Indonesia has a lot of biodiversity and plants that can be used as a source of traditional medicine. Plants used as a source of medicine have existed since ancient times, both hereditary and scientifically proven. Plants have been an integral part of pharmacotherapy throughout history. Medicinal plants have an essential role in the discovery of bioactive molecules1. One of the plants that have the potential to be developed as a medicinal plant is Epiphyllum oxypetalum (DC.) Haw. or Wijaya Kusuma (family: Cactaceae).

Epiphyllum oxypetalum is an ornamental with much history and is widely used to decorate homes. The plant has the potential to be employed as a medicine. Epiphyllum oxypetalum is a plant native to Southern Mexico, but it can also be found in North America and Southeast Asia. The plant is also known as night-blooming cereus because of its likeness to a lotus flower. In Indonesia, E. oxypetalum has a story that is particularly popular in Central Java. It is said, if someone sees the flowers blooming, then his wishes will come true and achieve success. Another popular myth in the culture is that the E. oxypetalum flower does not always bloom, depending on the planter. Many people plant this flower, hoping that it will bring them luck2.

Epiphyllum oxypetalum may reach a height of 2-6 m, are ancient with a green hue, and have dark green leaves. The trunks and shoots of these plants can reach a diameter of 2 cm or more, are woody, and have many branches. The leaves on these plants are low sideways and lancet-shaped. Glossy green leaves on the upper surface and underside of sharp-pointed leaves, thinning, wavy, and serrated leaves, the top of narrow leaves in a linear fashion with the interest of 1.6 to 1.8 mm, nocturnal (bloom at night) funnel-shaped, and scented3. The growth of flowers is heavily influenced by light and wind4. Epiphyllum oxypetalum is growing in an area with no light, and only a tiny breeze does not blossom until it is fully mature. The temperature has a significant impact on the growth of plant germination5.

Many E. oxypetalum research articles have been published, but there is no review of this plant's pharmacognosy, phytochemical, and pharmacological aspects. In an era with more scientific publications than ever, article reviews are an essential type of scientific writing. Article reviews were intended to highlight key aspects of contemporary research and compare them to prior studies on related subjects6. Based on this, we highlight the potential of this plant from pharmacognosy, phytochemical, and pharmacological aspects through a narrative review. This review is aimed to provide researchers with a summary of information on E. oxypetalum's potential as a medicinal plant.

Table I shows the classification of E. oxypetalum. Species information is essential for the identification stage of medicinal plants. This is useful to prevent errors in collecting and using plant samples7.

TableI. Classification of E. oxypetalum2

The identification of a plant is critical for the advancement of traditional medicine. Observations at the microscopic and macroscopic levels help to achieve this objective8. Devi et al.3 reported that the transverse section of E. oxypetalum leaf from Bangalore district, Karnataka, India showed the presence of upper epidermis, paracytic stoma, cystolith crystal, mesophyll with midrib vascular tissue, mesophyll with the upper epidermis, needle-shaped crystals, starch grains, xylem vessels, phloem, sclerenchyma of bundle sheath, and pith tissue, xylem vessels, phloem layer, sclerenchyma patches of bundle sheath. Meanwhile, the powder leaves of E. oxypetalum microscopically show the presence of star-shaped calcium oxalate crystals, tetracytic stoma, anisocytic stoma, starch grains, and xylem vessel with spiral wall thickening.

The epidermis is the cell layer that protects the surface of leaves, flowers, fruits, seeds, stems, and roots. The epidermis protects tissues from external effects and is a regulator of gas exchange in the leaves. Stomata and trichomes are formed from the epidermis9. Anisocytic stomata are observed in E. oxypetalum leaves. Anisocytic stomata have three adjacent cells of different sizes around each guard cell10. Stomata are involved in gas exchange by controlling water loss during transpiration and absorbing CO2 during photosynthesis. Because of the importance of stomata in the photosynthesis process, it will impact the generation of metabolites in plants11. Mesophyll tissue contains chloroplasts in cells12.

Non-specific characteristics like a loss of drying and ash content impact the quality of plant material. Loss in drying and total ash value of E. oxypetalum dried leaves was 2 ± 0.10% and 4.6 ± 0.4%3. Ingale and Mansoori13 reported that the loss on drying in the stem extract was 22.6158 g/100 g, and the leaves extract was 10.4658 g/100 g. Meanwhile, the ash content of the stem extract was 2.0625 g/100 g, and the leaves extract was 2.6024 g/100 g.

