Saponins, Esculeosides B-1 and B-2, in Tomato Juice and Sapogenol, Esculeogenin B1

848 Chem. Pharm. Bull. 63, 848–850 (2015) Vol. 63, No. 10 Note

Toshihiro Nohara,*,a Yukio Fujiwara,b Jian-Rong Zhou,a Jun Urata,a Tsuyoshi Ikeda, a Kotaro Murakami,a Mona El-Aasr,c and Masateru Onod a Faculty of Pharmaceutical Sciences, Sojo University; 4–22–1 Nishi-ku, Ikeda, Kumamoto 860–0082, Japan: b Graduate School of Medical Sciences, Faculty of Life Sciences, Kumamoto University; 1–1–1 Honjo, Chuo- ku, Kumamoto 860–8556, Japan: c Faculty of Pharmacy, Tanta University; Tanta 31111, Egypt: and d School of Agriculture, Tokai University; 5435 Minamiaso, Aso, Kumamoto 869–1404, Japan. Received May 29, 2015; accepted July 9, 2015

It has been shown that commercial tomato juice packaged in 900 g plastic bottles contains rare, naturally occurring steroidal solanocapsine-type tomato glycosides in which the saponins consist of esculeosides B-1 (2) and B-2 (3) in 0.041% as major components lacking esculeoside A. We suggest that these saponins are derived from esculeoside A (1) when the juice in plastic bottles is prepared by treatment with boiling water, similar to the process used in preparing canned tomatoes. Herein, the obtained tomato saponins (2)

and (3) provided sapogenols esculeogenin B1 (4) and B2 (5), respectively, by acid hydrolysis. The former was identical to esculeogenin B previously reported, and the latter was a new sapogenol characterized to be (5α,22S,23S,25S)-22,26-epimino-16β,23-epoxy-3β,23,27-trihydroxycholestane. Key words Solanum lycopersicum; tomato juice; tomato saponin; esculeoside B-1; esculeoside B-2; esculeo-

genin B1

Every Solanum lycopersicum L. tomato reviewed in this were individually treated and passed through highly porous study including Momotaro, mini, medium, yellow and black polystyrene gel (Diaion HP-20), and the resulting methanol tomatoes from Japan, and European and American varieties residue was then subjected to dextran gel (Sephadex LH-20) contains tomato saponin, esculeoside A (1),1–4) as a major in- column chromatography, and then eluted with 90% methanol. gredient occurring at levels approximately four times higher The first eluate includes tomato saponins and the following than those of lycopene.3) The structure of this saponin was fraction without saponin was collected. The 90% methanol determined to be spirosolane bisdesmoside, as shown in Chart eluates from the dextran column apparently lacked esculeoside 1. Thus far, the bioactivity of tomatoes has been attributed A (1) but contained esculeosides B-1 (2) and B-2 (3) on TLC solely to lycopene. Therefore, pharmacological examination of with chloroform (CHCl3)–methanol (MeOH)–water (6 : 4 : 1). esculeoside A in the near future should be important. We recognized that the esculeoside A in fresh tomato converts Fujiwara et al.5) revealed that oral administration of es- to esculeosides B-1 (2) and B-2 (3) when these tomatoes are culeoside A (1) to apolipoprotein E-deficient mice significantly packed in bottles via sterilization with boiling water similar to reduces levels of serum cholesterol glycerides and low-density that in canned preparation.8) Next, a mixture of esculeosides lipoprotein-cholesterol in addition to the areas of athero- B-1 (2) and B-2 (3) obtained from juice was separated with sclerotic lesions with no detectable side effects. Zhou and octadecylsilane (ODS) to give two saponins. Esculeoside B-2 6) colleagues reported that oral administration of esculeoside (3) was hydrolyzed by refluxing with 2 N HCl for 1 h to obtain

