Preparation And Biological Activity Of Phorbol Derivatives

Phorbol Esters are the main active ingredients contained in the Croton of the Euphorbiaceae family,and are often present as phorbol diesters in nature.Phorbol esters have a variety of biological activities,including anti-tumor,anti-HIV,anti-tuberculosis,etc.Among them,12-O-tetradecanoylphorbol-13-acetate（TPA）has entered phase II clinical research in leukemia,And 12-deoxy-phorbol-13-acetate（prostratin）,has also entered the phase I clinical trial of HIV.However,the natural product separation has many disadvantages,such as complicated work,difficult separation,and little amount,which makes it difficult to study systematically and structure activity relationships（SAR）of phorbol esters.The full synthesis or semi-synthesis of natural products provides feasibility to solve the above disadvantages.Phorbol esters are abundantly present in Croton seed oil.Hydrolysis of Croton oil gives the phorbol,the parent nucleus of phorbol esters.At present,the research on the structure modification of phorbol is relatively mature,including the selective protection of hydroxyl,esterification and deprotection.However,the previous studies focused on the length of the saturated fatty acid and the ester-forming position.Especially in recent years,little research has been conducted and no phorbol derivatives with better activity and lower toxicity have been found.In order to systematically study phorbol derivatives,a series of phorbol derivatives were designed and synthesized.The theory of privileged substructure and pharmacophore merging play an important role in drug design and structure modification of natural products.In this study,cinnamic acid and its derivatives were chosen to be the privileged substructural motifs,and were merged with phorbol.In addition,the phorbol derivatives were synthesized based on the structural features of the parent nucleus.The design ideas are summarized in the following three points:1 Select cinnamic acid derivatives as the privileged substructural motifs and synthesize a series of phorbol-cinnamate derivatives;2 Different from the saturated side chains of phorbol esters of natural products,a series of unsaturated fatty acids were esterified with phorbol,and a number of phorbol-unsaturated derivatives were obtained.3Combined with the characteristics of phorbols,a series of phorbol monoesters,diesters and triesters were designed and synthesized.According to the design concept,44 phorbol derivatives were obtained.44 compounds were tested for antitumor activity and 27 compounds were screened for Anti-HIV activity.The cytotoxicity to human cells（MRC-5）of the 17 compounds with anti-HIV activity was also tested.Results:14 compounds showed antitumor activity(GI₅₀0.08→40μM).The compound phorbol-13-eicosanoate（P31）had the strongest inhibitory activity against A549 and MDA-MB-231 cells,and the GI₅₀was respectively 0.08μM and0.21μM.The compound phorbol-12,13-dicinnamate（P5）had the best inhibitory activity against KB,KB-VIN cells,and the GI₅₀was 6.45 and 6.82μM,respectively.The compound 12-O-tetradecanoylphorbol-20-acetate（P35）had the best inhibitory activity against MCF-7 cells with a GI₅₀value of 5.27μM.In terms of anti-HIV assay,20 compounds showed potent anti-HIV activity(IC₅₀0.49→5461 nM).Among them,the compound phorbol-12,13-diphenylpropionate（P16）had the best activity(IC₅₀0.49nM).There were 5 compounds with high cytotoxicity(IC₅₀<10μM)and 7 compounds with low cytotoxicity(IC₅₀>100μM)in the cytotoxicity asssy.Compound P7 can continue to be researched and developed as a lead compound in antitumor activity;Compound P31 has research and development value both in anti-HIV and anti-tumor activities.