An Overview of Genus Zanthoxylum with Special Reference to Its Herbal Significance and Application

The plants of genus Zanthoxylum are effectually utilized in conventional and present-day medicine system to fight many diseases and disorders like pain, seizures, inflammation, cancer, liver and heart malady. Many of its plants—trees and shrubs, are citrus in nature, with curative antimicrobial, antihelminthic, antipyretic, and antiviral activities. More than 100 of its plant species have been identified and recorded for their potential as an herb in modern pharmacopeia. The species of this genus also have potent ethno-pharmacological significance. Many medicinal secondary metabolites like terpenoids, flavonoids, and alkaloids have also been profiled in many Zanthoxylum species. Additionally, fruit of many of the species is also significantly utilized as a major spice under the name “Sichuan pepper” in many countries like China and India. Thus, this unique blend of herb and spice characteristic of the genus needs a detailed description. This chapter highlights the major significant discoveries in the recent decade in this genus, which can add a step in the way of development of herbal medicines. Documentation of such medicinal plants may aid in derivation of plant-based medicines, which is the demand of the hour.


Introduction
Herbal or phyto-based medicines are in the mainstream of present pharmacological world [1].Nearly two-thirds of the medicines throughout the world is plant based, the rest being the conventional ones [2].The main reasons behind the preference of herbal drugs over the synthetic ones are that they have negligible side effects, are cost-effective, and easily available [3].Also, the knowledge of herbal sources has led to the formation of base for many modern medicines.Some examples mentioned by Vickers and Zellman [4] are aspirin taken from willow bark, digoxin from foxglove, and morphine from opium poppy.Many researchers have also stated the development of resistance to allopathic drugs after a long medicament leading to becoming ineffective [5].Thus, a documentation of medicinal plants and its herbal aspect becomes the first step toward a "botanical healing."

Zanthoxylum as herbal medicine in ancient pharmacology
Several species under Zanthoxylum genus have been used by various regions of the world since ancient times for benefits of mankind and their live stocks [5,30,31].Z. liebmannianum bark is used for removal of parasites in Mexico [32].For malaria, Z. rhoifolium, [33,34] and Z. acutifolium [5] have been preferred from this genus.Nyishi tribe of India utilizes Z. armatum fruit, seed and bark in a traditional "Honyur" mix to treat stomach disorder, fever, and cholera, respectively [10].Z. chiloperene var.angustifolium Engl. is also known as an antiparasitic agent in Paraguay [35].Z. integrifolium bark is utilized by YaMei and Lanyu indigenous tribes of Taiwan, to treat dyspepsia and fever [5].Freitas et al. [36] has reported antitumor and colitis-relief in Z. rhoifolium Lam.Z. monophyllum has found a place in the Venezulan medicine for treating jaundice, and ophthalmia [5].Roots of Z. zanthoxyloides have been used to treat sickle cell anemia [37].Z. alatum has been used for treatment of diabetes, toothaches, and abnormal cell growth [38].

