NEPHROPROTECTIVE PLANTS

NEPHROPROTECTIVE PLANTS

Moona A Latheef MadhukkalHH, Sithara Ravindran

National College of Pharmacy, Manassery, Calicut

Cite this: Moona A Latheef Madhukkal, Sithara Ravindran, "NEPHROPROTECTIVE PLANTS", B. Pharm Projects and Review Articles, Vol. 1, pp. 700-745, 2006. (http://farmacists.blogspot.in/)

 

INTRODUCTION

Man and his domesticated animals have since the time immemorial been largely dependent on plants for the essential for their existence by way of food, clothing, shelter and medicines etc, besides various other uses.¹ Since disease, decay and death always coexisted with life, the study of diseases and their treatment must have also been contemporaneous with the dawn of the human intellect. The primitive man must have used as therapeutical agents and remedial measures those things which he was able to procure most easily. There is no authentic record of medicines used by the primitive man. But the Rigveda which is the oldest book in the library of man supplies curious information on the subject.

In his work on plants and animal under domestication, Darwin says "From innumerable experiments made through dire necessity by savages of every land, with the result handed down by tradition, the nutritious, stimulating and medicinal properties of the most of unpromising plants were probably first discovered."

The doctrine of signatures would all account for the use of several plants as medicinal agents. The reason for the extensive use of vegetable drugs may be the fact that plants are everywhere at hand, their number is very great and their focus are distinct and peculiar and these are procured without trouble.

It is greatly to the credit of people of India, that they were acquainted with a far large no. of medicinal plants than the natives of any other country on the face of the earth.² Many Indian fruits, grains and vegetables employed as useful dietary articles forms a chief factor in the cure of diseases, as well as preservation of health and good nutrition.³ Herbs have always been the principle form of medicine in India and they are becoming popular throughout the world, as people strive to stay healthy in the face of chronic stress and pollution and to treat illness with medicine that work in concert with the body's own defences. Thus medicinal plants play an important role in the lives of rural people.⁴ A plant is said to be medicinal when "at least one part possesses therapeutic properties."

One may recognize four stages in the development of the implements in the treatment of disease. In the first stage, crude drug were employed, prepared in the roughest manner, such as powered cinchona or metallic antimony. In the next stage, these were converted to more active and more manageable forms, such as extractions or solutions, watery or alcoholic. In the third stage, the pure active principles, separated from the crude drugs were employed Eg: morphine and quinine. In the 4^th stage, instead of attempting to extract out medicine from the natural products in which they are contained, such substances are synthesized which possess particular desired actions.² Medicinal plants have curative properties due to the presence of various complex chemical substances of different composition, which are found as secondary plant metabolites in one or more parts of these plants.

The purpose of pharmaceuticals research is to develop new drugs. The discovery of medicinal value of foxglove (Digitalis purpurea) is the case where traditional herbal knowledge led to major advance in medicine. Phytochemical investigations on plants have not only yielded many compounds of medicinal importance, but have also enriched our knowledge of the subject and understanding of natural products.

Ayurveda and siddha system of medicine, the traditional heritage of India include many true tested medicinal plants/drugs for various diseases and to which there is no answer in modern medicine till today.

Nephrology is indeed an ancient discipline with a noble and distinguished legacy that spans at least three previous millennia. A bronze artifact closely resembling the human kidney and dating to 1300BC was excavated from the ruins of the temple of kition and at least thirteen references to the kidney can be found in the old tastement. Before the time of the christ, Greek physicians prescribed botanical material to promote diuresis and employed blood letting and other means for removal of excess body fluids. Hyppocrates (460-375BC) was skilled in microscopic detail of urine analysis. Artaeus of Cappadoicia (30-90AD) and Galan (130-200AD) recognized kidney as the organ responsible for urine formation.⁵ By the middle of 1800, the structural complexity of mammalian kidney was revealed & unraveled through improved optics & microscopy. If a few names had to be chosen among the pioneers, we could mention Marcello Malpighi and Loreuzo Bellin in Italy & Antoine Ferrein in France for the birth of renal anatomy, Sir William Bowman in England & Karl Ludwig in Germany for renal physiology & Richard Bright in London & Pierra Rayer in Paris for the diseases of kidney. Kidney is an important excretory organ in the human body. The function of kidney is not only to excrete metabolic waste products, but also to maintain the acid base balance, endocrine function like erythropoietin production.⁶

Ancient literature has prescribed various herbs for the cure of kidney disease. The term "Pashanabeda" has been sited in literature to identify a group of plants, which have been extensively used in indigenous system of medicine to dissolve urinary calculi & stones. Eg: Aerva lanata, Crataeva nurvala, Pongamia prinnata etc. Some other plants mentioned in literature include T.terrestris, O.sanctum, Zea mays etc.

