Piper nigrum Extract Inhibits the Growth of Human Colorectal Cancer HT-29 Cells by Inducing p53-Mediated Apoptosis.

Colorectal cancer (CRC) is a prevalent malignancy of the digestive tract with the second highest mortality rate globally. Piper nigrum is a widely used traditional medicinal plant, exhibiting antitumor activity against various tumor cells. At present, research on the effect of Piper nigrum on CRC is limited to in vitro cytotoxicity, lacking comprehensive mechanism investigations. This study aimed to explore the inhibitory effect and mechanism of Piper nigrum extract (PNE) on HT-29 cells. Firstly, we identified the chemical components of PNE. Then, MTT assay, colony formation assay, JC-1 staining, and flow cytometry were used to analyze the effect of PNE on HT-29 cells in vitro. A xenograft model, histopathological examination, immunohistochemistry, and western blot were used to evaluate the tumor growth inhibitory activity and mechanism of PNE in vivo. The results indicated that PNE could inhibit cell proliferation and colony formation, reduce mitochondrial membrane potential, induce cell apoptosis in vitro, and inhibit tumor growth in vivo. Furthermore, PNE could regulate p53 and its downstream proteins, and subsequently activate the caspase-3 pathway. In summary, PNE probably induced apoptosis of HT-29 cells through the mitochondrial pathway mediated by p53. All these results suggested that PNE might be a potential natural-origin anti-CRC drug candidate.

Ethanol extract of Piper wallichii ameliorates DSS-induced ulcerative colitis in mice: Involvement of TLR4/NF-κB/COX-2 signaling pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Piper wallichii (family: Piperaceae), a folk herbal medicine with anti-inflammatory and anti-thrombotic properties, has been traditionally used to treat rheumatic arthralgia, lumbocrural pain, gastrointestinal flatulence, and other intestinal diseases in China, Thailand, and India. However, there is no scientific report on the efficacy and potential mechanisms of Piper wallichii for ulcerative colitis (UC). AIM OF THE STUDY: The study aims to investigate the therapeutic effect and possible molecular mechanisms of the ethanol extract of Piper wallichii (EEPW) on DSS-induced UC in BALB/c mice. MATERIALS AND METHODS: The main components in EEPW were characterized by UPLC-QE-Orbitrap-MS. Subsequently, the anti-inflammatory effect of EEPW in vitro was preliminarily evaluated in RAW264.7 cells stimulated with LPS. UC model mice were triggered by free access to 4% DSS aqueous solution for 12 consecutive days, and simultaneously, EEPW (25, 50, and 100 mg/kg) and tofacitinib (positive control, 30 mg/kg) were orally administrated, respectively. The therapeutic efficacy of EEPW on UC was assessed by body weight, DAI, colon length, and pathological morphology. Besides, we investigated the effects of EEPW on intestinal barrier function, inflammatory factors, and immune systems of UC mice through immunohistochemistry (IHC), flow cytometry, and other techniques. Moreover, the expression of related proteins in the TLR4/NF-κB/COX-2 pathway was analyzed by Western blot. RESULTS: A total of 14 components were identified in the positive and negative modes, including isofutoquinol A (11), hancinone C (12), and futoquinol (14) which characterized by references. In the RAW264.7 cells experiments, the extract significantly suppressed the levels of TNF-α and IL-6. More importantly, EEPW distinctly improved the symptoms of DSS-induced UC mice as reflected by a significant recovery from body weight, colon length, pathological injuries of the colon, and so on. Further research found that EEPW remarkably restored the levels of occludin, promoted proliferation, and inhibited apoptosis in colon to maintain the integrity of intestinal barrier. In addition, the down-regulation of TNF-α and IL-1ß in colon, Th1 and Th17 cells in spleen, as well as the up-regulation of IL-10 in colon and Th2 cells in spleen were distinctly observed in EEPW-treated groups. Furthermore, the protein expression of TLR4, p-IκB-α, p-p65, and COX-2 were significantly inhibited by EEPW. CONCLUSIONS: This study confirmed for the first time that EEPW effectively ameliorated DSS-induced UC in mice, which might be related to improving intestinal barrier function, maintaining the levels of inflammatory factors, and regulating the immune system. In addition, we found that the anti-inflammatory effect of EEPW on UC mice was involved in the TLR4/NF-κB/COX-2 signaling pathway. In conclusion, Piper wallichii can be used as a candidate for the treatment of UC.

Proteome analysis of bermudagrass stolons and rhizomes provides new insights into the adaptation of plant stems to aboveground and underground growth.

As an important perennial warm-season turfgrass species, bermudagrass (Cynodon dactylon L.) forms underground-growing rhizomes and aboveground-growing stolons simultaneously, making it a fast propagating clonal plant with strong regeneration ability. In the current study, we compared the internode proteomes of rhizomes and stolons at the same developmental stage in the bermudagrass cultivar Yangjiang using iTRAQ. The results indicated that 228 protein species were differentially accumulated in the two specialized stems. In agreement with the different contents of starch, chlorophyll, anthocyanin and H2O2 in the two types of stems, photosynthesis and flavonoid biosynthesis were enriched with differentially accumulated protein species (DAPs) in stolons, whereas starch and sucrose metabolism, glycolysis, and H2O2 metabolism were enriched with DAPs in rhizomes. Burying stolons in the soil resulted in the gradual degradation of chlorophyll and anthocyanin, accumulation of starch, and increment of H2O2, which is similar to the physiological characteristics of rhizomes. These results collectively revealed that stolons and rhizomes of bermudagrass have significant differences at the proteome level and light might play important regulatory roles in the discrepancy of the proteome profiles and specialization of the two stems, providing new insights into the adaptation of plant stems to aboveground and underground growth. BIOLOGICAL SIGNIFICANCE: As two types of specialized stems that grow underground and aboveground respectively, rhizomes and stolons play important roles in overwintering and ecological invasion of many perennial and clonal plants. However, because rhizomes and stolons rarely coexist in single plant species, the differences between the two stems remain unclear at the molecular level. In this study, through an iTRAQ comparative proteomic analysis, we reported the identification of 228 differentially accumulated protein species (DAPs) in rhizomes and stolons of bermudagrass for the first time. We found that the 228 DAPs were interconnected to form protein networks in regulating diverse cellular activities and biochemical reactions. We also observed that stolons growing underground showed similar physiological activities and DAP expression as those of underground-growing rhizomes, suggesting that light might play important regulatory roles in the specialization of stolons and rhizomes. These results expanded our understanding of the mysterious adaption of plant stems to different growth conditions.