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Abstract

A new neoflavonoid, named as (7R)-(-)-3′,5-dihydroxy-4′,2,4-trimethoxy-dalbergiquinol (1) and a new phenanthrenedione, named as 3′,7-dihydroxy-3,6- dimethoxy-9-phenyl-1,4-phenanthrenedione (2), together with 4 known compounds, 5-O-methyldalbergiphenol (3), 3′,7-dihydroxy-4′,3,6-trimethoxy-9-phenyl-1,4-phenanthrenedione (4), (+)-obtusafuran (5), and melanoxin (6) were isolated from the heartwood of Dalbergia melanoxylon. Their structures were elucidated on the basis of chemical and spectral evidence, as well as by comparison with literature data. Moreover, compound 1 showed a protective effect on hypoxia/reoxygenation injury in H9c2 at 10.0 μM by decreasing lactate dehydrogenase and malondialdehyde activity and enhancing superoxide dismutase activity.

Keywords

H9c2 protective effect hypoxia/reoxygenation

Myocardial hypoxia/reoxygenation (H/R) injury can lead to significant morbidity and mortality.¹ In previous reports, latifolin isolated from Dalbergia genus exhibited cardioprotective effects against doxorubicin-induced cardiotoxicity by macrophage polarization in mice.²

Dalbergia melanoxylon, belonging to the genus Dalbergia (Fabaceae family), is widely cultivated in tropical and subtropical African areas.³ Dalbergia melanoxylon called by African people as “African Blackwood” or “Mpingo”⁴ have been commonly used for the treatment of abdominal pain, joint pain, headache, hernia, gonorrhea, and bronchitis.⁵ Dalbergia melanoxylon has a rich source of biologically active constituents, including neoflavones,⁶ flavanones,⁵ benzofurans,⁷ N-cinnamoyl,⁸ quinoid⁹ derivatives, and a phenanthrenedione.¹⁰ However, the pharmacological activities and mechanisms of D. melanoxylon about the protective effect on H/R injury are still unknown.

In a continuing phytochemical study of the dichloromethane extract, a new neoflavonoid (1), a new phenanthrenedione (2), and 4 known ones (3-6) were obtained (Figure 1). Herein, we report the isolation, structure elucidation, and protective effect on H/R injury in H9c2 of compounds 1-6.

Figure 1

Chemical structures of compounds 1-6.

Materials and Methods

General Experimental Procedures

Ultraviolet (UV) spectra were obtained on a 210A double-beam spectrophotometer (Shimadzu, Japan). Mass spectrometry (MS) data were obtained on a Triple TOF 5600 + MS (AB SCIEX, USA). One-dimensional (1D) and 2D nuclear magnetic resonance (NMR) spectra were recorded on a Bruker AV 600 spectrometer (Bruker Corporation, Fallanden, Switzerland). Circular dichroism (CD) spectra were recorded using a JASCO J-1500 spectropolarimeter (CA, USA). Preparative high-performance liquid chromatography (HPLC) was performed on an LC 3000 (Beijing Tong Heng Innovation Technology Co., Ltd., China) with a semipreparative C₁₈ column (250 × 10 mM, 10 µM, Phenomenex, USA). Optical rotations were measured using a JASCO P-1020 polarimeter (JASCO Corporation, Tokyo, Japan). Sephadex LH-20 (25, 100 mm, Pharmacia Fine Chemical Co Ltd, Uppsala, Sweden) was used for column chromatography. Analytical thin-layer chromatography plates (GF 254 Silica gel) and column chromatography silica gel (100-200 mesh, 200‐300 mesh) were purchased from Qingdao Haiyang Chemical Co, Ltd. (Qingdao, China). All solvents were of analytical grade. The H9c2 culture supernatants were tested with lactate dehydrogenase (LDH) assay kits (Jiancheng Bioengineering Institute, Nanjing, China). The homogenates of H9c2 were tested with malondialdehyde (MDA) and superoxide dismutase (SOD) assay kits (Jiancheng Bioengineering Institute, Nanjing, China). The value of optical density was measured by Absorbance Microplate Reader (SpectraMax 190, Molecular Devices Corporation, USA).