A (1) improved the effects of atopic dermatitis like disease on a sapogenol, esculeogenin B2 (5) as colorless needles, melting mice caused by 2,4-dinitrochlorobenzene. point (mp) 223–226°C (decomp), which was identical to the In previous work, we performed qualitative analyses of esculeogenin B previously reported.9) Esculeoside B-1 was fresh tomato, tomato boiled in water, tomato heated in a mi- similarly hydrolyzed with 2 N HCl to give a new sapogenol, crowave oven, and freeze-dried tomato prior to their develop- named esculeogenin B1 (4). Esculeogenin B1 (4) was obtained ment for health foods.7) In all cases, esculeoside A (1) was a as a colorless needles showing mp 232–235°C (decomp) and major component. Next, we investigated the tomato saponins [α]D −89.6° (pyridine). Positive high-resolution fast atom in Italian canned tomatoes. Such tomatoes contain tomato bombardment mass spectrometry (HR-FAB-MS) exhibited saponins, rare, naturally occurring steroidal solanocapsine- a quasi-molecular ion at m/z 448.3424 corresponding to the 1 type glycosides, a 0.095% mixture of esculeosides B-1 (2) and molecular formula [C27H45NO4+H]. The H-NMR spectrum 8) B-2 (3) lacking esculeoside A (1). We reﬂuxed esculeoside A (in pyridine-d5) showed two tertiary methyl signals at δ 0.78 (1) with water for 6.5 h, providing a mixture of esculeosides (3H, s) and 0.99 (3H, s), one secondary methyl signal at δ 1.26 B-1 (2) and B-2 (3) quantitatively; therefore, we hypothesized (3H, d, J=6.3 Hz), two nitrogen-bearing methylene protons at that these substances might be derived from esculeoside A (1) δ 2.67 (1H, t-like, J=11.9 Hz) and 3.34 (1H, d, J=11.9 Hz), one when the cans are processed with boiling water.8) nitrogen-bearing methine proton at δ 3.05 (1H, d, J=11.5 Hz), In the present study, we analyzed the amount of tomato two hydroxymethyl protons at δ 3.73 (2H, d, J=5.7 Hz), and saponin in tomato juice commercially processed in 900 g two oxygen-bearing methine protons at δ 3.84 (1H, m) and 13 plastic bottles to compare the respective ingredients in each 4.66 (1H, m). The C-NMR signals (in pyridine-d5) displayed bottles. Five kinds juice produced by different companies a total of twenty-seven carbon signals comprised of three

Chart 1. Chemical Correlation of Esculeosides A (1), B-1 (2), B-2 (3), and Esculeogenins B1 (4), and B2 (5) methyls (δ 12.4, 15.2, 17.6), one hydroxymethyl (δ 65.1), one hemiketal carbon (δ 96.6), one nitrogen-bearing methine carbon (δ 62.7), one nitrogen-bearing methylene carbon (δ 43.8), and two oxygen-bearing methine carbons (δ 70.4, 70.7). By the aid of proton–proton chemical shift correlated spectroscopy (1H–1H-COSY), 1H-detected heteronuclear correlation through multiplet quantum coherence (HMQC) and heteronuclear multiple-bond correlation (HMBC; Fig. 1), all of the carbon signals of 4 were assigned as follows: C-1–C-27 of sapogenol: δ 37.3, 32.3, 70.7, 39.1, 45.0, 28.9, 32.3, 35.1, 54.5, 35.7, 21.2, 40.5, 41.9, 53.4, 33.5, 70.4, 62.4, 15.2, 12.4, 27.4, 17.6, 62.7, 96.6, 38.7, 38.0, 43.8, 65.1. On this assignment, the HMBC between H3-21 (δ 1.26) and C-22 (δ 62.7), and the occurrence of the hemiketal carbon function (δ 96.6) in particular con- Fig. 1. HMBC of Esculeogenin B1 (4) clusively characterized a novel sapogenol moiety, which has a rare, natural solanocapsine-type framework.10) Next, nuclear whereas it appeared at δ 1.59 in a 1,3-diaxial correlation11)

