Damascenone: Functions in Osteoclastogenesis Inhibition and Wine Aroma

Beta-damascenone is a cyclic monoterpene ketone that is 2,6,6-trimethylcyclohexa-1,3-diene substituted at position 1 by a crotonoyl group. It has a role as a fragrance, a volatile oil component and a plant metabolite.

Damascenone inhibits osteoclastogenesis

Damascenone (Dama) is an active compound extracted from Epipremnum pinnatum, a popular indoor ornamental plant with an air-cleaning effec. It has been reported that Dama has anti-inflammatory, antioxidant, and anti-cancer functions; however, potential effect of Dama on osteoporosis remains unclear. At the molecular level, NRF2 is downstream of Dama, whose transcriptional activity is induced under Dama treatment. Furthermore, Damascenone suppresses pro-inflammatory cytokine expression and NF-κB signaling. Nevertheless, the precise mechanism by which Dama regulates NRF2 and NF-κB signaling remains unclear.Natural herbs are important sources of drug development. Bioactive compounds derived from natural herbs are more safe and sometimes more effective. Dama is a terpene existing in Epipremnum pinnatum and some fruits. Previous studies have ascertained that it can exert an antioxidant effect by regulating the transcriptional activity of NRF2. Meanwhile, NF-κB signaling is also a downstream target of Damascenone (Pan et al., 2019). Since NRF2, ROS, and NF-κB pathway are active participants in osteoclastogenesis, the prospect of Dama in osteoporosis treatment is quite promising. Therefore, we first determined the impact of Dama on osteoclast formation in vitro. Our findings demonstrate that Dama could suppress the formation and function of osteoclasts in a concentration-dependent manner. TRAP staining and F-actin ring formation assays revealed a reduction in the number and size of multinuclear osteoclasts. Moreover, bone slice assays showed a decrease in resorption area. Consistent with the cell differentiation phenotypes, Dama attenuated the expression of osteoclast-related markers in both concentration and time-dependent manners. These in vitro results primarily confirm the effect of Damascenone on inhibiting osteoclastogenesis.[1]

To clarify the accurate mechanism of Dama, we first investigated the potential effects on critical signaling pathways in the formation of osteoclasts. Dama suppressed the phosphorylation of major elements in MAPKs and NF-κB pathways, which further suppressed the nuclear translocation of P65 and NFATc1. Considering that ROS is a key factor that activates MAPKs and NF-κB, and Damascenone exhibits antioxidant activity, we further examined the ROS alterations under Dama treatment. Indeed, Dama significantly suppressed the ROS levels by up-regulating several ROS scavenging enzymes including HO-1, GSR, NQO1, and CAT. NRF2 is a vital transcriptional activator of genes containing antioxidant response elements (ARE), and previous reports have shown that Dama also induces ARE. However, whether this stimulative effect is mediated by NRF2 remains unclear. Our results demonstrated that Damascenone up-regulated both mRNA and protein levels of Nrf2, indicating that an increase in antioxidant enzymes is primarily due to stronger Nrf2 expression. Moreover, using an NRF2 inhibitor ML-385, we verified that the osteoclast inhibitory effect of Dama is partially dependent on NRF2. Recent studies have also found that several natural compounds can enhance bone health by modulating ROS/KEAP1/NRF2 signaling axis. For example, alpinetin, tussilagone, and 4-methylcatechol have been shown to inhibit ROS by reducing the Nrf2 inhibitor, KEAP1, leading to impaired osteoclastogenesis. Oroxylin A and notopterol could suppress bone loss by up-regulating Nrf2 mRNA level and enhancing the expression of ROS-scavenging enzymes. In this work, Damascenone directly up-regulated Nrf2 mRNA expression, similar to the mechanism of oroxylin A and notopterol. Moreover, Damascenone exhibited stronger inhibitory effects on in vitro osteoclastogenesis at comparable doses than oroxylin A and notopterol, suggesting its promising potential for osteoporosis treatment.

