New Diterpenes from Arenga pinnata (Wurmb.) Merr. Fruits

Ethno-pharmacological and industrial attributes on the underutilized Arenga species in India

The genus Arenga belongs to the Arecaceae family, which has a significant economic value. Several species of this genus have a decent potential of becoming an industrial crop. In India, four species of the genus, namely Arenga pinnata, A. obtusifolia, A. micranta, and A. wightii have been reported. These species have not been cultivated on a commercial scale in most of the growing regions. People use this plant directly from the forest or those produced in their backyard, even though productivity is minimal. To date, several studies from throughout the world have reported numerous beneficial roles of such species. Proper use of such plants or their products has immense significance in the food, fiber, and pharmaceutical industry. These plants are also recognized as ecologically significant plants. In this article, we have presented an up-to-date review on the species of Arenga reported from India along with their potential utility as industrial crops. This review is motivated by the desire to produce many eco-friendly resources from A. pinnata and other species of Arenga, which can contribute to an increase in the standard of living and economy of many nations, including India. PRACTICAL APPLICATIONS: Arenga has a lot of potential as medicinal as well as industrial raw materials. Despite this, these plants are somehow underutilized and have not gained much attention in international trade. In this communication, we have presented some aspects of these plants by reviewing many research articles and conference proceedings. The utilization of these plants as traditional medicine serves an important part in basic health care for many people in developing nations. Gradual study and clinical trial of different formulations of these plants can explore novel drugs for some critical disorders. We also highlighted the industrial uses of these species. Biofuel and fiber obtained from A. pinnata have been appreciated by the researchers. This article points out some attributes of these plants that required further improvement. Botanists and phytochemists will appreciate the description of the medicinal properties of these plants and the biological data provided in the article.

Anti-nociceptive and anti-inflammatory effects of the ethanol extract of Arenga pinnata (Wurmb) Merr. fruit

ETHNOPHARMACOLOGICAL RELEVANCE

Arenga pinnata (Wurmb) Merr. is a medicinal and edible plant belonging to family Palmae. The fruits of this plant were used in traditional folk medicine due to its analgesia and anti-inflammatory activities. This study aimed to investigate the analgesic and anti-inflammatory properties and the mechanism of the ethanol extract of A. pinnata (Wurmb) Merr. fruit (EAF) on different experimental models.

MATERIALS AND METHODS

High-performance liquid chromatography (HPLC) was used to determine the chromatographic profile and to analyze the composition of EAF. In the acute toxicity test, all mice were orally administered EAF at a maximum dosage of 26 g/kg and were then monitored for 14 days. The potential analgesic activity of EAF was evaluated by using animal pain models, namely the acetic acid-induced writhing test and the hot plate test in mice. The underlying mechanisms of analgesia were determined by pretreating with naloxone, capsaicin and cinnamaldehyde to evaluate the involvement of the opioid system and transient receptor potential channels (TRP channels). The anti-inflammatory activity of EAF was evaluated by using the following inflammatory animal models: xylene-induced ear edema in mice and Complete Freund's adjuvant (CFA)-induced paw swelling in rats. EAF was orally administered at the doses of 1.625, 3.25 and 6.5 g/kg in mice and 1.125, 2.25 and 4.5 g/kg in rats. The underlying mechanism of the anti-inflammatory activity was determined by enzyme-linked immunosorbent assay (ELISA) kits and real time-PCR used to measure the expression levels of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), prostaglandin E2 (PGE₂) and cyclooxygenase-2 (COX-2). Western blot analysis was used to determine the expression levels of proteins related to the nuclear factor-κB (NF-κB) and mitogen-activated protein kinases (MAPK) signaling pathways in paw tissues.

RESULTS

Five compounds, namely (5-(hydroxymethyl) furan-2-yl) methanediol,4'-hydroxy-N-(4-hydroxy-3-methoxybenzoyl)-3',5'-dimethoxybenzamide, (+)-lyonirenisol-3a-O-β-D-glucopyranoside, (-)-lyonirenisol-3a-O-β-glucopyranoside and liquiritin, were firstly identified from A. pinnata (Wurmb) Merr. fruit by HPLC-UV analysis. In the acute toxicity test, no treatment-related toxicological signs or mortality was observed in mice administered doses up to 26 g/kg. Bodyweight was not obviously different among the treatment groups and the vehicle group. EAF significantly inhibited the pain response induced by acetic acid and increased the latency time in the hot plate test in mice. The anti-nociception effect of EAF in the formalin test was not alleviated by pretreatment with naloxone. However, the nociception induced by injection with capsaicin and cinnamaldehyde was significantly reduced by EAF. Compared with vehicle treatment, EAF significantly inhibited the formation of xylene-induced ear edema and CFA adjuvant-induced paw swelling. EAF markedly inhibited the production of IL-1β, TNF-α, PGE₂ and IL-6 induced by CFA in paw tissues. Furthermore, the phosphorylation of IKKα, IKKβ, IκBα, p38, ERK1/2, and JNK and the nuclear translation of NF-κB p65 induced by CFA in paw tissues were significantly inhibited by EAF treatment compared with vehicle treatment.

CONCLUSION

For the first time, this study provides pharmacological evidence for the analgesic and anti-inflammatory activities of EAF and the underlying mechanism, suggesting that EAF might be a potential candidate for reducing pain and inflammatory disorders.