Application of nanotechnology to herbal antioxidants as improved phytomedicine

Phytotherapy, based on medicinal plants, have excellent potential in managing several diseases. A vital part of the healthcare system is herbal medicines, consisting of therapeutic agents with high safety profile and no or least adverse effects. Herbs or medicinal plants show anticancer, antioxidant, and gene-protective activity, which is useful for pharmaceutical industries. In vitro, the extract of antioxidant compounds prevents the growth of colon and liver cancer cells, followed by a dose-dependent method. The screening of extracts is done by using in vitro models. Reactive oxygen species (ROS) and free radicals lead to diseases based on age which promotes oxidative stress. Different types of ROSs available have central roles in the normal physiology and functioning of processes. Herbal or traditional plant medicines have rich antioxidant activity. Despite the limited literature on the health effect of herbal extract or spices. There are many studies examining the encouraging health effects of single phytochemicals instigating from the medicinal plant. This review provides a detailed overview on herbal antioxidants and how application of nanotechnology can improve its biological activity in managing several major diseases, and having no reported side effects.


Introduction
Antioxidants are mainly present in medicinal plants, defined as agents that prevent oxidation chain reactions in different molecules [1].Herbal plants have a high percentage of phenolic compounds, which acts as antioxidant compounds.Antioxidant compounds have redox properties which show their action by neutralizing the free radicals and decomposing peroxides [2].Natural antioxidants are considered safe and effective as compared to synthetic antioxidants, which are avoided due to their toxic effect on the body [3].In the United States, culinary herbs improve the flavor of food products and have been used for many years [4].Medicinal plants contain various phytochemicals and phenolic compounds [1].These phytochemicals show antioxidant activity and are used in the treatment of cancer.As a result, there is less mortality in numerous human cohorts [5].Nowadays, herbal medicines are available as food supplements [6].
Oxidative stress is a significant risk element for health as it leads to severe diseases like diabetes, Alzheimer's disease, cancer, aging, etc.It produces Reactive oxygen species (ROS) that disturb the function and structure of the brain ′ s glial cells resulting in dementia [7].Herbal antioxidants are proven to be more effective and safer [8].Phytotherapy has involved herbs and medicinal plants in treating diseases for thousands of years [9,10].Moreover, the research and scientific publications based on herbal medicines are increasing daily [11].In biology, the current development regarding free radicals and ROS assures promising results in controlling the diseases [12].Oxygen is an essential component for the existence of life [13]; however, the destructive effects of oxygen are primarily because of the development of ROS, which can give oxygen to other elements.Free radicals and antioxidants are currently used to treat diseases [12].Antioxidants are stable molecules that neutralize the electron donated to charged free radicals and reduce the ability to destroy the human body.Antioxidants postpone or stop the damage in human cells due to free radical chain reactions.The antioxidants, having low molecular weight react with free radicals before they lead to damage to the critical molecules.Different antioxidants like uric acid, ubiquinol, and glutathione are produced during normal metabolic rates.The human body has various enzymes that hunt free radicals, consisting of macronutrients, vitamin E, and β-carotene [14,15].

Search strategy
The systematic qualitative review analyzed globally accepted databases, including peer-reviewed and indexed journals from Scopus, Medline, PubMed, Research Gate, and Google Scholar.Various reports from 2000 to 2022 were included.The search was made using keywords such as herbal antioxidant, Classification of antioxidants, Enzymatic and non-enzymatic antioxidants, Reactive oxygen species, Mechanism of action of antioxidants, Characterization tests for antioxidants, antioxidants in disease management, and nanocarriers containing herbal antioxidants.The botanical names and families of the plants used for herbal antioxidants were mentioned after verification from published literature and databases.Data selection criteria are according to phytoconstituents, in vitro and in vivo models used, nanocarriers, and clinical studies involving herbal antioxidants in disease treatment.The broad inclusion criteria of the reports in the present review are (i) herbal antioxidants reported for various disease treatment, (ii) nanocarriers containing herbal antioxidants used in the management of different diseases, and (iii) herbal antioxidants based clinical trials for various diseases.

Reactive oxygen species and its effects on normal physiology
The ROS containing oxygen species are reactive and divided into radical and non-radical ROS.Free radical species have unpaired electrons in the outermost orbit, and non-radical species do not contain unpaired electrons.It leads to severe diseases, which affect the whole body, as shown in Fig. 1.However, non-radical ROS are reactive chemically, which get altered to free radical ROS.

Reactive oxygen species in cell signaling
Cells have to identify their surroundings and transform their activities depending on the microenvironment to survive, which is done by cell signaling.In a simple signal pathway, signals are conveyed by modifying the action of proteins.A molecule known as a mediator promotes the step of the signaling pathway, and the purpose of ROS is explained at various places in the signaling pathway.ROS is the prime stimulus that begins the signaling path and the initiator that is the last step of the signaling pathway, also known as effectors [16].

