Physicochemistry, Nutritional, and Therapeutic Potential of Ficus carica – A Promising Nutraceutical

Introduction

Since time immemorial, humans have centred their lives on plants in an effort to preserve good health and alleviate ailments and diseases.¹ Currently, synthetic antioxidants are being widely used in food and medication where it can both induce or promote detrimental health effects.² Therefore, the use of synthetic antioxidants, especially its concentration, is regulated rigorously during manufacturing processes to ensure the stability and safety of the substances within the allowable limit.³ For this reason, research on potential natural additives and antioxidants are paramount nowadays. Various fruits and their derivatives are well known for having a high concentration of naturally occurring polyphenolic chemicals.⁴ Polyphenols are plant secondary metabolites with antioxidant properties that serve as free radical inhibitors and play essential roles in reducing oxidative stress⁴ towards maintaining human health.⁵ In line with this, Ficus carica L. is a promising lead since it naturally contains polyphenols and other beneficial bioactive compounds.

The fig tree (F. carica L) is among the most ancient fruit-bearing trees and valued not only as a source of food, but also for its medicinal properties.⁶ Ficus is one of the largest angiosperm genera, with over 800 species of trees, shrubs, hemiepiphytes, climbers, and creepers found throughout the tropics and subtropics.⁷ F. carica, or commonly known as fig, is a deciduous tree in the Moraceae family and is one of the oldest cultivated trees in the world, with both fresh and dry consumption.^8–10 According to a recent market report by Future Market Insights (FMI), the Middle East and Africa regions are the largest markets for fresh F. carica, and hold 71.2% of the market share for the year 2022.¹¹ FMI also reported an increase in the demand for fresh as well as processed F. carica products in developed countries owing to the viability of the fresh plant. F. carica is valued for its fresh dried fruits because of its abundant source of vitamins, carbohydrates, minerals, sugars, phenolic compounds, organic acids, and fat cholesterol.^2,12,13

What is most interesting about the F. carica plant is that most of its parts, such as fruits, leaves, shoots, roots, latex, and bark as shown in Figure 1, have been widely researched to hold their own values and are used to treat various human diseases.^13,14 F. carica latex (F. latex) exhibits antioxidants, milk-clotting,² anti-cancer,^15,16 anti-fungal, chitinolytic, cytotoxic, antiviral, antibacterial, and anthelmintic activities.^2,17 Li et al reported that F. carica leaves are commonly used in tea as well as traditional medicine.¹⁸ F. carica leaves were found to yield beneficial effects in gastrointestinal diseases, respiratory diseases, cardiovascular diseases, diabetes, skin diseases, ulcers, dysentery, hemorrhoids, cough, lung diseases, and dissolution of blood congealed by bruises or falls.¹⁸ The same study also reported that F. carica leaves contain a total of 126 chemical constituents and exhibit antioxidant, anti-cancer, antidiabetic, hepatoprotective, anticholinesterase, anti-Herpes simplex virus type 1 (anti-HSV-1), antibacterial, anti-inflammatory, and renoprotective properties.¹⁸ Nevertheless, further research and identification of the constituent functional chemicals are highly essential.

Figure 1 Different part of F. carica. (a) unripe fruit; (b) ripe fruit; (c) opened ripe fruit; (d) upper side of the leave; (e) down side of the leave; (f) branches; (g) young shoots; (h) latex.

This present review describes F. carica as a potential nutraceutical plant that exhibits various pharmacological benefits, and addresses future research directions on the exploration of this medicinal plant.

Materials and Methods

Pertinent articles were gathered from databases including PubMed, ScienceDirect, Scopus, and Google Scholar. Articles related to F. carica studies that have been published since 1932 were archived using specific keywords; “Ficus carica” OR “Ficus carica L”. AND “Moraceae” OR “Chemistry” OR “In vitro” OR “In vivo” OR “Biological properties” OR “Extracts” OR “Toxicity studies” OR “Phytochemistry” OR “Pharmacodynamics” OR “Pharmacokinetics” OR “Pharmaceuticals” OR “Therapeutics” OR “Nutritional Value”.

Studies that were not written in English or had no abstracts were excluded from the initial screening. Articles chosen for this review were filtered after the inclusion and exclusion criteria were met (Figure 2). The review revolved around key findings of F. carica studies including its physicochemistry, extraction methods, nutritional values, cosmetic usage, and toxicity profile (Figure 3), and further elaboration on its pharmacological properties (Figure 4) were deeply explored. A total of 126 studies or articles were included in this present review paper.

Figure 2 Flow chart of the identification and screening of the studies included in this review.

Figure 3 Key properties and findings on F. carica included in this review.

Figure 4 Potential therapeutic and pharmacological properties of F. carica.

Figure 5 Classification of known phytochemicals of F. carica.