Plant Material

The heartwoods of D. melanoxylon were purchased from Fang Cheng Gang market, Guangxi Province, China, in July 2014 and identified by Professor Feng Xu at the product quality inspection center of Guangxi University. A voucher specimen (No.Liu-20140702) was deposited in the Key Laboratory of Innovation Drug and Efficient Energy-saving Pharmaceutical Equipment, Jiangxi University of Traditional Chinese Medicine.

Extraction and Isolation

The air-dried pieces of the heartwood of D. melanoxylon (50.0 kg) were powdered, passed through a 40-mesh sieve, and was extracted with 70% ethanol under refluxing 3 times. After removing the solvent under reduced pressure, the residue (13.9 kg) was suspended in water and partitioned with dichloromethane (CH₂Cl₂; 5 L × 15), ethyl acetate (EtOAc; 5 L × 10), and n-butanol (n-BuOH; 5 L × 5) to afford CH₂Cl₂ (8.5 kg), EtOAc (1.8 kg) and n-BuOH (0.8 kg) fractions, respectively.

The CH₂Cl₂ extract (8.5 kg) was chromatographed over silica gel eluting with a gradient of petroleum ether-EtOAc (100:1 to 10:1, v/v) to yield 22 subfractions (A1-A22). Subfraction A1 (14.8 g) was purified by silica gel column chromatography eluting with petroleum ether-acetone to (50:1 to 2:1, v/v) yield 11 subfractions (A1a-A1k). Subfraction A1a (2.2 g) was separated by silica gel eluting with petroleum ether-EtOAc (20:1 to 2:1, v/v) to yield 3 subfractions (A1a1-A1a3). Subfraction A1a3 (1.0 g) was separately performed on a semipreparative C₁₈ column (250 × 10 mM, 10 µM, Phenomenex, USA) eluting with methanol (CH₃OH or MeOH)/water |(H₂O) (v/v, 60:40, flow rate: 4 mL/min) to afford compound 5 (10.7 mg, t_R 43.1 minutes). Subfraction A1g (32.2 mg) was chromatographed over Sephadex LH-20 eluting with CH₂Cl₂-MeOH to obtain compound 3 (30.5 mg). Fr. A7 (447.5 g) was applied to silica gel column chromatography with CH₂Cl₂-MeOH (1:1, v/v)to yield 7 subfractions (A7a-A7g). Fr. A7c (41.3 g) was separated by silica gel eluting with petroleum ether-EtOAc (100:1 to 10:1, v/v) to yield 6 subfractions (A7c1-A7c6). Subfraction A7c2 (2.1 g) was chromatographed over Sephadex LH-20 eluting with CH₂Cl₂-MeOH (1:1, v/v) to obtain compound 1 (1.9 g). Subfraction A7d (1.8 g) was chromatographed on Sephadex LH-20 column chromatography with CH₂Cl₂-MeOH (1:1, v/v) to yield 4 subfractions (A7d1-A7d4). Subfraction A7d2 (1.1 g) was chromatographed over Sephadex LH-20 eluting with CH₂Cl₂-MeOH (1:1, v/v) to obtain compound 2 (16.9 mg). Subfraction A8 (147.4 g) was applied to silica gel column chromatography with CH₂Cl₂-MeOH (200:1 to 10:1, v/v) to yield 8 subfractions (A8a-A8h). Subfraction A8d (44.7 g) was separated by silica gel eluting with CH₂Cl₂-MeOH (500:1 to 50:1, v/v) to yield 3 subfractions (A8d1-A8d3). Fr. A8d1 (1.3 g) was separately performed on a semipreparative C₁₈ column (250 × 10 mM, 10 µM, Phenomenex, USA) eluting with acetonitrile/H₂O (v/v, 60:40, flow rate: 4 mL/min) to afford compound 6 (22.0 mg, t_R 36.7 minutes). Fr. A8d2 (2.3 g) was purified by silica gel eluting with petroleum ether-acetone (100:1 to 10:1, v/v)to obtain compound 4 (15.9 mg).

