Synthesis and preliminary bioevaluation of 99mTc(CO)3-17α-triazolylandrost-4-ene-3-one derivative prepared via click chemistry route.

Azolyl steroids are known to manifest antiprostate cancer and antiandrogenic activities. These azolyl steroids have been shown to express affinity toward androgen receptors (ARs) overexpressed on LNCaP (human prostate adenocarcinoma) cell line. Hence, suitably derivatized azolyl steroids can be envisaged as potential vectors for targeting overexpression of ARs in prostate cancer. In the present study, testosterone has been derivatized to 17α-azidoandrost-4-ene-3-one using microwave-mediated azidation of the mesylate. Subsequently, a facile one-pot Cu(I)-catalyzed Click reaction was carried out to synthesize (99m)Tc(CO)(3)-labeled 17α-triazolylandrost-4-ene-3-one, which was characterized by HPLC. The chemical characterization of (99m)Tc(CO)(3)-17α-triazolylandrost-4-ene-3-one was carried out by preparing its corresponding rhenium complex using [NEt(4)](2)[Re(CO)(3)Br(3)] precursor. The radiolabeled complex could be prepared in >95% radiochemical yield as determined by HPLC. In vitro studies of (99m)Tc(CO)(3)-17α-triazolylandrost-4-ene-3-one complex in LNCaP cell lines overexpressing ARs showed binding of 4.95%±1.2%, with inhibition of 8%±0.9%. In vivo biodistribution studies in male Wistar rats have shown uptake in the prostate to the extent of 0.48%±0.19% injected dose/g at 1 hpi and retention therein till 3 hpi. The present study demonstrates a novel and facile one-pot reaction for preparation of (99m)Tc-labeled 17α-triazolylandrost-4-ene-3-one complex using Click chemistry. The corresponding Re-analog has been prepared for purpose of comparative characterization with the (99m)Tc-labeled complex. The radiosynthetic strategy described in this article can be further extended toward preparation of radiolabeled complexes of other triazolyl steroidal derivatives.

Stereoselective synthesis of an iodinated resveratrol analog: preliminary bioevaluation studies of the radioiodinated species.

Stereoselective synthesis of an E-hydroxystilbene has been carried out using the McMurry reaction. Synthesis of a monoiodinated hydroxystilbene has been carried out by a McMurry cross-coupling reaction. For the purpose of biological evaluation, the facile electrophilic substitution route has been attempted to radioiodinate it with (125)I. The HPLC pattern of the radioiodinated hydroxystilbene, which could be obtained in >90% radiochemical purity, was found to be identical to that of its non-radioactive analog that has been independently prepared using the McMurry cross-coupling route. In vitro cell uptake studies were carried out in breast cancer cells MCF7, overexpressing estrogen receptors. In vivo biodistribution studies in female Swiss mice show a uterine uptake of 0.85±0.4% ID/g at 3h.p.i. with a uterus to muscle ratio of 2.83. Uptake in the thyroid was insignificant indicating good in vivo stability of the radioiodinated hydroxystilbene.

Preparation and preliminary bioevaluation of 99mTc(CO)3-11ß-progesterone derivative prepared via click chemistry route.

INTRODUCTION: Progesterone receptors (PRs) overexpressed in breast cancers serve as potential targets for developing radiotracers for use in nuclear medicine. Hence, suitably derivatized progesterone can be envisaged as a potential vector for targeting overexpression of receptors in breast cancer. In the present article, we report the preparation of a (99m)Tc(CO)(3)-progesterone triazole using the Cu(I)-catalyzed novel click chemistry route. Preliminary evaluation of the radiolabeled derivative has been carried out in binding studies with MCF 7 cell lines. METHODS: 11-Hydroxyprogesterone has been synthetically derivatized to 11-azidoprogesterone. Subsequently, the cycloaddition reaction between progesterone azide and propargyl glycine was carried out to prepare 1,4-bifunctionalized progesterone triazole analogue. The clicked progesterone triazole derivative was radiolabeled with (99m)Tc and characterized by HPLC. The chemical characterization of (99m)Tc(CO)(3)-progesterone triazole has been carried out by preparing its corresponding rhenium complex using the [NEt(4)](2)[Re(CO)(3)Br(3)] precursor. While in vitro studies were carried out in MCF7 cell lines, in vivo distribution studies were performed in female Swiss mice. RESULTS: The radiolabeled complex could be prepared in >95% radiochemical yield as determined by HPLC. In vitro studies of (99m)Tc(CO)(3)-progesterone complex in MCF7 cell lines overexpressing receptors for breast cancer showed binding up to 30%. In vivo distribution studies in female Swiss mice have shown uterine uptake of 0.41 (0.06) % ID/g at 3 h postinjection (pi) and retention therein till 24 h pi. CONCLUSION: The present study demonstrates a novel and facile route for preparation of (99m)Tc-labeled progesterone complex using click chemistry. This strategy can be further extended towards preparation of radiolabeled complexes of other steroidal derivatives.