Formation of reactive oxygen species
The molecules of ROS formed throughout the reduction process of oxygen from water.A single electron addition to oxygen gives superoxide; this reduction process forms hydrogen peroxide (H 2 O 2 ).ROS formation is due to endogenous and exogenous stimuli, which involve ultraviolet (UV) radiation, environmental toxins, and chemotherapy [17].ROS formation takes place in various cellular sections of enzymes like nicotinamide adenine dinucleotide phosphate (NADPH), nitric oxide (NO), xanthine oxidase (XO), and the electron transport chain of mitochondria [18].It consists of seven NADPH oxidases, trans-membrane proteins resulting in superoxide or H 2 O 2 .The additional enzymes are different in their cellular compartment, their ascending activators, and linked subunits.Recognized nicotinamide oxidases inducers are growth elements, vitamin D, and cytokines [19].
Mitochondria are supposed to yield ROS conventionally, simply as an undesirable by-product of energy creation in the electron transmission chain.On the other hand, ROS production also ensues from the mitochondria.This arises at least to some extent by the reluctance of Cytochrome C oxidase using NO brings about more superoxide production deprived of distressing energy creation.Mitochondrial superoxide dismutase (MSOD) alters superoxide into H 2 O 2 to pass from the membrane and initiates cytosolic signaling [20].

How reactive oxygen species are observed?
ROS alters the fabrication, constancy, and role of proteins.Thus redox reaction changes the action of transcription elements in the nucleus.Generally, the reduced transcription factor is connected with deoxyribonucleic acid (DNA) and supports the transcription step.The oxidized transcription factor will not bind to DNA and thus not support transcription.Moreover, the oxidation process of proteasomes exaggerated the protein stability.This oxidation of proteasomes reduces inactive form and does not result in protein degradation [21].This leads to retaining or high protein levels.Lastly, the role of proteins and molecules could be improved by oxidation from subsequent three approaches: (1) The proteins, for instance, thioredoxin, are oxidized, causing alteration in protein activity.(2) This oxidation hunts chaperone protein which generally stops protein action.In oxidation, proteins are separated, commencing their inhibitor, and converted to the active form.(3) The objectives for oxidation are phosphatases and kinases, which consequently modify the action of proteins by post-translational alterations.Protein tyrosine phosphatases become inactive by oxidation frequently; however various kinases usually become activated.Additional oxidation of targeted molecules can cause permanent oxidative destruction.
Oxidized cysteine residues are the general objective and are secured as oxidation by employing the construction of thiol bridges [22].The transcription factors consist of activation protein (AP)− 1, nuclear factor erythroid 2-related factor 2 (Nrf2), cyclic adenosine monophosphate response element binding (CREB), Homeobox B5, and nuclear receptors like estrogen receptor [23,24].Complex antioxidant systems are developed to offset possible lethal ROS effects and allow ROS to perform in the signaling path.It is highly dedicated to relations of both elimination of particular ROS and compartmentalization of antioxidants [18].

Classification of antioxidants
The antioxidant enzyme forms an interactive network to prevent cell damage from oxidative stress [25].During this process, superoxide is released.Firstly, oxidative phosphorylation is converted into hydrogen peroxide (H 2 O 2 ), then reduced to produce water.The multiple enzymes result in a detoxification pathway; the first step involves superoxide dismutase (SOD) catalysis and then various peroxidases removing H 2 O 2 [26].The antioxidants are classified into two types, as shown in Fig. 2.

Superoxide dismutase
The SODs are antioxidant enzymes; they catalyze the breaking of superoxide anion and give oxygen to H 2 O 2 [27].In all aerobic cells and extracellular fluids, an antioxidant enzyme of SOD is present [28].Depending upon the cofactor of metal, it consists of three types of most crucial SOD families: Cu 2+ or Zn 2+ , Fe 2+ or Mn 2+ types, and Ni 1+ type bind with nickel [29].As in developed plants, SOD isozymes are confined in several cell compartments.The Mn 2+ type of SOD is found in mitochondria.The peroxisomes and Fe 2+ type of SOD are found generally in the chloroplasts.However, antioxidants are identified in peroxisomes.The Cu-Zn type of SOD is confined in peroxisomes, cytosol, chloroplasts, and apoplast [30].Three different types of SOD exist in humans, i.e., SOD1 (dimer), SOD2, and SOD3 are present in the cytoplasm, mitochondria, and extracellular, respectively.The SOD2 and SOD3 contain four subunits; SOD1 and SOD3 involve Cu and Zn, while SOD2 consist of Mn in their reactive form [31].

Catalase
In most living organisms, catalase enzymes are available for water and oxygen, catalyzing H 2 O 2 decomposition [32]⋅H 2 O 2 shows its action as a destructive by-product of various metabolic procedures to avoid damage.It rapidly altered into a reduced amount of harmful substances.The H 2 O 2 is decomposed in oxygen and water in cells by the catalase.All the animals utilize catalase in every organ, mainly in the liver in higher concentrations [33].

