Sesquiterpene lactones and other constituents from a cytotoxic extract of Michelia floribunda

Costunolide, a Sesquiterpene Lactone, Suppresses Skin Cancer via Induction of Apoptosis and Blockage of Cell Proliferation

Costunolide is a naturally occurring sesquiterpene lactone that demonstrates various therapeutic actions such as anti-oxidative, anti-inflammatory, and anti-cancer properties. Costunolide has recently emerged as a potential anti-cancer agent in various types of cancer, including colon, lung, and breast cancer. However, its mode of action in skin cancer remains unclear. To determine the anti-cancer potential of costunolide in skin cancer, human epidermoid carcinoma cell line A431 was treated with costunolide. A lactate dehydrogenase assay showed that costunolide diminished the viability of A431 cells. Apoptotic cells were detected by annexin V/propidium iodide double staining and Terminal deoxynucleotidyl transferase mediated dUTP nick end labeling assay assay, and costunolide induced cell apoptosis via activation of caspase-3 as well as induction of poly-ADP ribose polymerase cleavage in A431 cells. In addition, costunolide elevated the level of the pro-apoptotic protein Bax while lowering the levels of anti-apoptotic proteins, including Bcl-2 and Bcl-xL. To address the inhibitory effect of costunolide on cell proliferation and survival, various signaling pathways, including mitogen-activated protein kinases, signal transducer and activator of transcription 3 (STAT3), nuclear factor κB (NF-κB), and Akt, were investigated. Costunolide activated the p38 and c-Jun N-terminal kinase pathways while suppressing the extracellular signal-regulated kinase (ERK), STAT3, NF-κB, and Akt pathways in A431 cells. Consequently, it was inferred that costunolide suppresses cell proliferation and survival via these signaling pathways. Taken together, our data clearly indicated that costunolide exerts anti-cancer activity in A431 cells by suppressing cell growth via inhibition of proliferation and promotion of apoptosis. Therefore, it may be employed as a potentially tumor-specific candidate in skin cancer treatment.

Anti-Infective and Anti-Cancer Properties of the Annona Species: Their Ethnomedicinal Uses, Alkaloid Diversity, and Pharmacological Activities

Annona species have been a valuable source of anti-infective and anticancer agents. However, only limited evaluations of their alkaloids have been carried out. This review collates and evaluates the biological data from extracts and purified isolates for their anti-infective and anti-cancer activities. An isoquinoline backbone is a major structural alkaloid moiety of the Annona genus, and more than 83 alkaloids have been isolated from this genus alone. Crude extracts of Annona genus are reported with moderate activities against Plasmodium falciparum showing larvicidal activities. However, no pure compounds from the Annona genus were tested against the parasite. The methanol extract of Annona muricata showed apparent antimicrobial activities. The isolated alkaloids from this genus including liriodenine, anonaine, asimilobine showed sensitivity against Staphylococcus epidermidis. Other alkaloids such as (+)-Xylopine and isocoreximine indicated significant anti-cancer activity against A549 and K-562 cell lines, respectively. This review revealed that the alkaloids from Annona genus are rich in structural diversity and pharmacological activities. Further exploration of this genus and their alkaloids has potential for developing novel anti-infective and anticancer drugs.

Sesquiterpenoids from Saussurea costus

Sixteen sesquiterpenoids (1 - 16), including two new compounds namely saussucostusosides A and B (1 and 2), were isolated from the roots of Saussurea costus by various chromatographic separations. Their structures were elucidated by 1 D and 2 D NMR and HR-QTOF-MS experiments. Among isolated compounds, costunlide (6), 3β-[4-hydroxymethacryloyloxy]-8α-hydroxycostunolide (10) and 11β,13-dihydrozaluzanin C (16) exhibited potent inhibitory effects on LPS-induced NO production in RAW264.7 cells with IC₅₀ values of 7.08 ± 0.34, 2.40 ± 0.06 and 5.55 ± 0.24 µM, respectively.

Costunolide causes mitotic arrest and enhances radiosensitivity in human hepatocellular carcinoma cells

PURPOSE

This work aimed to investigate the effect of costunolide, a sesquiterpene lactone isolated from Michelia compressa, on cell cycle distribution and radiosensitivity of human hepatocellular carcinoma (HCC) cells.

METHODS

The assessment used in this study included: cell viability assay, cell cycle analysis by DNA histogram, expression of phosphorylated histone H3 (Ser 10) by flow cytometer, mitotic index by Liu's stain and morphological observation, mitotic spindle alignment by immunofluorescence of alpha-tubulin, expression of cell cycle-related proteins by Western blotting, and radiation survival by clonogenic assay.

RESULTS

Our results show that costunolide reduced the viability of HA22T/VGH cells. It caused a rapid G2/M arrest at 4 hours shown by DNA histogram. The increase in phosphorylated histone H3 (Ser 10)-positive cells and mitotic index indicates costunolide-treated cells are arrested at mitosis, not G2, phase. Immunofluorescence of alpha-tubulin for spindle formation further demonstrated these cells are halted at metaphase. Costunolide up-regulated the expression of phosphorylated Chk2 (Thr 68), phosphorylated Cdc25c (Ser 216), phosphorylated Cdk1 (Tyr 15) and cyclin B1 in HA22T/VGH cells. At optimal condition causing mitotic arrest, costunolide sensitized HA22T/VGH HCC cells to ionizing radiation with sensitizer enhancement ratio up to 1.9.

CONCLUSIONS

Costunolide could reduce the viability and arrest cell cycling at mitosis in hepatoma cells. Logical exploration of this mitosis-arresting activity for cancer therapeutics shows costunolide enhanced the killing effect of radiotherapy against human HCC cells.

A New Sesquiterpene and other Constituents from Saussurea Lappa Root

Five sesquiterpenes, dehydrocostus lactone (1), santamarine (5), β-cyclocostunolide (6), 4α-hydroxy-4β-methyldihydrocostol (7) and 10α-hydroxyl-artemisinic acid (9), along with four other compounds, β-sitosterol (2), daucosterol (3), 5-hydroxy-methyl-furaldehyde (4), and trans-syingin (8), were isolated and identified from the roots of Saussurea lappa (Compositae). Based on previous reports and our study, sesquiterpene derivatives are common and characteristic constituents of the genus Saussurea. Among the nine compounds obtained, 9 is a new sesquiterpene. It is an artemisinic acid derivative, whose structural skeleton has not been reported for Saussurea species before, but artemisinic acid is a common compound in another Compositae species, Artemisia annua. Dehydrocostus lactone (1) is present in high-content and is a possible bioprecursor of 10α-hydroxyartemisinic acid (9).