Background
Cancer cachexia is a multifactorial debilitating syndrome that directly accounts for more than 20% of cancer deaths while there is no effective therapeutic approach for treatment of cancer cachexia. Carnosol (CS) is a bioactive diterpene compound present in Lamiaceae spp., which has been demonstrated to have antioxidant, anti‐inflammatory, and anticancer properties. But its effects on cancer cachexia and the possible mechanism remain a mystery.
Methods
The in vitro cell models of C2C12 myotube atrophy and 3T3‐L1 mature adipocyte lipolysis were used to check the activities of CS and its synthesized analogues. C26 tumour‐bearing BALB/c mice were applied as the animal model to examine their therapeutic effects on cancer cachexia in vivo. Levels of related signal proteins in both in vitro and in vivo experiments were examined using western blotting to study the possible mechanisms.
Results
Carnosol and its analogues [dimethyl‐carnosol (DCS) and dimethyl‐carnosol‐D6 (DCSD)] alleviated myotube atrophy of C2C12 myotubes and lipolysis of 3T3‐L1 adipocytes in vitro. Interestingly, CS and its analogues exhibited stronger inhibitive effects on muscle atrophy induced by tumour necrosis factor‐α (TNF‐α) (CS, P < 0.001; DCS, P < 0.001; DCSD, P < 0.001) in C2C12 myoblasts than on muscle atrophy induced by IL‐6 (CS, P < 0.05; DCS, P = 0.08; DCSD, P < 0.05). In a C26 tumour‐bearing mice model, administration of CS or its analogue DCSD significantly prevented body weight loss without affecting tumour size. At the end of the experiment, the body weight of mice treated with CS and DCSD was significantly increased by 11.09% (P < 0.01) and 11.38% (P < 0.01) compared with that of the C26 model group. CS and DCSD also improved the weight loss of epididymal adipose tissue in C26 model mice by 176.6% (P < 0.01) and 48.2% (P < 0.05) increase, respectively. CS and DCSD treatment partly preserved gastrocnemius myofibres cross‐sectional area. CS treatment decreased the serum level of TNF‐α (−95.02%, P < 0.01) but not IL‐6 in C26 tumour‐bearing mice. Inhibition on NF‐κB and activation of Akt signalling pathway were involved in the ameliorating effects of CS and its analogues on muscle wasting both in vitro and in vivo. CS and its analogues also alleviated adipose tissue loss by inhibiting NF‐κB and AMPK signalling pathways both in vitro and in vivo.
Conclusions
CS and its analogues exhibited anticachexia effects mainly by inhibiting TNF‐α/NF‐κB pathway and decreasing muscle and adipose tissue loss. CS and its analogues might be promising drug candidates for the treatment of cancer cachexia.
Chronic inflammation is associated with various chronic illnesses including immunity disorders, cancer, neurodegeneration, and vascular diseases. Iridoids are compounds with anti-inflammatory properties. However their anti-inflammatory mechanism remains unclear. Here, we report that scropolioside B, isolated from a Tibetan medicine (Scrophularia dentata Royle ex Benth.), blocked expressions of TNF, IL-1, and IL-32 through NF-κB pathway. Scropolioside B inhibited NF-κB activity in a dose-dependent manner with IC50 values of 1.02 μmol/L. However, catalpol, similar to scropolioside B, was not effective in inhibiting NF-κB activity. Interestingly, scropolioside B and catalpol decreased the expression of NLRP3 and cardiolipin synthetase at both the mRNA and protein level. Our results showed that scropolioside B is superior in inhibiting the expression, maturation, and secretion of IL-1β compared to catalpol. These observations provide further understanding of the anti-inflammatory effects of iridoids and highlight scropolioside B as a potential drug for the treatment of rheumatoid arthritis and atherosclerosis.
Eutypenoids A–C (1–3), pimarane diterpenoid alkaloid and two ring A rearranged pimarane diterpenoids, were isolated from the culture of Eutypella sp. D-1 obtained from high-latitude soil of the Arctic. Their structures, including absolute configurations, were authenticated on the basis of the mass spectroscopy (MS), nuclear magnetic resonance (NMR), X-ray crystallography, and electronic circular dichroism (ECD) analysis. The immunosuppressive effects of eutypenoids A–C (1–3) were studied using a ConA-induced splenocyte proliferation model, which suggested that 2 exhibited potent immunosuppressive activities.
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