Calpain and caspase orchestrated death signal to accomplish apoptosis induced by resveratrol and its novel analog hydroxystilbene-1 [correction of hydroxstilbene-1] in cancer cells.

Stomach ulceration is a major side effect of most chemopreventive drugs. We have established that although resveratrol is a promising chemopreventive compound, it delays the ulcer healing process. However, its analog hydroxystilbene-1 (HST-1) was devoid of such an ulcerogenic side effect. Consequently, here we tried to explore the chemopreventive efficacy of HST-1 compared with resveratrol in different cancer cell lines and identified the probable signaling pathways responsible for cell death. Our cell viability study established that HST-1, compared with resveratrol, showed better chemopreventive potential in all of the cell lines tested, with U937 and MCF-7 being the cells most affected. Furthermore, in U937 and MCF-7 cell lines, terminal deoxynucleotidyl transferase dUTP nick end labeling assay, cell cycle analysis, and nuclear fragmentation by confocal microscopy established that both HST-1 and resveratrol switched on the apoptotic death cascade to execute cell death. The initiator signal was Fas-independent but synchronized in terms of cytosolic Ca(2+) influx, dissipation of mitochondrial membrane potential, and oxidative burst. It is noteworthy that the executioner signal was cell-specific as in U937 cells; HST-1 and resveratrol treatment induced mitochondrial permealization followed by cardiolipin depletion and cytochrome c release, which eventually activated downstream caspases 9 and 3 to execute the death process. In contrast, in MCF-7 cells the death process was executed in a caspase-independent but calpain-dependent manner as calpain activation induced cleavage of cytosolic alpha-fodrin, stimulated mitochondrial release of apoptotic inducing factor and endonuclease G, and thus harmonized cytosolic and mitochondrial death signals to accomplish apoptosis.

Improved antiulcer and anticancer properties of a trans-resveratrol analog in mice.

Despite its potential, use of trans-resveratrol as an anticancer drug is severely constrained because of its tendency to prolong gastric ulceration. We found that in addition to delaying ulcer healing, trans-resveratrol also aggravated acute gastric ulceration induced by the nonsteroidal anti-inflammatory drugs by reducing the synthesis of prostaglandin (PG) E(2) via a specific inhibition of cyclooxygenase (COX)-1 that also hampered angiogenesis. However, for the first time, we showed that the 3'-5'-hydroxylated congener [(E)-HST-1] of trans-resveratrol, synthesized in multigram scale, exerted potential chemotherapeutic property but was nonulcerogenic in nature, rather moderately accelerated healing of indomethacin-induced gastric ulceration. HST-1 did not suppress COX-1, COX-2 expression, and PGE(2) synthesis but reduced the level of inflammatory myeloperoxidase (MPO) activity. The healing was augmented primarily through the nitric oxide synthase (NOS)-dependent pathway. HST-1 treatment induced endothelial NOS (eNOS) expression and reduced inducible NOS (iNOS), resulting in increased eNOS/iNOS ratio. The selective iNOS inhibitor [L-N(6)-(1-iminoethyl) lysine hydrochloride] and nonselective NOS inhibitor (N(omega)-nitro-L-arginine methyl ester) treatment revealed that eNOS could be the probable molecular switch to accelerate the indomethacin-induced ulcer healing in HST-1-treated mice. Furthermore, the anticancer effect of HST-1 on U937 and K562 leukemia cell lines was found to be significantly better than that of trans-resveratrol. Overall, these established HST-1 as a potentially better anticancer compound than trans-resveratrol, considering it is devoid of any ulcerogenic side effects. In conclusion, for the first time, we showed that a novel analog of trans-resveratrol, HST-1, was devoid of ulcerogenic adversative effects of trans-resveratrol but retained potentially better anticancer property.