Glutathione peroxidase
The glutathione system consists of glutathione reductase, peroxidases, and S-transferases.It is present in microorganisms, animals, and plants [34].The antioxidant enzyme glutathione peroxidase consists of four selenium cofactors.These cofactors catalyze H 2 O 2 and organic hydroperoxides.In animals, four different glutathione peroxidase isozymes are present.Glutathione peroxidase 1 works very effectively on H 2 O 2 .Glutathione peroxidase 4 is more dynamic through lipid hydroperoxides, while glutathione S-transferases indicate more activity about lipid peroxides in the liver.It also shows its function in detoxification [35].

Non-enzymatic antioxidant 2.2.1. Ascorbic acid
Ascorbic acid is, also known as "vitamin C," present in both animal and plant sources but not be produced in humans.Therefore, it is essential to consume a diet or have a diet containing vitamin C. It is a vitamin and monosaccharide antioxidant [36].Animals are capable of synthesizing ascorbic acid in their bodies.Glutathione (GSH) reaction occurs in cells to maintain ascorbic acid in its reduced form.Ascorbic acid is catalyzed using protein disulfide isomerase and glutaredoxins.It acts as an antioxidant, reducing agent, and neutralizes ROS [37].Ascorbic acid or its substrate plays a vital role in stress management in plants [30].

Glutathione
Glutathione (GSH) is a peptide containing cysteine.It is found in aerobic organisms and produced in cells by amino acids, and is not required in the diet.Glutathione, showing antioxidant activity, consists of a thiol group in its cysteine moiety.It is a reducing agent and reversibly gets oxidized.It is maintained in cells in the reduced form through the enzyme glutathione reductase.As a result, it reduces further metabolites and enzyme systems that react directly with oxidants [38].Glutathione is a major cellular antioxidant and can be replaced by other thiols [39].

Melatonin
Chemically, antioxidant melatonin is N-acetyl-5-methoxytryptamine [40].It is a naturally occurring hormone in animals and other living organisms, including algae [41].Melatonin is an effective antioxidant that easily passes the cell membranes and blood-brain barrier (BBB), which is also a suicidal and terminal antioxidant.Melatonin does not go through redox cycling.Once the melatonin gets oxidized, it is not reduced to its previous state due to numerous stable end-products forming in response to free radicals [42].

Tocopherols and tocotrienols
Vitamin E or Tocopherols and Tocotrienols show antioxidant properties.These are fat-soluble vitamins [43].Lipid soluble α-tocopherol is the main antioxidant that defends membranes against oxidation by reacting to lipid radicals produced in the lipid peroxidation chain reaction [44,45].It eliminates the free radical intermediates and protects the propagation reaction by enduring.

Uric acid
Uric acid is a type of non-enzymatic antioxidant, which shows coarsely half capacity of antioxidant in plasma.It facilitates the synthesis of ROS [15,46].

Mechanism of action of antioxidants
There are two proposed mechanisms of action for antioxidants: chain-breaking mechanism and ROS/reactive nitrogen species initiators mechanism [47,48].The mechanism of antioxidants is based on different stages that are defined as follows: The preventive antioxidants reduce the production of free radicals.While in vivo, the precise mechanism and actual site of radical formation is not explained.The radical-scavenging antioxidant works as the active radical suppressor of chain initiation and propagation reactions.Several endogenous hydrophilic radical-scavenging antioxidants have been identified, while vitamin E is the most effective lipophilic radicalscavenging antioxidant.The de novo antioxidants are based on repairing cells.These recognize, destroy and eradicate increased oxidative proteins and avoid the building-up of oxidative proteins.Besides, the DNA repair system performs a significant role compared to oxidative damage in the total defense system.Glycosylases and nucleases are enzymes used to repair the injured DNA.Another vital role of antioxidants is adaptation, consisting of production signals and free radical reactions that persuade the development and transportation of suitable antioxidants at a proper place [47].

DPPH radical scavenging assay
The free radical scavenging capacity of plant extracts can be analyzed using 1, 1-diphenyl-2-picrylhydrazyl (DPPH).To determine the antioxidant activity, a stable DPPH radical is utilized.This assay includes the addition of various extract concentrations in a suitable solvent (10 µL) into 90 µL of methanolic DPPH solution (100 µM) and then a final 100 µL volume in 96 well plates.Then, the ingredients are mixed well and incubated for 30 min at 37 • C. Ascorbic acid is utilized as a standard antioxidant.The microplate reader measures the absorbance at 517 nm compared to the control solution having maximum absorption.This decline in absorbance shows high scavenging activity [49].The DPPH radical scavenging activity is represented in % form and calculated by: For evaluation of flavonoids, DPPH radical scavenging activity of quercetin is utilized as standard, and free radical scavenging activity is measured in triplicates [50].

