Phytochemicals, labeled as primary or secondary meta-bolites, primarily focus on their function in the plants metabolism. Studies have discovered a broad array of functional capability on human physiology of secondary phytochemicals such as alkaloids, terpenes, flavonoids, curcumins, saponins, phenolics, flavo-noids, and glucosides (Makkar et al., 2007). A wide range of secondary metabolites is found in the plant family Oleaceae having high level of pharmacological values (Huang et al., 2019). But, little is known regarding the chemistry and pharmacology of N. arbortristis Linn., (Night jasmine) of this family. 

It is a shrub of 10m long with flowers of high frag-nance which bloom at night and fall off before sunrise. N. arbortristis is indigenous to India, widely distri-buted in South East Asia, and also cultivated in tropical and subtropical regions globally (Rani et al., 2012). Earlier studies on this plant revealed that several iridoid glycosides (Sing et al., 1995; Tunti-wachwuttikul et al., 2003, Khanapur et al., 2014), three carotenoid glucosides (Mathuram and Kundu, 1991), phenyl-propanoid glycoside (Tuntiwachwut-tikul et al., 2003), desrhamnosylverbascoside (Mathu-ram et al., 1997), rengyolone (Tuntiwachwuttikul et al., 2003), 6ß hydroxylloganin, nyctanthoside (Jensen and Nielsen, 1982) were isola-ted from the plant. N. arbortristisis a mythological plant and has high therapeutic values used in Homeopathic, Sidha, Unani, and Ayurveda (Rani et al., 2012). The commonly used case highlights its anti-helminthic and antipyretic effects (Khanapur et al., 2014). Furthermore, the isolated pure compounds possess significant bioacti-vity like anti-inflammatory, antiallergic, immune-modulatory, anticancer, antiviral, and antileishmania (Agrawal and Pal, 2013; Shukla et al., 2011). Therefore, the present investigation has an aim to determine the diversity and bioactivity of several plant parts using the solvents of different polarity. 

Collection and drying of the plant - The leaves and bark of N. arbortristis were collected from several household gardens in Noakhali, Bangladesh, and identified by botanists. The leaves and bark are dried in room temperature and humidity. It is then heated at 60°C in an oven for 10 hours for the final drying before the grinding. 

Extraction of phytochemicals - Each powdered portion was soaked into ethyl acetate and methanol for 1st 7 days and 2nd 7 days. After every seven days, the filtrates were subjected to cold extraction procedures using a rotary evaporator. The final concentrated four extracts preserved in fridge labeling NALE, N. arbortistis leaf in ethyl acetate; NALM, N. arbortistis leaf in methanol; NABE, N. arbortistis bark in ethyl acetate; NABM, N. arbortistis bark in methanol. 

Phytochemical screening

Detection of alkaloids - The extracts were dissolved individually in dilute Hydrochloric acid. Then alkaloid detection was carried out treating the sample with Mayers reagent (Potassium Mercuric Iodide), Wag-ners reagent (Iodine in Potassium Iodide), and Drag-endorffs reagent (solution of Potassium Bismuth Iodide). The formation of turbidity or precipitation scored positive for alkaloids (Kaur and Arora, 2009). 

Tests for glycosides - Keller-Killiani test: Dissolved plant extracts (100 mg) in absolute methanol (2 ml) were treated with glacial acetic acid (2 ml). Then, 5% of ferric chloride solution (1ml) and concentrated sulfuric acid (1ml) were added. The appearance of a reddish-brown ring indicated the presence of cardiac glycoside (Harborne, 2005). 

Borntrager test - Filtrate of 100mg plant extracts in chloroform (5 ml) was shaken with an equal volume of 10% NH4OH. The appearance of pink-violet or red color in the bottom layer is positive for anthraquinones (Raaman, 2006). 

Test for steroids

Salkowskis Test - Filtrates of extracts with chlo-roform were treated concentrated sulfuric acid. The appearance of reddish-brown color at the interface after shaking indicates steroids presence (Joshi et al., 2013). 

Liebermann Burchards test - Extracts in chloroform were treated with acidic anhydride, boiled, cooled and followed by concentrated sulfuric acid addition. Formation of greenish transient color scores positive for steroids (Raaman, 2006). 

Test for Saponins - 20 ml diluted extracts were shaken in a graduated cylinder for 15 minutes. A one-centimeter layer of foam indicated the presence of saponins (Raaman, 2006). 

Thin Layer Chromatography (TLC) 

Detection of major phytochemicals was also carried out by pre-coated (Kiesel gel 60 PF254) TLC plate (Wagner et al., 2004). Mix solvents (Toluene: Ethyl acetate = 90%: 10%) is used to plate development and observed under visible light as well as UV light (254 nm and 365 nm). The number and diversity of colors with different Rf differentiate the types of compounds present in the extracts. 

Free Radical Scavenging Activity (DPPH Method) - The hydrogen-donating abilities of extracts were examined through the method described by Khanapur et al., 2014, with a little bit modification. Briefly, 1.6 mg of different extracts was dissolved in methanol to get a mother solution. Serial dilution of each 2 ml mother and addition with 2 ml 2, 2-diphenyl-1-picrylhydrazyl in methanol (20 µg/ml) got a total of 4 ml mixture of different sample concentration from 200.0 to 0.78125 µg/ml. Methanol (95%) and ascorbic acid (same concentrations as a sample) were used as blank and reference. The UV absorbance was taken at 517 nm after 30 minutes incubation at a dark place. 50% of DPPH free radical scavenging concentration. (IC50) has been measured using the regression equation attain from the values of at least five consequent dilutions. 

Antimicrobial Test - The antibacterial potential of the four extracts of N. arbortristis was determined by the disc diffusion method described by Santoyo et al., 2005 against two gram-positive bacteria (Staphylo-coccus aureus, Enterococcus sp.), three gram-negative bacteria (Escherichia coli, Salmonella typhi, Pseudo-monas sp.), and one fungus (S. cerevisiae). Each disc of plant extracts contained 40µg and the zone of inhibition compared to ciprofloxacin (20µg/disc) and ketoconazole (20 µg/disc). 

In the study, ethyl acetate (medium polar) and methanol (polar) were used to extract both polar and slightly polar compounds of N. arbortristis leaf and bark. A total of four samples were designated as NALE, NALM, NABE, and NABM. The samples showed distinguishable features in phytochemical screening and antioxidant activity, which indicates the impact of the solvents polarity and the unequal distribution of phytoconstituents in leaf and bark. 

Qualitative Phytochemical screening

Table 1: Level of phytoconstituents presence in samples 

The present study on ethyl acetate and methanolic extracts of N. arbortristis explored a profile of several phytoconstituents and an excellent antioxidant activity. Phytochemical screening marked the high presence of alkaloids and glycosides. Though no antimicrobial activity is observed, the amazing radical scavenging capability of the plant pointed out its potential to use against aging, cancer, cardiac disease. Therefore, the plant is a good source of bioactive compounds and might be a potential drug discovery source.

I am grateful to Almighty God to give me the ability to complete this study. I give thanks to my respected Head of the Department for his inspiration and support to the successful research study.

The author (s) declared no potential conflicts of the interest with respect to the research, authorship and/or publication of this article.