Anticancerous activity
Z. leprieurii and Z. zanthoxyloides inhibits cancerous activity of leukemia (HL60) and (MCF7) breast cancer cell line [39].It also shows moderate anticancerous activity (MCF-7), liver (WRL-68), prostrate (PC-3) and colon (CACO 2 ) carcinoma cell lines [37].In another study, methanolic extract (ME) of the pericarp of Z. armatum revealed the presence of compounds ZP-amide A, C, D, E, hydroxyl α and β sanshool, and Timuramide A, B, C and D [9].All these compounds inhibited the growth of mouse glioma cells that were deficient of tumor suppressor genes NF1 homolog-Nf1, whereas only few compounds showed activity against cell lacking Trp 53-the genes responsible for encoding tumor suppressor gene p53, at a concentration that is nontoxic to the nontumor cells.Z. alatum Roxb.stem bark petroleum ether extract (PE) possesses various anticancerous lignans, namely sesamin, kobusin, and 4′0 demethyl magnolin [38].Out of which 4′0 demethyl magnolin, which is a novel compound, gave the best anticancerous output against lungs (A549) and pancreatic (MIA-PaCa) cancer cell lines, in comparison to the standard docetaxel.Z. armatum dried root ethyl acetate extract (EAE) (a good antioxidant) and its two components flavonoids, apigenin and kaempferol-7-O-glucoside, also possess an anticancerous trait against A-549, MIA-PaCa, MCF-7, and CACO 2 cancer colon cell lines [40].In an extensive study, the ME of leaf of Z. armatum induced apoptosis in cervical cancer cell lines (HeLA) at IC 50 (60 μg/mL) through Caspase 3-independent and extracellular signal-regulated kinases (ERK)-dependent mitogenactivated protein kinases (MAPK) apoptosis pathways [41].Karmakar et al. [42] demonstrated that at an IC 50 value of 102.30 μg/mL, the ME of the leaves of Z. armatum exhibited toxicity against Ehrlich Ascites cancer cells.The toxic effect was attributed to the presence of phenol and flavonoid compounds in the plant extract.Karmakar et al. [43] stated that the ME of leaves of this plant are capable of apoptosis by regulation of bcl-2/bax protein expressions and DNA damage in cancer cells and determined the presence of flavonoids, rutin, myricetin, and quercetin in the methanolic extract as potent anticancerous phytochemicals.Zanthonitrile [{4-[(3-Methyl-2-buten-1-yl) oxy] phenyl}acetonitrile] isolated from the leaves of the plant eluted by hexane: ethyl acetate solvent has a cytotoxic effect on Ehrlich Ascites Cancer cells with an IC 50 value of 57.28 μg/mL [44].Aqueous extract (AE) of Z. piperitum De Candolle fruit induces c-Jun N-terminal kinase autophagic cell death in colorectal (DLD-1), hepatocarcinoma (HepG2), and CACO 2 cancer cell lines but not in A549, MCF7, and colon (WiDr) cells [45].Alam et al. [46] demonstrated that ME and crude saponins from leaves, fruit, and bark of Z. armatum have a potential of exerting a cytotoxic effect on breast (MDA-MB-468, MCF-71) and colorectal cancer (Caco-21) cell lines using the mechanism of apoptosis.Another compound Tambulin, a flavonoid isolated from the fruit exhibited antiproliferative action on certain cancer cell lines like MCF-7, WRL-68, COLO-205, MDAMB-231, with an IC 50 ranging from 37.96 to 48.7 μg/mL [45].Three compounds isolated from Z. zanthoxyloides fruits ME, hesperidin, skimmianine, and sesamine, possess anticancerous activity up to some level against A549, MCF7, and PC3 cell lines [47].Pang et al. [48] confirms the anti-proliferative activity of seed oil of Z. bungeanum Maxim.on melanoma (A375) cells by arresting G1 phase and inducing apoptosis.Component analysis revealed the presence of unsaturated fatty acid in the seed oil.The EAE fraction of the fruit of Z. acanthopodium has been found effective for breast cancer cell line (T47D) toxicity [49].Another isolated compound scoparone, a coumarin from the fruit of Z. leprieurii, at an IC 50 of 44.93 μg/mL can be used to design anticancerous agents against human HepG2, with the least amount of toxicity to normal Chang liver cell lines [49].Fruit of Z. acanthopodium in n-hexane fraction is also, effectively anticancerous toward T47D cell line [50].The possible mechanism for this is cell cycle inhibition, apoptosis induction, and downregulation of cyclin D1 activity.Geranyl acetate is present in the highest percentage in the effective fruit n-fraction.

Neuroprotectant activity
Nakamura et al. [51] has reported that Z. bungeanum could reduce scopolamineinduced dementia.Gx-50, an isolate of Z. bungeanum could also aid in Alzheimer's disease, PE of the same plant can act as an antidepressant [52].This compound gx-50 has the ability to cross blood-brain barrier and stop the degradation of nerve cells.Qinbunamide isolated from pericarp of Z. bungeanum can activate the nerve growth factor to further activate neurite outgrowth at 20 μM concentration [53].Three alkaloids berberine, chelerythrine, and columbamine isolated from chloroform extract of Z. schreberi inhibit cholinesterase and butyrylcholinesterase [51].As these enzymes are responsible for breakdown of acetyl choline, their inhibition leads to increase in number of nerve messengers, especially helpful in case of Alzheimer's and myasthenia gravis.