Extraction of F. carica

In an extraction method described by Mahmoudi et al for phytochemical analysis, 10g of F. carica fruit was permeated in 100mL of pure methanol at room temperature for 24h.¹² The mixture of F. carica and methanol was filtered and the solvent evaporated using a rotary evaporator at 40^°C to obtain the final product.¹² Following the method by Takahashi et al, F. carica leaves were freeze-dried and grounded into fine powder, then added with methanol.¹⁹ The mixture was shaken in a rotary shaker at 120rpm for 3h, followed by centrifugation for 10mins at 1700g, and repeatedly until the collected supernatant reached 50mL.¹⁹ The extract was finally filtered using a 0.45μm syringe filter.¹⁹ Meanwhile, Saoudi et al extracted F. carica stems by grounding them, then soaked in water, and shaken for 15–20mins (10 g/L, v/w), before filtration using Whatman filter paper.²⁰

In a study using F. carica seeds, they were grounded into powder form and mixed with petroleum ether for 6h.²¹ The product was then subjected to a rotary evaporator to remove the solvent, flushed with nitrogen, and finally stored at −18^°C.²¹ Harzallah et al used F. carica peel and pulp juice extract to assess their phytochemical content.²² The peel and pulp blend was centrifuged at 3000rpm for 10mins, the supernatant filtered and stored at −20^°C for methanolic extraction process the following day.²² In another study, dried F. carica extract was prepared by dissolving 50g of macerated pulp in 200mL mixture of distilled water, 80% methanol, 70% ethanol, and 50% acetone.²³ The mixture was then agitated at room temperature in the dark for 24h, then concentrated using a rotary evaporator at 40^°C.²³ These extraction methods were performed for various purposes such as to determine and calculate the amount or concentration of flavonoids, to identify its active compounds, or to assess its biological properties for potential therapeutic approaches.

Phytochemistry of F. carica

Phytochemicals are defined as bioactive nutrient plant chemicals that may provide desirable health benefits beyond basic nutrition.²⁴ It can be classified as primary or secondary constituents depending on their roles in plant metabolism. Secondary metabolites can be further classified based on their chemical structures and functional groups, including polyphenols, terpenoids, alkaloids, phytosterols, and organosulfur compounds as shown in Figure 5.²⁵

In contrast to primary metabolites, secondary metabolites have drawn increased attention owing to their remarkable therapeutic properties, such as antioxidant,²⁶ antimicrobial,^27–29 anti-cancer,^30,31 and hepatoprotective properties.^32,33 Recently, secondary metabolites have been widely used as valuable compounds in the pharmaceutical, cosmetic, fine chemical, and nutraceutical industries, with potential health benefits.³⁴

Flavonoids are present in nearly all plant tissues, including F. carica.³⁵ Numerous studies have shown that flavonoids have multiple beneficial attributes, including antioxidant, anti-cancer, antimicrobial, anti-inflammatory, neuroprotective, and anti-fungal activities.⁶ Flavonoids typically feature a basic structure consisting of a 15-carbon skeleton with two phenyl rings and a heterocyclic ring.³⁶ Flavonoids are further divided into subclasses based on their heterocyclic ring oxidation and substitutes.³⁶ Figure 6 shows the sub-classes of flavonoids which have been found in F. carica, which are flavones, anthocyanidins, flavan-3-ols, isoflavones, and flavonols.^36–41 The phytochemical analysis of F. carica has led to the isolation of several classes of compounds and metabolites from various parts of the plant, and studied for their biological properties as listed in Table 1.

Table 1 Phytochemical Studies Conducted on F. Carica

Figure 6 The flavonoids which have been found to be contained in F. carica. (A) flavones; (B) anthocyanidins; (C) flavan-3-ols; (D) isoflavones; (E) flavonols.

Nutritional Values of F. carica

F. carica was also found to possess various nutritional values. Table 2 highlights the nutritional composition of F. carica (50mg per serving) obtained from the United States Department of Agriculture (USDA) FoodData Central.⁵¹ In the most recent publication, it was reported that F. carica fruit is rich in vitamins, nutrients, phytochemicals, and minerals, and low in fat and cholesterol.⁶ Among the minerals, calcium (Ca) is the most abundant in fig seeds and leaves, while in fig fruits, potassium (K) is found the most concentrated.⁶ Other minerals such as magnesium (Mg), sodium (Na), and phosphorus (P). Zinc (Zn), manganese (Mn), copper (Cu), and iron (Fe) are also present in varying amounts.^6,51

Table 2 Nutritional Composition of F. Carica Based on 50g per-Serving

Therapeutic Potential of F. carica

F. carica has been reported to possess a diverse array of pharmacological properties. Many parts of this plant such as the leaves and roots are used to treat various conditions, such as gastrointestinal (colic, indigestion, loss of appetite, and diarrhea), respiratory (sore throat, cough, and bronchial problems), inflammatory, and cardiovascular disorders, as well as antispasmodic.⁵² Studies using both in vitro and in vivo models have identified numerous other biological properties such as antioxidant, antimicrobial, anti-neurodegenerative, anti-arthritic, anti-cancer, anti-diabetic and many more.^52–57

Antioxidant Properties

Benmaghnia et al reported that dried F. carica has high antioxidant properties owing to the presence of phenolic compounds, flavonoids, and tannins.²³ As previous studies have suggested that cell death rates can be lowered by the scavenging effects of natural antioxidants,^58,59 various researches have been conducted on numerous natural compounds, particularly those with high phenolic content. Multiple pre-clinical studies have reported that F. carica possess good antioxidant properties.^54,57,60 Phenolic compounds are common secondary metabolites that play a role as antioxidative agent by donating a hydrogen atom or electron to other compounds, thus scavenging free radicals, and quenching singlet oxygen.⁶¹

