(7R, 8S, 8′S, 7″S, 8″R)-abiesol A 4″-O-β-d-glucopyranoside, capselloside.

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(7R, 8S, 8′S, 7″S, 8″R)-abiesol A 4″-O-β-d-glucopyranoside, and it was named capselloside.

Capselloside (1): Brownish gum; ${[α]}_{D}^{25}$ −34.0 (c = 0.05, MeOH); UV (MeOH) λ_max (log ε) 280 (1.4), 228 (3.3), 214 (3.1) nm; IR (KBr) ν_max 3261, 2946, 2816, 1638, 1489, 1261 cm⁻¹; CD (MeOH) λ_max (Δ ε) 291 (−), 280 (−) 257 (−) 230 (−) 223 (+); ¹H (700 MHz) and ¹³C (175 MHz) NMR data, see Table 1; HR-FABMS (positive-ion mode) m/z: 723.2626 [M + Na]⁺ (calcd. for C₃₆H₄₄O₁₄Na, 723.2629).

Compound 1 was obtained as a brownish gum. The molecular formula was established as C₃₆H₄₄O₁₄using HR-FABMS, which showed a positive ion [M + Na]⁺ at m/z: 723.2626 (calcd. for C₃₆H₄₄O₁₄Na, 723.2629, so the molecular formula was deduced to be C₃₆H₄₄O₁₄.

The ¹H-NMR spectrum of 1 revealed the presence of two 1,3,4-trisubstituted aromatic rings (δ_H 7.16 (d, J = 8.3 Hz, H-5′′), 7.15 (d, J = 8.2 Hz, H-5), 7.05 (d, J = 1.7 Hz, H-2), 7.01 (d, J = 1.7 Hz, H-2′′), 6.95 (dd, J = 8.2, 1.7 Hz, H-6), and 6.90 (dd, J = 8.2, 1.7 Hz, H-6″)), a 1,3,4,5-tetrasubstitued aromatic ring (δ_H 6.76 (s, H-6′), 6.78 (s, H-2′)), two oxygenated methines (δ_H 5.58 (d, J = 5.9 Hz, H-7) and 4.85 (m, H-7′′)), two oxygenated methylenes (δ_H 3.85 (m, H-9b), 3.78 (m, H-9a), and 3.88 (m, H-9′′a), 3.68 (dd, J = 10.9, 6.7 Hz, H-9b′′)), a methylene 2.96 ((dd, J = 13.5, 5.0 Hz, H-7′a), and 2.57 (dd, J = 13.3, 11.0 Hz, H-7′b)), three methines (δ_H 3.48 (m, H-8), 2.75 (sep, J = 6.5, 5.5 Hz, H-8′), and 2.38 (quin, J = 6.9 Hz, H-8″)), three methoxy groups (δ_H 3.88 (s, 3-OCH₃), 3.87 (s, 5′-OCH₃) and 3.84 (s, 3′′-OCH₃)), and a glucopyanosyl unit (δ_H 4.91 (d, J = 7.3 Hz, H-1′′′), 3.69 (m, H-6′′′), 3.51 (m, H-2′′′), 3.41 (overlap, H-4′′′, 5′′′) and 3.39 (m, H-3′′′).

The ¹³C-NMR spectrum displayed 36 carbon signals, including 18 aromatic carbons δ_C 151.1 (C-3″), 147.9 (C-4′, 3′), 147.8 (C-3), 147.5 (C-4, 4″), 145.5 (C-5′), 139.7 (C-1″), 135.7 (C-1), 134.9 (C-1′), 119.7 (C-6″), 119.5 (C-6), 118.4 (C-6′), 118.2 (C-5″), 118.1 (C-5), 114.7 (C-2′), 111.5 (C-2″) and 111.3 (C-2), three oxygenated carbons δ_C 88.6 (C-7), 83.9 (C-7″), and 73.5 (C-9′), three methylene carbons δ_C 65.1 (C-9), 60.5 (C-9″), 33.9 (C-7′) and three methine carbons δ_C55.7 (C-8), 54.2 (C-8″), 44.0 (C-8′), and, three methoxy carbons (δ_C 56.9 and 56.8 (×2)), and glucose carbons δ_c 103.1 (C-1′′′), 78.5 (C-3′′′), 78.4 (C-5′′′), 75.1 (C-2′′′), 71.6 (C-4′′′), and 62.6 (C-6′′′) (Table 1).

