Medicinal plants are the richest resource of natural compounds having a wide range of applications for the well-being of human population. In the modern age, the dependence of humans on plants for the majority of commercial products including pharmaceutical, healthcare, food, beverages, textiles, cosmetics, and aromas is being obtained from plants. Therefore, plants are and will remain economically, industrially, environmentally, spiritually, historically, and aesthetically important for survival, sustenance, and prosperity of life on Earth [1,2,3,4].
Moringa oleifera (MO) is the most commonly grown species that belongs to the monogeneric family: Moringaceae that is native to the Himalayan and sub-Himalayan areas cultivated throughout Pakistan, India, Afghanistan, Bangladesh, and other tropical and sub-tropical countries of the world [5, 6]. The MO has been utilized for flowers, fruit, and leaves as a vegetable particularly in India and Pakistan and many other parts of Asia and Africa [7,8,9]. In tropical areas of developing countries, MO is consumed by livestock as a forage, moringa micronutrient liquid, natural anthelmintic, and adjuvant against endemic diseases [5]. In many countries, roots, leaves, flowers, and seeds of MO are used in folk medicine for ailments and treatment of arthritis, asthma, blood pressure, body pain, cough, diabetes, diarrhea, dropsy, epilepsy, fever, headaches, hysteria, irritations, paralytic, skin infection, sores, tumors, weakness, wound, and employed as emmenagogues, expectorants, and mild diuretics, etc. [10,11,12]. They are of pungent taste and promote digestion [13]. The MO is a well-known miracle tree enriched with important minerals (calcium, potassium, zinc, magnesium, iron, and copper), vitamins (vitamin A, B, C, D, and E), carbohydrate, crude protein, ash, sugar, fat, glutelin, albumin, and globulins which can be used by doctors, nutritionists, and community health cautious persons to cure illness [5, 14,15,16].
The MO possess several phytochemicals such as ascorbates, beta-sitosterol, carotenoids, flavonoids, kaempferol, moringine, omega fatty acids, phenolic, quercetin, tocopherols, and vanillin, that have various biological activities including antiatherosclerotic, anticancer, antidiabetic, anti-inflammatory, antimicrobial, antioxidant, antiulcer, antiviral, and immune-boosting [8, 17,18,19,20,21,22,23]. Among these phytochemicals, phenolic acids are the most abundant secondary metabolites of plants and are involved in many biological activities. They are of benzoic acid and cinnamic acid derivatives including caffeic, chlorogenic, coumaric, ferulic, gallic, and quinic acids, tannins, and many others having more than 8000 phenolic structure found in various fruits and vegetables [24, 25]. Prabakaran et al. [26] reported the presence of total phenolic and total flavonoids contents in leaves as compared to roots, barks, and flower extracts of MO.
Cancer is the largest group of diseases causing death of 9.6 million people worldwide [27]. The most common type of cancer in females are breast, cervical, colorectal, lung, and thyroid cancers. Among them, cervical cancer is the fourth most leading cause of death in women and causing 270,000 deaths annually [28]. It is well known that 74% of anticancer medicines are being derived from various plant species [29]. The MO leaves extracts showed remarkable effects against various cancerous cells [30]. Balamurugan et al. [31] reported the anticancer effect of MO leaf extracts against hepatic cancer cell line (HepG2). The phytochemicals showed a dynamic role in treatment and prevention of cancer by hindering cancer cells through activating hormones and enzymes, stimulation of DNA repair mechanism, enhancing the production of protective enzymes that induce antioxidant action and enhance immunity [32,33,34]. Because of these facts, the current study was conducted to evaluate the composition of phenolic compounds and anticancer activities of different solvent fractions of MO leaves extracts. To achieve the purpose of the current study, solvent fractions of MO leaves extracts were prepared using n-hexane, ethyl acetate, butanol, and water to their polarities. For phenolic compounds, various solvent-fractions (SF) were analyzed using reversed-phase high-performance liquid chromatography. The SF extracts were analyzed on Hela cancer cell lines for their antiproliferative activity.