Oxygen radical absorption capacity assay
Oxygen radical absorption capacity (ORAC) assay evaluates the capability of antioxidants to protect the targeted molecule open to a free radical source.This assay is commonly used to determine oxidative stress and antioxidant by H atom transfer.In this assay, peroxyl radical is mixed with fluorescent probe 3 , resulting in a nonfluorescent mixture that easily gets quantitated via fluorescence.The antioxidant inhibits the peroxyl radical-induced oxidation and prevents the deterioration of FL.The antioxidant ability of extract is determined by calculating the reduced rate and quantity of product obtained.The area under the curve (AUC) shows the favorable antioxidant capacity of the antioxidants having a lag phase or without a lag phase.It is beneficial for a wide range of samples, like raw vegetables and fruit, extracts, pure phytochemicals, and plasma.The high-throughput evaluation can regularly examine several hundred samples by one plate-reader combined through a multichannel programmed liquid handling system [53].

Anti-inflammatory activity
Lipopolysaccharide (LPS) promotes the maturation of dendritic cells, which mainly produce tumor necrosis factor (TNF)-α.In this assay, 100 μg of each flavonoid sample was taken along with salicylic acid and quercetin as standards.For flavonoid derivatives, diene conjugate and conjugated diene assays were performed using a specified method [54].Flavonoid derivatives were identified by modifying the 96-well microtiter plate method to inhibit hyaluronidase activity [55].
The anti-inflammatory activity of M. oleifera flower extract was assessed by the protein denaturation technique using Padmanabhan method.Drug diclofenac sodium acts as a standard non-steroidal antiinflammatory drug.This standard diclofenac sodium (100 and 200 µg/ mL) or 2 mL of M. oleifera flower extract (100-500 µg/mL) and 2.8 mL phosphate buffered saline (PBS pH 6.4) was stirred with 2 mL of egg albumin and incubated for 15 min at 27 ± 1 • C. Denaturation was induced by keeping the reaction mixture in the water bath for 10 min at 70 • C.After cooling, the absorbance was measured at 660 nm using double distilled water as blank [56].The percentage inhibition of protein denaturation was calculated by: The LPS convinces dendritic cell growth generating an excessive amount of TNF-α for assessing the antioxidant and anti-inflammatory activity of herbal/plant extracts [57].

Cytotoxicity assay
The LPS produces pro-inflammatory cytokine in the human monocyte cell line (THP)− 1.In this assay, THP-1 cells were cultured with penicillin and streptomycin (100 U/mL).It was immunized from 10% fetal bovine serum in RPMI 1640 culture media.The cells were separated with phorbol myristate acetate (PMA), and cell plating indicated the test compounds in 0.5% dimethyl sulfoxide (DMSO).The plate should be incubated for 30 min at 37 ºC.The nonlinear regression method is used to calculate 50% inhibitory concentration (IC 50 ) values [58].

XO inhibitory assay
In XO inhibitory assay, different activities of plant extract were observed spectrophotometrically in aerobic conditions using xanthine as a substrate.The reaction mixture of assay comprised 1 mL extract on various concentrations (0.5-8.0 mg/mL), 0.1 mL solution of XO enzyme (0.1 units/mL of phosphate buffer pH 7.5), and 2.9 mL of fresh phosphate buffer pH 7.5.The reaction started after the pre-incubation for 15 min at 25 ℃ by adding 2 mL of substrate solution containing 150 µM of xanthine in the same buffer.Then the assay mixture was incubated for 30 min at 25 ℃.The addition of 1 mL of 1 N hydrochloric acid stopped the reaction.The absorbance was measured by a spectrophotometer at 290 nm.The allopurinol (0.5-8.0 mg/mL), known as XO inhibitor, was used as per positive controller.AXO unit is enzyme amount essential to yield 1 mmol uric acid/min (25 ℃).The XO inhibitory assay expressed in the form of XO inhibition percent as shown: where A is the activity of enzyme deprived of extraction, B is control without enzyme and extraction, and C, D are extraction activities with or without XO, respectively [59].

Urease inhibitory assay
An improved Berthelot spectrophotometric technique can assess the primary urease inhibitory action of extracts at 625 nm.Inhibition action of hydroxyurea was examined as standard for urease.To prepare the assay solution, 850 µL urea, 0-100 µL extract, and 100 mM phosphate buffer pH 7.4 were mixed.After adding 15 µL urease enzyme, the enzymatic reactions started, which were measured by quantifying ammonia concentration after 60 min by means of 500 µL solution A, which contained 0.5 g of phenol and sodium nitroprusside (2.5 mg) in 50 mL distilled water and 500 µL solution B, which contained 250 mg of sodium hydroxide and 820 µL of 5% sodium hypochlorite in 50 mL of distilled water for 30 min at 37 • C. The uninhibited urease activity was selected as 100% control activity [60,61].