In a previous study using high-performance liquid chromatography (HPLC), the phenolic content of F. latex extract was found to be predominantly chlorogenic (59%), followed by rutin (20%), catechin, protocatechuic acid (both 8%), caffeic acid (3%), vanillic acid, and sinapic acid (both 1%).⁵⁴ Calculating the total phenolic content as gallic acid equivalents (GAE) per gram of the dry plant material, and total flavonoid content as catechin equivalent (CE) per gram, the total phenolic and flavonoid content determined in the study were 50.2GAE/g and 12.5CE/g latex, respectively.⁵⁴ However, using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay to evaluate antioxidant properties reported slightly lower antioxidant activities of the F. latex extract with 13.6μg/mL compared to Ficus sycomorus (7.0μg/mL) and Euphorbia tirucalli (6.0μg/mL) methanolic latex extracts.⁵⁴ Mahmoudi et al also evaluated the antioxidant properties of F. carica leaf extract using DPPH assay from ten varieties of Algerian F. carica trees, including Onk Elhamam, Chatwi, Bidha, Bither, and Zarrouk.⁶⁰ They found that antioxidant capacity in F. carica leaves was significantly correlated with phenolic content (r=0.748).⁶⁰ A previous study extracted the phenolic compounds from F. carica using the Soxhlet method, followed by analysis using the Folin–Ciocalteu colorimetric method.⁶² It was found that the Chatwi extract had the lowest IC₅₀ value among all other types of extracts with 659.97±0.92mg/mL indicating the highest free radical scavenging activity.⁶²

An in vitro analysis evaluating the antioxidant properties of F. carica and Ginkgo biloba using DPPH assay revealed that both extracts demonstrated good antioxidant effects as the concentration increased, whereby the IC₅₀ value of F. carica (203.8μg/mL) was slightly higher compared to Ginkgo biloba (183.7μg/mL).⁵⁷ However, at the same concentration of 250µg/mL, both extracts showed a similar percentage of antioxidant activities with 71.2% and 72.7% for F. carica and Ginkgo biloba, respectively.⁵⁷ In a study assessing the potential of F. Carica leaves, fruits, and pulps, it was revealed that F. carica leaves methanolic extract exerted the highest DPPH inhibition effect, indicating high antioxidant potential owing to their high phenolic content.⁴⁹

Anti-Neurodegenerative Properties

Due to the largely irreversible nature of neurodegenerative disorders, it has become a challenge for scientists around the world to find alternatives for treatment of related diseases. Current treatments may also cause adverse effects that can be harmful to patients, especially when neurodegenerative diseases mostly affect older people. Neurodegenerative disorders are often related to oxidative stress as the main contributing factor.⁶³ Recent researches on F. carica exposing its high levels of antioxidants due to its phytochemical composition has paved the way for the studies of its use as treatments for neurodegenerative diseases which is highly associated with oxidative stress. Hence, multiple F. carica studies have been conducted to assess its effects as a neuroprotective agent owing to its antioxidative properties.^64,65

In addition, F. carica has been shown to demonstrate cholinesterase inhibitory activity. These inhibitory effects are not only focused on the neuroprotection in Alzheimer’s disease, but they extend to the therapy of glaucoma, myasthenia gravis, and treatment of intellectual disabilities such as Down’s syndrome due to their cholinergic action.⁶⁴ The study revealed that n-hexane and acetone extracts of F. carica exerted a notable inhibition activities against acetylcholinesterase (AChE) at 62.9±0.9% and 50.8±2.1%, respectively, and butyrylcholinesterase (BChE) at 76.9±2.2% and 45.6±1.3%, respectively.⁶⁴ Previous studies that looked into the effects of F. carica on Alzheimer’s disease and other conditions related to neurodegenerative disorders are listed in Table 3.

Table 3 Studies on the Therapeutic Potential of F. Carica for Conditions Related to Neurodegenerative Disorders

Antiepileptic and Anticonvulsant Properties

Epilepsy is a central nervous system disorder in which brain activities become abnormal.⁷⁰ Although studies on the direct activity of F. carica extraction in epilepsy cases are still limited, studies are worthwhile because of its properties that can act as a skeletal muscle relaxant and anxiolytic action on the central nervous system.⁷¹ Bhanushali et al suggested that F. carica can be a potential alternative for treating anxiety and epilepsy by modulating norepinephrine and 5-hydroxytryptamine in the brain.⁷² Essa et al observed that F. carica extract significantly reduced neuroinflammation by reducing the activities of inflammatory cytokines interleukin (IL)-1β, IL-2, IL-3, IL-4, IL-5, IL-6, IL-9, IL-10, tumor necrosis factor (TNF)-α, and Eotaxin in APPsw/Tg2576 mice.⁷³

A study by Bhanushali et al reported the effect of aerial parts of F. carica aqueous acetonic extract on the central nervous system (CNS) in mice.⁷¹ In the study, F. carica concentrations of 250mg/kg and 500mg/kg reduced sleep latency and increased ketamine-induced sleeping time, similar to conventional drug, diazepam (0.5mg/kg), indicating its sedative-hypnotic properties.⁷¹ Various tests to evaluate F. carica’s muscle relaxant and anxiolytic properties such as motor coordination Rotarod test, Elevated-plus maze test, and Staircase test revealed that the effects of both doses of F. carica (250mg/kg and 500mg/kg) were similar to that of diazepam (0.5mg/kg).⁷¹ Utilizing mouse seizure models, the same study also demonstrated that F. carica extract at both doses suppressed clonic seizures induced by Pentylenetetrazole and tonic seizures induced by maximal electroshock.⁷¹ These findings provided evidences of F. carica as antiepileptic, sedative-hypnotic, skeletal muscle relaxant and anxiolytic drug to improve CNS disorders.

