Antibacterial And Antitumor Activity Of Synthesizedβ-Pinene Derivatives

As an important renewable natural resource in China, turpentine has the abundantavailability, a unique structure, and widely bioactivity. β-pinene, one important component ofturpentine, is valuable in some fields due to its high chemical reactivity.In this thesis,45derivatives of amide, ester, oxime ester, and acylthiourea fromdihydrocumic acid as well as amide and ester from pinene-maleic acid were synthesizedthrough oxidation, isomerization, Diels-Alder reaction, esterification, and so on. Structures ofthese compounds were characterized by FTIR, NMR, MS, and Elemental Analysis. Theantibacterial activity and antitumor activity of these compounds were studied. According to thedata obtained from antibacterial test, the mechanism and the structure-activity relationship ofantibacterial activity were preliminarily discussed. The research provided new approaches ofthe deep processing and the utilization of turpentine.Nopinic acid was synthesized using β-pinene as raw material, potassium permanganateof alkaline as oxidant, and water/tert-butanol (v/v=1:2) as reaction medium, through which thecrystal structure of nopinic acid was firstly obtained. Dihydrocumic acid was synthesizedthrough reaction of dehydration, rearrangement, and ring-opening in the presence of sulfuricacid.38compounds of amides, esters, acylthioureas, and oxime ester were synthesized throughacylation, esterification, vulcanization, and so on. The crystal structure of4-isopropyl-N-phenylcyclohexa-1,3-dienecarboxamide was obtained. Through Diels-Alder reaction of β-pinene and maleic anhydride, two carboxyl groups was introducted into pinene, then amide andester from pinene-maleic acid were synthesized.The antibacterial activity of the derivatives was estimated by the2-fold agar dilutionmethod. Gram-negative bacteria (Escherichia coli, Klebsiella pneumonia, Pseudomonasaeruginosa, Escherichia aerogenes) and Gram-positive bacteria (Staphyloccocus epidermidis,Staphyloccocus aureu) were selected as test species. The results showed that most derivatives from dihydrocumic acid displayed antibacterial activity. Oxime esters from dihydrocumic aciddisplayed excellent antibacterial activity against all test species. MIC of compounds5a,5c,5d,5e, and5g against Escherichia aerogenes were lower than16μg/mL (lower than threereferences: Bromogeramine, Ampicillin Sodium, and Erythromycin). Except compound5g,MIC of oxime esters against Pseudomonas aeruginosa were lower than2μg/mL. MIC ofcompounds5e and5d against Staphyloccocus aureu were8μg/mL (equivalent toBromogeramine). MIC of compounds5c,5d, and5e against Staphyloccocus epidermidis werelower than8μg/mL (equivalent to Bromogeramine and Ampicillin Sodium). Oxime estersderivatives of dehydrocumic acid have potential value for further research to explore excellentantibacterial agent. Esters from dihydrocumic acid showed good antibacterial activity againstStaphyloccocus epidermidis and Staphyloccocus aureu. Except compounds3f,3k,3m, and3n,MIC against Staphyloccocus aureu were lower than16μg/mL. Acylthiourea fromdihydrocumic acid showed good antibacterial activity against Escherichia coli.Four kinds of cancer cell (human non-small cell lung cells, human breast cancer cells,human hepatoma cells, and human colon cancer cells) were selected as test cancer cells. Theantitumor activity in vitro of the derivatives of amide, acylthiourea, ester, and oxime ester fromdihydrocumic acid were estimated by the MTT method. The results showed that a part ofderivatives from dihydrocumic acid displayed some antitumor activity in vitro against cancercells. Among them, acylthiourea from dihydrocumic acid showed some antitumor activity invitro against human breast cancer cell MCF-7and human hepatoma cancer cell HCT116. TheIC50of compound4d against human breast cancer cell MCF-7was26.58μg/mL, and the IC50of compound4c against human hepatoma cancer cell HCT116was56.67μg/mL, which werelower than100μg/mL.The structure of derivatives and antibacterial activity were analyzed, and the resultshowed that dehydrocumic acid was the key group for antibacterial activity. The effection ofdifferent substituent in derivatives of dehydrocumic acid was studied. The structure-activityrelationship of derivatives was investigated preliminarily. In most cases, for the same kind of derivatives, compounds with lower molecular weight and less brabched substituents showedbetter antibacterial activity. The structures of PABA, dehydrocumic acid, and sulfa antibacteiralagent were compared. There were some structural similarity between these three compounds.After penetration into cell membrane, it is possible that derivatives of dihydrocumic acid couldtake the place of PABA, and play antagonistic effects on the metabolism of bacterium.