Antiparasitic activity
Z. chiloperone leaves EO and one of its major component canthin-6-one, showed an inhibition of parasitic activity of Trypanosoma cruzi at 10 mg/kg of oral and subcutaneous dose in comparison to standard benznidazole (dose 50 mg/kg) [35].ME of Z. armatum seeds, at a concentration of 50 mg/mL induced paralysis in Pheretima posthuma (test model) in lesser time than the reference drug piperazine citrate (10 mg/mL) [54].Z. armatum methanolic leaves extract at the concentrations of 250-1000 μg/mL showed a moderate trypanocidal activity on blood parasite found both in humans and animals-Trypanosoma evansi in an in vitro condition utilizing mice cells as a model [28].Hexane bark extract of Z. heitzii acts as an inhibitor of P. falciparum at an IC 50 0.050 μg/mL [55].Dihydronitidine one of the major components of the extract also acts as an antimalarial compound at an IC 50 value of 0.0089 μg/mL [55].In another investigation, anti-leishmanial activity was seen in crude extract and its hexane fraction of Z. armatum fruit against Leishmania major [46].The essential oil (EO) of Z. monophyllum leaves also possess acute toxicity against larvae of Anopheles subpictus (LC 50 41.50μg/mL), Aedes albopictus (LC 50 45.35μg/mL), and Culex tritaeniorhynchus (LC 50 49.01μg/mL).Among its two major compounds Germacrene D-4-ol has better efficiency than α-Cadinol [56].Also, The EO, along with Germacrene D-4-ol, and α-Cadinol, EO has very low toxicity against Gambusia affinis, an eradicator of malarial larvae.Costa et al. [57], has reported antiparasitic activity of three noval compounds (5,7,8-trimethoxy coumarin, syringaresinol, and dictamine, isolated from the ethanol extract (EE) of roots of Z. tingoassuiba against Leishmania amazonensis and Trypanosoma cruzi, similar to positive control benznidazole and amphotericin.The larval stage of Schistosoma haematobium, a bladder cancer causing parasite can be successfully eliminated by acridone compound arborinine, isolated from fruit of Z. leprieurii at an IC 50 value of 6.98 μg/mL [57].

Antiviral activity
Z. coreanum root extract at an IC 50 of 1.0 μg/mL inhibited porcine epidemic diarrhea virus growth [5].Moreover Z. planispinum also exhibited the similar activity at an IC 50 of 6.4 and 7.5 μg/mL respectively.Patino et al. [5] also reported the anti-HIV activity of Z. ailanthoides, Z. integrifoliolum, and Z. scandens.

