Prof. R. Nagarajan, School of Chemistry and Prof. Prakash Babu Phanithi, School of Life Sciences have been granted an Indian patent titled “Thiazolyl-indole derivatives as fluorescence probes” on 4th January 2024. The work was carried out by PhD students Dr Ponnusamy Pon Sathiesh Kumar and Mr Rahul Shankar Rao Rayilla and Woman Scientist Dr Anwita Mudiraj under the supervision of Prof R. Nagarajan and Prof. P. Prakash Babu.

The salient features of this work include the total synthesis of thiazolyl-indole alkaloid, Barakacin from commercially available starting materials with 43% overall yield. Synthesis of barakacin and its analogues involves key Friedel-Crafts type bisindole formation of thiazole-2-carboxaldehyde with two equivalents of indole in presence of Lewis acid.

Its biological application as fluorescent probes have been studied. One of the derivative, 2-methylbarakacin possesses significant fluorescence and selectivity towards mitochondria. We have shown that it can effectively stain mitochondria in both live and fixed tissues. The staining protocol is quick and versatile and is compatible under in vitro and in vivo conditions.

Further it can also label macrophages, which enable in vivo imaging and tracking. We demonstrated fluorescence of 2-methylbarakacin can be monitored in real time pathological paradigm by using a sciatic nerve injury rat model. The observed in vivo fluorescence was good and retained well with time enabling the monitoring of macrophages produced in response to injury till 10th day. This patent explored thiazolyl indoles potential application as fluorescent bioimaging probes. Inflammatory processes that go on in any pathological conditions can be identified and monitored by bioimaging using this probe.