A previous study by Raafat and Wurglics reported that the F. carica stem bark ethanolic extract and its most active fraction, the oligosaccharide-rich fraction (OFG) possessed anticonvulsant activity with a good safety margin.⁷⁴ In the study, both F. carica extract and OFG suppressed convulsion induced by strychnine, and protected the experimental animals from strychnine-lethality.^74,75

Antimicrobial Properties

Flavonoids, tannins, and terpenoids in F. carica leaf extract have been proven to possess antibacterial properties, as reported by Nirwana et al who showed no bacterial growth at 50% F. carica extract concentration.⁷⁶ Benmaghnia et al also revealed that dried F. carica possessed antimicrobial activities against various bacteria such as Bacillus subtilis, Clostridium perfringens, Vibrio cholera, Escherichia coli, and Proteus mirabilis, demonstrating a large inhibition zone when compared with gentamicin.²³

Utilizing two antimicrobial assays, a disc diffusion and macrodilution assays, Mahmoudi et al tested ten varieties of F. carica leaf extract and reported the effects of its phenolic compounds on both Gram-negative and Gram-positive bacteria.⁶⁰ In another study, Staphylococcus aureus and Bacillus cereus, which are foodborne pathogens, were found to be sensitive to the extracts, and reported moderate anti-fungal activity.⁷⁷ In addition, Gram-positive bacteria revealed to be more susceptible to inhibition by F. carica leaf extract than Gram-negative with 15.4±0.6mm and 11.3±0.2mm, respectively.⁷⁷ Using a macrodilution assay to evaluate the minimal inhibitory concentration (MIC) and minimal lethal concentration (MLC) of the F. carica extracts, B. cereus was found to be the most susceptible to the extracts with 2.19mg/mL and 4.38mg/mL of extracts concentration for MIC and MLC, respectively.⁶⁰ This finding shows that lower concentrations of F. carica leaf extract (Dhokkar variety) were able to inhibit and kill the tested bacteria.⁶⁰

Another study by Souhila et al reported the antimicrobial properties of the methanolic extract of dried F. carica fruit (Sidi Bendjebbar variety) on one of the urinary tract infectious agents, Enterobacter cloacae.⁵³ Using the paper disk method to measure the zone of inhibition against E. cloacae, the methanolic extract of this plant produced 17mm inhibition zones when compared to ampicillin and aqueous extract, both with 15mm inhibition zones indicating the extract’s potential to treat urinary tract infection.⁵³

Antiviral Properties

The activity of F. Latex against Herpes simplex virus type 2 (HSV-2) was confirmed by significantly decreasing the number of viral copies in the HSV-2 culture medium.⁷⁸ Interestingly, F. Latex produced a positive synergistic effect when combined with standard drug, acyclovir, producing a stronger effect on HSV-2 than acyclovir alone.⁷⁸ F. latex from the Tunisian Jrani caprifig variety has also been reported to possess antiviral properties, postulated to be attributed to its high level of Triterpenes.^13,27,79 Their mode of action against HSV-1, Echovirus-11 (ECV-11), and Adenovirus influenza virus (ADV) were discovered to be at all stages of multiplication, hence is a potential application for treatment of those virus infections.²⁷ F. carica and F. Latex have also been reported to reduce viral titers in an in vitro study and were able to interfere with Caprine Herpesvirus type 1 (CpHV-1) replication.^13,72,80

F. carica L and F. Latex have long been documented for their strong therapeutic effects and antiviral properties, and produce no cytotoxicity in Vero cells.^57,81,82 The study by Antonopoulou et al reported that the aqueous extract, hexanic and hexane-ethyl acetate from the latex of F. carica have been shown to be effective antivirals against HSV-1, ECV-11, and ADV.⁸³ It was shown that the viruses were inhibited when the extracts were incubated with infected cells as well as when they were incubated prior to virus contacts with the cells.⁸³ The study also documented that F. carica extracts could inhibit viral DNA for HSV-1 and ADV and RNA replication for ECV-11, as well as demonstrating virucidal action.⁸³ Mawa et al reported that the water extract of F. carica leaves exhibited the ability to directly kill HSV and exert low levels of toxicity.⁸⁴ Ali et al reported a total of 21 active compounds in F. Latex, where the compounds lupeol, α-amyrin, and luteolin showed the highest binding affinities and intense interactions with the SARS-CoV-2 vital catalytic residues His 41 and Cys 145.⁸⁵ Molecular dynamics simulation revealed that amyrin was the most stable compound with higher binding free energy, suggesting that this compound can compete with the native ligands of the SARS-CoV-2 main protease inhibitor in mediating viral replications and transcriptions.⁸⁵