Although the above results indicate that Dama regulates Nrf2 expression, the specific mechanism and direct molecular target of Damascenone remains unclear. Therefore, we performed network pharmacology analysis to clarify the specific molecular target of Dama. We identified 30 molecules that correlated with both Dama and osteoporosis. GO enrichment results displayed multiple signaling pathways related to transcription regulation. Moreover, PPI analysis revealed that the top 3 hub molecules included HIF1A, NF-κB1, and HDAC2. Intriguingly, they are all closely related to the transcription process, which corroborates GO enrichment analysis results. To further determine the most likely target of Dama, we performed a molecule docking assay and found that the Damascenone and HDAC2 combination was the most stable. Therefore, we considered that HDAC2 is a direct target of Damascenone. The MST and CTSA results further confirmed that Damascenone could bind to HDAC2. Of note, HDAC2 belongs to class I HDACs, which eliminates acetylation modifications on proteins. Histone is one of the most common targets of HDAC2. The acetylation modification on histone is a promoting signal for transcription. HDAC2 could decrease acetylation levels of histone and negatively regulate gene expression, which is also referred to as epigenetic regulation. Intriguingly, several studies have shown that Nrf2 expression undergoes various types of epigenetic modifications such as acetylation and methylation. Chen et al. revealed that running exercise could down-regulate methylation levels of the Nrf2 promoter. Another report indicated that HDAC1 could decrease the acetylation levels of the Nrf2 promoter at the H3K27ac site and inhibit Nrf2 expression. Nonetheless, although the NRF2 level negatively correlates with HDAC2 levels, whether HDAC2 could epigenetically regulate Nrf2 remains obscure. Our results revealed that Dama inhibits HDAC2 activity in vitro. HDAC2 directly binds to the Nrf2 promoter and decreases acetylation levels at H3K27ac; Damascenone treatment could reverse this alteration and restore Nrf2 expression. Therefore, we confirm that Dama directly suppresses HDAC2 and epigenetically up-regulates Nrf2 expression.

The Potential Effect of β-Ionone and β-Damascenone on Sensory Perception of Pinot Noir Wine Aroma

β-ionone and β-damascenone are C-13 norisoprenoid volatile aroma compounds that are found in grapes and their respective wines. There is considerable interest in the effect of these compounds on wine aroma as, anecdotally, it is thought that higher levels of these compounds may improve wine quality. Specifically, there is interest in increasing the content in grapes and wine above what is normally found through using vineyard management practices. These compounds are varietal aroma compounds found in grapes and derived from the breakdown of carotenoids through enzymatic and acid catalyzed hydrolysis. This breakdown results in the formation of free form volatile aroma compounds or non-volatile glycoconjugates within the vacuoles of grape skin cells. β-ionone is a secondary metabolite derived from β-carotene. β-damascenone is a breakdown product of different aglycons and neoxanthin.[2]

Volatile compounds are responsible for driving the aroma of wine. Because of their low perception thresholds, norisoprenoids may play an important role in wine aroma. Studies have shown that β-damascenone may act as an aroma enhancing compound. However, the direct impact on wine aroma is unclear. Our study examined the direct impact of β-ionone and β-damascenone on the aroma sensory perception of Pinot noir wines. Triangle tests were used to determine if assessors could distinguish between wines with varying concentrations of β-ionone and β-damascenone in three different Pinot noir wine matrixes. Descriptive analysis was performed on these treatments, perceived as different in triangle tests. Results show that β-ionone acts as a significant contributor to aromas in Pinot noir wine, as individuals could differentiate both the low and high concentration wines from the control. How β-ionone impacted wine aroma depends on the wine matrix, as different aroma descriptors were affected based on the model wine used, resulting in floral, red berry or dark berry aromas. The effect of β-damascenone on Pinot noir aroma was less clear, as perception seems to be heavily influenced by wine matrix composition. This study contributes to our understanding of the complex chemical causation of fruity aromas in Pinot noir wine.

References

[1]Ma, Qingliang et al. “Damascenone inhibits osteoclastogenesis by epigenetically modulating Nrf2-mediated ROS scavenge and counteracts OVX-induced osteoporosis.” Phytomedicine : international journal of phytotherapy and phytopharmacology vol. 135 (2024): 156205. doi:10.1016/j.phymed.2024.156205

[2]Tomasino E, Bolman S. The Potential Effect of β-Ionone and β-Damascenone on Sensory Perception of Pinot Noir Wine Aroma. Molecules. 2021 Feb 27;26(5):1288. doi: 10.3390/molecules26051288. PMID: 33673491; PMCID: PMC7956508.

You may like