Hybrid Polyketides from a Hydractinia-Associated Cladosporium sphaerospermum SW67 and Their Putative Biosynthetic Origin.

Five hybrid polyketides (1a, 1b, and 2-4) containing tetramic acid core including a new hybrid polyketide, cladosin L (1), were isolated from the marine fungus Cladosporium sphaerospermum SW67, which was isolated from the marine hydroid polyp of Hydractinia echinata. The hybrid polyketides were isolated as a pair of interconverting geometric isomers. The structure of 1 was determined based on 1D and 2D NMR spectroscopic and HR-ESIMS analyses. Its absolute configuration was established by quantum chemical electronic circular dichroism (ECD) calculations and modified Mosher's method. Tetramic acid-containing compounds are reported to be derived from a hybrid PKS-NRPS, which was also proved by analyzing our 13C-labeling data. We investigated whether compounds 1-4 could prevent cell damage induced by cisplatin, a platinum-based anticancer drug, in LLC-PK1 cells. Co-treatment with 2 and 3 ameliorated the damage of LLC-PK1 cells induced by 25 µM of cisplatin. In particular, the effect of compound 2 at 100 µM (cell viability, 90.68 ± 0.81%) was similar to the recovered cell viability of 88.23 ± 0.25% with 500 µM N-acetylcysteine (NAC), a positive control.

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

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.

Bioactivity evaluations of betulin identified from the bark of Betula platyphylla var. japonica for cancer therapy.

Identification of bioactive natural products with anticancer activity as well as alleviating effects on chemotherapy-induced side effects has significant implications for cancer treatment. Betula platyphylla var. japonica, commonly known as Asian white birch, has been used in Chinese traditional medicine for a variety of purposes. In this study, the medicinal properties of betulin from B. platyphylla var. japonica useful for cancer management were investigated. LC/MS analysis revealed that betulin is a main chemical component of the EtOH extract of B. platyphylla var. japonica bark, and betulin was isolated from EtOH extract using an LC/MS-guided isolation method. Its structure was identified with 1H and 13C NMR spectroscopic data and LC/MS analysis and then compared to the previously reported spectroscopic and physical data. We first verified the cytotoxicity of betulin against three human lung adenocarcinoma cell lines, A549, H1264, and Calu-6, with IC50 values ranging from 18.7 to 39.6 µM. Regarding alleviation of side effects associated with anticancer chemotherapy, betulin ameliorated cisplatin-induced renal cell damage to 80% of the control value from the concentration of 5 µM. In addition, betulin showed anti-gastritis activity against ethanol-induced gastric damage in rats and notably reduced the gastric damage index compared to control in a concentration-dependent manner. These findings provide the first experimental evidence for potential use of B. platyphylla var. japonica as a functional food for cancer treatment that simultaneously alleviates the side effects of chemotherapy.

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).

Flavonoids and a Limonoid from the Fruits of Citrus unshiu and Their Biological Activity.

The fruits of Citrus unshiu are one of the most popular and most enjoyed fruits in Korea. As we continue to seek for bioactive metabolites from Korean natural resources, our study on the chemical constituents of the fruits of C. unshiu resulted in the isolation of a new flavonoid glycoside, limocitrunshin 1, along with seven other flavonoids 2-8 and a limonoid 9. All structures were identified by spectroscopic methods, namely 1D and 2D NMR, including HSQC, HMBC, and (1)H-(1)H COSY experiments, HRMS, and other chemical methods. Compounds 3, 5, and 9 are reported to be isolated from this fruit for the first time. The isolated compounds were applied to activity tests to verify their inhibitory effects on inflammation and nephrotoxicity. Compounds 6 and 9 showed the most potent inhibitory activity on renal cell damage and nitric oxide production, respectively. Thus, the fruits of C. unshiu could serve as a valuable natural source of bioactive components with health benefits for potential application in functional foods.

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.

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.

Bioassay-guided Isolation of Antiproliferative Triterpenoids from Euonymus alatus Twigs.

Euonymus alatus (Celastraceae) has been used as an anticancer agent in Korean traditional medicine. However, the potential bioactive contributors to the anticancer effects have not been thoroughly studied. Our screening test revealed that the MeOH extract of E. alatus twigs exhibited significant cytotoxicity against A549, SK-OV-3, and SK-MEL-2 cell lines. A bioassay-guided separation of the MeOH extract of E. alatus twigs resulted in the isolation and identification of 14 triterpenes as main phytochemicals. The structures of the compounds were elucidated on the basis of spectroscopic evidence as lupeol (1), betulin (2), 3ß,28,30-lup-20(29)-ene triol (3), lupenone (4), betulone (5), 28,30-dihydroxy-3-oxolup-20(29)-ene (6), messagenin (7), glut-5-en-3ß-ol (8), maslinic acid (9), hederagenin (10), 3-oxo-11α-methoxyolean-12-ene (11), 3ß-hydroxy-1-oxo-olean-12-en-28-oic acid (12), ursolic acid (13), and 2a-hydroxy- ursolic acid (14). Of these compounds, 3, 6-8, and 10-14 were isolated for the first time from this plant. All isolated triterpenoids had consistent antiproliferative activities against A549, SK-OV-3, SK-MEL-2, and HCT-15 cell lines. Compounds 2, 5, and 7 showed significant cytotoxicity against all four cell lines tested, with IC50 values of 3.26-8.61 µM.