An in vitro study by Camero et al reported that F. Latex reduced the viral titers produced by CpHV-1-infected Madin-Darby bovine kidney (MDBK) cells by interfering with the replication of CpHV-1.⁸⁰ A recent report by Sieniawska et al which compiled a wide range of antiviral properties from different species of Ficus as shown in Table 4, reported that F. latex inhibited caprine herpes virus-1 (CpHV-1) replication in MDBK cells, as well as HHV-1, ECV-11 and ADV replication in Vero cells.⁸⁶

Table 4 Various Ficus Species and Its Potential Antiviral Properties

Anti-Inflammatory and Anti-Arthritic Properties

The effects of F. carica against inflammation-induced injuries have been reported in several studies. Eteraf-Oskouei et al investigated the anti-inflammatory mechanisms of F. carica leaf methanolic extract compared with diclofenac and dexamethasone.⁸⁷ In the study, the highest dose of F. carica leaf methanolic extract (50mg/pouch) led to a significant inhibition of WBC with 76.5% rate.⁸⁷ As the dosage of the extract increased, the exudate volume decreased significantly, and these effects were found to be similar when using diclofenac (1.0mg/kg) and dexamethasone (0.4mg/kg).⁸⁷ In addition, the highest extract dose of 50mg/pouch resulted in the highest reduction in granulomatous tissue weight when compared to the other doses (5 and 25mg/pouch), and was similar to diclofenac.⁸⁷ It was postulated that the mechanism underlying the anti-inflammatory properties of F. carica leaf extract was through the downregulation of tumour necrosis factor-alpha (TNF-α), vascular endothelial growth factor (VEGF) and pro-inflammatory prostaglandin E2 (PGE2) which are important cytokine mediators involved in the angiogenesis of inflammation.⁸⁷

A study on paracetamol-induced acute hepatitis found that F. carica leaf extract could significantly reduce the levels of aspartate transaminase (SGOT) and alanine transaminase (SGPT) compared to the controls.⁵⁵

A phytochemical analysis of F. carica leaves observed a potent anti-arthritic activity based on in vitro inhibition using a protein denaturation method.⁵² Notably, it was found that several secondary metabolites, such as steroids, triterpenoids, alkaloids, and flavonoids, were responsible for these properties.⁵² An increase concentration of the extract resulted in increased percentage inhibition of protein denaturation suggesting a protective mechanism.⁵² Another study by Bahadori et al revealed that lupeol, a dietary triterpene found in F. carica also demonstrated anti-arthritic properties, although the mechanism is yet to be fully elucidated.⁵⁶

Anti-Hyperlipidemic Properties

An earlier study on the benefit of F. carica as a lipid-lowering agent was performed by Pérez et al in 1999.⁸⁸ The study utilized a hypertriglyceridemia rat model by allowing the animal free access to 20% of long-chain triglyceride (LCT) emulsion without supplying other food for 2 hours after a fasting period of 22 hours.⁸⁸ Acute intraperitoneal administration of F. carica leaf decoction (5000mg/kg) resulted in a significant reduction in plasma triglyceride (TG) levels at 60 and 90min post-treatment.⁸⁸ In another study, acute administration of F. carica leaf aqueous extract (aqueous fraction that remained in the petroleum ether-treated total extract) at various dosages of 10, 50, and 250g/kg, lowered total cholesterol (TC) levels in the serum and liver of hyperlipidemic-induced rats.⁸⁹ Phytochemical screening from the same study showed that the F. carica leaf extract had a small amount of alkaloids, moderate level of flavonoids, and a large amount of tannins that may contribute to the acute in vivo anti-hyperlipidemic effects.⁸⁹

Administration of F. carica leaves and twigs extracts with the dosage of 150 and 300mg/kg in hyperlipidemia-induced mice with a single intravenous injection of Triton WR 1339 (300mg/kg body weight) resulted in a significant decrease of serum TG, TC, low-density lipoprotein (LDL-C) and very low density lipoprotein (VLDL-C), while the high-density lipoprotein (HDL-C) was increased.⁵⁰ The study recorded the LD₅₀ value of twigs and leaves extracts of F. carica greater than 5000mg/kg, while the phenolic and flavonoid content of F. carica leaves and twigs varied from 12.84 to 19.78mg gallic acid equivalents (GAE), and 5.02 to 9.72mg EQ/g dry matter, respectively.⁵⁰

The protective effect of chronic administration of F. carica ranging from 3 to 12 weeks against hyperlipidemic and hypercholesterolemic animal models has been previously documented.^90–93 Supplementation of F. carica leaf extracts at doses of 50 and 100mg/kg for 6 weeks,⁹¹ and 400mg/kg for 3 weeks⁹³ in high-fat diet (HFD) rats led to significant reductions in TG, interleukin-6 (IL-6), atherogenic index (AI), coronary risk index (CRI), TC, and LDL-C.

Similarly, there were significant reductions in the plasma levels of TC, TG, LDL-C, and AI after HFD-induced rats were supplemented with 400mg/kg of F. carica fruit extracts for 3 weeks⁹³ and 8 weeks.⁹⁰ These findings suggest that the hypolipidemic and hypocholesterolemic effects of the fruit extract may be due to the presence of flavonoids, especially apigenin 8-C-glucoside (vitexin) and quercetin-3-O- rutinoside (rutin).⁹⁰ Recently, Perveen et al demonstrated similar findings where supplementation with F. carica pulp extracts (1250mg/kg) for 12 weeks in HFD-induced rats resulted in a significant decrease in the plasma levels of TC, TG, LDL-C, HDL/LDL ratio and AI, with elevated HDL-C.⁹² Studies on the effects of F. carica extracts as therapeutic agents against hyperlipidemia and hypercholesterolemia in rodents are summarized in Table 5.