Jaundice
Bauhinia malabarica Roxb.belongs to the Leguminosae family, which shows hepatoprotective effect and is used as folkloric medical practice to manage unknown liver diseases.Therefore, the extract of stem bark of B. malabarica Roxb.containing methane was tested with the antioxidant markers in liver tissues of Wistar albino rats.The biochemical analysis and the histopathological interpretations of liver expressed hepatoprotective activity of B. malabarica Roxb.stem bark [62].Herbal plants contain phenolic compounds with antioxidant properties reported to treat several diseases like diabetes mellitus, cancer, jaundice, and neurogenerative diseases [63].
Ghaffari, et al. examined multiple doses of methanol active fraction (MAF) and revealed considerably greater levels (p < 0.05) of antioxidant enzymes in liver homogenates.The histological study showed the complete neutralization of the carbon tetrachloride (CCl 4 )-induced liver injury by the extract.In vitro studies proved that the pre-treatment of MAF prohibited the H 2 O 2 -induced oxidative stress, genotoxicity, and expressively improved (~6-fold, p < 0.01) gene expression for the antioxidant enzymes.The Orthosiphon diffusus (Benth.)MAF confirmed the hepatoprotective activity contrary to CCl 4 -induced hepatotoxicity through antioxidant mechanisms similar to silymarin.The H 2 O 2induced oxidative stress was totally neutralized by MAF from improved gene expression for antioxidant enzymes.Additionally, Orthosiphon diffusus MAF is a robust applicant for improving herbal hepatoprotective agents [64].The various parts, especially flowers and fruits of Elaeagnus angustifolia L., have antioxidant properties, which can be used to treat various common illnesses like jaundice, cough, nausea, fever, asthma, and diarrhea [65].

Alzheimer's disease
Alzheimer's disease (AD) is a prolonged neurodegenerative disease that grows gradually and turns into a significant health-related disease worldwide.Clinically, cognitive declination and progressive dementia are the main features of AD, even though pathologically, amyloid beta (Aß) plaques and tau-neurofibrils are the symbols.Oxidative stress is a major risk factor that results in AD development.ROS can increase the structural and functional abnormalities in the glial cells of the brain resulting in cognitive decline and then dementia.Therefore, antioxidants showed effective results in controlling this oxidative stress in the glial cells.Vitamins A, E, and C show antioxidant action in treating AD [8].and the reversible interaction of A. vasica against AChE make them effective and promising agents for treating AD [67].

Hepatic diseases
Several drugs have been used to treat liver damage.However, the remedial effect of acute and chronic liver diseases was frequently not satisfactory.Still, many studies presented that herbal medicines play a vital part in dealing with hepatic disorders due to their potent antioxidant property [68,69].The extracts of lobelia can expressively decrease the stages of glutamic oxalic transaminase (GOT), glutamate-pyruvate transaminase (GPT), and malondialdehyde (MDA), along with the increase in the activity of SOD.This enhanced the free radical scavenging, reduced lipid peroxidation, and stabled cell membrane organization to safeguard the liver from acute liver injury in mice.However, more investigation is necessary to evaluate the pharmacological activity of the constituents and go to clinical trials of liver injury [70].

Vitiligo
Flavonoids, glutathione, resveratrol, soybean, and vitamins are the antioxidants in herbal medicines to treat vitiligo.The antioxidant property of plants helps to accelerate the repigmentation of cutaneous in patients suffering from vitiligo [72].
Biological activities related to managing skin diseases are divided into four classes: wound healing, antimicrobial, antioxidant activity, and anti-inflammatory.Drug development and herbal weeds act to treat skin ailments besides encouraging sustainable usage of natural sources [73].Cinnamaldehyde is the main chemical constituent of Cinnamomum zeylenicum Blume consists of two biological activities: an antioxidant effect mediated by Nrf2/ heme oxygenase (HO)− 1 signaling and inhibitory action on aryl hydrocarbon receptor (AHR) activation.Cinnamaldehyde helps to treat disorders allied to oxidative stress like acne, dioxin intoxication, and vitiligo [74].

Breast cancer
Herbal plants are used to manage cancer globally, as they have ease of availability and effective cost.Different combinations of active constituents existing in plant extract demonstrate synergistic action, increasing the therapeutic activity several folds, recompensing toxicity, and raising bioavailability.The recent work on herbal antioxidants revealed that the butanoic fraction of Arisaema tortuosum Wall.tuber demonstrated free radical scavenging action while chloroform and nhexane fractions of leaves considerably lead to in vitro anticancer perspective in contrast to breast carcinoma (MCF-7) cell.Therefore, it would be the cause of pharmacologically active chemical entities for revealing novel antioxidants and magic bullets.Still, detailed research is necessary to separate the phytoconstituents and recognize the systematic intracellular pathways responsible for diminishing oxidative stress [75].
Saraca indica L. of Caesalpiniaceae family has therapeutic and pharmacological activities.S. indica L. (SIE) extract showed anti-breast cancer and antioxidant activity.By toxicological studies, SIE is proven safe for use and used as a corresponding and substitute treatment for breast cancer treatment [76].
The rhizome of Cyperus rotundus L. of Cyperaceae family shows a broad spectrum pharmacological action comprising antioxidant and anti-inflammatory activity.Park et al. investigated that C. rotundus L. rhizomes have pro-apoptotic effects in breast carcinoma MDA-MB-231 cell lines.The MDA-MB-231 cells were treated with ethanol and methanol extract but not water extract, resulting in an effective antiproliferative property.Further, the ethanolic extract has more significant action in initiating apoptosis than methanolic extract [77].