ANATOMY & PHYSIOLOGY OF KIDNEY

Figure. 1: Section of Kidney

Paired kidneys are reddish bean shaped organs about 10-12cm long, 5-7cm wide, 3cm thick and has a mass of 135-150g.¹⁰ The kidneys lie on the posterior abdominal wall, one on each side of vertebral column, behind the peritoneum and below diaphragm. They extend from the level of 12^th thoracic vertebrae to 3^rd lumbar vertebrae.⁹ Near the centre of concave boarder is a deep vertical fissure called the renal hilum, through which the ureter emerges from the kidney along with blood vessels, lymphatic vessels & nerves.

The kidney consists of two distinct region, outer renal cortex & inner renal medulla. The urine collects to calyx and then to renal pelvis which empties into ureter. The functional unit of kidney is nephron and there are about 1million nephron in each kidney.¹⁰

STRUCTURE OF NEPHRON

Figure.2: Nephron

It consists of a tubule closed at one end, and the other end opening into a collecting tubule. The closed end form Bowmann's capsule, which encloses the glomerulus.

The remaining parts of nephron is about 3cm long & consist of

• Proximal convoluted tubule (PCT)
• Henley's loop
• Distal convoluted tubule

These nephrons are packed tightly to make up the kidney parenchyma.⁹

FUNCTIONS OF KIDNEY

The main function of kidney can be categorized as

• Formation of urine
• Water & electrolyte balance
• Production of hormones & enzymes

In the resting adult, kidney receives 1.2-1.3litres of blood/min. In an adult, the GFR averages 120ml/min. The collecting duct of kidney is an area of fine control of ultrafiltrate composition & volume, where final adjustment in electrolyte composition is made by the action of mineralocortioid & ADH. The hypertonicity of medullary interstitium plays an important role in concentrating the urine. The kidney not only excretes the metabolic substances, but also toxic agents from the body.⁶ Hence kidney becomes one of the important targets for the toxicity of agents more than other organs in body. Factors that make kidney particularly prone to actions of nephrotoxicity include,

• High levels of toxins are delivered to the kidney's large blood supply.
• The large surface area of renal tubular epithelium provide site for toxin interaction & uptake.
• The availability of specific transport mechanisms that mediate cellular uptakes.
• The normal concentrating mechanism of kidney can increase concentration of toxins.

The presence of the metabolic processes in the renal tubular cell, can release toxic components & induce damage.

RENAL FAILURE

The term renal failure primarily denotes failure of the excretory function of kidney, leading to the retention of nitrogenous waste products of metabolism in blood. In addition, there is failure of regulation of fluid & electrolyte balance along with endocrine dysfunction.⁷ The renal failure is fundamentally categorized into acute renal failure & chronic renal failure.

ACUTE RENAL FAILURE

Acute renal failure is characterized by azotemia that progresses rapidly over several hours or days. It may or may not accompanied by oliguria & there is a sudden & reversible loss of renal function.

Fig.3 Histopathology of kidney with ARF Fig.4. Histopathology of normal kidney

Early recognition of ARF is critical, because it is often asymptomatic. It is detected by measuring serum creatinine level & is more specific than measurement of blood urea nitrogen (BUN). There are many causes of ARF which could be,

Pre renal ARF

It is due to under perfusion of kidney. It accounted for 21% of ARF cases. It can be thought of as "a good kidney looking at a bad world." It is quickly reversible with appropriate therapy.

Post renal ARF

It is caused by obstruction of urinary tract. It accounted for 10% of cases.