(7R)-(-)-3',5-Dihydroxy-4',2,4-Trimethoxydalbergiquinol (1)

Yellow amorphous powder; $[α]_{D}^{25}$ −31.3° (c 0.03, MeOH); UV (MeOH) λ_max 259, 290 nm; CD (MeOH): 240 (∆ɛ −4.11) nm; IR (potassium bromide [KBr]) λ_max 3480, 1601, 1605, 1504 cm^{−1; 1}H NMR (acetone-d ₆, 600 MHz) and ¹³C NMR (acetone-d ₆, 151 MHz) data, see Table 1; high-resolution electrospray ionization mass spectrometry (HRESIMS) (negative) m/z 315.1229 [M − H]⁻ (calcd. for C₁₈H₁₉O₅ 315.1238).

Table 1

¹³C and ¹H Nuclear Magnetic Resonance Data for Compounds 1 and 2 (600 and 150 MHz, Δ in Ppm).

Position	1 (Acetone-d ₆)		2 (DMSO-d ₆)
Position	δ _C	δ _H (J in Hz)	δ _C	δ _H (J in Hz)
1	124.2	-	185.3	-
2	150.2	-	107.6	6.27 (1H, s)
3	98.3	6.69 (1H, s)	161.3	-
4	145.8	-	182.4	-
4a	-	-	131.5	-
4b	-	-	126.4	-
5	140.2	-	106.4	9.01 (1H, s)
6	115.7	6.67 (1H, s)	152.9	-
7	46.3	4.98 (1H, d, 6.9)	149.6	-
8	141.3	6.27 (1H, ddd, 17.1/10.1/6.9)	109.1	7.27 (2H, d, 9.0)
8a	-	-	123.6	-
9	114.6	5.13 (1H, dd, 10.2/3.3) 4.92 (1H, dd, 17.1/3.5)	144.7	-
10	-	-	120.4	7.71 (1H, s)
10a	-	-	130.3	-
1′	136.6	-	141.3	-
2′	115.4	6.71 (1H, d, 2.0)	116.6	6.85 (1H, s)
3′	146.1	-	157.9	-
4′	146.2	-	115.9	6.92 (1H, dd, 8.2/2.3)
5′	111.3	6.84 (1H, d, 8.4)	129.7	7.37 (1H, t, 7.8)
6′	119.3	6.64 (1H, dd, 8.4/2.0)	120.9	6.88 (1H, d, 7.8)
OCH₃-4′	55.7	3.79 (3H, s)	-	-
OCH₃-2	56.2	3.73 (3H, s)	-	-
OCH₃-3	-	-	57.1	3.89 (3H, s)
OCH₃-4	55.4	3.84 (3H, s)	-	-
OCH₃-6	-	-	55.9	3.97 (3H, s)
3′-OH	-	7.51 (1H, s)	-	9.72 (1H, s)
5-OH	-	7.17 (1H, s)	-	-
7-OH	-	-	-	10.27 (1H, s)

Abbreviation: DMSO, dimethyl sulfoxide.

3′,7-Dihydroxy-3,6-Dimethoxy-9-Phenyl-1,4-Phenanthrenedione (2)

Reddish amorphous powder; UV (MeOH) λ_max 248, 307 nm; IR (KBr) λ_max 3201 1725 1600 1504 cm^{−1; 1}H NMR (DMSO-d ₆, 600 MHz) and ¹³C NMR (DMSO-d ₆, 151 MHz) data, see Table 1; HRESIMS (postive) m/z 377.0848 [M + H]⁺ (calcd. for C₂₂H₁₇O₆ 377.0846).