Diabetes
The medicinal plants, herbs, and spices having antioxidant properties deal with the treatment of diabetes [78].Kalpaamruthaa (KA; comprising an equal ratio of Semecarpus anacardium Linn., Emblica officinalis Gaertn.and honey) improves the actions of enzymatic antioxidants as well as non-enzymatic antioxidants levels in the pancreas of cardiovascular disorders (CVD)-induced rats.This KA efficiently decreased the carbonyl and lipid peroxides content in the pancreas of CVD-induced rats.It reduced the cellular injury by enhancing the marker enzyme activities in the plasma, liver, and heart.Additionally, KA decreased the CVD by reducing the proteinase activated receptor (PAR)− 1 expression in the heart.Therefore, it plays defending role in type II diabetes by changing PAR-1 [79].
Juneja et al. reported that the hydroalcoholic extract (HAE) of Callicarpa arborea Roxb.stem bark contained hypoglycemic property (p < 0.05), showing antidiabetic action as compared to the normal control experimental rats group.HAE proved as safe and effective in doses up to 2000 mg/kg body weight of rat.Hence, the HAE of C. arborea Roxb.stem bark acts like herbal antioxidants to prevent and treat oxidative stress-induced diabetes mellitus.The presence of flavonoid and phenolic contents is accountable for the antidiabetic effect of C. arborea Roxb.stem bark [80].
Tiong et al. investigated the in vitro antidiabetic and antioxidant activity of various alkaloids of Catharanthus roseus (L.) leave extract.Four alkaloids, such as vindoline I, vindolidine II, vindolicine III, and vindolinine IV, were determined and isolated from dichloromethane extract (DE) of leaves.The DE and isolated compounds were not cytotoxic in pancreatic β-TC6 cells at the maximum dose of 25 µg/mL.These four alkaloids convinced more glucose acceptance in pancreatic β-TC6 or the myoblast C2C12 cells, including vindolicine III expressing maximum activity.Furthermore, the II-IV compounds revealed noble protein tyrosine phosphatase-1B inhibition action.Alkaloid vindolicine III indicated the maximum antioxidant ability in DPPH and ORAC assays.It reduced the H₂O₂-induced oxidative injury in β-TC6 cells at 12.5 µg/mL and 25 µg/mL concentrations [81].

Psychiatric disorders
Psychiatric disorders include insomnia, anxiety, stress, seizures, and epilepsy [82].These disorders, specifically neurodegenerative diseases, are due to oxidative and free radical induced stress [83].The antioxidant property of medicinal plants is one of the widely used approaches.The reduction of ROS and oxidative stress helps in the prevention of disease.Ginkgo biloba L. containing ginkgolides showed antioxidant and neuroprotective, including cholinomimetic activities.The efficiency of ginkgolides and Ginkgo extract in Alzheimer's disease has been found to be comparable to prescribed drugs like donepezil or tacrine.More significantly, Gingko does not show side effects.Various other plants like Melissa officinalis and Salvia officinalis have antioxidant, cholinergic, and memory-improving activities [84].
Phytoflavonoids show various valuable ameliorative properties on altered neurological illnesses by their antioxidant effect.Singh et al. investigated the effect of flavonoid-rich ethyl acetate fraction of crude fig (Ficus religiosa L.) extract combined with phenytoin on seizure harshness, depressing behavior, and intellectual shortage in pentylenetetrazol (PTZ)-kindled mice.The extract demonstrated the important antioxidant properties in different in vitro free radical scavenging assays.The combined administration of fraction (2.5, 5, and 10 mg/kg; i. p.) and sub-effective dosage of phenytoin (15 mg/kg; i.p.) in post kindled animals once a day till 15 days presented a dose-dependent reduction in the severity of seizure score, fewer mistakes, more stepdown potential in passive shock evasion model, and declined rigidity period in tail suspension experiment as in contrast with only phenytointreated group.The biochemical studies of tissue brain presented amelioration of reduced catalase and acetylcholinesterase (AChE) activities, reduced GSH levels, and thiobarbituric acid reactive substances (TBARS) by oxidative stress destruction.Authors found that flavonoidrich fraction of F. Religiosa L. has a defensive effect besides phenytoin sub-effective amount in cognitive shortage linked to PTZ-kindling and the depressing behavior include the oxidative stress reduction.It associates the requisite clinical assessment of flavonoid supplementation laterally through antiepileptic drugs (AEDs) to treat epilepsy, psychiatric and cognitive disorders [85].

