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Bioactivity-guided isolation of antioxidant triterpenoids from Betula platyphylla var. japonica bark

The bark of Betula platyphylla var. japonica (Betulaceae) has been used to treat pneumonia, choloplania, nephritis, and chronic bronchitis. This study aimed to investigate the bioactive chemical constituents of the bark of B. platyphylla var. japonica. A bioassay-guided fractionation and chemical investigation of the bark of B. platyphylla var. japonica resulted in the isolation and identification of a new lupane-type triterpene, 27-hydroxybetunolic acid (1), along with 18 known triterpenoids (2-19). The structure of the new compound (1) was elucidated on the basis of 1D and 2D NMR spectroscopic data analysis as well as HR-ESIMS. Among the known compounds, chilianthin B (17), chilianthin C (18), and chilianthin A (19) were triterpene-lignan esters, which are rarely found in nature. Compounds 4, 6, 7, 17, 18, and 19 showed significant antioxidant activities with IC50 values in the range 4.48-43.02μM in a DPPH radical-scavenging assay. However, no compound showed significant inhibition of acetylcholine esterase (AChE). Unfortunately, the new compound (1) exhibited no significance in both biological activities. This study strongly suggests that B. platyphylla var. japonica bark is a potential source of natural antioxidants for use in pharmaceuticals and functional foods.

Cytotoxic Triterpenoids from the Barks of Betula platyphylla var. japonica.

Phytochemical investigation on the barks of Betula platyphylla var. japonica (Betulaceae) was carried out, resulting in the isolation and identification of three new triterpenoids, 27‐O‐cis‐caffeoylcylicodiscic acid (1), 27‐O‐cis‐feruloylcylicodiscic acid (2), and 27‐O‐cis‐caffeoylmyricerol (3), along with six known triterpenoids, obtusilinin (4), winchic acid (5), 27‐O‐trans‐caffeoylcylicodiscic acid (6), uncarinic acid E (7), myriceric acid B (8), and 3‐O‐trans‐caffeoyloleanolic acid (9). The structures of the new compounds were elucidated by extensive spectroscopic methods, including 1D‐ and 2D‐NMR, and HR‐ESI‐MS. All of the isolated compounds were evaluated for cytotoxicity against four human tumor cell lines (A549, SK‐OV‐3, SK‐MEL‐2, and Bt549). Compounds 2, 6, 8, and 9 exhibited potent cytotoxicity against all of the tumor cells tested (IC50 < 10.0 μm), while compounds 3, 4, 5, and 7 showed moderate cytotoxicity against all of the tumor cells tested (IC50 < 20.0 μm).

A new aliphatic alcohol and cytotoxic chemical constituents from Acorus gramineus rhizomes.

A new aliphatic alcohol, (2R,6R)-oct-7-ene-2,6-diol (1), and seven other known compounds (2-8) were isolated from Acorus gramineus rhizomes. The structure of 1 was elucidated by a combination of extensive spectroscopic analyses, including 2D NMR, HR-MS, and the modified Mosher’s method. Compounds 3-8 displayed consistent antiproliferative activities against the cell lines tested with IC50 values ranging from 7 to 48 μm.

Antioxidant and α-glucosidase inhibitory phenolic constituents of Lactuca indica L.

Lactuca indica L. (Compositae) has been used as a folk medicine for the treatment of intestinal disorders. Phytochemical constituents of L. indica were investigated, and their antioxidant and α-glucosidase inhibitory activities thoroughly studied. A phytochemical investigation of the aerial parts of L. indica resulted in the isolation and identification of eight phenolic compounds. The structures of the compounds were elucidated on the basis of spectroscopic evidence as apigenin, luteolin, isoquercitrin, chlorogenic acid, protocatechuic acid, p-hydroxymethyl benzoic acid, trans-cinnamic acid, and p-coumaric acid. Luteolin, isoquercitrin, chlorogenic acid, and p-hydroxymethyl benzoic acid showed antioxidant activities with IC50 values in the range of 35.5–52.5 μM. In addition, apigenin and luteolin showed α-glucosidase inhibition activities with IC50 values of 96.4 and 100.7 μM, respectively. These findings strongly suggest that L. indica is a potential source of natural antioxidants and/or anti-diabetic agents in pharmaceutical and health functional foods.

The effects of phenolic glycosides from Betula platyphylla var. japonica on adipocyte differentiation and mature adipocyte metabolism

Abstract Betula platyphylla var. japonica (Betulaceae) has been used traditionally in Asian countries for the treatment of inflammatory diseases. A recent study has reported a phenolic compound, platyphylloside from B. platyphylla, that shows inhibition on adipocyte differentiation and induces lipolysis in 3T3-L1 cells. Based on this finding, we conducted phytochemical analysis of the EtOH extract of the bark of B. platyphylla var. japonica, which resulted in the isolation of phenolic glycosides (1–4). Treatment of the isolated compounds (1–4) during adipocyte differentiation of 3T3-L1 mouse adipocytes resulted in dose-dependent inhibition of adipogenesis. In mature adipocytes, arylbutanoid glycosides (2–4) induced lipolysis related genes HSL and ATGL, whereas catechin glycoside (1) had no effect. Additionally, arylbutanoid glycosides (2–4) also induced GLUT4 and adiponectin mRNA expression, indicating improvement in insulin signaling. This suggests that the isolates from B. platyphylla var. japonica exert benefial effects in regulation of adipocyte differentiation as well as adipocyte metabolism. Graphical Abstract