Title : Cocos nucifera inflorescence, a constituent of the Ayurvedic rasayana drug, reduces inflammation, nociception and acts as an effective hepatoprotective agent
Cocos nucifera L, Arecaceae is a monocotyledonous plant known as ‘Kalpavriksha’/ ‘Kalpatharu’/ ‘Kalpadruma’ in Sanskrit meaning wish fulfilling divine tree in Indian mythology. Every part of the tree is useful in one way or other and different parts of the tree are used as food, medicine and in construction of houses and furniture, preparation of edible oils, toddy, jaggery and arrack, thatching of roofs, preparation of active carbon, mats and a lot more products. In Ayurveda, the flowering inflorescence of C. nucifera is used for the preparation of ‘Thengin pookuladi avaleha’, a rasayana (rejuvenating) drug widely used for back ache and gynaecological disorders such as menopausal syndrome, menorrhagia, leucorrhoea, debility menstrual disorders etc.
In order to scientifically validate this traditionally used nutraceutical, we carried out a detailed investigation on the biological activities of the acetone extract of fresh C. nucifera inflorescence. C. nucifera acetone extract (CnAE is a powerful antioxidant and is rich in polyphenols (226.6mg gallic acid equivalent/g) and flavonoids (120.8mg quercetin equivalent/ g). Acute toxicity studies showed no mortality even after 14 days of administration of CnAE in mice at 5000 mg/kg b.w. Therefore, the LD50 value is <5000mg/kg b.w. The antioxidant activity was assessed using 3 methods namely DPPH radical scavenging assay, ABTS radical scavenging assay and ferric reducing antioxidant power assay and the IC50 values were found to be 65.72, 66.94 and 89.84mg/ml respectively. Effect of CnAE (100, 200 and 400mg/kg b.w) and Siliymarin (100 mg/kg b.w against acetaminophen induced liver toxicity was evaluated in wistar rats. The study showed that CnAE pre treated groups remarkably prevented the increase in serum alanine aminotransferase, aspartate aminotransferase, and alkanine phosphatase level and decrease in the level of liver superoxide dismutase, reduced glutathione, glutathione-S-transferase and glutathione peroxidase. The extract also suppressed the elevated level of malondialdehyde. The biochemical parameters supported the histopathological examination and blood parameter findings.
CnAE did not show any observable toxicity in RAW 264.7 macrophages by MTT assay. The calorimetric analysis (total COX, 5-LOX, MPO, iNOS and NO),ELISA (IL-1β, IL-6, TNF-α and PGE2) and qRT-PCR (IL-1β, IL-6, TNF-α and NF-κB) were performed in LPS-induced RAW264.7 macrophages. Phosphorylation of NF-κBp65 and IκB was determined by western blotting. CnAE (100 µg/mL) remarkably inhibited total COX (68.67%) and 5-LOX (63.67%) activities, and subsequent release of iNOS, NO and PGE2 (p≤0.05) in RAW264.7 cells treated with LPS. ELISA showed CnAE markedly decreased the level of pro-inflammatory cytokines IL-1β (p≤0.001), IL-6 (p≤0.001) and TNF-α (p≤0.001) in LPS treated RAW264.7 cells. CnAE (100 µg/mL) also significantly down-regulated the mRNA expressions of pro-inflammatory cytokines (IL-1β, p≤0.05; IL-6, p≤0.01 and TNF-α, p≤0.001) and NF-κB (p≤0.001) against LPS-induction. Moreover, LPS-induced phosphorylation of IκB-α and NF-κB p65 was significantly inhibited by CnAE (100 µg/mL). In vivo anti-inflammatory studies showed that CnAE (400 mg/kg) significantly inhibited carrageenan-induced acute paw oedema (59.81%, p≤0.001) and formalin-induced chronic paw oedema (52.90%, p≤0.001) in mice. CnAE at a dose of 400 mg/kg also showed a significant anti-nociceptive effect on acetic acid-induced writhing (48.21%, p≤0.001) and Eddy’s hot plate methods.
Thus, the present study validates the traditional use of Cocos nucifera inflorescence as a rejuvenating nutraceutical with multiple therapeutic properties.