Intrinsic ARF

It is due to disease in parenchyma. It accounted for 69% of cases. Among the renal causes of acute renal failure, acute tubular necrosis is more common accounting for 85% of incidence. ATN occurs due to either ischaemia or toxins. The toxins can be either exogenous or endogenous. The exogenous agents are radiocontrast agents, cyclosporins, antibiotics, chemotherapeutic agents, organic solvents, acetaminophen, & illegal abortifacients.⁷

CHRONIC RENAL FAILURE

It is a syndrome characterized by progressive & irreversible deterioration of renal due to slow destruction of renal parenchyma, eventually terminating in death when sufficient no. of nephrons have been damaged.⁸ Various causes are glomerulonephritis, diabetes mellitus, chronic pyelonephritis, hypertension.⁹ antineoplastic agents like cyclophosphamide, viniristne, cisplatin etc.⁷

NEPHROTOXIC AGENTS

Drugs, diagnostic agents & chemical are well known to be nephrotoxic. The following are some of the important nephrotoxic agents.¹¹

A) Heavy metal

Mercury, arsenic, lead, bismuth

B) Antineoplastic agents

Alkylating agents

Cisplatin, cyclophosphamide

Nitrosoureas: Streptozotocin, Carmustine, Lomustine & Semustine

Antimetabolites

High dose Methotrexate, Cytosine Arabinose, high dose 6-thioguanine, 5-flurouracil

Antitumour antibiotics

Mitomycin, Mithramycin, Doxorubicin

Biologic agents

Recombinant leukocyte and interferon

C) Antimicrobial agents

Tetracycline, Acyclovir, Pentamidine, Sulphadiazine, Trimethoprin, Rifampicin

AmphotericinB

D) Aminoglycosides

Gentamicin, Amikacin, Kanamycin, Streptomycin

E) Miscellaneous

Radiocontrast agents

Non-steroidal anti-inflammatory agents: Ibuprofen, Indomethacin, Aspirin etc

NEPHROPATHIES
DUE TO TOXIC MECHANISM

Toxins may directly affect membrane permeability. Eg: with amphotericin & polyene antibiotics. They can act by increasing the activity of membrane phospholipase & by inhibiting normal reconstruction of the membrane. Phospholipid degradation products, lysophospholipids & free fatty acids have membrane detergent properties. Even in the absence of major changes in membrane permeability, the failure of plasma membrane pumps will cause potential injury changes in the cation homeostasis of the cell eg: Na-K-ATPase & Ca ATPase pumps. The activity of each may be affected by limitation of ATP, compromise of function of enzyme protein or changes in the phospholipid microenvironment surrounding the enzyme.¹² Toxin may also lead to remodelling of the surface of the renal tubular cell, thus changing the area available for transportation.

Numerous experiments have shown during cellular insult, an early and common change is the accumulation of intracellular Calcium. This increase is found at plasma membrane, in mitochondria and endoplasmic reticulum & in cytoplasm. An increase in intracellular Ca can modify the permeability of internal membrane of the mitochondria & thus change in the electrochemical gradient across it, which decreases the oxidative phopsphorylative capacity of the mitochondria. Disordered permeability will then lead to loss of enzymes & nucleotides.¹²

In rats given gentamicin, the appearance of cellular necrosis & renal failure is well so related with an increase in Ca in renal cortex & mitochondria. The intracellular metabolism of drugs leads to the formation of reactive metabolites, which are toxic for cell, as are free radicals. The superoxide ion normally formed, during oxidation forms hydroxyl radicals, which lead to lipid peroxidation. This inturn causes oxidative deterioration of polyunsaturated lipids of membranes & causes the dramatic modification of structure & function. The toxic agent reduces the concentration of antioxidants, superoxide dismutase, glutathione, catalase, vit.E, ascorbic acid which are the protective tissues that reacts & remove reactive oxygen species.⁴ Nephrotoxin induced changes in tubule cells integrity may be sublethal or lethal. Such prelethal changes include development of abnormally enlarged lysosomes & myeloid bodies, loss of brush border membrane & vacuolization & dilation of the endoplasmic reticulum. Enzymuria resulting from loss of some of these damaged membranes in the urine has been used to gauge the occurrence of renal tubule cell injury & to follow it serially.¹¹

