Sweet Olive Extract Attenuates Dextran Sulfate Sodium-Induced Colitis in Mice

Glycolipid-enriched fraction of Osmanthus fragrans inhibits LPS-induced expression of inflammatory genes, COX-2, E-selectin, and Interleukin-8

ETHNOPHARMACOLOGICAL RELEVANCE

Osmanthus fragrans Lour. is a small ornamental tree native to the Southeastern parts of China. It is mainly cultivated because of its characteristic fragrance, and used in the food and perfume industry. Besides, its flowers are used in traditional Chinese medicine to treat a variety of diseases including those related to inflammation.

AIM OF THE STUDY

The aim of the study was to investigate in more detail the anti-inflammatory properties of O. fragrans flowers, and to characterize their active principles and mechanisms of action.

MATERIALS AND METHODS

O. fragrans flowers were successively extracted with n-hexane, dichloromethane and methanol. The extracts were further fractionated by chromatographic separation. COX-2 mRNA expression in PMA-differentiated, LPS-stimulated THP-1 cells was used as lead assay for activity-guided fractionation. The most potent fraction was chemically analyzed by LC-HRMS. The pharmacological activity was also evaluated in other inflammation-related in-vitro models, such as analysis of IL-8 secretion and E-selectin expression in HUVECtert cells and selective inhibition of COX-isoenzymes.

RESULTS

n-Hexane and dichloromethane extracts of O. fragrans flowers significantly inhibited COX-2 (PTGS2) mRNA expression. Additionally, both extracts inhibited COX-2 enzyme activity, whereas COX-1 enzyme activity was affected to a significantly lower extent. Fractionation of the extracts led to a highly active, glycolipid-containing fraction. In total, 10 glycolipids were tentatively annotated by LC-HRMS. This fraction also inhibited LPS-induced COX-2 mRNA expression, IL-8 secretion and E-selectin expression. The effects were limited to LPS-induced inflammation and not observed when inflammatory genes were induced by TNF-α, IL-1β or FSL-1. Since all these inducers of inflammation act via different receptors, it is likely that the fraction interferes with the binding of LPS to the TLR4-receptor, which mediates pro-inflammatory effects of LPS.

CONCLUSION

Taken together, the results demonstrate the anti-inflammatory potential of O. fragrans flower extracts in general, and of the glycolipid-enriched fraction in particular. The effects of glycolipid-enriched fraction are potentially mediated via the inhibition of the TLR4 receptor complex.

Verbascoside and isoverbascoside ameliorate transforming growth factor β1-induced collagen expression by lung fibroblasts through Smad/non-Smad signaling pathways

AIMS

Pulmonary fibrosis (PF) is a chronic, irreversible, and debilitating lung disease that typically leads to respiratory failure, and is a major cause of morbidity and mortality. Few drugs are effective for the treatment of patients with PF or for reducing the rate of disease progression.

MAIN METHODS

Transforming growth factor-β1 (TGF-β1) is a profibrotic cytokine that signals through Smad and non-Smad pathways. Verbascoside (VB) and isoverbascoside (isoVB) exhibit anti-oxidative and anti-inflammatory activities, however, their anti-fibrotic effects remain unclear. This study evaluated the effects of VB and isoVB on TGF-β1-stimulated murine lung fibroblasts (MLg 2908) and also human lung fibroblasts (confirmed by immunostaining).

KEY FINDINGS

Neither VB nor isoVB had a cytotoxic effect on MLg 2908 fibroblasts. Both compounds (10 μM) reduced intracellular reactive oxygen species and markedly attenuated collagen I expression in TGF-β1 (5 ng/ml)-induced MLg 2908 cells compared to TGF-β1 alone. Both compounds suppressed the TGF-β1-induced phosphorylation of Smad2/3 and ERK/p38 mitogen-activated protein kinases (MAPKs). VB and isoVB, but not pirfenidone and nintedanib, inhibited TGF-β1-induced pSmad2/3, ERK/p38 MAPK, and collagen I expression. VB and isoVB also decreased collagen I deposition in TGF-β1-induced MLg 2908 cells. Only isoVB significantly suppressed collagen I deposition in TGF-β1-induced human pulmonary cells. Our results indicated that VB and isoVB may exert antifibrotic effects by inhibiting TGF-β1-induced collagen I expression via inhibition of oxidative stress and downregulation of the Smad/non-Smad pathway.