Activity Assay

H9c2 cells were purchased from the Cell Bank of the Chinese Academy of Sciences (Shanghai, China). The cells were cultured in Dulbecco’s Modified Eagle’s Medium (Invitrogen, USA) supplemented with 10% fetal bovine serum at 37 °C with carbon dioxide incubation. Cells were split when a confluence of 80% was achieved using trypsin-ethylenediaminetetraacetic acid (EDTA), seeded onto 96-well plates at a density of 5.0 × 10⁴/mL (100 µL/well), incubated for 24 hours before treatment.

H9c2 cells were randomly divided into 3 groups¹¹: (1) the control group was cultured under normal medium; (2) the model group was cultured under oxygen and glucose deprivation (OGD) for 20 hours, and then the cells were maintained in normal culture medium for 4 hours (reoxygenation); (3) the drugs groups, which were pretreated with compounds 1-6 (2.5, 5, 10 µM) for 24 hours before OGD. Thereafter, the cells with compounds 1-6 (2.5, 5, 10 µM) were exposed to OGD for 20 hours, and then the cells with compounds 1-6 (2.5, 5, 10 µM) were cultured under normal medium for 4 hours. The protective effects of compounds 1-6 on H/R-induced myocardial injury were assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The optical density of each well was then measured on a microplate spectrophotometer at a wavelength of 490 nm.

The H9c2 culture supernatant was used for the estimation of LDH. H9c2 cells were washed with phosphate-buffered saline (PBS), enzymatically dissociated with the use of trypsin/EDTA, and finally collected in PBS buffer. H9c2 were lysated by ultrasound in 3 times, and the lysates of H9c2 were centrifuged for 10 minutes at 1000 r/min at 4 ℃. The homogenate of H9c2 was used to estimate the activities of SOD and MDA.

Statistical Analysis

All data are presented as mean ± SD, and analyses were performed with SPSS 20.0 software. The multigroup comparisons were conducted by a one-way analysis. Values of P < 0.05 were considered to indicate a statistically significant difference.