Insecticidal activity
Di-chloromethane extract of Z. usambarense bark displayed insecticidal activity against Masca domestica at 5000 g/ha, but its individual component could not produce any insecticidal results [70].The EO contained sabinene, D-germacrene, β-mycrene, β-elemene and γ-elemene.The larvicidal potential of EO and its constituent from the seeds of Z. armatum were screened against three mosquito species, Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus [15].Among these three species, C. quinquefasciatus showed the highest sensitivity at lowest concentration LC 50 and LC 95 at 49 and 146 ppm, respectively.However, linalool the most important constituent present at the maximum concentration (57%) in the EO failed to establish any significant larvicidal effect individually [15].Hieu et al. [76] revealed that mixtures of Z. armatum seed oil (ZA-SO) and its constituents either alone (0.2 mg/cm 2 ) or as a binary mixture (0.01 + 0.99 mg/cm 2 ) with An Overview of Genus Zanthoxylum with Special Reference to Its Herbal Significance… DOI: http://dx.doi.org/10.5772/intechopen.92459Calophyllum inophyllum nut oil (CI-NO) can be potential repellents against stable fly, Stomoxys calcitrans.An aerosol of the mixture (ZA-SO-2.5% + CI-NO-2.5%) was also found effective as a repellent of stable fly.Among all its constituents tested, only methyl cinnamate exhibited a significant effect [77].In a different study, three bioactive compounds-piperitone, myrtanol, and citronellal from Z. armatum seed oil were assessed for fumigant toxicity potency against stable fly with a simultaneous comparison of chlorpyrifos and dichlorvos, which are the organophosphorus insecticides [78].The fumigant toxicity potential of seed oil and all three compounds according to the vapor phase assay was high with LC 50 value 0.242-0.456μg/cm 3 , but their toxic level was five magnitudes below the organophosphorus insecticides, which reflects that Z. armatum may be further used as a bio-insecticide [78].Additionally, constituents of EO-cuminaldehyde citronellal, neral, linalool, linalool oxide, terpinen-4-ol, 1,8-cineole, and piperitone induced a significant repellent behavior in the stable fly [76].The in vitro insecticidal efficacy of the EE of the bark of the plant has been observed against mustard aphid Lipaphis erysimi at the concentrations of 0.5, 1.0, 1.5, and 2.0 mg/L [79].After 24 h of spray at a concentration of 2.0 mg/L, 100% mortality of the aphid was there, proving that Z. armatum may be a good insecticide [79].Nanoencapsulated EO of Z. rhoifolium leaves efficiently reduced the number of eggs and nymphs of Bemisia tabaci at 1-5% concentration [80].Out of 32 constituents identified from the EE of Z. armatum twigs, 1,8-cineole piperitone, and limonene in particular were efficient as an insecticide against Lasioderma serricorne and T. castaneum [81].While, in another study, the effect of Z. armatum leaves methanolic extract has been checked for antifeedant activity on the adults of "Red flour beetle"-T.castaneum [82].Another study stated the effects of n-hexane, EE, and ME of leaves of Z. armatum on Plutella xylostella, diamondback moth [83].In this investigation, the n-hexane fraction exhibited the best larvicidal activity at an LC 50 value of 2988.6 ppm.Moreover, two compounds, particularly 2-undecanone and 2-tridecanone identified from the n-hexane fraction of leaf extract of Z. armatum through GC-MS analysis, which may be responsible for the larvicidal activity [83].Egg laying capacity of Bemisia tabaci, a major tomato pest, can be reduced (85-98%) by using EO of Z. rhoifolium and Z. riedelianum at 1.0-2.0%concentration [84].

Hepatoprotective activity
Glycoprotein isolates of Z. piperitum DC fruit inhibited hypoxanthine/xanthine oxidase [87].It also decreased the level of lactate dehydroenase, thio barbituric acid, while increasing the level of antioxidant enzymes in carbon tetrachloride acute liver damage.The leaf EE of Z. armatum significantly decreased all the symptoms of hepatotoxicity in Wistar albino rats by normalizing the elevated levels of hepatic enzymes, which was induced by carbon tetrachloride [24].It induced hepatoprotective activity at a concentration of 500 mg/kg of body weight in comparison to standard drug silymarin at a dose of 100 mg/kg body weight.This effect was there due to the radical scavenging activity of the phytochemicals, especially flavonoids present in the plant [24].In a different study, the EE of bark of Z. armatum significantly expressed hepatoprotective activity at concentrations of 100, 200, and 400 mg/kg when administered orally in Wistar albino rats (where liver damage was instigated by paracetamol) by decreasing the levels of hepatic enzymes, bilirubin and at the same time increasing catalase, superoxide dismutase, and glutathione in comparison to silymarin [88].In a recent study the ME at a dose of 500 mg/kg exhibited successful hepatoprotective activity with 66.87, 64.84, 67.95, 60.76, and 65.85% protection on aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, total bilirubin, and total protein enzyme levels of the liver, respectively in Wistar rats [89].

Gastroprotective activity
Z. rhoifolium Lam.stem bark EE prevents the formation of gastric lesions at 125-500 mg/kg dose by increasing enzymes like catalase (reduces oxidative stress) and also mucous secretion, nitric oxide (repair of gastrointestinal tract injury) [36].It also helps in opening K ATP channel to control H + pump and acid secretion.Z. bungeanum pericarp extract reduces the level of TNF-α, IL-1β, and IL-12 to reduce the inflammation in J774.1 colon cells [90].Thus it can be utilized to treat ulcerative colitis.

