Three New Multiflorane-Type Triterpenes from Pumpkin (Cucurbita maxima) Seeds

Abstract

Three new multiflorane-type triterpenes; 7α-methoxymultiflor-8-ene-3α,29-diol 3-acetate-29-benzoate (1), 7-oxomultiflor-8-ene-3α,29-diol 3-acetate-29-benzoate (2), and multiflora-7,9(11)-diene-3α,29-diol 3-p-hydroxybenzoate-29-benzoate (3), were isolated from seeds of Cucurbita maxima, along with three known compounds. Compound 3 and multiflora-7,9(11)-diene-3α-29-diol 3-benzoate (5) exhibited potent inhibitory effects on melanogenesis, with low cytotoxicities, and 2 exhibited single-digit micromolar cytotoxicity against HL-60 and P388 cells.

Three New Triterpene Esters from Pumpkin (Cucurbita maxima) Seeds

“…The 1 H- and 13 C-NMR spectra (Table 1) displayed signals for seven tertiary methyl groups [δ H 0.97, 0.98, 1.00, 1.05, 1.082, 1.084, 1.13 (each s)], an oxymethylene [δ H 4.08, 4.16 (each d); δ C 72.9 (t)], two oxymethines [δ H 3.54 (brs), 4.95 (t); δ C 73.8 (d), 78.1 (d)], a tetrasubstituted olefin [δ C 135.3 (s), 139.7 (s)], and two benzoyl groups [δ H 7.43 (tt), 7.45 (tt), 7.54 (tt), 7.55 (tt), 8.04 (dd), 8.05 (dd); δ C 128.3 (d), 128.4 (d), 129.4 (d), 129.6 (d), 130.7 (s), 130.8 (s), 132.6 (d), 132.7 (d), 166.3 (s), 166.6 (s)]. The above data suggested that the structure of 2 is similar to that of 7α-methoxymultiflor-8-ene-3α,29-diol 3-acetate-29-benzoate [9], except for the lack of the 3- O -acetyl group and the existence of a 3- O -benzoyl group. In the HMBC experiment, the following correlations were observed: H 2 -29 [δ H 4.08, 4.16 (each d)] to 29-O C O [δ C 166.6 (s)]; H-3 [δ H 4.95 (t)] to 3-O C O [δ C 166.3 (s)]; H-5 and H-6α to C-7 [δ C 73.8 (d)]; H-6α, H-7β, and Me-26 to C-8 [δ C 135.3 (s)]; H-7β, H 2 -11 and Me-25 to C-9 [δ C 139.7 (s)].…”

“…Multiflorane-type triterpenes are unusual, and most of them have been isolated from cucurbitaceae plants, such as Cucumis melo [11], Cucurbita pepo [3,4], Momordica cochinchinensis [12], and Trichosanthes kirilowii [13]. Only a few of their biological activities, such as anti-tumor promoting activities [14], anti-oxidant effects [15], cytotoxic activities [9,16], and melanogenesis inhibitory activities [9,16], have been reported. In this study, we evaluated them for melanogenesis inhibitory effects and cytotoxic activities against cancer cell lines.…”

“…The concentration of DMSO in the sample solution was 2 μL/mL. b Melanogenesis inhibitory and cytotoxicity data from [9]. c Reference compound.…”

“…Additionally, it was demonstrated that the seeds and flowers of Cucurbita maxima contain sterols [6,7,8]. Recently we have reported the isolation of six multiflorane-type triterpenes including three new triterpenes: 7α-methoxymultiflor-8-ene-3α,29-diol 3-acetate-29-benzoate, 7-oxomultiflor-8-ene-3α,29-diol 3-acetate-29-benzoate, and multiflora-7,9(11)-diene-3α,29-diol 3- p -hydroxybenzoate-29-benzoate, from seeds of C. maxima produced in Japan, and the melanogenesis inhibitory and cytotoxic activities of these compounds [9]. In a continuing study to explore new compounds possessing potent biological activities from C. maxima seeds, we have isolated four multiflorane-type triterpenes from seeds of C. maxima produced in India, and determined the structures of three new compounds: 7α-hydroxymultiflor-8-ene-3α,29-diol 3-acetate-29-benzoate ( 1 ) 7α-methoxymultiflor-8-ene-3α,29-diol 3,29-dibenzoate ( 2 ), and 7β-methoxymultiflor-8-ene-3α,29-diol 3,29-dibenzoate ( 3 ).…”

Cytotoxic and Antitumoral Activities of Compounds Isolated from Cucurbitaceae Plants

“…Compound (30′) did not show significant cytotoxic activity, with an IC 50 > 100 μM in both lines, but compounds 31 and 32 showed cytotoxic activity against HL-60, with IC 50 values of 7.1 and 7.1 μM, respectively. The IC 50 values for P388 were 55.9 and 92.6 μM, respectively [32].…”