Table 5 Effects of F. Carica Extracts on Hyperlipidemia and Hypercholesterolemia in Rodents

Anti-Angiogenic Properties

Angiogenesis, the formation of new blood vessels from pre-existing vessels is involved in various processes, including embryonic vascular development, wound healing, tumour growth, and diabetic microvascularization.⁹⁴ Anti-angiogenic effects of F. carica has been suggested to be beneficial in the prevention of angiogenesis-related disorders, especially cancer.^95,96 In an in vitro anti-angiogenic study using a three-dimensional collagen matrix of human umbilical vein endothelial cell (HUVECs) capillary tube formation, different concentrations of F. latex extracts ranging from 50 to 200µg/mL were used.⁹⁶ The results showed that the extracts were able to inhibit angiogenesis in HUVECs tube formation model at the concentration of 100–200µg/mL.⁹⁶ A study by Ghambarali et al using the same model revealed that angiogenesis was significantly inhibited by F. carica leaf ethanolic extract at concentrations from 5 to 25µg/mL in a concentration-dependent manner, with the ability to significantly decrease the mRNA expression of VEGF-A and integrin β3.⁹⁵

In an in vitro study using the chorioallantoic membrane (CAM) of embryonated chicken eggs, administration of F. carica leaf aqueous extract at doses of 75, 90, and 110µg resulted in a significant inhibitions of blood vessels formation as well as marked reduction of VEGF expression in the vascular endothelial cells of the CAM.⁹⁷ The study reported that the optimal dose of F. carica leaf aqueous extract to inhibit angiogenesis by 65.5% and reduce VEGF expression by 45% was 90µg.⁹⁷

In an in vivo study using a rat air pouch model of inflammation, Eteraf-Oskouei et al investigated the effects of F. carica leaf methanolic extract administered intraperitoneally on VEGF and angiogenesis of granulation tissue by measuring the hemoglobin content.⁸⁷ The findings demonstrated a significant decrease in hemoglobin and VEGF levels at F. carica concentrations of 5, 25, and 50mg/pouch, in a concentration-dependent manner.⁸⁷ The reduction in angiogenesis and VEGF by 50mg/pouch of F. carica leaf methanolic extract was similar to that of diclofenac sodium used as the positive control in the study.⁸⁷

Hematologic Parameters

The benefit of F. carica extract as a blood-building agent has been shown in several animal studies.^98–100 An earlier study by Nebedum et al showed that supplementation with 200mg/kg ethanolic extract of F. carica leaves for 14 days in healthy albino rats of both sexes significantly increased the hemoglobin concentration, packed cell volume (PCV), and red blood cell (RBC) count.⁹⁹ The study also reported a significant decrease in the total white blood cell (WBC) count and percentage of neutrophils compared to those in the control group.⁹⁹ Similar findings were observed in a study that used a longer duration of 4 weeks to administer F. carica leaf aqueous extracts (100, 200, and 400mg/kg), where the effects were found to be concentration- and time-dependent.¹⁰⁰

Furthermore, it was also demonstrated that F. carica fruit aqueous extract may provide a protective effect against irradiation-induced free radical injury in different hematological parameters.⁹⁸ Prior supplementation of F. carica fruit aqueous extract (1mL/day) at a ratio of 1:3 w:v for 3 weeks before a single dose of 8Gy whole-body gamma irradiation resulted in a significant increase of WBC, platelet, lymphocyte, and neutrophil counts along with no significant changes in RBC indices.⁹⁸ The presence of flavonoids, tannins, cardiac glycosides, steroids, and saponins, with flavonoid and tannins in high and moderate abundance were postulated to contribute to the effects of F. carica as a blood-building agent.^99,100

Antidiabetic and Hypoglycemic Properties

A study revealed that the use of F. carica in every day diet is beneficial for lowering sugar levels and can potentially be used as antidiabetic therapy.⁴⁰ Although the use of conventional drugs to treat diabetes is well defined and elaborated, the potential of remedies from various plants as complementary medicine have been widely been explored. For instance, the use of F. carica leaf ethanolic extract has been shown to reduce glucose levels in diabetic rats.¹⁰¹ Another study reported that F. Carica extract administered to laboratory animals lowered body weight, serum glucose, cholesterol, TG, LDL-C and VLDL-C, as well as increase the protective effect of HDL-C dose independently.¹⁰² A study also demonstrated that F. carica leaves have the ability to reduce glucose levels by increasing the serum levels of insulin, as well as tissue sensitivity to insulin, thus simultaneously facilitate carbohydrate metabolism.⁴⁹ Fig leaves, peel and pulp can be utilized as effective remedy to control abnormal carbohydrate metabolism associated with diabetes and hyperglycemia.⁴⁹

Anti-Cancer and Cytotoxic Properties

Flavonoids from F. carica have been studied to exert anti-cancer activities in multiple ways, such as by promoting apoptosis, trigger the production of protective conjugate enzymes, suppress angiogenesis, release hydrogen atoms and electrons, prevent lipid peroxidation, and inhibit DNA oxidation.^15,103,104 According to Ghandehari et al, F. latex can reduce the number of mitotic abilities and the extent of apoptosis in breast cancer cells without affecting hematological or histological functions.¹⁰⁵ A study by Purnamasari et al, which evaluated the effects of F. carica leaf and fruit extracts treatment on Huh7it liver cancer cell line, reported that the percentage of apoptotic and necrotic cells increased with increasing concentrations of the extracts.¹⁰⁴ The highlight of the study is summarized in Table 6.

