Mitochondria play a pivotal role in most eukaryotic cells, as they are responsible for the generation of energy and diverse metabolic intermediates for many cellular events. During endosymbiosis, approximately 99% of the genes encoded by the mitochondrial genome were transferred into the host nucleus, and mitochondria import more than 1000 nuclear-encoded proteins from the cytosol to maintain structural integrity and fundamental functions, including DNA replication, mRNA transcription and RNA metabolism of dozens of mitochondrial genes. In metazoans, a family of nuclear-encoded proteins called the mitochondrial transcription termination factors (mTERFs) regulates mitochondrial transcription, including transcriptional termination and initiation, via their DNA-binding activities, and the dysfunction of individual mTERF members causes severe developmental defects. Arabidopsis thaliana and Oryza sativa contain 35 and 48 mTERFs, respectively, but the biological functions of only a few of these proteins have been explored. Here, we investigated the biological role and molecular mechanism of Arabidopsis mTERF15 in plant organelle metabolism using molecular genetics, cytological and biochemical approaches. The null homozygous T-DNA mutant of mTERF15, mterf15, was found to result in substantial retardation of both vegetative and reproductive development, which was fully complemented by the wild-type genomic sequence. Surprisingly, mitochondria-localized mTERF15 lacks obvious DNA-binding activity but processes mitochondrial nad2 intron 3 splicing through its RNA-binding ability. Impairment of this splicing event not only disrupted mitochondrial structure but also abolished the activity of mitochondrial respiratory chain complex I. These effects are in agreement with the severe phenotype of the mterf15 homozygous mutant. Our study suggests that Arabidopsis mTERF15 functions as a splicing factor for nad2 intron 3 splicing in mitochondria, which is essential for normal plant growth and development.

Monascus-fermented red mold dioscorea (RMD) has been proven to possess greater hypolipidemic effect than red mold rice (RMR) even though they include equal levels of cholesterol-lowering agent monacolin K. However, higher concentrations of yellow pigments (monascin and ankaflavin) were found in RMD than in RMR. In this study, purified monascin and ankaflavin were administered to hyperlipidemic hamsters for 8 weeks, respectively, to test whether these two compounds were novel hypolipidemic ingredients. In the statistical results, monascin and ankaflavin showed significant effect on lowering cholesterol, triglyceride, and low-density lipoprotein cholesterol levels in serum, as well as aorta lipid plaque (p < 0.05). Importantly, monascin and ankaflavin, unlike monacolin K, were able to perform up-regulation rather than down-regulation on high-density lipoprotein cholesterol (HDL-C) levels in serum. This finding not only explained why RMD showed greater hypolipidemic and HDL-C-raising effect than RMR but also proved that monascin and ankaflavin would act as novel and potent hypolipidemic ingredients.

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The aim of the present work is to investigate the effects of Monascus secondary metabolites, monascin (MS) and ankaflavin (AK), on cell proliferation, adipogenesis, lipolysis and heparin-releasable lipoprotein lipase (HR-LPL) in 3T3-L1 preadipocyte. MS and AK inhibit the proliferation of 3T3-L1 cells in a dose-dependent fashion. At 8 μg/mL concentration MS inhibits proliferation for 80.5% after 48 h, whereas the value for AK is 69.2%. Adipogenesis is inhibited by MS and AK without dose-dependency. Triglyceride is decreased 37.1% and 41.1% respectively by treating 0.125 μg/mL MS and AK. Adipocyte-specific transcription factors peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer binding protein β (C/EBPβ), C/EBPδ and C/EBPα mRNA levels are measured by real-time polymerase chain reaction. The expression of the four transcriptional factors analyzed (PPARγ, C/EBPβ, C/EBPδ and C/EBPα) is reduced at the initial and the middle period. At the later period, there is no effect on the expression of PPARγ and C/EBPα by treating MS and AK. Furthermore, both MS and AK increase basal lipolysis of mature adipocytes by 113.2% and 278.3% upregulation, respectively. And both MS and AK reduce the activity of HR-LPL, by 45.3% and 58.1% reduction, respectively. This study reveals for the first time that Monascus secondary metabolites, MS and AK, can prevent the differentiation of preadipocyte and stimulate basal lipolysis of mature adipocytes, avoiding the accumulation of lipid.