The loss on drying aims to provide a maximum range linked to the number of compounds lost during the drying process, whereas the ash content intends to offer an overview of the internal and external mineral content from the starting process to the generation of the extract14. The location where the plant samples were gathered, and the extraction solvent might impact the concentration of chemicals in the plant. Environmental elements such as nutrition supplies, pH, growth location, humidity, and light are the key factors that influence the concentration of chemicals in a plant15. Epiphyllum oxypetalum was sampled from several sites across India for this study. As a result, environmental factors significantly impact the concentration of chemicals in plants, resulting in a wide range of results in each research. Microbial contamination is caused by excess moisture, whereas microbial decomposition is suppressed by low water content3.

Epiphyllum oxypetalum leaf powder has a carbohydrate content of 0.0237 ± 0.001 mg/0.5 mL3, protein content was 14 mg/g, lipids content was 4.6 mg/g, and niacin content was 0.18 mg/g16. While, the levels of phenolics, flavonoids, tannins are 19.09 ± 0.08 g/0.6 mL, 8.728 ± 0.02 g/mL, and 31.32 ± 0.08%, respectively3. The leaves and flowers of E. oxypetalum have been extensively studied in the research, as well as the development of pharmaceuticals. Several studies on the chemical composition of this plant have been published. Table II summarizes the chemical composition of E. oxypetalum.

Plant chemicals are selectively soluble in suitable solvents. The extraction method used and the sample at various sites in each study can impact compound results. Maceration and soxhlet are two typical procedures researchers use to extract chemical components of E. oxypetalum. Maceration does not go through a heating process, so it is unlikely that the compounds contained are damaged17. The long maceration process allows the compound to be extracted completely. Soxhlet extraction is a highly effective hot extraction process. However, it should be noted that hot extraction can damage the samples' compounds for thermolabile compounds18.

The choice of solvents considerably impacts the extraction efficiency of any traditional technique. The polarity of the substance to be studied is the most significant consideration when selecting a solvent. In choosing a solvent for bioactive component extraction, consider molecular affinity between the solvent and the solute, mass transfer, the use of a co-solvent, environmental safety, human toxicity, and financial feasibility19.

Based on Table II, flowers and leaves of E. oxypetalum are reported to have metabolites that play a role in pharmacological activity. Alkaloids play a role in activities such as anticancer, antimalarial, and antihyperglycemic. Saponins play a role in antibacterial and antioxidant activities. Tannins play a role in antibacterial activity. Flavonoids have antioxidant properties20. Most of these compounds can be dissolved in either methanol, ethanol, or water19.

TableII. Chemical composition of E. oxypetalum

Several chemical constituents of E. oxypetalum were identified using the gas chromatography-mass spectroscopy (GC-MS) method20,22,23. The summary can be seen in Table III. Hexadecanoic acid was detected in leaves and flowers. This compound is reported to have potential as an antioxidant, flavor, pesticide, hemolytic, and other. Ethanol extract of E. oxypetalum leaves also contains flavonoids ([7- hydroxy-3(1,1-dimethyl prop-2enyl) coumarin) and fatty acids (oleic acid, nonadecanoic acid, and hexadecanoic acid)20.

TableIII. Chemical constituents identified in E. oxypetalum

Several structures of essential compounds in E. oxypetalum are presented in Figure 1. A molecular docking study reported that megastigmatrienone and testosterone cypionate found in E. oxypetalum leaves have the potential to be developed as an antiviral22.

The summary of pharmacological activity from E. oxypetalum is shown in Table IV. Because animal tests are expensive, time-demanding, and susceptible to ethical controversy, in vitro procedures are frequently preferred over in vivo assays25. According to Table IV, most E. oxypetalum research has been done in vitro. The leaves are more studied than the flowers. Flowers may be more challenging to obtain because not all plants planted can produce flowers.

Figure1. Several chemical structures identified in E. oxypetalum20,22,23

Alcohols, both ethanol and methanol, as polar solvents, are more often used in the test. This solvent can extract metabolites with a wider polarity, such as polyphenols, flavonoids, tannins, alkaloids, glycosides, terpenoids, and steroids26. The extraction methods that are widely used are maceration and soxhlet extraction. Both of these methods are commonly used in the extraction of medicinal plants27. However, currently, the use of non-conventional extraction techniques (such as ultrasonic-assisted extraction or microwave-assisted extraction) is auspicious to be applied in the development of this plant to produce effective, efficient extracts and environmentally friendly28,29. The plant metabolites play a role in the pharmacological effects of plants. Each pharmacological activity of the plant will be discussed at separate points.

