Ubiquitin-Proteasome Modulating Dolabellanes and Secosteroids from Soft Coral Clavularia flava.

We performed a high-content screening (HCS) assay aiming to discover bioactive molecules with proteasome inhibitory activity. By structural elucidation, we identified six compounds purified from soft coral Clavularia flava, which potentiates proteasome inhibition. Chemical structure elucidation revealed they are dolabellane- and secosteroid-based compounds including a new dolabellane, clavinflol C (1), three known dolabellanes, stolonidiol (2), stolonidiol-17-acetate (3), and clavinflol B (4) as well as two new secosteroids, 3,11-dihydroxy-24-methyl-9,11-secocholest-5-en-9,23-dione (5) and 3,11-dihydroxy-24-methylene-9,11-secocholest-5-en-9,23-dione (6). All six compounds show less cytotoxicity than those of known proteasome inhibitors, bortezomib and MG132. In summary, the high-content measurements of control inhibitors, bortezomib and MG132, manifest the highest ratio >2 in high-content measurement. Of the isolated compounds, 2 and 5 showed higher activity, followed by 3 and 6, and then 1 and 4 exhibited moderate inhibition.

A High-Content Screening Assay for the Discovery of Novel Proteasome Inhibitors from Formosan Soft Corals.

The ubiquitin-proteasome system (UPS) is a major proteolytic pathway that safeguards protein homeostasis. The main 26S proteasome consists of a 20S catalytic core proteasome and a 19S substrate recognition proteasome. UPS dysfunction underlies many important clinical diseases involving inflammation, tumors, and neurodegeneration. Currently, three 20S proteasome inhibitors, bortezomib, carfilzomib, and ixazomib, have been approved for the treatment of multiple myeloma. We aim to screen UPS inhibitors for biomedical purposes. The protein interaction network of human cytomegalovirus UL76 targets UPS, resulting in aggregations of ubiquitinated proteins termed aggresomes. In this study, we demonstrated that cell-based high-content measurements of EGFP-UL76 aggresomes responded to bortezomib and MG132 treatment in a dose-dependent manner. Employing this high-content screening (HCS) assay, we screened natural compounds purified from Formosan soft corals. Four cembrane-based compounds, sarcophytonin A (1), sarcophytoxide (2), sarcophine (3), and laevigatol A (4), were found to enhance the high-content profiles of EGFP-UL76 aggresomes with relative ratios of 0.2. By comparison to the mechanistic action of proteasome inhibitors, compounds 1 and 3 modulated the accumulation of ubiquitinated proteins, with a unique pattern likely targeting 19S proteasome. We confirmed that the EGFP-UL76 aggresome-based HCS system greatly improves the efficacy and sensitivity of the identification of proteasome inhibitors.

Inhibitory Effects of Siegesbeckia orientalis Extracts on Advanced Glycation End Product Formation and Key Enzymes Related to Metabolic Syndrome.

Metabolic syndrome typically includes Type 2 diabetes associated with hyperglycemia, central obesity, dyslipidemia and hypertension. It is highly related to oxidative stress, formation of advanced glycated end products (AGEs) and key enzymes, such as carbohydrate digesting enzymes like pancreatic α-amylase and intestinal α-glucosidase, pancreatic lipase and angiotensin I-converting enzyme (ACE). This study used an in vitro approach to assess the potential of four extracts of Siegesbeckia orientalis linne on key enzymes relevant to metabolic syndrome. In this research, S. orientailis was firstly extracted by ethanol. The ethanol extract (SE) was then partitioned sequentially with hexane, ethyl acetate and methanol, and these extracts were named SE-Hex, SE-EA and SE-MeOH, respectively. The experimental results showed that SE-EA had the highest total phenolic content (TPC, 76.9 ± 1.8 mg/g) and the total flavonoids content (TFC, 5.3 ± 0.3 mg/g). This extract exhibited the most significant antioxidant activities, including DPPH radical-scavenging capacity (IC50 = 161.8 ± 2.4 µg/mL), ABTS radical-scavenging capacity (IC50 = 13.9 ± 1.5 µg/mL) and reducing power. For anti-glycation activities, SE-EA showed the best results in the inhibition of AGEs, as well as inhibitory activities against α-glucosidase (IC50 = 362.3 ± 9.2 µg/mL) and α-amylase (IC50 = 119.0 ± 17.7 µg/mL). For anti-obesity activities, SE-EA indicated the highest suppression effect on pancreatic lipase (IC50 = 3.67 ± 0.52 mg/mL). Finally, for anti-hypertension activity, SE-EA also demonstrated the strongest inhibitory activity on ACE (IC50 = 626.6 ± 15.0 µg/mL). Close relationships were observed among the parameters of TPC, antioxidant activities, inhibitory activities on α-amylase, α-glucosidase, lipase and ACE (R > 0.9). Moderate correlations were found among the parameters of TFC, antioxidant activities, and suppression of dicarbonyl compounds formation (R = 0.5-0.9). Taken together these in vitro studies reveal the therapeutic potential of SE-EA extract in the prevention and treatment of metabolic disorders.

