An Overview of Antioxidant and Pharmacological Potential of Common Fruits

Current study was performed to evaluate the antioxidant and pharmacological potential of numerous common fruits. Prunus Domestica (Prunes) are excellent sources of dietary antioxidants and cause lowering of LDL cholesterol plasma level. Strawberries (Fragaria Ananassa) have ascorbic acid content (5-50 mg/100 g of fresh weight) and are effective in in oral cancer and cardiovascular diseases. Citrus fruits (Citrus limon) are rich in flavonoids (naringin and hesperidin), polyphenols and vitamin C; the extracts of citrus peels are effective against food borne bacteria. Lime oil from Citrus aurantifolia has been used as a component of skin care products and to impart tase and flavor in food industry. Grapes (Vitis Vinifera) are rich in phenolic compounds and are active against cancer, cholera, smallpox, nausea, eye infections and skin/kidney/liver diseases. Blackberry (Rubus ulmifolius) contains polyphenol ingredients and possesses neuroprotection potential against age-related diseases. Different parts of Jamun or Java Copyright © 2021 The Authors. Production and hosting by School of Science, University of Management and Technology is licensed under a Creative Commons Attribution 4.0 International License Plum (Syzygium Cumini) demonstrate excellent antioxidant and antimicrobial potential and used as a remedy for diabetes mellitus, leucorrhea, fever, constipation and gastropathy. Ziziphus mauritiana (Ber) consists of cyclopeptide alkaloid, lupine and ceanathone triterpenes; it displays sedatives, analgesic, antibacterial and excellent antioxidant potential. Vaccinium oxycoccus (cranberries) has 10mg/100g of ascorbic acid content; its extract can prevent urinary tract infections.


Introduction
Plants are well known for their nutritional and medicinal value [1][2][3]. Different parts of the plant (root, stem, leaves, flowers and fruits) are rich in antioxidants and antimicrobial contents [1,4].
Fruits have an immense significance in the lives of human beings. Besides their delicious taste, fruits contain a lot of natural organic products having an excellent nutritional value. Organic products are much necessary for the proper healthy growth of a body. They help body in preventing from dangerous diseases and act as a shield against cancerous and microbial diseases [5]. They have the ability to defend the body against malignant growth, other degenerative ailments [6] and oxidative harm. It is worth mentioning that oxidative species can cause huge harm in the body [7] and may lead to cardiovascular ailments, malignant growth, diabetes, Alzheimer's infection, waterfalls, chemical imbalance and maturing [8].

Antioxidants and Pharmacological Potential of Fruits
There is an important relationship of diet with aging and it has been largely investigated. Healthy foods, in addition to the provision of dietary antioxidants, are responsible to delaying the processes of aging. Healthy foods, including fruits, are important sources of natural bioactive compounds and dietary nutrients and possess antioxidant potential to prevent aging and other age-related disorders. Numerous health benefits are associated with intake of fruits, as reported in large number of earlier studies. They reduce the formation of free-radicals and thus suppress the oxidative stress created in the human body and also prevent aging. The fruits like cherries, grapes, berries, oranges, apples etc are important sources of natural antioxidants such as antiaging phytochemicals (e.g., quercetin, resveratrol used to postpone the aging process), minerals, vitamins, phenolic, anthocyanins [9]. Fruits also provide protection against numerous diseases including cardiovascular diseases, inflammatory disorders, type 2 diabetes and cancer. In addition to this, fruits also possess health-promoting effects and pharmacological potential including neuroprotective, anti-diabetic, anti-cancerous, anti-inflammatory [9]. Some important antioxidants of plants are discussed below:

Lycopene
Lycopene is a plant nutrient having excellent antioxidant potential. It is a pigment which gives pink and red coloured fruits such as pink grape fruit, water melons and tomatoes [10]. Lycopene is very much effective against the fat related problems; it also reduces the risk of skin malignant growth and prostate diseases in men. An abundant quantity of lycopene is present in tomatoes and its bioavailability is increased by heating the tomatoes in cooking oil [11].

Anthocyanins
Anthocyanins are natural pigments which belong to the group of flavonoids and are responsible for the taste and colour of many vegetables and fruits [12]. Anthocyanins possess an excellent antioxidant potential against the oxidants like reactive oxygen species. Researches have shown that anthocyanin is highly beneficial in protecting the pancreas from oxidation and hence, it prevents the body from diabetes [13]. However, anthocyanin shows inhibitory effects against some digestive enzymes such as α-amylase and maltase. Due to this inhibitory action, absorption of glucose in intestinal portion is decreased which in return decreases the postprandial blood glucose [14,15]. Anthocyanins are water-soluble pigments characterized by a shift in hue from red to purple or blue depending on the pH of the cellular fluids. Anthocyanins assist in enhancing the elasticity of vascular wall and improve blood circulation, promote cardiovascular health and improve night vision [11].

Flavanols
Many fruits like apple, Chinese bayberry and grapes are enriched with flavanol compounds.
Flavanols show many properties like antihyperglycemic, antioxidant and antimicrobial etc. They also show inhibitory action against α-glucosidase [14]. In addition to this, they also lower the blood glucose level which in fact reduces the rate of diabetes [16].