Results and Discussion

Structural Elucidation of Compounds 1-6

Compound 1 was isolated as a yellow amorphous powder. Its molecular formula was determined to be C₁₈H₂₀O₅ based on HRESIMS (Supplemental Figure S6) m/z: 315.1229 (calculated for C₁₈H₂₀O₅, 315.1238 [M − H]⁻). The UV absorption bands (Supplemental Figure S5) were observed at λ_max 256 and 290 nm. The infrared (IR) spectrum (Supplemental Figure S7) clearly exhibited the absorption bands of a hydroxy group (3480 cm^-−1) and an aromatic group (1601 cm⁻¹). The ¹H NMR spectrum (Supplemental Figure S1) (Table 1) presented 3 ABX-type aromatic protons (ring B) (δ_H 6.84 [1H, d, J = 8.4 Hz], 6.71 [1H, d, J = 2.0 Hz], and 6.64 [1H, dd, J = 8.4, 2.0 Hz]), 2 singlet aromatic peaks (δ_H 6.67 [1H, s, H-6] and 6.69 [1H, s, H-3]), 3 singlet methoxy groups (δ_H 3.84 [3H, s, OCH₃-4], 3.79 [3H, s, OCH₃-4′], and 3.73 [3H, s, OCH₃-2]) and 2 hydroxy groups [δ_H 7.51 (1H, s) and 7.17 (1H, s)]. The signals at δ_H 6.27 (1H, ddd, J = 17.1, 10.1, 6.9 Hz, H-8), 5.13 (1H, dd, J = 10.2, 3.3 Hz, H-9a), 4.98 (1H, d, J = 6.9 Hz, H-7), and 4.92 (1H, dd, J = 17.1, 3.5 Hz, H-9b) are in agreement with those of dalbergiquinol derivatives.¹⁰ Based on ¹³C NMR (Supplemental Figure S2) and heteronuclear single quantum coherence (HSQC ) spectra (Supplemental Figure S4), 18 carbon signals, including 14 aromatic carbons [(δ_C 150.2, 146.2, 146.1, 145.8, 141.3, 140.2, 136.6, 124.2, 119.3, 115.7, 115.4, 114.6, 111.3, 98.3)], 3 methoxy carbons [δ_C 56.2 (OCH₃-2), 55.7 (OCH₃-4′), and 55.4 (OCH₃-4)] and a tertiary carbon (δ_C 46.3) were observed. The heteronuclear multiple bond correlation (HMBC) (Supplemental Figure S3) of H-3 (δ_H 6.69) with C-1 (δ_C 124.2) and C-5 (δ_C 140.2) along with the correlation of H-6 (δ_H 6.67) with C-2 (δ_C 150.2) and C-4 (δ_C 145.8) have confirmed the signals at δ_H 6.69 and 6.67 at ring A and assigned as H-3 and H-6, respectively. The HMBCs from 3′-OH (δ_H 7.51) to C-2′ (δ_C 115.4) and C-3′ (δ_C 146.1) evidenced a hydroxyl was located at C-3′ of ring B, and 5-OH (δ_H 7.17) to C-4 (δ_C 145.8), C-5 (δ_C 140.2), and C-6 (δ_C 115.7) evidenced a hydroxyl was located at C-5 of ring A. In HSQC and HMBC spectra, the correlations between H-6′ (δ_H 6.67) and C-4′ (δ_C 146.2), the OCH₃ (δ _H 3.79) and C-4′ (δ_C 146.2) suggested that this methoxyl group (δ _C 3.79) was located at C-4′. Moreover, the methoxy groups [δ_H 3.84 (OCH₃-4) and 3.73 (OCH₃-2)] were positioned at C-4 and C-2, respectively. Based on the key HMBCs between H-6 (δ_H 6.67) and C-4 (δ_C 145.8), C-5 (δ_C 140.2) along with the HMBC between H-7 (δ_H 4.98) and C-2 (δ_C 150.2). According to the HMBC and HSQCs, 2 methoxy carbons OCH₃-4 (δ_H 3.84) and OCH₃-2 (δ_H 3.73) were located at C-4 (δ_C 145.8) and C-2 (δ_C 150.2). The value of optical rotation was −31.3° (c 0.03, MeOH) indicated C-7 with the R-configuration.¹² Meanwhile, the CD spectrum of compound 1 (Figure 2) showed a negative Cotton effect at 240 nm suggesting that the absolute configuration at C-7 was R.¹³ Thus, the structure of compound 1 was fully elucidated and was identified as (7R)-(-)-3′,5-dihydroxy-4′,2,4-trimethoxydalbergiquinol.

Figure 2

Circular dichroism spectrum of compounds 1 and 3 in methanol.