Nanotechnology enabled nanocarriers containing herbal antioxidant
The fastest growing and most exciting research field is the development of colloidal nanoparticles (NPs).It shows a compelling impact on the development of nanotechnology over the past decades.The fabrication of nanoparticles through herbal extracts plays a vital role in nanotechnology.It is called green technology because it does not involve harsh chemicals.The central goal of green methods is to utilize harmless biomolecules like carbohydrates, DNA, enzymes, proteins, and plant extracts to produce biocompatible NPs; however, these biomolecules are somewhat costly, simply decomposable, and can be adulterated.
The Salvia miltiorrhiza Bunge (Danshen) stimulates blood circulation and represents worthy antioxidant action.Liu et al. demonstrated that formulations prepared by nanotechnology showed greater antioxidant bioactivities than the antioxidant properties of herbal plant-based formulations fabricated by traditional grinding techniques.Their results showed that active constituents in nanotechnology trials unconstrained faster as associated with samples powdered traditionally [86].

Metal nanoparticles
Silver (Ag) and gold (Au) NPs are two generally synthesized plasmonic NPs showing their unique inherent activities.AgNPs are active and worldwide accepted germicidal agents to several microbes.The preparation of AgNPs from plant extracts offers modest, one-step, and fast processes compared to other production methods.The extracts produced from different plant parts show their action as possible reducing and stabilizing agents used to produce AgNPs of different sizes and shapes.The extraction method employed differs based on the variety of content present in the extracts.The usage of plant extracts yields many advantages compared to other biomolecules (peptides, proteins, enzymes, and DNA).These are cheap, easily producible, and available.These are environmentally approachable NPs with the capability for large-scale production.Plant extract-directed NPs are used in many bioanalytical and biomedical uses as antioxidants, antimicrobial agents, diagnostic tools, anticancer agents, therapeutics, and drug delivery agents [87].
Y. Mishra et al.

Table 1
Structures and biological sources of phytoconstituents explored as prophylactic and therapeutic agents in the treatment of various diseases.

Biological source
Family Active constituent (s) Pharmacological activities

Shakeel et al. worked to determine the protective action of
Cinnamomum cassia (L.) bark-based titanium dioxide NPs (TiO 2 NPs) administered in rats.Subcutaneous injection of 150 mg/kg bodyweight of TiO 2 NPs or TiO 2 bulk salt along with the cinnamon extract indicated ameliorative properties of the antioxidant system, protecting characteristic histological injuries and certain hematological limits in the rat liver cured with TiO 2 NPs or bulk salt [88].
Nagaich et al. developed AgNPs by flavonoids of apple extract and incorporated them into hydrogels.The synthesized AgNPs were evaluated by UV spectroscopy, zeta potential, surface morphology, and particle size.AgNPs loaded hydrogels were tested for viscosity, physical appearance, spreadability, antioxidant studies by DPPH radical scavenging assay, pH, porosity, ex vivo permeation, in vitro release, and antibacterial activity on E. coli and S. aureus.Hydrogels showed 98.01 ± 0.37% in vitro release and 98.81 ± 0.24% ex vivo permeation in 24 h.The percent radical inhibition value was found to be 75.16± 0.04%, proving its great antioxidant property [89].
Barbinta-Patrascu et al. used a simple and eco-friendly bottom-up method to fabricate silver bio-nanostructures by Salvia officinalis L (sage) leaf extract.The sage showed bioreduction properties during AgNPs preparation, which was evaluated by UV-VIS and ATR-FTIR spectroscopy.To increase biocompatibility and stability, sage AgNPs were hosted in two liposomes, i.e., Chla-DPPC-and soybean lecithinlipid vesicles.X-Ray Fluorescence study proved the presence of silver in liposomes or sage-AgNPs biohybrids.Herbal AgNPs or liposomes bioconstructs stability was determined by zeta potential magnitude.Chla-DPPC or sage-AgNPs was a more stable biohybrid with a value of zeta potential − 34.2 mV.Antioxidant activity evaluation of silver bionanostructure was done by chemiluminescence assay.These advanced environmentally friendly silver phytonanostructures developed by saga extract marked robust 86.5-98.6%antioxidant activities [90].

