Two New Megastigmanes from the Leaves of Cucumis sativus

Abstract

Cucumis sativus L., which belongs to the Cucurbitaceae family, is cultivated worldwide as a vegetable crop. The fruit of C. sativus (cucumber) is used not only as food, but also in folk medicines and folk cosmetics. The leaves, stems and roots of C. sativus are reportedly used in Chinese folk medicine as antidiarrheal, detoxicant and antigonorrheal agents. 1)However, these are not major uses, so after harvest of the cucumber fruits, almost all the remaining plant material is waste. There have been few chemical studies regarding the constituents of this material. The only reports are by Enslin et al., who isolated the triterpenoid cucurbitacin C, 2) and McNally et al., who isolated C-glycosyl flavonoid.3) Thus, in the present study, we attempted to identify useful components of cucumber plant material to support its development as a medicinal resource.As part of our ongoing search for medicinal materials in cucumber plant material, chromatographic separation and purification led to the identification of two new megastigmanes, one known megastigmane, one known carotenoid, one known lignan and three other known compounds. In the present paper, we report the isolation and structural elucidation of the new megastigmanes. Results and DiscussionAir-dried leaves of C. sativus were extracted using methanol (MeOH). The MeOH extract was partitioned into an ethyl acetate (EtOAc)-water mixture to furnish EtOAcsoluble and water-soluble parts. The EtOAc-soluble part was subjected to normal-and reversed-phase column chromatography and HPLC to yield compounds 1, 3, 4, 5, 6 and 7 (Fig. 1). The water-soluble part was again extracted with EtOAc, then with n-butanol (BuOH), using an automatic extractor. The n-BuOH-soluble part was subjected to normal-and reversed-phase column chromatography and HPLC to yield compounds 2 and 8 (Fig. 1).Compound 1 C heteronuclear multiple bond coherence (HMBC) study for 1, long-range correlations were observed between the following protons and carbons: H-4 and C-2; H-2a, 2b and C-3; H-13 and C-4; H-2a, 2b, 4, 7, 8, 13 and C-6; H-7, 8 and C-9; and H-10a, 10b and C-8 (Fig. 2). Furthermore, acetylation of 1 with acetic anhydride in dry pyridine yielded di-O-acetate (1a), whose 13 C-NMR spectrum showed an acetylation shift around the 9 and 10 position of 1a. These findings and comparisons of the 1 H-and 13 C-NMR spectra of 1 and 1a with those of a known megastigmane led us to formulate the 3-oxo-6,9,10-trihydroxy-ionone structure of 1 (Fig. 1). The absolute configuration of C-6 of 1 was determined by application of the circular dichroism (CD) helicity rule 4) with known (ϩ)-dehydrovomifoliol (3). The CD spectrum of 3 showed a positive Cotton effect (De ϩ27.00) at 243.2 nm, and the 6-position was determined to have an S configuration by the CD helicity rule.4) On the basis of this evidence, the CD spectrum of 1 exhibited a positive Cotton effect (De ϩ15.79) at 240.8 nm, and the 6-position was shown to have an S configuration. In order to clarify the absolute stereostructure of the 9-position of 1, a...

Chemical constituents of theAnnona glabrafruit and their cytotoxic activity

“…Furthermore, the HMBC correlations between H-1 00 ( H 5.54) and C-1 ( C 166.0); H-1 000 ( H 4.38) and C-3 ( C 73.9) suggested that two glucopyranosyl moieties were at C-1 and C-3 0 of the aglycone. Based on the above evidence, the structure of compound 1 was determined to be (2E,4E,1 (Ngan et al, 2012), icariside D 2 (3) (Miyase et al, 1989) (Pan & Lundgren, 1995), 3,4-dihydroxybenzoic acid (6) (Scott, 1972), blumenol A (7) (González et al, 1994), cucumegastigmane I (8) (Kai et al, 2007), and icariside B 1 (9) (Hisamoto et al, 2004) (see Figure 2). Their structures were established on the basis of spectral and chemical evidence, which were in agreement with those reported in the literature.…”

New Rotenoids and Coumaronochromonoids from the Aerial Part of <i>Boerhaavia erecta</i>

“…Among those ten were rapidly identified as boeravinone G (1), 12) boeravinone H (2), 12) boeravinone C (4), 13) 10-demethylboeravinone C (5), 14) boeravinone J (7), 15) cucumegastigmane (9), 16) isovitexin (12), 17) quercetin 3-O-β-d-glucopyranoside (13), 18) isorhamnetin 3-O-α-l-rhamnopyranosyl-(1→ 6)-β-d-glucopyranoside (14), 18) and kaempferol 3-O-α-l-rhamnopyranosyl-(1→ 6)-β-dglucopyranoside (15) 18) ( Fig. 1) by comparison of their spectral data with those reported in the literature.…”

“…Its molecular formula was determined as C 21 C-NMR data of 11 with those of other glucosides isolated in the same material. [16][17][18] The β configuration of the glucose residue was deduced from its anomeric proton at δ H 6.35 (1H, d, J=7.5 Hz, H-1″) and its corresponding acetal carbon resonated at δ C 104.6. The remaining doublet at δ H 6.57 (1H, d, 7.5 Hz, H-2) correlated with the second acetal carbon at δ C 104.0 in the HSQC spectrum of 11.…”

Inhibitors for cholesterol ester accumulation in macrophages from Chinese cabbage

“…Since AV contains much fatty acids, probably they inhibited the incorporation of [ 3 H] 2 -oleic acid into the macrophages. 14) CU is known to contain much triterpenes, 15,16) and we already reported that the triterpenes in plants inhibited the accumulation of CE and showed the suppressive effect on atherosclerosis in apolipoprotein E (apoE)-deficient mice. 9,17) Therefore, the triterpenes in CU possible inhibit the accumulation of CE.…”