Main constituents and cytotoxic activity of the essential oil of Piper artanthe

Abstract

The identification of novel antitumor agents that demonstrate efficacy is necessary to improve medical treatment based on new drugs. The pharmaceutical industries have been working together in this area for several years to try to find novel compounds with good antitumor activity. Brine shrimp (Artemia salina) larvae have been reported as an organism that can detect bioactive compounds. Since there is a good correlation between the toxicity on Artemia salina and antitumor [1, 2], phototoxicity [3], and anti-Trypanosoma cruzi [4] activity, this test is a good prescreening method for identifying new potential antitumor agents. Piper artanthe C.DC. (Piperaceae) is commonly known as the “cordoncillo.” It is a shrub or small tree growing to 1 to 2 m, and it is widespread in America [5] and used in folk medicine for the treatment of different disease symptoms. Despite phytochemical studies on the Piper species describing the isolation of several bioactive compounds [6], to our knowledge P. artanthe has not been investigated for its biological activity, and no data can be found concerning the chemical composition of this species. The main purpose of this study was not only to evaluate the biological activities using the Artemia salina toxicity model as a prescreening procedure but also to evaluate the composition and structural characterization of the main components of the essential oil from the aerial parts of P. artanthe C.DC. As shown in Table 1, 41 compounds consisting of more than 87% of the total hydrodistilled essential oil were identified. The chromatographic data on both columns, HP-5MS and DB-1, indicate that the major components were apiol (14.52%), -elemene (11.69%), (E)-caryophyllene (10.24%), epi-cubebol (8.85%), myristicin (6.38%), and cubebol (6.30%). Over 44% of these compounds were sesquiterpenes, and 45% of them were oxygenated sesquiterpenes. The evaluation of biological activity using the brine shrimp lethality test showed that the essential oil of the fresh aerial parts of P. artanthe displayed an LC 50 value of 107.1 g/mL ( n-1 : 8.9 g/mL). According to [7], crude extracts resulting in LC 50 values of less than 250 g/mL are considered significantly active. For that reason, this oil can be regarded as a promising candidate for further investigation. Accordingly, our following objective was to isolate and identify the major components of this essential oil in order to evaluate their individual biological activities. Though all constituents could not be isolated, the main component was made pure by means of column chromatography on silica gel as a yellowish oil (980 mg). This compound displayed an LC 50 value of 13.1 g/mL ( n-1 : 0.4 g/mL). Plant polyalkoxybenzenes display a broad spectrum of biological activities. For example, apiol has previously been reported to be a specific inhibitor of the biosynthesis of aflatoxin G1, a calcium antagonist, and a diuretic, abortive, sedative, antioxidant, and insecticidal agent 8–11.