Polymeric nanoparticles
The p-hydroxybenzyl alcohol (HBA), a herbal agent containing phenolic compounds, protects from diseases related to oxidation damage.Park et al. established a novel biodegradable peroxalate copolymer wherein HBA was incorporated chemically in its backbone.This HBAincorporated copolyoxalate (HPOX) was prepared by the condensation reaction of oxayl chloride and 1,4-cyclohexamethanol.It released active HBA by hydrolytic degradation.It was also dispersed in a single emulsion meant to prepare NPs of 500 nm diameter.The HBA NPs prevent the formation of nitric oxidase, which suppresses the inducible nitric oxide synthase (iNOS) in lipopolysaccharide (LPS)-activated RAW 264.7 macrophage cells.Moreover, HPOX NPs reduced the TNF-α production.The outstanding property of HPOX is the complete degradation of the polymer [91].
Using pH and heating-induced electrostatic adsorption techniques, the pectin coating was magnificently employed on NaCas/zein NPs.The pectin coating has not distressed the particle size and polydispersity index (PDI) of NaCas/zein NPs.Moreover, it intensely amended their physical strength in simulated gastrointestinal situations.Curcumin, an active constituent of Curcuma longa L., containing NaCas/zein NPs coated with pectin 490 boosted its antioxidant property in an aqueous medium and delivered controlled release in simulated gastric and intestinal fluids on oral delivery [92].
Novel rutin-loaded zein-sodium caseinate NPs were synthesized by using their antioxidant activity.The quantity ratio of zein for sodium caseinate, ethanol, and rutin expressively affect the physical features of zein NPs.The rutin-loaded NPs were found to be round with high encapsulation efficacy.The DPPH and ABTS assays showed 52.7% and 71.2% free radical scavenging activity.The total antioxidant capacity was found to be 0.40 nmol/g.Based on these results, zein-sodium caseinate NPs can be employed as a novel nano carrier system for rutin and other water insoluble active ingredients [93].

Solid lipid nanoparticles
Solid lipid nanoparticles (SLNs) are encouraging colloidal delivery systems, which help to deliver the herbal compounds to different organs, comprising the brain, through oral delivery.The extent of drug present in phytocompounds encumbered in SLNs was found to be around 5-10 times more than its native type.In addition, the controlled release of the bioactive compounds of herbs through oral delivery can be attained by surface alteration of the SLNs.This unlocks the path for improving different new phytocompounds loaded in SLNs to manage various chronic ailments [94].

Herbal Kudingcha nanoparticle
The Kudingcha NPs are spherical, having a size of 100-600 nm.The acute toxic effects proved that it is a harmless constituent.The Kudingcha NPs were more significant in dropping the body weight, adipose tissue, and fatty liver paralleled to plain Kudingcha.It is a powerful lipid-lowering agent that plays an essential part in managing hyperlipidemia and disease related to the fatty liver [95].

Carbon dots
The carbon dots (CDs) presented tremendous fluorescence intensity (in blue, red, and green filters), great photo-stability, and effectual multi-colored fluorescent emission depending on the excitation.The non-aqueous solvable curcumin is altered to extremely hydrophilic CDs.The passivation of the surface results in improving the rate and extent of drug and fluorescent activities.The passivated carbon dots (CDP) are spherical with a size below 10 nm.CDP is simple, economical, and effective.Depending on the cellular application and excitation, CDP showed outstanding multi-fluorescent properties, optical behaviors, and surface functionalization [96].
Sachdev and Gopinath worked on the green fabrication of CDs by leaves of Coriander sativum L. and represented their ability as a sensor, antioxidant, and bioimaging agent.Authors treated coriander leaves hydrothermally to prepare CDs and investigated their antioxidant properties [97].

Dendrimers
The combination of dendrimers with herbal antioxidants reveals the advancement of the drug delivery system (DDS) for cancer management.
The use of dendrimers in nanomedicine helps to reduce the inherent toxic effects of anticancer agents.Therefore, it enhances the treatment efficacy and patient compliance [98].The Chimeric advanced drug delivery nano systems (chi-aDDnSs) are defined as combined nanosystems with various biomaterials that have great potential as DDS.Alkannin and shikonin are hydroxyl naphthoquinones that occur naturally and have a fixed spectrum of antimicrobial, wound healing, antioxidant, anti-inflammatory, and currently recognized antitumor action.Kontogiannopoulos et al. worked on the three generations of hyperbranched aliphatic polyesters to form complexes using shikonin and liposomal Chi-aDDnSs.The authors observed drug encapsulation, drug release profile, and examined the physical stability of Chi-aDDnSs at 4 • C. Their results are encouraging and may be utilized to design in vivo experiments [99].
The structures of different phytoconstituents explored as prophylactic and therapeutic agents in the treatment of various diseases have been represented in Table 1.

Clinical trials
Clinical trial data have depicted the role of different herbs in the treatment of various pathological conditions.The details of completed, ongoing, and withdrawn clinical trials investigating the potential of herbals in treating a plethora of diseases are presented in Table 2.

Conclusion
Phytotherapy is safe and effective therapy based on traditional medicine.Anticancer drugs lead to nephrotoxicity by initiating oxidative stress, damage-associated molecular patterns (DAMPs) production, inflammatory processes, and cell apoptosis, whereas herbal plants and their products acts as to decrease the nephrotoxicity and side effects of anticancer drugs via their antioxidant and anti-inflammatory properties.Herbs or herbal medicines comprise the significant antioxidant property.More research is required to study the effects of antioxidant-rich herbs and spices based on oxidative-stress ailments.

Table 2
Clinical studies highlight the application of phytochemicals in the treatment of various diseases[113].

Table 2
(continued ) (continued on next page) Y. Mishra et al.