, and physione improved bile duct health Other anthraquinones emodin and chrysophanol had minimal effect Ding, Yan et al. 2008. “Exploration of Emodin to treat alpha-naphthylisothiocyanate-induced cholestatic hepatitis via anti-inflammatory pathway. ” European journal of pharmacology 590(13): 377– 86. 22

Renal Activity Rhubarb extract reversed renal failure symptoms in a study using an adenine-induced model (Yokozawa et al. 1983). High doses of rhubarb caused nephrotoxicity in rats (Yan et al. 2006), but normal doses using the correct means of administration seem to safely produce beneficial effects (Wang et al. 2009). Yokozawa, T. et al. 1983. “Effect of Extract from Rhei Rhizoma on Adenine-Induced Renal Failure in Rats. ” Chem. Pharm. Bull. 31(8): 2762– 2768. Wang, Jiabo et al. 2009. “Assessment of the renal protection and hepatotoxicity of rhubarb extract in rats. ” Journal of ethnopharmacology 124(1): 18– 25. Yan, Ming, Lu-Yong Zhang, Li-Xin Sun, Zhen -Zhou Jiang, and Xiao-He Xiao. 2006. “Nephrotoxicity study of total rhubarb anthraquinones on Sprague Dawley rats using DNA microarrays. ” Journal of ethnopharmacology 107(2): 308– 11. 23

Renal Activity Metal- and antibiotic-induced nephrotoxicity was reduced by water-soluble rhubarb extract Insoluble rhubarb extract was not as effective, and actually increased gentamicin-induced toxicity (Alam et al. 2005). Rhubarb tannins provide additional protection due to antioxidant activity (Zeng et al. 2013). Anthraquinones act differently, with some increasing toxicity and some displaying a protective effect (Ali et al. 2013). Alam, M M Azhar, Kalim Javed, and M a Jafri. 2005. “Effect of Rheum emodi (Revand Hindi) on renal functions in rats. ” Journal of ethnopharmacology 96(1 -2): 121– 5. Zeng L, Ma Z, Zhao Y, Zhang L, Li R, Wang J, Zhang P, Yan D, Li Q, Jiang B, Pu S, Lu Y, Xiao X. 2013. The protective and toxic effects of rhubarb tannins and anthraquinones in treating hexavalent chromium-injured rats: The yin/yang actions of rhubarb. J Hazardous Materials 246247: 1– 9 Ali, Badreldin H et al. 2013. “Abrogation of cisplatin-induced nephrotoxicity by emodin in rats. ” Fundamental & clinical pharmacology 27(2): 192– 200. 24