Table 6 Percentage of Huh7it Cells That Undergo Apoptosis and Necrosis in Response to Different Concentrations of F. Carica Treatments

In another study, Ghanbari et al revealed that F. latex can reduce the proliferation of cervical cancer cells via the overexpression of tumour suppressor proteins p53 and pRb, which was likely a result of the low production of human papillomavirus (HPV) oncoproteins E6 and E7.¹⁵ Increased p53 gene activity, which in turn stimulates p21 transcription factors, can cause cyclin-dependent kinase 2 (CDK2) to interact with cyclin E and halt the cell cycle.¹⁰⁴ CDK2 is a serine/threonine protein kinase that plays an important role in the G1/S phase, the initiation of DNA synthesis, and the regulation of the S phase.¹⁰⁶ In addition, studies have shown that flavonoids present in F. carica, such as quercetin, can interrupt cell cycle phases such as the G0/G1 phase, S phase, and G2/M phase in different cancer types.^107–109

A study on molecular docking by Gurung et al demonstrated that the ß-bourbonene compound identified in F. carica can act as an anti-cancer candidate molecule against specific macromolecular receptors, namely three targets: topoisomerase-I, topoisomerase-II, and VEGFR-2.¹¹⁰ Different concentrations of ß-bourbonene inhibited the growth of PC-3M prostate cancer cell line in a dose-dependent manner.¹¹⁰ In addition, stem bark infusion and methanolic extract of F. carica showed antineoplastic activity against cervical adenocarcinoma and colon cancer cell lines.⁸⁶

AlGhalban et al demonstrated that varying concentrations of F. latex were toxic to MDA-MB-231 breast cancer cell line, with anti-proliferative and anti-metastatic activities, as well as substantial effects on cell shape.¹⁶ A study by Jeivad et al examined the cytotoxicity effects of F. latex in HepG2 liver cancer cell and NIH fibroblast cell lines, and found that F. carica was 3.4 times more cytotoxic to the HepG2 cells compared to NIH cell lines, with IC₅₀ values of 0.219 and 0.748mg/mL, respectively.¹¹¹ Another study by Jasmine et al revealed a substantial variation in cell viability (%) of MCF-7 breast cancer cell line based on the concentration of F. carica fruit extracts used.¹¹² The cell viabilities decreased as the F. carica extracts concentration increased as summarized in Table 7.¹¹²

Table 7 The Cell Viability of MCF-7 Cells Exposed with Different Concentrations of F. Carica Fruit Extracts and Different Time Exposure

Antimutagenic Properties

A study by Agabeĭli and Kasimova demonstrated that F. Carica extract reduced the level of mutagenicity in rat marrow cells induced by sodium fluoride (NaF).¹¹³ Lightburn and Thomas showed that F. carica leaf extract suppressed spontaneous DNA damage and enhanced DNA repair in diethylstilbestrol (DES)-Induced DNA strand breaks in MCF10A breast cells, suggesting that it has anti-carcinogenic and anti-cancer effects in the early stages of breast cancer.¹¹⁴ Cytogenetic studies performed by Fahmy et al evaluating the genetic endpoints such as micronuclei in polychromatic erythrocytes and chromosomal aberrations in the bone marrow, as well as expression of liver genes, namely, TNF-α, iNOS and NF-kB, all yielded favourable findings by F. carica in alleviating cisplatin-mediated mutagenic changes.¹¹⁵

Cosmetic Applications of F. carica

Apart from its biological properties, F. carica has also been studied for potential cosmetic applications. A study by Khan et al claimed that F. carica-enriched plant extracts could be used to stimulate and enhance the rate of collagen biosynthesis and recover the hydration level of the dermis.¹⁰⁵ This phenomenon was postulated due to F. carica’s high level of antioxidant properties such as vitamin C, anthocyanins, carotenoids and phenolic compounds.¹¹⁶

An in vitro psychological stress study in the skin keratinocytes revealed that F. carica cell suspension culture extract (FcHEx) decreased the levels of epinephrine, IL-6, lipid peroxide, and protein carbonylation, activated ceramide synthesis and ameliorated lipid barrier performance.¹¹⁷ In the same study, an in vivo analysis demonstrated that the extract of the F. carica cell suspension cultures reduced transepidermal water loss, sebum production, desquamation, and prevention of facial skin turning to pale colour from acute stress.¹¹⁷ Findings of the study suggests the potential of F. carica to fight against the signs of psychological stress in the skin.