Monascus purpureus NTU 568 was a mutant strain from M. purpureus HM105. The methanol extract of red mold rice fermented by this strain exhibited four major yellow pigment signals on HPLC profile. By repeated chemical chromatography methods, three new azaphilone derivatives, namely, monaphilone A (1), B (2) and C (3), along with the known pigments ankaflavin (4) and monascin (5), were isolated and characterized. Based on spectroscopic analyses, mainly 1D and 2D NMR data, the structures of compounds 1-3 were completely elucidated; in addition, 1-3 were determined to be new azaphilone structures, due to the decrease of carbon monoxide for producing a gamma-lactone ring, compared with other azaphilone derivatives. Biological evaluations showed that monaphilone A (1) and B (2) exhibited an antiproliferative effect against HEp-2 (human laryngeal carcinoma cell line) and WiDr (human colon adenocarcinoma cell line), and none of the five compounds had toxicity to normal human lung cell lines (WI-38 and MRC-5) at 70 muM.

Monascus-fermented monascin and ankaflavin are found to strongly inhibit differentiation and lipogenesis and stimulate lipolysis effects in a 3T3-L1 preadipocyte model, but the in vivo regulation mechanism is unclear. This study uses obese rats caused by a high-fat diet to examine the effects of daily monascin and ankaflavin feeding (8 weeks) on antiobesity effects and modulation of differentiation, lipogenesis, and lipid absorption. The results show that monascin and ankaflavin had a significant antiobesity effect, which should result from the modulation of monascin and ankaflavin on the inhibition of differentiation by inhibiting CCAT/enhancer-binding protein β (C/EBPβ) expression (36.4% and 48.3%) and its downstream peroxisome proliferator-activated receptor γ (PPARγ) (55.6% and 64.5%) and CCAT/enhancer-binding protein α (C/EBPα) expressions (25.2% and 33.2%) and the inhibition of lipogenesis by increasing lipase activity (14.0% and 10.7%) and decreasing heparin releasable lipoprotein lipase (HR-LPL) activity (34.8% and 30.5%). Furthermore, monascin and ankaflavin are the first agents found to suppress Niemann-Pick C1 Like 1 (NPC1L1) protein expression (73.6% and 26.1%) associated with small intestine tissue lipid absorption. Importantly, monascin and ankaflavin are not like monacolin K, which increases creatine phosphokinase (CPK) activity, known as a rhabdomyolysis indicator.

The goal of this study was to elucidate whether triggering the sphingomyelin pathway modulates LPS-initiated responses. For this purpose we investigated the effects of N-acetylsphingosine (C2-ceramide) on LPS-induced production of NO and PGE2 in murine RAW 264.7 macrophages and explored the signaling pathways involved. We found that within a range of 10–50 μM, C2-ceramide inhibited LPS-elicited NO synthase and cyclooxygenase-2 induction accompanied by a reduction in NO and PGE2 formation. By contrast, a structural analog of C2-ceramide that does not elicit functional activity, C2-dihydroceramide, did not affect the LPS response. The nuclear translocation and DNA binding study revealed that ceramide can inhibit LPS-induced NF-κB and AP-1 activation. The immunocomplex kinase assay indicated that IκB kinase activity stimulated by LPS was inhibited by ceramide, which concomitantly reduced the IκBα degradation caused by LPS within 1–6 h. In concert with the decreased cytosolic p65 protein level, LPS treatment resulted in rapid nuclear accumulation of NF-κB subunit p65 and its association with the cAMP-responsive element binding protein. Ceramide coaddition inhibited all the LPS responses. In addition, LPS-induced PKC and p38 mitogen-activated protein kinase activation were overcome by ceramide. In conclusion, we suggest that ceramide inhibition of LPS-mediated induction of inducible NO synthase and cyclooxygenase-2 is due to reduction of the activation of NF-κB and AP-1, which might result from ceramide’s inhibition of LPS-stimulated IκB kinase, p38 mitogen-activated protein kinase, and protein kinase C.

Red mold dioscorea (RMD) is a fermented product of Monascus purpureus NTU 568 using dioscorea as culture substrate. To investigate the bioactive components of RMD, six orange pigments including four new azaphilones with yellow fluorescence, monapilol A-D (1-4), and known monascorubrin (5) and rubropunctatin (6) were isolated and characterized. Structural elucidation of new isolates was based on nuclear magnetic resonance ((1)H NMR, (13)C NMR, COSY, HMQC, and HMBC) and other spectroscopic analyses. The structures of monapilols (1-4) were similar to those of monascorubrin (5) and rubropunctatin (6); however, the hydroxyl group (8-OH) in compounds 1-4 substituted for the C-8 carbonyl in compounds 5 and 6. Biological evaluation indicated that compounds 1-4 inhibited nitric oxide (NO) production on lipopolysaccharide-stimulated RAW 264.7 cells. Compounds 1-4 also exhibited antiproliferative activities against human laryngeal carcinoma (HEp-2) and human colon adenocarinoma (WiDr).