Antioxidant

Antioxidants are chemical substances that, when consumed sufficiently, can prevent damage produced by the oxidation process30. In other words, the body needs a substance such as an antioxidant that helps protect against free radical attack31. The method that has been used to test antioxidant activity is the DPPH method and hydrogen peroxide scavengers which were tested on samples of methanol extract, ethanol extract, water extract, and petroleum ether fraction. DPPH•, on the other hand, is not a natural radical, but its reaction mechanism with antioxidants is close to that of peroxyl radicals ROO•32. When the DPPH solution is mixed with a substrate that can donate a hydrogen atom, it gives rise to a reduced form with a loss of purple color33. In this test, ascorbic acid, Trolox, gallic acid, butylated hydroxytoluene (BHT), and butylated hydroxyanisole (BHA) are often used as references34.

The secondary metabolites, such as flavonoids and saponins, contribute to this activity. Saponins can reduce superoxide by forming hydroperoxide intermediates to prevent damage by free radicals. The antioxidant mechanism of steroids is by scavenging reactive species, such as superoxide and chelating metals (Fe2+ and Cu2+)35. While flavonoids are polyphenols that can donate hydrogen atoms to free radicals, the antioxidant activity of polyphenolic compounds can be generated from a neutralization reaction or at the termination of a chain reaction36.

TableIV. Pharmacological activities of E. oxypetalum

Antihyperuricemia

Determination of uric acid levels was determined by the enzymatic method using uric acid reagent FS-TBHBA (2,4,6-tribromo-3-hydroxybenzoic acid). The mechanism in this method is that the enzyme uricase oxidizes uric acid with the help of H2O and O2 into allantoin, CO2, and H2O2. The H2O2 formed will react with 4-amino antipyrine and FS-TBHBA to form pink quinonimine; the peroxidase enzyme catalyzes the reaction43. Compounds that play a role in lowering uric acid levels are flavonoids. The flavonoid group of compounds inhibits the activity of xanthine oxidase and superoxidase, thereby reducing the formation of uric acid44.

Anti-inflammatory

Epiphyllum oxypetalum has pharmacological activity as an anti-inflammatory. In a study by Dwita et al.42, E. oxypetalum leaf extract contains secondary metabolites such as alkaloids, flavonoids, tannins, saponins, and steroids. Several studies have demonstrated the mechanism of flavonoids in wound healing by modulating the expression of cytokines and nitric oxide in the inflammatory phase.

Antidiabetic

The antidiabetic activity of methanol extract of E. oxypetalum leaf showed inhibition of α-amylase. α-amylase is helpful as a hypoglycemic agent to control hyperglycemia, especially in patients with type 2 diabetes mellitus. This enzyme delays carbohydrates and prolongs carbohydrate digestion time, causing a reduction in the rate of glucose absorption and consequently reducing the postprandial rise in plasma glucose45. Secondary metabolite compounds such as phenolics, flavonoids, alkaloids, and steroids have antidiabetic activity46.

Antibacterial

The chemical content of the E. oxypetalum leaf extract has the potential as an antibacterial, both against gram-negative and gram-positive bacteria, compared to antifungals16. When paired with antibiotics, nanoparticle technology using silver (silver nanoparticles, AgNPs) synthesized from an aqueous extract of E. oxypetalum is more effective. This formulation is both environmentally friendly and cost-effective and may be precious in biomedical applications40.

AgNPs can be used effectively against many drug-resistant bacteria because their large surface area and small size make them easy to interact with substances and enhance their antibacterial efficacy. AgNPs can be a new generation of antimicrobial with broad-spectrum activity. Biological methods for the synthesis of nanoparticles have several advantages over chemical and physical methods because these methods do not involve chemical toxins, and sometimes reactions take place at very high temperatures. Using plants to synthesize nanoparticles can be an advantage over microorganisms because it eliminates the culture maintenance process40.

The phenolic compounds contained in E. oxypetalum are one of the compounds suspected of having antibacterial activity16. Alkaloids are thought to have the ability as an antibacterial that can interfere with the peptidoglycan components of bacterial cells so that the cell wall layer is not formed completely. Terpenoids are other plant metabolites with antimicrobial, antifungal, antibacterial, and antiviral properties. The flavonoids act as an antibacterial agent by building complex molecules with proteins that damage the bacterial cell membrane's integrity. These substances can degrade cell walls and interfere with cell permeability. In addition to flavonoids, a type of polyphenolic compounds that have antibacterial action, particularly tannins47.