SIGNIFICANCE

The present findings suggest that VB or isoVB may be used as a supplement to alleviate PF.

Exploration of Osmanthus fragrans Lour.'s composition, nutraceutical functions and applications

Osmanthus fragrans (Thunb.) Lour. has been cultivated in China for over 2500 years. Due to the unique and strong fragrance, O. fragrans flowers have long been added into food, tea, and beverages. Not only the O. fragrans flowers, but also leaves, barks, roots, and fruits possess some beneficial effects such as relieving pain and alleviating cough in Traditional Chinese Medicine. Modern pharmacological researches demonstrated that O. fragrans possesses a broad spectrum of biological activities including antioxidant, neuroprotective, antidiabetic and anticancer activities etc. A large number of phytochemicals identified in O. fragrans are responsible for its health promoting and disease preventing effects. The components of volatile compounds in O. fragrans are complex but the content is less abundant. The present review mainly focuses on the bioactive ingredients identified from O. fragrans, the therapeutic effects of O. fragrans and its applications in food, cosmetics and medicines.

Acteoside, the Main Bioactive Compound in Osmanthus fragrans Flowers, Palliates Experimental Colitis in Mice by Regulating the Gut Microbiota

The present study investigated the effects of Osmanthus fragrans flowers and acteoside on murine colitis and the underlying mechanisms. The O. fragrans flower extract (OFE) and acteoside were administrated to chemically induced colitic mice. The results showed that OFE or acteoside ameliorates intestinal inflammation, oxidative stress, and activation of nuclear factor-κB (NF-κB) in colitic mice. The dysbiosis of the gut microbiome in colitic mice was also partly restored by OFE or acteoside, which was characterized by the alteration of the gut microbiome structure and the enrichment of beneficial bacteria (Akkermansia muciniphila and Bacteroides thetaiotaomicron). Dextran sulfate sodium (DSS)-induced gut metabolome dysfunctions (e.g., sphingosine metabolism and amino acids metabolism) in colitic mice were also partly restored by OFE and acteoside. A fecal microbiota (FM) transplantation study suggested that, compared with the FM from the normal diet-dosed donor mice, the FM from the OFE- or acteoside-dosed donor mice significantly suppressed colitic symptoms.

A newly identified polyunsaturated macamide alleviates dextran sulfate sodium-induced colitis in mice

Macamides are a class of bioactive amide alkaloids found only in maca (Lepidium meyenii). Recent studies have shown that macamide-rich extracts possess various biological activities, such as antioxidative, immune-enhancing, and reproductive health-improving activities. In the present study, N-benzyl docosahexaenamide (NB-DHA), a newly identified macamide with the highest degree of unsaturation among all identified macamides, was identified from the maca extract. Microalgae oil, a docosahexaenoic acid-rich substance, was used as the starting material for the synthesis of NB-DHA. The effects of NB-DHA in colitis-induced mice were evaluated. NB-DHA significantly alleviated weight loss, shortening of colon length, and occult blood occurrence in mice with dextran sulfate sodium-induced colitis. Histological analysis revealed that following the administration of NB-DHA in mice with colitis, the infiltration of inflammatory cells and levels of proinflammatory factors, such as tumor necrosis factor-α, interleukin (IL)-1β, IL-6, and myeloperoxidase, decreased, whereas the level of the anti-inflammatory factor IL-10 increased. Furthermore, the decreased expression of intestinal tight junction proteins caused by colitis was upregulated by the administration of NB-DHA. These results indicate that NB-DHA could be developed as a therapeutic agent for ulcerative colitis.

Effects of Different Drying Methods on the Contents of Nine Components and Immunomodulatory Activities of Four Components in Osmamthus fragrans Flowers

The effects of drying methods on the contents of four nonvolatile and five volatile components and the immunoregulatory activities of four components in Osmamthus fragrans flowers were investigated. In general, microwaving preserved more nonvolatile components than the other methods, while the sun or shade method preserved more volatile components. Nonvolatile components such as salidroside and acteoside and volatile ingredients such as linalool and linalool oxide exhibited better immunoregulatory activity than the other ingredients. Taken together, O. fragrans flowers dried by microwaving resulted in the best immunoregulatory activity. This study provides evidence for the optimal drying method for O. fragrans flowers as food and medicine.