**Table 1.** ¹H (700 MHz) and ¹³C (175 MHz) NMR data of 1 in methanol-d₄ (δ in ppm) ^a.
Position	δ_C, Type	δ_H (J in Hz)
1	135.7, C
2	111.3, CH	7.05, d (1.7)
3	147.8, C
4	147.5, C
5	118.1, CH	7.15, d (8.2)
6	119.5, CH	6.95, dd (8.2, 1.7)
7	88.6, CH	5.58, d (5.91)
8	55.7, CH	3.48, m
9	65.1, CH₂
a		3.78, m
b		3.85, m
1′	134.9, C
2′	114.7, CH	6.78, s
3′	147.9, C
4′	147.9, C
5′	145.5, C
6′	118.4, CH	6.76, s
7′	33.9, CH₂
a		2.96, dd (13.5, 5.0)
b		2.57, dd (13.3, 11.0)
8′	44.0, CH	2.75, sep (6.5, 5.5)
9′	73.5, CH₂
a		3.78, m
b		4.05, dd (8.3, 6.6)
1″	139.7, C
2″	111.5, CH	7.01, d (1.7)
3″	151.1, C
4″	147.5, C
5″	118.2, CH	7.16, d (8.3)
6″	119.7, CH	6.90, dd (8.2, 1.7)
7″	83.9, CH	4.85, overlap
8″	54.2, CH	2.38, quin (6.9)
9″	60.5, CH₂
a		3.88, m
b		3.68, dd (10.9, 6.7)
Glc-1′′′	103.1, CH	4.91, d (7.3)
2′′′	75.1, CH	3.51, m
3′′′	78.5, CH	3.39, m
4′′′	71.6, CH	3.41, m
5′′′	78.4, CH	3.41, m
6′′′	62.6, CH	3.69, overlap
OCH₃ (3″)	56.9	3.84, s
OCH₃ (3)	56.8	3.88, s
OCH₃ (5′)	56.8	3.87, s

^a The assignments were based on HSQC and HMBC experiments.

The ¹H- and ¹³C-NMR spectra (Table 1) were very similar to those of abiesol A [17], except for the presence of a glucose unit in 1. The positions of three methoxy groups were confirmed as 3-OCH₃ (δ_H3.88)/C-3 (δ_C 147.8), 5′-OCH₃ (δ_C 3.87)/C-5′ (δ_C 145.5), and 3″-OCH₃ (δ_H 3.84)/C-3″ (δ_C 151.1). HMBC correlation (H-1′′′ to C-4″) indicated that a D-glucose moiety was linked to C-4″ (Figure 2a), and identified the β form by the coupling constant (J = 7.3 Hz) [18]. The stereochemistry of 1 was assigned on the basis of examination of the CD spectrum in combination with the NOESY experiment. The absolute configurations of C-7 and C-8 were confirmed as 7R and 8S from the positive Cotton effect at 223 nm and the negative effect at 245 and 291 nm in the CD spectrum [19]. The absolute configurations of C-8′/C-7″/C-8″ were identified as 8′S, 7″S and 8R from the negative Cotton effect at 231 nm and 280 nm, respectively (Figure S8, Supplementary Materials) [19]. HMBC correlations and NOESY cross-peaks (Figure 2) reconfirmed the suggested structure of 1. The enzymatic hydrolysis of 1 afforded d-glucose, which was identified by the sign of the specific rotation

{[α]}_{D}^{25}

+48.2 (c = 0.03, H₂O) and by co-TLC (CHCl₃:MeOH:H₂O = 2:1:0.1; R_f = 0.21) [20] and the aglycone 1a, which was identified by ¹H-NMR and MS data [17]. Thus, the structure of 1 was determined as (7R, 8S, 8′S, 7″S, 8″R)-abiesol A 4″-O-β-d-glucopyranoside, and it was named capselloside.

Figure 2. Key ¹H-¹H COSY, HMBC (a) and NOESY (b) correlations of 1.

Molecules2017, 22(6), 1023; doi:10.3390/molecules22061023

Article

Phenolic Glycosides from Capsella bursa-pastoris (L.) Medik and Their Anti-Inflammatory Activity

Joon Min Cha ¹, Won Se Suh ¹, Tae Hyun Lee ¹, Lalita Subedi ²^,³, Sun Yeou Kim ²^,³ and Kang Ro Lee ¹^,*

Natural Products Laboratory, School of Pharmacy, Sungkyunkwan University, Suwon 16419, Korea

Gachon Institute of Pharmaceutical Science, Gachon University, 191 Hambakmoero, Yeonsu-gu, Incheon 21936, Korea

College of Pharmacy, Gachon University, 191 Hambakmoero, Yeonsu-gu, Incheon 21936, Korea

Correspondence: Tel.: +82-31-290-7710; Fax: +82-31-290-7730

Received: 16 May 2017 / Accepted: 18 June 2017 / Published: 20 June 2017

Image result for Gachon Institute of Pharmaceutical Science, Gachon University,

Abstract:

A new sesquilignan glycoside 1, together with seven known phenolic glycosides 2–8 were isolated from the aerial parts of Capsella bursa-pastoris. The chemical structure of the new compound 1 was elucidated by extensive nuclear magnetic resonance (NMR) data (¹H- and ¹³C-NMR, ¹H-¹H correlation spectroscopy (¹H-¹H COSY), heteronuclear single-quantum correlation (HSQC), heteronuclear multiple bond correlation (HMBC), and nuclear overhauser effect spectroscopy (NOESY)) and HR-FABMS analysis. The anti-inflammatory effects of 1–8 were evaluated in lipopolysaccharide (LPS)-stimulated murine microglia BV-2 cells. Compounds 4 and 7 exhibited moderate inhibitory effects on nitric oxide production in LPS-activated BV-2 cells, with IC₅₀ values of 17.80 and 27.91 µM, respectively.

Keywords:

Capsella bursa-pastoris; Cruciferae; sesquilignan glycoside; anti-inflammatory