TOXIC ACTIVATION AND FREE RADICAL PRODUCTION

Numerous in
vivo & in vitro studies have demonstrated the effect of free radicals like reactive oxygen metabolites viz. superoxide, hydroxyl ions & hydrogen peroxide which are important mediators of tissue injury. Free radicals can be defined as chemical species possessing unpaired electrons, which are formed by hemolytic cleavage of a covalent bond of a molecule, by loss of a single electron from a normal molecule or by the addition of a single electron to a normal molecule. Free radicals may be positively charged (cation radical), negatively charged (anion radical) or neutral These free radicals have very short half-life, high reactivity & damaging activity towards macromolecules like proteins, DNA & lipids. These species may be either oxygen derived reactive oxygen species (ROS) or nitrogen derived reactive nitrogen species (RNS). ROS includes superoxide, hydroxyl, hydroperoxyl, peroxyl, alkoxyl as free radicals & hydrogen peroxide, hypochlorous acid, ozone & singlet oxygen as non-radicals. The RNS are mainly nitric oxide, peroxynitrile, & nitrogen dioxide & dinitrogen trioxide. Free radical injury & oxidative stress have been implicated in many renal diseases like acute renal failure, IgA nephropathy, anaemia of chronic renal failure & ischaemic kidney.

Superoxide ion & hydroxyl radical are formed during natural oxidative reaction by the action of endoplasmic recticulum, mixed function oxidases, NADPH oxidases, xanthine oxidases etc. The hydroxyl radical is highly reactive species formed by process of Fenton's reaction .The hydroxyl radical can also be formed from oxidative metabolism of arachidonate by cyclooxygenase in the presence of hydroperoxides.⁴

Many studies have shown that infusion of ROS from a chemical or cellular origin produces glomerular dysfunction & injury to mesangial or endothelial cells with associated altered golmerular permselectivity (protienuria). H₂O₂ perfusion via renal artery can produce mesangiolysis & endothelial cell detachment.¹³

FORMATION OF FREE RADICAL

Free radical can be formed in three ways:

• By hemolytic cleavage of covalent bond of a normal molecule, with each fragment retaining one of the paired electrons.
• By loss of single electron from normal molecule.
• By addition of a single electron to a normal molecule.¹⁴ They are constantly generated in vivo.

PRODUCTION OF FREE RADICALS IN CELLS

Free radicals are produced by¹⁵

• Ionising radiation.
• Accidental or deliberate
• Some enzymes utilize free radicals at their at their active sites in the process of catalysis. Activated phagocytes also deliberately generate free radicals such as superoxide.
• These are produced by the leakage of electron transport chain such as those in mitochondria & Endoplasmic reticulum.
• Metabolities of certain compounds exert toxicity through free radical mechanism eg.Carbon tetra chloride is metabolized to toxic trichloromethyl free radicals by CYP 450 in liver.¹⁴
  

CISPLATIN TOXICITY

Cisplatin is a potent anticancer drug. It is used intensively in man, being effective in ovarian & bladder carcinoma, neuroblastoma & head & neck carcinoma, & lymphoma as well as thyroid endometrial neoplasm. However the most significant activity is observed in testicular cancer. The clinical use of cisplatin is often complicated by nephrotoxicity Ototoxicity, gastrointestinal disturbances like nausea, vomiting & myelosuppression. Early clinical trials of cisplatin in cancer patients showed a striking incidence of persistent azotaemia & acute renal failure.

Cisplatin infusion at a dose of 20-mg/m² over 4hr caused an increase in the filtration fraction & decreased glomerular filtration rate. (offerman 1984). Nephrotoxicity is importantly modulated as a result of biotrasformation. Tubular dysfunction has also been demonstrated very early after cisplatin administration. The predominant pattern of injury include

• Focal areas of tubular necrosis
• Desquamation of necrotic epithelial cells
• Necrotic cells with swollen mitochondria
• Cell membrane rupture with subsequent vesicle formation
• Necrotic debris filling the tubular lumens.
• Loss of brush border
• Nuclear condensations.

Cisplatin has site-specific nephrotoxic effect on the proximal tubule of the rat. Three distinct segments S₁, S₂, S₃ been
described
for the proximal tubule of the rat by a number of investigators. A focal loss or thinning of the microvillus
brush border was evident at all levels of microscopy. In some cells the brush border was completely obliterated with only a few microvilli remaining. The cytoplasm of many cells appeared condensed. Clumping of nuclear chromatin & increased number of cytoplasmic vesicles could be seen in many of the injured cells. Other cells appeared to round up & lose their normal orientation & often protruded into the tubular lumen. Completely necrotic cells were evident & could be seen sloughing into the tubular lumen. In some areas, only a bare basal lamina remained. Cells adjacent to these areas appeared to flatten out & send long thin cytoplasmic process out to reline the basal membrane.