A previous study identified several phenolic compounds in the leaf extract of F. carica including fumaric acid, ferulic acid, p-coumaric acid, and malic acid which contributes to the cosmetic effects of the plant.¹¹⁸ For instance, fumaric acid is a common compound used to treat psoriasis,⁹⁷ whereas ferulic acid has been shown to protect the skin against damage caused by ultraviolet (UV) irradiation.¹¹⁹ Malic acid and p-coumaric acids have been shown to possess anti-hyperpigmentation effects, while polyphenols predominantly found F. carica are important in cosmetic product development.¹²⁰

An in vitro study by Turkoglu et al demonstrated that the F. carica extract significantly downregulated VEGF, TNF-α, interleukin 1-alpha (IL-1α) and 5 alpha-reductase type II (SRD5A2) in human keratinocyte cells compared to the control, suggesting its possible molecular mechanism.¹¹⁸ VEGF is mainly involved in altered angiogenesis, which is related to many pathological conditions, such as tumour growth, metastasis, atherosclerosis, psoriasis, and other skin diseases.¹¹⁸ Therefore, the inhibition of angiogenesis through VEGF downregulation can stunt skin cancer cells. This phenomenon could occur indirectly by blocking the supply of nutrients and oxygen to the cells.⁹⁷ The TNF-α is synthesized in epidermal keratinocytes and plays a key role in the pathogenesis of hair follicle disease, alopecia areata.¹²¹ Reports have also shown that TNF-α, IL-1α and 5 alpha-reductase type II SRD5A2 were involved in the pathogenesis of acne.¹¹⁸ Hence, the use of F. carica leaf extract to downregulate these genes provide the cosmetic benefits related to skin care.

Toxicity of F. carica

Owing to their natural origin, phytochemicals from medicinal plants are generally considered safe for consumption. A study revealed that varying quantities of F. Carica extracts offered no threats to normal, healthy fibroblast cells, demonstrating the general quality of the extracts.⁷⁶ Nevertheless, several natural compounds found in commonly consumed plants can be toxic at high doses or in long-term consumption. As for F. carica, the studies on its toxicity are still limited. Among the various parts of the F. carica plant, dermal exposure to milky sap (latex) exuding from the cut branches, leaves, and skin of the fruits, may be of health concerns.¹²² The sap constituents which are composed of various proteolytic enzymes (ficin, triterpenoids, protease, lipodiastase, and amylase) and furocoumarins possess irritant and pruritic properties that are thought to induce various clinical skin syndromes.¹²² Many cases of inflammatory skin reactions (phytophotodermatitis) have been reported as a result of external contact with F. latex, primarily leaf and shoot latex.¹²² Pain, itching, redness, swelling, and occasionally blister development are the most common symptoms of F. latex-induced phytophotodermatitis.¹²³ Two natural furocoumarin compounds [5-methoxypsoralen and 8-methoxypsoralen (8-MOP)] in F. carica were reported to be responsible for the development of phytophotodermatitis, where furocoumarin binds to DNA upon contact, inducing DNA crosslinking, which prevents cell division, DNA repair, and DNA synthesis, ultimately leading to cell death.¹²⁴ This phenomenon occurs mostly in the epidermal DNA, resulting in vesicle production and blistering.¹²⁴

In a reproductive toxicity study, Makoolati et al demonstrated that F. Carica had no harmful effects on spermatogonial stem cells and enhanced their viability and proliferation.¹²⁵

Future Direction

In recent years, numerous studies on F. carica have focused on its nutraceutical and pharmacological potential. A vast array of pre-clinical studies, in vitro and in vivo experiments have been conducted. However, clinical trials and human studies involving F. carica supplementation or intervention are still lacking; hence, more well-designed, randomized control trials are crucial to gather sufficient data and valid evidence for its efficacy and safety in human. This will further validate the nutraceutical potential of F. carica, in particular on cancer, neurodegenerative diseases, inflammation, and oxidative stress-related conditions.

It would also be beneficial to explore the molecular mechanisms underlying the therapeutic effects of F. carica. Advance genetics, molecular docking, and metabolomic studies should be in the pipeline for future research in personalizing F. carica as a therapy or nutritional supplementation with a proper dosage recommendation. This includes the study of F. carica on the gut microbiota and the synergistic combinations of F. carica with other supplements or medication to achieve the best outcome while minimizing potential side effects or adverse reactions.

Studies on the compound or drug formulation and delivery to enhance the bioavailability of F. carica’s bioactive compounds involving nanotechnology, novel extraction techniques, and recent technology in the farming and cultivation practices of F. carica should also be considered to improve its efficacy and optimize its potential benefits. Transdisciplinary exploration, and collaboration between researchers, clinicians, and industry partners will be crucial in advancing the potential use of F. carica as a promising nutraceutical.

Conclusion

F. carica is considered a potential medicinal plant as it contains numerous beneficial polyphenols and bioactive compounds. Polyphenols serve as free radical inhibitors and play essential roles in reducing oxidative stress, which is involved in various pathological conditions. Multiple parts of F. carica have been widely studied and found to possess pharmacological properties for the treatment of various human diseases. Through this present comprehensive review into its bioactive compounds and biological effects, we have gained valuable insights into the various ways F. carica can positively affect human health.

As most previous studies on F. carica have been limited to in vitro and pre-clinical trials, more clinical and human studies are required before F. carica can be fully integrated into clinical practice and personalized nutrition. In depth mechanistic studies, exploration of novel delivery methods, drug synergy, and clinical trials will contribute to a more comprehensive understanding of F. carica’s pharmacological effects and its nutraceutical potential for human health.