Siegesbeckia orientalis Extract Inhibits TGFß1-Induced Migration and Invasion of Endometrial Cancer Cells.

Type II endometrial carcinoma typically exhibits aggressive metastasis and results in a poor prognosis. Siegesbeckia orientalis Linne is a traditional Chinese medicinal herb with several medicinal benefits, including the cytotoxicity against various cancers. This study investigates the inhibitory effects of S. orientalis ethanol extract (SOE) on the migration and invasion of endometrial cancer cells, which were stimulated by transforming growth factor ß (TGFß). The inhibitory effects were evaluated by determining wound healing and performing the Boyden chamber assay. This study reveals that SOE can inhibit TGFß1-induced cell wound healing, cell migration, and cell invasion in a dose-dependent manner in RL95-2 and HEC-1A endometrial cancer cells. SOE also reversed the TGFß1-induced epithelial-mesenchymal transition, including the loss of the cell-cell junction and the lamellipodia-like structures. Western blot analysis revealed that SOE inhibited the phosphorylation of ERK1/2, JNK1/2, and Akt, as well as the expression of MMP-9, MMP-2, and u-PA in RL95-2 cells dose-dependently. The results of this investigation suggest that SOE is a potential anti-metastatic agent against human endometrial tumors.

Antioxidant and anti-inflammatory activities of Lonicera japonica Thunb. var. sempervillosa Hayata flower bud extracts prepared by water, ethanol and supercritical fluid extraction techniques.

Lonicera japonica Thunberg (LJ) has long been used as an antipyretic, anti-inflammatory and anti-infectious agent in East Asia. The subspecies L. japonica Thunb. var. sempervillosa Hayata (LJv) is a variant that mainly grows in Taiwan. This study examined the antioxidant and anti-inflammatory activities of the extracts from the flower buds of these two species. The extracts were obtained by three extraction methods: water extraction, ethanol extraction, and supercritical-CO2 fluid extraction (SFE). The antioxidant activities of dry LJ (dLJ) extracts were superior to those of LJv extracts. Water extracts possessed higher activities than that prepared by ethanol or SFE. The total polyphenols content, total flavonoids content, and the amount of chlorogenic acid and luteolin-7-O-glucoside were all higher in the water extracts compared to the other two. The SFE extracts of these two species all exhibited excellent anti-inflammatory activities. Although the water and ethanol extracts of dLJ extracts had higher anti-inflammatory activity than that of LJv extracts, the SFE extracts prepared from fresh LJv flower buds (fLJv) exhibited the highest activity among all extracts. The SFE effectively isolates the bioactive components of L. japonica and can obtain the L. japonica extracts with high anti-inflammatory activity.

Anti-proliferative effects of Siegesbeckia orientalis ethanol extract on human endometrial RL-95 cancer cells.

Endometrial cancer is a common malignancy of the female genital tract. This study demonstrates that Siegesbeckia orientalis ethanol extract (SOE) significantly inhibited the proliferation of RL95-2 human endometrial cancer cells. Treating RL95-2 cells with SOE caused cell arrest in the G2/M phase and induced apoptosis of RL95-2 cells by up-regulating Bad, Bak and Bax protein expression and down-regulation of Bcl-2 and Bcl-xL protein expression. Treatment with SOE increased protein expression of caspase-3, -8 and -9 dose-dependently, indicating that apoptosis was through the intrinsic and extrinsic apoptotic pathways. Moreover, SOE was also effective against A549 (lung cancer), Hep G2 (hepatoma), FaDu (pharynx squamous cancer), MDA-MB-231 (breast cancer), and especially on LNCaP (prostate cancer) cell lines. In total, 10 constituents of SOE were identified by Gas chromatography-mass analysis. Caryophyllene oxide and caryophyllene are largely responsible for most cytotoxic activity of SOE against RL95-2 cells. Overall, this study suggests that SOE is a promising anticancer agent for treating endometrial cancer.