Cardiovascular activity
Z. bungeanum EO at the concentration of 5, 10, and 20 mL/kg had a significant effect on deduction of cholesterol, hyperlipidemia, triglyceride, and low-density lipoprotein; it also aided in the induction of high-density lipoprotein [91].The EO of Z. bungeanum also helped in relaxation of contracted aortic muscles by reducing calcium influx via calcium channels [90].Z. armatum fruits hydroethanolic extract (dose administered-200 and 400 mg/kg body weight) succeeded in decreasing the elevated levels of cardiac diagnostic marker enzymes (aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, creatine kinase-MB, troponin-T), lipid profile and antioxidants (enzymatic and nonenzymatic), to normal conditions.The results were comparable to a positive control verapamil, expected phytochemicals are yet to be identified [92].

Zanthoxylum as spice
"Sichuan pepper" with its pungent odor and numbing taste belongs to the genus Zanthoxylum [93].According to Ji et al. [94] five species of Zanthoxylum-Z.armatum, Z. bungeanum, Z. shinifolim, Z. simulans, Z. piperitum, are commonly considered as "spice" species of the family.Not only seeds, fruit, leaves, bark, and even root of this genus is used as spice in China, Japan, and Korea [95].This pepper is used by the people of China to create a special "Mala" flavor, which literally refers to numbness and spiciness.More than hundred volatile compounds have been isolated, which are responsible for the unique spicy note and fragrance of this genus [96].Some nonvolatile compounds have also been identified like alkylamides (sanshools, capsaicin) and polyphenolic compounds [97].The genus has found a place in culinary as "five spice powder," in cosmetics, as well as in pharmaceutical too [98].In cosmetics, the variable fragrance provided by the genus-sweet, spearmint, herbal, floral, fruity, rose, citrus-is of great significance [99].This diversity is due to the presence of more than hundred volatile compounds like 1,8-cineole, 1-terpineol, 2,-nonenal, 2-tridecanone, α-elemol, α-pinene, β-pinene, geraniol, myrcene, neryl acetate, piperitone, rosefuran etc. [100].The pungent property of the spice of this genus has been attributed to the presence of α-, β-, γ-δ-sanshool and hydroxyl α and β-sanshool [99].In pharmacology the presence of polyphenolic compounds like flavonoids and glycosides make Sichuan pepper a good antioxidant and anti-inflammatory agent.Zhu et al. [98] has also reported the presence of antibacterial activity against both gram positive and negative bacteria in EO of Z. bungeanum fruit.EO of Z. shinifolium and Z. piperitum (broad spectrum) has been reported to have antiviral properties [94].Most significantly, Sichuan pepper and its component sanshool amide have displayed inhibitory action on the formation of hetercyclic amines, which are carcinogenic to humans in beef grilling procedure [11,101].Utilization of analytical techniques to compare component analysis is lacking in the literature related to spice knowledge of the genus.Also according to Ji et al. [94] if the effect of heat (while cooking) is elaborated on the spice and its individual compound, it would be more beneficial to the herb and spice world.

Conclusion and future perspective
Zanthoxylum genus is a stockpile of medicinal plants brewing with therapeutic properties, as gathered from the above references of the recent decade.The readers can benefit with the traditional and current knowledge on the herbal aspect of several species Z. acanthopodium, Z. acutifolium, Z. ailanthoides, Z. armatum, Z. bungeanum, Z. chalybeum, Z. chiloperone, Z. coreanum, Z. elephantiasis, Z. fagara, Z. flavum, Z. heitzii, Z. integrifoliolum, Z. leprieurii, Z. liebmannianum, Z. limonella, Z. martinicense, Z. monophyllum, Z. piperitum, Z. planispinum, Z. rhoifolium, Z. riedelianum, Z. scandens, Z. schinifolium, Z. schreberi, Z. tingoassuiba, Z. usambarense, Z. zanthoxyloides to name a few, of this genus.The information can form the basis of research regarding drug formulations, conservation of medicinal plants, pharmacokinetics, and new drug discoveries, which are plant based in the future.