Overhauser effect spectroscopy (NOESY; Fig. 2) led to the with the C-23-OH group in esculeogenin B2 (5). Therefore, the assignments of the configurations at C-22 and C-23. Namely, structure of 4 could be represented as (5α,22S,23S,25S)-22,26- the observation of NOESY between H-20 (δ 2.12, m) and H-22 epimino-16β,23-epoxy-3β,23,27-trihydroxycholestane, and the 8) (δ 3.05), and between H3-21 (δ 1.26) and H-22 revealed the configuration at C-22 in esculeoside B-1 (2) should be re- configuration of both H-20 and H-22 to be cis-correlation. vised to S from R. Thus, we have shown that tomato juices The configuration of the hydroxymethyl group at C-25 was packaged in plastic bottles contain tomato saponins, esculeo- also deduced to be equatorial on the basis of the coupling sides B-1 (2) and B-2 (3), which provide esculeogenins B1 (4) constants of H2-26 signals at δ 2.67 (1H, t-like, J=11.9 Hz, and B2 (5), respectively, by 2 N HCl hydrolysis. We concluded Hax) and 3.34 (1H, d, J=11.9 Hz, Heq). The configuration of that tomato saponins in juice packaged in plastic bottles were the hydroxyl group at C-23 was estimated as β-axial because derived from esculeoside A (1) when the juiceis processed the H3-21 signals stayed at δ 1.26 in the usual chemical shift, with boiling water. 850 Chem. Pharm. Bull. Vol. 63, No. 10 (2015)

Acid Hydrolysis of Respective Esculeosides B-1 (2) and B-2 (3) After a solution of esculeoside B-2 (3, 350 mg) in 2 N HCl (5 mL) was reﬂuxed for 1 h, its reaction mixture was neutralized with 2 N KOH and added with water, which was passed through Diaion HP-20 and washed with water, then eluted with methanol to give a sapogenol. Crude sapogenol was puriﬁed on silica gel column chromatography

with CHCl3–MeOH–water=9 : 1 : 0.1 to afford the sapogenol (25 mg), which was identical with esculeogenin B (renamed as

esculeogenin B2) obtained by enzymatic hydrolysis of 3. Simi- larly, esculeoside B-1 (2, 280 mg) was treated with 2 N HCl and puriﬁed on silica gel chromatography to give a sapogenol

(4, 18 mg), named esculeogenin B1. Esculeogenin B1 (4) Colorless needles (from dil. MeOH), mp 232–235°C (decomp), [α]D −89.6° (c=0.5, pyridine). Positive HR-FAB-MS: a quasi-molecular ion at m/z 448.3424 1 [C27H45NO4+H, 448.3427]. The H-NMR spectrum (in pyridine-d5) δ: 0.78 (3H, s, H3-19), 0.99 (3H, s, H3-18), 1.26 Fig. 2. Conﬁgulations at C-22, 23 and 25, and Key NOESY in Esculeo- (3H, d, J=6.3 Hz, H -21), 2.12 (1H, m, H-20), 2.67 (1H, t-like, genin B (4) and Esculeogenin B (5) 3 1 2 J=11.9 Hz, Hax-26) and 3.34 (1H, d, J=11.9 Hz, Heq-26), 3.05

