Effect of oridonin, a Rabdosia diterpenoid, on radiosensitization with misonidazole

Recent Development of Oridonin Derivatives with Diverse Pharmacological Activities

Oridonin is one of the major components isolated from Isodon rubescens, a traditional Chinese medicine, and it has been confirmed to exhibit many kinds of biological activities including anticancer, anti-inflammation, antibacterial and so on. However, the poor pharmaceutical property limits the clinical applications of oridonin. So many strategies have been explored in the purpose of improving the potencies of oridonin, and structure modification is one thus way. This review outlines the landscape of the recent development of oridonin derivatives with diverse pharmacological activities, mainly focusing on the biological properties, structure-activity relationships, and mechanism of actions.

Oridonin enhances the radiosensitivity of lung cancer cells by upregulating Bax and downregulating Bcl-2

Oridonin is an active component of the traditional Chinese herb Rabdosia rubescens. The present study aimed to evaluate the antitumor effects of oridonin on human non-small cell lung cancer (NSCLC) cells and explore whether oridonin could enhance their radiosensitivity. Oridonin was demonstrated to inhibit the proliferation of SPC-A-1 and HCC827 lung cancer cells in a time- and dose-dependent manner, which was detected using the MTT assay. In addition, pretreatment with oridonin for 24 h prior to irradiation was identified to enhance the radiosensitivity of SPC-A-1 cells. Furthermore, the levels of apoptosis regulator BAX (Bax) and apoptosis regulator Bcl-2 (Bcl-2) were detected by western blotting analysis. The results demonstrated that the level of Bax was increased and the level of Bcl-2 was decreased in SPC-A-1 cells treated with oridonin and irradiation compared with the group that received irradiation alone. These results indicate that oridonin may have a novel application as a radiosensitizing agent for the treatment of human NSCLC.

Phytotherapeutics Oridonin and Ponicidin show Additive Effects Combined with Irradiation in Pancreatic Cancer in Vitro

Background

Chemoradiation of locally advanced non-metastatic pancreatic cancer can lead to secondary operability by tumor mass reduction. Here, we analyzed radiomodulating effects of oridonin and ponicidin in pancreatic cancer in vitro. Both agents are ent-kaurane diterpenoids, extracted from Isodon rubescens, a plant that is well known in Traditional Chinese Medicine. Cytotoxic effects have recently been shown in different tumor entities for both agents.

Materials and methods

Pancreatic cancer cell lines AsPC-1, BxPC-3, Panc-1 and MIA PaCa-2 were pretreated with oridonin or ponicidin and irradiated with 2 Gy to 6 Gy. Long-term survival was determined by clonogenic assay. Cell cycle effects and intensity of γH2AX as indicator for DNA double-strand breaks were investigated by flow cytometry. Western blotting was used to study the DNA double-strand break repair proteins Ku70, Ku80 and XRCC4.

Results

Oridonin and ponicidin lead to a dose-dependent reduction of clonogenic survival and an increase in γH2AX. Combined with irradiation we observed additive effects and a prolonged G2/M-arrest. No relevant changes in the levels of the DNA double-strand break repair proteins were detected.

Conclusions

Pretreatment with oridonin or ponicidin followed by irradiation lead to an additional reduction in survival of pancreatic cancer cells in vitro, presumably explained by an induced prolonged G2/M-arrest. Both agents seem to induce DNA double-strand breaks but do not interact with the non-homologous end joining (NHEJ) pathway.

Covalent Modifiers: A Chemical Perspective on the Reactivity of α,β-Unsaturated Carbonyls with Thiols via Hetero-Michael Addition Reactions

Although Michael acceptors display a potent and broad spectrum of bioactivity, they have largely been ignored in drug discovery because of their presumed indiscriminate reactivity. As such, a dearth of information exists relevant to the thiol reactivity of natural products and their analogues possessing this moiety. In the midst of recently approved acrylamide-containing drugs, it is clear that a good understanding of the hetero-Michael addition reaction and the relative reactivities of biological thiols with Michael acceptors under physiological conditions is needed for the design and use of these compounds as biological tools and potential therapeutics. This Perspective provides information that will contribute to this understanding, such as kinetics of thiol addition reactions, bioactivities, as well as steric and electronic factors that influence the electrophilicity and reversibility of Michael acceptors. This Perspective is focused on α,β-unsaturated carbonyls given their preponderance in bioactive natural products.

Can the therapeutic gain of radiotherapy be increased by concurrent administration of Asian botanicals?

Therapeutic gain by radiotherapy can be achieved through improved targeting, selectively sensitizing malignant cells, or protecting normal tissue. The majority of synthetic chemical radiation sensitizers and normal tissue protectors have proved to be too toxic at effective clinical doses. However, Asian botanicals (from both Chinese and Ayurvedic medicine) are being evaluated for their ability to improve therapeutic gain through the modulation of reactive oxygen species. An increase in the efficacy of radiotherapy on tumor tissue allows a reduction in the dose applied to normal tissues. In addition, some botanicals may selectively protect normal tissue or increase its repair following radiation therapy. The results are promising enough to consider clinical trials.