[Studies on the chemical components and antibacterial activity of essential oil from the leaves of Rubus corchorifolius].

OBJECTIVE: To analyze the chemical components of essential oil from the leaves of Rubus corchorifolius. METHODS: The essential oil was extracted by steam distillation, and then an analysis was conducted by applying GC-MS and Xcalibur Software. K-B filter paper method was used for their bacteriostasish. RESULTS: 44 compounds were identified, accounting for 88.52% of the total essential oil. The volatile oil concentration of 50% had a good bactericidal effect and the concentration of 0.5% still had excellent antibacterial effect. CONCLUSION: It provides the foundation for reasonable utilization and development of the leaves of Rubus corchorifolius.

Identification of terpenoids from Rubus corchorifolius L. f. leaves and their anti-proliferative effects on human cancer cells.

The leaves of Rubus corchorifolius L. f. have been consumed as a herbal tea for a long time. In this study, two novel (1 and 5) and four known (2, 3, 4 and 6) terpenoids were isolated from the leaves of Rubus corchorifolius L. f. Structural analysis was performed using various spectroscopic methods (1H NMR, 13C NMR and MS) to identify the following six compounds: (16α)-16,17,18-trihydroxy-ent-kauran-18-O-ß-d-glucoside (1), ent-16ß,17-dialkyl-3-oxygen-kaurane (2), ent-kaurane-3α,16ß,17-triol (3), ent-kaurane(5R,8S,9R,10R,13R,16R)-2-one-16α,17-diol (4), (16R)-16ß,17,19-trihydroxy-ent-kaur-3-one (5) and ent-16α,17-dihydroxy-kauran-19-oic-acid (6). These compounds showed different inhibitory effects on various human cancer cells. Compounds 3 and 6 exhibited stronger inhibitory effects on human colon cancer HCT116 cells than the other 4 compounds. Flow cytometry analysis demonstrated that both compounds 3 and 6 caused cell cycle arrest at the G0/G1 phase and induced cellular apoptosis in HCT116 cells. Compounds 3 and 6 modulated the expression levels of key signaling proteins closely related to cell proliferation and apoptosis, i.e., increasing the levels of poly(ADP-ribose) polymerase, p53, and p27, and decreasing the levels of EGFR, cyclin D1, CDK2 and CDK4. Overall, our findings provided insight into the anticancer components of Rubus corchorifolius L. f. leaves, which could facilitate their utilization as functional food ingredients.

Identification of pinostilbene as a major colonic metabolite of pterostilbene and its inhibitory effects on colon cancer cells.

SCOPE: Pterostilbene (PTE) is a resveratrol derivative mainly found in blueberries, and it has been shown to inhibit colon carcinogenesis in multiple animal models. To shed light on the mechanism of PTE in inhibiting colon carcinogenesis, we investigated the PTE metabolites in the mouse colon and in the human colon cancer cells. METHODS AND RESULTS: CD-1 mice were fed PTE-containing diet for 3 weeks, and colonic content and colonic mucosa were collected and subjected to LC-MS analysis. Pinostilbene (PIN) was identified as a major metabolite of PTE in the mouse colon. Importantly, the level of PIN was found to be approximately equivalent to that of PTE in the colonic mucosa. PIN significantly inhibited the growth of human colon cancer cells, i.e., HCT116 and HT29. These inhibitory effects were similar to those produced by PTE. Moreover, under physiologically relevant conditions, 20 and 40 µM of PIN caused cell cycle arrest at S phase and induced apoptosis in colon cancer cells. These effects were associated with profound modulation of signaling proteins related with cell proliferation and programmed cell death. CONCLUSION: Our results demonstrated that PIN is a major metabolite of PTE in the colon of mice fed with PTE, and PIN may play important roles in the anti-colon cancer effects elicited by orally administered PTE.

Anti-inflammatory effects of 4'-demethylnobiletin, a major metabolite of nobiletin.

Nobiletin, a citrus flavonoid has been associated with various beneficial biological activities. 4'-Demethylnobiletin (4DN) is a major metabolite of nobiletin and its tissue level was found to be much higher than that of nobiletin after oral administration of nobiletin in mice. Anti-inflammatory effects of 4DN were studied in lipopolysaccharide (LPS)-treated RAW 264.7 macrophages. The results showed 4DN not only dose-dependently inhibited LPS-induced nitric oxide production, but also significantly reduced expression of pro-inflammatory mediators, namely PGE2, IL-1ß and IL-6. 4DN potently suppressed the expression of iNOS and COX-2 at both protein and mRNA levels. 4DN also inhibited nuclear translocation of NF-κB and AP-1. Furthermore, we demonstrated that 4DN activated transcription factor Nrf2 and its dependent genes including HO-1 and NQO1 whose expression may contribute to anti-inflammatory effects. The results demonstrated anti-inflammatory effects of 4DN and provided a scientific basis for using nobiletin as a nutraceutical to inhibit inflammation-driven diseases.