MECHANISM OF ACTION OF CISPLATIN INDUCED RENAL TOXICITY

The exact mechanism of cisplatin nephrotoxicity is unclear. Experimental studies have shown that there is an abrupt fall in the effective renal plasma flow within 3 hrs of the i.p. dose of cisplatin. It is known to be filtered by the glomeruli & concentrated in the glomerular filterate from which it is activated in the presence of a low intra cellular chloride concentration. The low intracellular concentration of chloride facilitates the displacement of chloride by the water molecule yielding a positively charged, hydrated & hydroxylated complex. Hydration of cisplatin induces formation of monochloro monoaquodiamino platin or diaquo diammineplatin. These agents alkylate the purine & pyrimidine bases of nuclear material.¹² Renal damage is seen in proximal tubular S₃ portion, the distal tubule & collecting duct.

Other proposed explanation of the nephrotoxicity of cisplatin include the possibility that it include generate reactive metabolites that bind covalently to tissue macromolecules. The nephrotoxic effects might also be due to sulphydryl binding of heavy metal. A reduction in sulphydryl groups in the rat renal cortex has been demonstrated; this occurred before any significant change in renal function could be detected, suggesting that this biochemical change may be a primary event. Cell fractionations have shown that the greatest decline of sulphydryl groups occurs in the mitochondrial & cytosol fractions; these also had the highest concentrations of platinum.¹² A recent study found that cisplatin induced proximal tubule injury could be ameliorated by the administration of hydroxylradical scavengers. In these studies cisplatin (5mg/kg BW) caused lipid peroxidation. The hydroxyl radical scavenger prevented acute renal failure by altering tubule damage & enhancing the regenerative response of damaged tubule cells protection from cisplatin toxicity has generally focused on providing free radical scavengers.⁴

AMINOGLYCOSIDE INCLUDED NEPHROTOXICITY

Aminoglycoside antibiotics including gentamicin are widely used in the treatment of gram-negative infections. However the major complication of the use of these drugs is nephrotoxicity, accounting for 10-15% of all cases of acute renal failure. The nephrotoxicity of gentamicin is well established in man & experimental animals. Renal tubular cell injury produced by gentamicin evolves subacutely over several days & is characterized by following

• Cellular necrosis
• Large lysosomes & myeloid bodies
• Mitochondrial structural alteration like swollen & ruptured mitochondria,
• Accumulation of gentamicin in renal proximal convoluted tubules.
• Suppression of free radical defence mechanism
• Phospholipidosis

The first step involved in the pathogenesis is the transport of the drug into proximal tubular cells where they become concentrated & where they exert their toxic influence. The second step involves the deleterious interaction of these agents with one or more intracellular metabolic processes, which ultimately is expressed as a depression of renal function. With regard to gentamicin, chronic exposure of cultured fibroblast to high levels of gentamicin, lead to accumulation of the antibiotic within lysosomes accompanied by inhibition of lysosomal sphingomylinase & a marked generalized phopholipidosis. The development of large lysosomes & myeloid bodies during gentamicin nephrotoxicity has been well documented and inhibition of kidney sphingomyelinase has been reported. Gentamicin induces inhibition of renal cortical mitochondrial oxidative phosphorylation before histological evidence of severe proximal cellular damage. There is significant reduction in whole kidney ATP levels, ADP dependant and dinitrophenol (DNP) uncoupled respiration.¹⁶ Gentamicin treatment in vivo increased renal cortical MDA levels decreased the total glutathione, increased the GSSH/GSH ratio, sharply reduces levels of esterified arachidonic acid and induced a generalized shift from polyunsaturated fattyacids. Gentamicin also decreased the activities of catalase & SOD.¹¹

MECHANISM OF ACTION OF GENTAMICIN INDUCED RENAL TOXICITY

Gentamicin binds to the receptors located on the apical membrane of proximal tubular cells. It is postulated that gentamicin being a cationic drug binds to the anionic phosphoinositides located on the apical membrane. The binding of drug receptor is followed by pinocytosis of the drug-receptor complex to a secondary lysosome. Within the lysosome, gentamicin might interfere with the catabolism of receptor by directly inhibiting phospholipase C, by modifying substrate-enzyme affinity or by raising the intralysosomal pH above the effective range of enzyme. Inhibition of the activity of lysosomal phospholipase C leads to the accumulation of phosphotidylinositol rich myeloid bodies within lysosomes leading to phospholipidosis.