(1H, d, J=11.5 Hz, H-22), 3.73 (2H, d, J=5.7 Hz, H2-27), 3.84 Experimental (1H, m, H-H-3), and 4.66 (1H, m, H-16). The 13C-NMR spec- General Procedure Optical rotations were measured trum (in pyridine-d5) δ: 37.3 (C-1), 32.3 (C-2), 70.7 (C-3), 39.1 with a JASCO P-1020 (l=0.5) automatic digital polarimeter. (C-4), 45.0 (C-5), 28.9 (C-6), 32.3 (C-7), 35.1 (C-8), 54.5 (C-9), FAB-MS were obtained with a glycerol matrix in the positive 35.7 ((C-10), 21.2 (C-11), 40.5 (C-12), 41.9 (C-13), 53.4 (C-14), ion mode using a JEOL JMS-DX300 and a JMS-DX 303 HF 33.5 (C-15), 70.4 (C-16), 62.4 (C-17), 15.2 (C-18), 12.4 (C-19), spectrometer. The 1H- and 13C-NMR spectra were measured 27.4 (C-20), 17.6 (C-21), 62.7 (C-22), 96.6 (C-23), 38.7 (C-24), in pyridine-d5 with JEOL α-500 spectrometer, and chemical 38.0 (C-25), 43.8 (C-26), 65.1 (C-27). shifts are given on a δ (ppm) scale with tetramethylsilane (TMS) as the internal standard. Column chromatographies Conflict of Interest The authors declare no conflict of were carried out on a Diaion HP-20 (Mitsubishi Chemical interest. Ind.), silica gel 60 (230–400 mesh, Merck), and ODS (pre- parative C18, 55–105 µm, Waters). TLC was performed on References silica gel plates (Kieselgel 60 F254, Merck) and RP C18 silica 1) Fujiwara Y., Yahara S., Ikeda T., Ono M., Nohara T., Chem. Pharm. gel plates (Merck). The spots on TLC were visualized by UV Bull., 51, 234–235 (2003). 2) Fujiwara Y., Takaki A., Uehara Y., Ikeda T., Okawa M., Yamauchi light (254/366 nm) and sprayed with 10% H2SO4, followed by heating. K., Ono M., Yoshimitsu H., Nohara T., Tetrahedron, 60, 4915–4920 Extraction of Tomato Juice in Plastic Bottles Five (2004). 3) Nohara T., Ikeda T., Fujiwara Y., Matsushita S., Noguchi E., Yoshi- types of juice products prepared by different companies were mitsu H., Ono M., J. Nat. Med., 61, 1–13 (2007). individually blended with water and were centrifuged to give 4) Nohara T., Ono M., Ikeda T., Fujiwara Y., El-Aasr M., J. Nat. Prod., a supernatant, which was then passed through Diaion HP-20 73, 1734–1741 (2010). and rinsed with water. Methanol was then passed through the 5) Fujiwara Y., Kiyota N., Hori M., Matsushita S., Iijima Y., Aoki K., gel to produce an eluate, which was evaporated to produce a Shibata D., Takeya M., Ikeda T., Nohara T., Nagai R., Arterioscler. residue. This methanolic residue was subjected to Sephadex Thromb. Vasc. Biol., 27, 2400–2406 (2007). LH-20 column chromatography and was then eluted with 6) Nohara T., Fujiwara Y., Zhou J.-R., Kimura Y., Murakami K., Ikeda T., Yokomizo K., Ono M., Abstracts of papers, the 8th JSP- 90% methanol. The first eluate was checked by TLC (CHCl3– MeOH–water=6 : 4 : 1) including tomato saponins, and the fol- CCTCNM-KSP Joint Symposium on Pharmacognosy, Fukuoka, lowing fraction excluding tomato saponin was collected. The p. 141, September 2014. 7) Manabe H., Murakami Y., El-Aasr M., Ikeda T., Fujiwara Y., Ono respective yields are shown as follows. MeOH eluate: residue M., Nohara T., J. Nat. Med., 65, 176–179 (2011). (0.129–0.216%; average, 0.166%), esculeosides B-1 (2) and B-2 8) Manabe H., Fujiwara Y., Ikeda T., Ono M., Murakami K., Zhou (3): 0.027–0.072%; average, 0.41%, others (including aromatic J.-R., Yokomizo K., Nohara T., Chem. Pharm. Bull., 61, 764–767 compounds): 0.074–0.114%, average, 0.101%. (2013). This first running 90% methanolic eluate from the Sep- 9) Yoshizaki M., Matsushita S., Fujiwara Y., Ikeda T., Ono M., Nohara hadex LH-20 column gave a residue (1834.7 mg, 0.024%), a T., Chem. Pharm. Bull., 53, 839–840 (2005). part of which (1550 mg) was then chromatographed on ODS 10) Schreiber K., Ripperger H., Liebigs Ann., 655, 114–135 (1962). column with 45% methanol to provide two tomato sapo- 11) Demarco P. V., Farkas E., Doddrell D., Mylari B. L., Wenkert E., J. nins, identical with esculeosides B-1 (2, 320 mg) and B-2 (3, Am. Chem. Soc., 90, 5480–5486 (1968). 410 mg).8)