Compound 2 was isolated as a reddish amorphous powder. Its molecular formula was determined to be C₂₂H₁₈O₆ based on HRESIMS (Supplemental Figure S13) m/z: 377.0848 [M + H]⁺ (calculated for C₂₂H₁₉O₆, 377.0846). The UV absorption bands (Supplemental Figure S12) were observed at λ _max 252, 312 nm. The IR spectrum (Supplemental Figure S14) clearly exhibited the absorption bands of a hydroxy group (3201 cm⁻¹), a carbonyl group (1725 cm⁻¹), and an aromatic group (1600 cm⁻¹). The ¹H NMR spectrum (Supplemental Figure S8) (Table 1) indicated the presence of 5 singlet aromatic peaks [δ_H 9.01 (1H, s), 7.71 (1H, s), 7.27 (1H, s), 6.85 (1H, s), and 6.27 (1H, s)], 2 methoxy groups [δ_H 3.97 (3H, s), 3.89 (3H, s)], and 2 hydroxyl groups [δ_H 10.27 (1H, s), 9.72 (1H, s)]. Based on ¹³C NMR (Supplemental Figure S9) and HSQC spectra (Supplemental Figure S11), 22 carbon signals, including 2 carbonyl carbons [δ_C 185.3 (C-1), 182.4 (C-4)], 18 aromatic carbons [δ_C 161.3, 157.9, 152.9, 149.6, 144.7, 141.3, 131.5, 130.3, 129.7, 126.4, 123.6, 120.9, 120.4, 116.6, 115.9, 109.1, 107.6, 106.4], and 2 methoxy carbons [δ_C 57.1 (OCH₃-3), 55.9 (OCH₃-6)] were observed. The ¹H and ¹³C NMR data of 2 (Table 1) were similar to those of pterolinus K.¹⁴ The other olefinic proton (δ_H 6.34) showed HMBC (Supplemental Figure S10) corrections with 2 carbonyl carbons (δ_C 185.3, 182.4) and C-3 (δ_C 161.3). The proton at δ_H 7.71 exhibited the HMBCs of C-1 (δ_C 185.3), C-4a (δ_C 131.5), C-8a (δ_C 123.6), C-9 (δ_C 144.7), and C-10a (δ_C 130.3). Based on the HMBC corrections from H-5 (δ_H 9.01) to C-4a (δ_C 131.5), C-8a (δ_C 123.6), C-6 (δ_C 152.9), C-7 (δ_C 149.6) and the HMBC corrections from H-8 (δ_H 7.27) to C-4b (δ_C 126.4), C-6 (δ_C 152.9), C-7 (δ_C 149.6), C-9 (δ_C 144.7) evidenced a hydroxyl and a methoxyl were located at C-7 and C-6, respectively. The correlations of HMBC (Figure 3) exhibited the 2 aromatic protons (δ_H 6.88 and 6.85) to C-9 (δ_C 144.7) and the correlations of HMBC showed hydroxy group (δ_H 9.72) to C-3′ (δ_C 157.9), C-4′ (δ_C 115.9). Therefore, the hydroxy group must be at C-3′. The HMBCs from the hydroxy group (δ_H 10.27) to C-6 (δ_C 152.9) and C-8 (δ_C 109.1) evidenced that the hydroxy group was located at C-7. Moreover, the methoxy groups [δ_H 3.97 (OCH₃-6), 3.89 (OCH₃-3)] were positioned at C-6 and C-3 from the HMBCs between H-5 (δ_H 9.01 [1H, s]) to C-6 (δ_C 152.9), C-7 (δ_C 149.6) and H-2 (δ_H 6.27 [1H, s]) to C-3 (δ_C 161.3), respectively. Ultimately, compound 2 was identified as 3′,7-dihydroxy-3,6-dimethoxy-9-phenyl-1,4-phenanthrenedione.

Figure 3

Selected heteronuclear multiple bond correlations of compounds 1 and 2.

The 4 known compounds were identified as 5-O-methyldalbergiphenol (3),^12,15 pterolinus K (4),¹⁴ (+)-obtusafuran (5),¹⁶ and melanoxin (6)¹⁷ by comparison of their NMR data (Supplemental Figure S15-S22) with those reported in the literature. R-(-)-3′-hydroxy-2,4,5-trimethoxydalbergiquinol showed a strong negative Cotton effect at 225‐234 nm.¹⁸ The CD spectrum of compound 3 (Figure 2) also showed a characteristic negative Cotton effect at 240 nm and the value of optical rotation was −29.6° (c 0.03, MeOH). These data indicated that compound 3 possesses an R-configuration at C-7.^13,15

Up to now, the structures of 7-hydroxy-3,6-dimethoxy-9-phenyl-1,4-phenanthrene-diones^10,14 and (2S,3S)-3-methyl-2-phenyl-2,3-dihydrobenzo[b]furan^18,19 were only isolated from the Fabaceae family. Moreover, the 7-hydroxy-3,6-dimethoxy-9-phenyl-1,4-phenanthrenediones were uncommon in natural products; there were only 2 derivatives that had been discovered.^10,14 So, the 2 skeletons of compounds 1 and 2 might be the ones with the characteristic components of the Fabaceae family.