Flavanone
Flavanones occur in tangerines, oranges, tangors, tangelos and citrus fruits [17,18] and are the bioactive compounds which show good antioxidant and antimicrobial effects. It has been proved from many studies that flavanone shows good results against the diabetes due to its inhibitory effects on many enzymes [19].

Prunus Domestica (Prunes)
The scientific name of Prunes is Prunus Domestica (Figure 1). The active compounds in prunes decrease the LDL cholesterol plasma level in patients with hypercholesterolemia [20]. Prune and prune juices are excellent sources of dietary antioxidants [21]. It has been reported that prune fiber causes lowering of plasma and liver cholesterol level in hyperlipidemic rats [22]. The oxidation of low-density lipoproteins (LDL) is inhibited by pitted prune extracts [21]. Strawberries have a very high amount of ascorbic acid; they have four times more ascorbate content than blue berries. In strawberries, the ascorbate content ranges from 5-50 mg/100 g of fresh weight [23]. Improvement in oral cancer by using strawberries has also been noted [24].
The risk of cardiovascular diseases is lowered by the antioxidants present in strawberries [25].  Figure 3). These flavonoids have been extensively used for treatment of cardiovascular diseases. Hesperidin is contained in oranges, tangerines, lemons and limes etc. The extracts of citrus peels have been appeared to be highly effective against food borne bacteria [26]. The fiber of citrus fruit contains bioactive compounds, such as polyphenols, like vitamin C (or ascorbic acid) and cure vitamin C deficiency which causes scurvy [27].

Citrus aurantifolia (Lime)
Lime fruits (Citrus Aurantifolia, Figure 4) are widely cultivated throughout the world and are commonly known as meetha in Pakistan [28]. The plant contains numerous secondary metabolites, triterpenoids, phenolic acids, flavonoids, essential oils, coumarins, carotenoids and alkaloids which are medicinally important. Aromatic compounds (e.g., monoterpenes and their derivatives, alcohols, esters, ketones, aldehydes) such as citral (4.4%), γ-terpinene (8.5%), γterpinene (8.5%) and limonene (58.4%) are abundantly present in citrus oil. Oil is mainly extracted by hydrodistillation of fruit and peel. The presence of limonoids owes aroma and bitter taste to the citrus fruit peels. Lime oil (essential oil) has been used in traditional medicines and as a component of skin care products due to its potent antifungal and antibacterial properties. It also finds applications in food industry to impart citric flavour and odour to cuisines. Its oil and juice also display multiple biological effects including hepatoprotective, antityphoid, hypolipidemic, anti-inflammatory, antiulcer, antioxidant, antimicrobial and antimicrobial properties [29]. Some compounds derived from the lime were successful against Pseudomonas Aeruginosa and Aspergillus Niger. Highest action of the natural product oil was seen against the parasites Candida spp and Aspergillus Niger [30,31].

Vitis Vinifera (Grapes)
Vitis Vinifera (grapes, Figure 5) are rich in phenolic compounds and almost 75% of polyphenols exists in the skin and seeds [32]. Grapes are effective in numerous health problems including cancer, cholera, smallpox, nausea, eye infections and skin/kidney/liver diseases [33]. Grape seed extracts can be used as a dietary supplement in the form of capsules, tablets and liquid form.
Grapes have active ingredients which possess pharmacological activities such anti-inflammatory, anticancer, antifungal, anti-bacteria and antioxidant [34].

Rubus ulmifolius (Black berries)
Blackberry (Rubus ulmifolius, Figure 6) has been used from a long time in medicine [35]; its leaves demonstrate antimicrobial and anti-inflammatory potential [36]. Rubus ulmifolius contains polyphenol ingredients which show good antioxidant potential [37]. Blackberries contain compounds which possess neuroprotection potential against age-related diseases [38]. Digested metabolites from wild blackberries protect neuronal cells against oxidative damage and also possess anti-inflammatory properties [39].

Syzygium Cumini (Java plum)
Jamun or Java Plum (Syzygium Cumini, Figure 7) is a common fruit which is found everywhere in the world. It is small in size but enriched in natural antioxidant and antimicrobial compounds [40]. Jamun plant is known to possess diverse phytochemicals, most of which are observed to have health benefits. Jamun leaves have been reported to possess natural antimicrobial and antioxidant compounds, and they are known to contain several flavanols like β-sitosterol, quercetin, myricitrin, the flavanol glycosides, and acylated flavanol glycosides [41]. Different parts of jamun plant have been used in ayurvedic medicine as a remedy for diabetes mellitus [42]. The leaf extract is beneficial for strengthening the gums and teeth and also used to treat leucorrhea, fever and gastropathy [43]. It also finds applications to treat constipation due to the laxative effect and in treating the blood discharged in the feces [44].  [47]. Z. mauritiana indicates high antioxidant potential and also shows high H2O2 scavenging activity as it contains a high amount of total proteins, reducing sugars, flavonoids, ascorbic acid contents, β-carotene, polyphenols, tannins and DPPH free radicals [48,49]. It is reported that methanolic seed extracts of this plants are markedly valuable against the cancerous cell lines. Also ethanolic extracts of seed markedly inhibit the proliferation of HL60 cells [50].