Antioxidant and anti-inflammatory activity of Ocimum labiatum extract and isolated labdane diterpenoid

Abstract

BackgroundPlants from the genus Ocimum are used as folk medicine for treating various diseases including inflammatory and immune-related diseases. Numerous reports have suggested plant extracts and their constituents as possible anti-inflammatory agents. Here, in vitro evidence of Ocimum labiatum’s immune-enhancing and antioxidant properties is presented for the first time.MethodsThe anti-inflammatory effect of O. labiatum ethanolic extract and an isolated diterpenoid was determined using a cytometric bead array (CBA) technique. The effect on phytohemagglutinin (PHA)-induced nitric oxide (NO) production in peripheral blood mononuclear cells (PBMCs) was also assessed. A battery of antioxidant assays were used for detecting antioxidant activity while the anti-inflammatory mechanism was evaluated using an ELISA-based activator protein (AP-1) (c-Jun) assay. Cytotoxicity was determined on TZM-bl and PBMCs using a tetrazolium dye and confirmed by a novel label-free real-time assay.ResultsA 25 μg/mL non-cytotoxic concentration of O. labiatum extract significantly (p < 0.05) inhibited the production of pro-inflammatory cytokines; IL-2, IL-4, IL-6 and IL-17A. Except for the dual acting pro- or anti-inflammatory cytokine, IL-6, which was upregulated, a non-cytotoxic 50 μM concentration of the isolated labdane diterpenoid compound significantly (p < 0.05) decreased the production of all the pro-inflammatory cytokines. In the anti-inflammatory pathway studies, the compound also inhibited AP-1 significantly (p < 0.05) at 50 μM. The extract demonstrated strong, dose dependent antioxidant activity with IC50 values ranging from 13 ± 0.8 to 54.86 ± 1.28 μg/mL while the terpene had no antioxidant property. The extract and diterpenoid decreased the production of the inflammatory mediator NO, at non-cytotoxic concentrations. The CC50 of the extract in TZM-bl and PBMCs was 62.6 ± 0.6 and 30.1 ± 0.4 μg/mL while that of the compound was 112.6 ± 0.2 and 70 ± 0.4 μM respectively. The real time studies confirmed tetrazolium dye assessed viability and also detected a unique growth pattern for the plant materials compared to untreated cells.ConclusionsO. labiatum extract demonstrated promising anti-inflammatory and antioxidant properties while the terpenoid showed anti-inflammatory but no antioxidant activity. The anti-inflammatory mechanism of the terpene was a result of inhibition of AP-1. These data represents promising first steps towards the development of naturally derived anti-inflammation drugs.

Antioxidant and anti-inflammatory activity of fruit, leaf and branch extracts of Paliurus spina-christi P. Mill

“…In particular, ethanol and ethyl acetate extracts obtained from branches and leaves of the plant have been found to have significant antioxidant activity and high amount of phenolic contents. Phenolic compounds present in plants are known to be powerful antioxidants [19]. Also, in the phytochemical studies on different parts of the plant, it have been reported that this species contained phenolic compounds such as flavonoids and tannins intensively.…”

Terpenoids as Source of Anti-Inflammatory Compounds

“…Anti-inflammatory effect of Ocimum labiatum ethanolic extract and an isolated diterpenoid was determined using a cytometric bead array technique. 25 μg/mL noncytotoxic concentration of O. labiatum extract significantly (p<0.05) inhibited the production of pro-inflammatory cytokines; IL-2, IL-4, IL-6, and IL-17A [14]. Free steroids, saponin contents of crude extract from leaves of Scutellaria agrestis showed significant analgesic effect and the anti-inflammatory doses of 30, 100, and 300 mg/kg of the formalin test [15].…”

“…Ethanol extract from Vernonia polyanthes leaves at doses of 200 and 400 mg/kg, administered 4 h before the carrageenan injection, significantly reduced the exudate volume (29.25% and 45.74%, respectively) and leukocyte migration (18.19% and 27.95%, respectively) [21]. Lindenanesesquiterpenoid (14) dimer, shizukaols B and D were isolated from the whole plant of Chloranthus serratus. The compound showed significant anti-inflammatory activities with IC50 values of 0.22, 0.15, and 7.22 μM, respectively [22].…”

Assessment of the in vitro anti-lipid peroxidative activity of Costus afer stem extract

“…Terpenoids are important phytochemicals that have significant antioxidant and anti-inflammatory potentials [26,27]. Alkaloids have also been demonstrated to scavenge diphenyl-2-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radicals, reduce cupric ions attributed to the ability of the pyrrole nitrogen to form an iminoquinone structure by donating either a hydrogen or electrons to the free radicals [28].…”