Pharmacological Activities of Compounds 1-6

The cytotoxicities of all compounds (1-6) were determined against the H9c2 cells. The half-maximal inhibitory concentration values of compounds 1-6 were more than 100.0 µM, indicating that none of the tested compounds (1-6) showed obvious cytotoxicity against H9c2 cells.

The protective effect of compounds 1-6 on H/R-induced injury in H9c2 cells was tested. Compound 1 exhibited a protective effect (Figure 4); the viability of 77.92% ± 1.71% at a concentration of 10.0 µM compared with the cell viability of 62.77% ± 2.86% in the model group. Compound 1 showed a protective effect on H/R injury in H9c2 at 10 µM by decreasing LDH and MDA level to 167.59 ± 5.63 U/L and 0.97 ± 0.12 nmol/mg prot, respectively, and enhancing SOD level to 23.11 ± 1.03 U/mg prot (Figure 5).

Figure 4

Protective effects of compounds 1-6 on hypoxia/reoxygenation (H/R)-induced injury in H9c2. Values are expressed as the mean ± SD of 4 replicates; *P < 0.05 versus H/R-induced cell; ^# P < 0.01 versus control.

Figure 5

Lactate dehydrogenase, malondialdehyde, and superoxide dismutase level of compounds 1-6 on hypoxia/reoxygenation (H/R)-induced injury in H9c2. Values are expressed as the mean ± SD of 3 replicates; *P < 0.05 versus H/R-induced cell; ^# P < 0.05 versus control.

Based on the above evidence, we suggested that neoflavonoids with a protective effect on H/R-induced injury are the main bioactive constituents of D. melanoxylon.

Conclusions

In summary, 1 new neoflavonoid (1) and 1 new phenanthrenedione (2), together with 4 known ones, 1 neoflavonoid (3), 1 phenanthrenedione (4), and 2 dihydrobenzo[b]furans (5 and 6) were isolated from the heartwood of D. melanoxylon. The CD spectrum of 1 was provided for reference to the structure of neoflavonoid with R-configuration. Moreover, compound 1 showed a significant protective effect on H/R injury at 10 µM by enhancing SOD level and cell viability to 23.11 ± 1.03 U/mg prot, 77.92 ± 1.71%, and decreasing LDH and MDA level to 167.59 ± 5.63 U/L and 0.97 ± 0.12 nmol/mg prot, respectively.

Supplemental Material

Supplementary Figures - Supplemental material for Two New Compounds From the Heartwood of Dalbergia melanoxylon and Their Protective Effect on Hypoxia/Reoxygenation Injury in H9c2

Supplemental material, Supplementary Figures, for Two New Compounds From the Heartwood of Dalbergia melanoxylon and Their Protective Effect on Hypoxia/Reoxygenation Injury in H9c2 by Yang Liu, Ni Zhang, Jun-wei He, Lan-ying Chen, Li Yang, Xiao-wei Meng, Feng Shao and Rong-hua Liu in Natural Product Communications

Footnotes

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was financially supported by the National Key R&D Program of China (2018YFC1706102), the National Natural Science Foundation of China (NSFC) (No. 81360629 and 81660676), the Natural Science Foundation of Jiangxi Province (No. 20171BAB205096 and 20202BABL216074), and the Postgraduate Innovative Foundation of Jiangxi University of traditional Chinese medicine (No. JZYC17S042).

ORCID iDs

Feng Shao

Rong-hua Liu

Supplemental Material

Supplemental material for this article is available online.

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