Caryota urens L. (English name: Fishtail palm, Bengali name: Bonsupari) belongs to Arecaceae family. The plant is a native of India, Myanmar and Sri lanka (Uddin et al., 2015). Traditionally root is used to treat  tooth  ailments.

Flower is useful in gastric ulcer and migraine. Bark is used to treat rheumatic swellings and snake bite (Charles et al., 2011; Uddin et al., 2015). Recent scientific investigations report that C. urens sap is nutritionally rich and contains mixture of simple sugars such as sucrose, glucose and fructose (Somasiri et al., 2008). Flavonoids have been isolated from the methanol extract of the fruits (Srivastav et al., 2015). The plant has been reported to possess significant antioxidant, anti-diabetic and anti-microbial activities in the last few years (Charles and Ramani, 2011; Ranasinghe et al., 2012; Krishnamoorthy et al., 2013; Azam et al., 2016; Wimalasiri et al., 2016; Sujitha and Kripa, 2018).

In investigating  Bangladesh medicinal plants (Sharmin et al., 2017-2018), the crude methanol extract of C. urens fruits in Bangladesh including its organic and aqueous soluble fractions was for the first time evaluated for the antioxidant potential based on total phenolic content, phosphomolybdenum total antioxidant activity free radical scavenging activity, cytotoxic, thrombolytic, membrane stabilizing and antimicrobial properties.

Plant materials

Fruits of C. urens were obtained from Mirpur, Dhaka, Bangladesh. A voucher specimen (DACB-39528) is maintained in Bangladesh National Herbarium, Dhaka, Bangladesh for use in future.

The fruits (800 g) were dried under the sun and ground into powder. It was then macerated in 2.5 L of methanol for one week. It was filtered via fresh cotton bed and with Whatman filter paper number 1. It was concentrated with a rotary evaporator at low temperature and pressure. A modified version of Kupchan partition protocol (VanWagenen et al., 1993) was used to fractionate an aliquot (5 g) of the concentrated methanol extract; the  partitionates obtained from there were evaporated to dryness with rotary evaporator. This yielded hexane soluble fraction (HXSF, 1.8 g), carbon tetrachloride soluble fraction CTCSF, 2.0 g), chloroform soluble fraction (CSF, 0.2 g) and aqueous soluble fraction (AQSF, 0.5 g). The residues were kept in a refrigerator for use later.

Total phenolic content

Folin-Ciocalteau reagent was used to determine the total phenolic content by Harbertson and Spayd (2006)’s method developed.

DPPH free radical scavenging assay

Brand-Williams et al. (1995)’s developed method was used to assess  the capacity of the study samples to scavenge the stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical. The positive controls were Butylated hydroxytoluene (BHT) and ascorbic acid.

Phosphomolybdenum antioxidant assay

Phosphomolybdenum antioxidant assay method (Prieto et al., 1999) was used to evaluate the total antioxidant activity of the extract.

Brine shrimp lethality bioassay

This was done to determine the overall  harmful activities   of  the dimethyl sulfoxide (DMSO) solutions of plant samples against Artemia salina in one day in vivo assay (Meyer et al., 1982). The positive control was Vincristine sulphate . 

Thrombolytic activity

Prasad et al. (2006)’s method was used to evaluate the thrombolytic property. The   positive control was streptokinase.

Membrane stabilizing activity

Omale and Okafor (2008)’s method was used to assess the membrane stabilizing property of the samples by analyzing their capacity to prevent hypotonic solution and heat-induced haemolysis of human erythrocytes.

Antimicrobial screening

Disc diffusion method was used to determine antimicrobial property (Bayer et al., 1966).

Statistical analysis

Three replicates of each sample were used for statistical analysis for all bioassays; the values are given as mean ± standard deviation (SD). A two-tailed Student's t-test was used to evaluate the results.

This research was done to analyze C. urens fruit extract for antioxidant, cytotoxic, thrombolytic, membrane stabilizing and antimicrobial activities.

The crude methanol extract of C. urens fruits have a high content of phenolic principles (106.88±0.19 mg of GAE/g of sample). The extract’s total phenolic content and the free radical scavenging activity correlate positively (IC₅₀= 62.74±0.16 µg/m) (Table 1).

All the fractions had significant cytotoxic potential against A. salina in brine shrimp lethality bioassay. The crude methanol extract showed the highest cytotoxic activity with LC₅₀ value of 0.59±0.34 μg/mL in comparison to 0.451 μg/mL for Vincristine sulphate (Table 1).

C. urens extract had mild thrombolytic activity. The carbon tetrachloride soluble fraction was 20.48% of clot lysis in contrast to 66.77% clot lysis by streptokinase used as standard (Table 2).

The high phenolic content of C. urens extract might contribute to its antioxidant potentials. Lupeol and ursolic acid have been isolated from the leaf of this plant (Muhaisen, 2013). Both compounds possess antioxidant potentials (Santiago et al., 2014; Tchimene et al., 2016). The antioxidant potential of C. urens extract might be due to the presence of these two compounds. Lupeol has been also found to be a potent cytotoxic component (Moriarity et al., 1998). Therefore, this compound might be responsible for the observed cytotoxic activity. 

C. urens extract showed membrane stabilizing property. Leakage of serum proteins and fluid into the tissue causes inflammation. Membrane stabilizing property can prevent induction of inflammation (Chaitanya et al., 2011). Ursolic acid possesses anti-inflammatory property (Checker et al., 2012; Wang et al., 2018). The presence of this compound in C. urens might contribute to the observed membrane stabilizing activity.

People have the common belief that nature is good. This belief has contributed to the increased popularity of traditional medicines. But consuming plant-based medicines might cause unwanted side effects because such medicines contain a large number of compounds with different activities. This study has revealed that C. urens fruit extract possesses significant antioxidant and membrane stabilizing potentials. Therefore, it is important to identify the compounds responsible for the observed activities from the fruit extract. Thus, the plant is a good candidate for further systematic, chemical and biological studies to isolate the active principles.

The authors have not declared any conflict of interests.