Maslinic Acid, a Triterpene from Olive, Affects the Antioxidant and Mitochondrial Status of B16F10 Melanoma Cells Grown under Stressful Conditions

Abstract

Maslinic acid (MA) is a natural compound whose structure corresponds to a pentacyclic triterpene. It is abundant in the cuticular lipid layer of olives. MA has many biological and therapeutic properties related to health, including antitumor, anti-inflammatory, antimicrobial, antiparasitic, antihypertensive, and antioxidant activities. However, no studies have been performed to understand the molecular mechanism induced by this compound in melanoma cancer. The objective of this study was to examine the effect of MA in melanoma (B16F10) cells grown in the presence or absence of fetal bovine serum (FBS). We performed cell proliferation measurements, and the reactive oxygen species (ROS) measurements using dihydrorhodamine 123 (DHR 123) and activities of catalase, glucose 6-phosphate dehydrogenase, glutathione S-transferase, and superoxide dismutase. These changes were corroborated by expression assays. FBS absence reduced cell viability decreasing IC50 values of MA. The DHR 123 data showed an increase in the ROS level in the absence of FBS. Furthermore, MA had an antioxidant effect at lower assayed levels measured as DHR and antioxidant defense. However, at higher dosages MA induced cellular damage by apoptosis as seen in the results obtained.

Figure 1

The chemical structure of maslinic acid (MA).

Figure 2

The effect of MA on B16F10 murine melanoma cell viability in the presence of FBS (a) and in the absence of FBS (b). MA cytotoxic doses are shown in (c). Cell proliferation was determined by MTT assay. Values are expressed as means ± SD.

Figure 3

Positive fluorescent Rh123 on B16F10 cells with or without FBS (a) and after MA treatment at different dosages without FBS (b).

Figure 4

CAT (a), G6PDH (b), GST (c), and SOD (d) specific activities on B16F10 cells. On the left side, cells cultivated with and without FBS, and on the right side, cell cultivated without FBS and different MA dosages. Values are expressed as means ± SD. Different letters indicate significant differences (P < 0.05).

Figure 5

Western blots of CAT (a), G6PDH (b), GST (c), and SOD (d) on B16F10 cells cultivated without FBS at different MA dosages. The levels of specific protein expression are shown as arbitrary intensity units of each band compared to arbitrary intensity units of actin. Values are expressed as means ± SD. Different letters indicate significant differences (P < 0.05).