Calanolides are tetracyclic 4-substituted dipyranocoumarins. Calanolide A, isolated from the leaves and twigs of Calophyllum lanigerum var. austrocoriaceum (Whitmore) P. F. Stevens, is the first member of this group of compounds with anti-HIV-1 activity mediated by reverse transcriptase inhibition. Calanolides are classified pharmacologically as non-nucleoside reverse transcriptase inhibitors (NNRTI). There are at least 15 naturally occurring calanolides distributed mainly within the genus Calophyllum, but some of them are also present in the genus Clausena. Besides significant anti-HIV properties, which have been exploited towards potential development of new NNRTIs for anti-HIV therapy, calanolides have also been found to possess anticancer, antimicrobial and antiparasitic potential. This review article provides a comprehensive update on all aspects of naturally occurring calanolides, including their chemistry, natural occurrence, biosynthesis, pharmacological and toxicological aspects including mechanism of action and structure activity relationships, pharmacokinetics, therapeutic potentials and available patents.

Centre for Natural Products Discovery School of Pharmacy and Biomolecular Sciences Liverpool John Moores University James Parsons Building Byrom Street Liverpool L3 3AF UK

Department of Botany Gurucharan College Silchar Assam 788004 India

Department of Life Science and Bioinformatics Assam University Silchar Assam 788011 India

Laboratory of Growth Regulators Institute of Experimental Botany ASCR and Palacký University Šlechtitelů 27 78371 Olomouc Czech Republic

School of Clinical Medicine University of Cambridge Cambridge CB2 OSP UK

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