Toxicity study

Safety is a major consideration in the development of medicinal plants. Eleven compounds found in methanol extract of E. oxypetalum leaves, through GC-MS analysis, were evaluated for their toxicity using QSAR – Toxicity Estimation Software Tool (TEST). Some of them were predicted to possess high to extreme toxicity against Daphnia magna, Tetrahymena pyriformis, and Pimephales promelas, such as oleic acid, eicosyl ester; hexadecanoic acid, 1-(hydroxymethyl)-1,2- ethanediyl ester; 17-pentatriacontene; cyclopropanebutanoic acid,2-[(2-[(2-[(2-pentylcyclopropyl)methyl]cyclopropyl)methyl]cyclopropyl)methyl]-,methyl ester; 17-(1,5-dimethylhexyl)-10,13-dimethyl-3-styrylhexadeca hydrocyclopenta(a)phenanthren-2-one; and ergosteryl acetate23.

Among the chemicals found in E. oxypetalum, 0-octadecenoic acid, methyl ester and ethanol, 2-(9-octadecenyloxy)-, (Z) were harmless to development. Meanwhile, 1,2-benzenedicarboxylic acid, butyl octyl ester; 1,2-benzenedicarboxylic acid, mono(2-ethylhexyl) ester; cyclopropanebutanoic acid,2-[(2-[(2-[(2-pentylcyclopropyl)methyl]cyclopropyl)methyl]cyclopropyl)methyl]-,methyl ester; 17-(1,5-dimethylhexyl)-10,13-dimethyl-3-styrylhexadecahydrocyclopenta(a)phenanthren2-one; ergosteryl acetate; glycine,N-[(3a,5a,7a,12a)-24-oxo-3,7,12- tris[(trimethylsilyl)oxy]cholan-24-yl]-,methyl ester; and (5a)pregnane-3,20a-diol,14a,18a-[4-methyl-3-oxo-(1-oxa-4-azabutane-1,4-diyl)]-,diacetate were poisonous. In oral rats, however, all compounds were predicted to have a low toxicity to nontoxic. Through in silico research, the usage of animals for toxicity estimates can be reduced23. This study was suspected that E. oxypetalum leaves are safe for humans and could be used to produce new medications in the future. Of course, before that, scientific evidence of in vivo toxicity from extracts and individual compounds of E. oxypetalum leaves in animal models is required.

Based on the information provided, the E. oxypetalum plant in the future has the potential to be developed into a source of medicinal ingredients. So, it can be used as a raw material for natural medicine to treat various diseases. The flower and leaves of this plant contain chemical compounds in the form of primary and secondary metabolites. Steroid chemicals dominate the chemical substances detected in this plant, such as testosterone cypionate, stigmasterol, and others. No active chemical compounds against specific pharmacological actions have been isolated on this plant. These isolates will determine quality standards from the extracts or fractions production. In the future, it will also be essential to investigate the plant's roots to complete the information about the plant. The pharmacological activity of E. oxypetalum has the potential as an anti-inflammatory, a source of antioxidants, and antimicrobials. The chemical compounds discovered in these plants, particularly steroids, need to be researched further to see whether they may be used for additional therapeutic purposes, such as hormone treatment for fertility, contraception, or even aphrodisiacs.

Epiphyllum oxypetalum contains chemical compounds such as carbohydrates, proteins, amino acids, alkaloids, saponins, terpenoids, steroids, flavonoids, tannins, glycosides, and resins. This plant has pharmacological activity such as anti-inflammatory, antimicrobial, antidiabetic, and a source of antioxidants. Epiphyllum oxypetalum is a plant that is safe because it is not toxic. Epiphyllum oxypetalum has the potential to be investigated and developed further so that the plant's benefits can be shared with the rest of the community.

The author thanks Dr. apt. Rini Prastiwi, M.Si. and Ema Dewanti, M.Si., who have provided input and suggestions so that the authors can complete this review article.

Chandra Adam Lesmana: conceptualization, investigation, data curation, resources, visualization, writing - original draft, and writing - review & editing. Ni Putu Ermi Hikmawanti: conceptualization, methodology, project administration, supervision, validation, visualization, writing - original draft, and writing - review & editing. Agustin Yumita: conceptualization, supervision, validation, writing - original draft.

None.

The authors have declared no conflict of interest.

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