AMELIORATION OF NEPHROTOXICITY

Antioxidant defence against ROS injury

Antioxidants are classified into 3 groups

• Enzymatic antioxidants
• Vitamins
• Miscellaneous

Enzymatic antioxidants

Enzymes are the basic natural protectives of the organism against oxygentoxicity(burk80)

Eg: Superoxide dismutase, catalase, glutathione reductase, glutathione peroxidase, G6PD.

Vitamins

These form another group of natural antioxidants

Eg: vit. A,C,E & K

Miscellaneous

Some other compound may also function as antioxidants

Eg: Uric acid, beta-carotene, bilirubin, albumin, retinol, flavonoids and other phenolic compounds of plant origin like curcumin dehydrozingerone, eugenol, isoeugenol.

An intricate system has evolved in respiring cells to prevent ROS causing injury. Two SODs are known that catalyse dismutation of superoxide to hydrogen peroxide cytoplasmic (copper & zinc) and mitochondrial (manganese) forms. Hydrogen peroxide is dealt with catalase containing enzyme present in peroxisomes, and by cytoplasmic glutathione peroxidase, a seleno enzyme which catalyses the reaction of glutathione disulphide. The glutathione disulphide is reduced back to glutathione by an NADPH dependant enzyme, glutathione disulphide reductase.

A number of non-enzymatic defences against oxidant injury are available to the cell such as alpha tocopherol, ascorbate, ceruloplasmin & the heat shock protein family. Melatonin, a pineal hormone with antioxidant property, protects against Gentamicin-Induced nephrotoxicity. It inhibits lipid peroxidation, restores the antioxidant levels & also regulates calcium channels.

The protective effect of sodium chloride has been shown in many experimental models of acute toxic renal failure. For cisplatin ,glycerol, mercuric chloride & uranyl nitrate, a high-salt diet is more protective than a normal diet. Sodium chloride may decrease the activity of the rennin-angiotensin system.¹²

Diuretics have been also prescribed to prevent the appearance of acute renal failure. Mannitol was the first to be used. It has been reported to ameliorate Amphotericin B & gentamicin nephrotoxicity. It prevents an increase in urea & blood creatinine concentration, but does not modify the intensity of the microscopic lesions.¹²

Flavanoids are phenolic compounds widely distributed in fruits, vegetables, plant extracts as well as plant derived beverages Eg : tea & red wine. These have generated interest because of their broad pharmacological effects such as vasoprotective, anti-inflammatory, antiviral & antifungal actions. Many of these affects are related to their antioxidant properties, which may be due to their ability to scavenge free radicals & to synergestic effects of other antioxidant. Another mechanism not yet extensively studied, may result from interaction between flavanoid & metal ions (esp iron & copper) leading to chelates. For Eg: it has been reported that concomitant administration of quercetin with cisplatin showed considerable decreases in levels of marker for nephrotoxicity & lipid peroxide & increased ATPase activities compared to CDDP treated group. Glutathione content & antioxidant enzyme activities were significantly increased.

ANIMAL MODELS USED IN EXPERIMENTAL STUDIES

IN VIVO MODELS

• GM treated albino rat
• Cisplatin treated albino rats
• Cisplatin treated rabbits
• GM treated guinea pigs
• Mercuric chloride treated mice
• Ethylene glycol treated mice

IN VITRO MODELS

• Vero cells

PLANT SHOWING NEPHROPROTECTIVE ACTIVITY

1 EFFECT OF Aerva lanata ON GENTAMICIN & CISPLATIN MODELS OF ACUTE RENAL FAILURE¹⁷

The ethanol extract of entire plant of Aerva lanata was studied for its nephroprotective activity in cisplatin & gentamicin induced acute renal injury in albino rats of either sex. In the curative regimen, the extract at dose levels of 75,150 & 300mg/kg showed dose dependant reduction in the elevated blood urea and serum creatinine & normalized the histopathological changes in the cisplatin model. In the gentamicin model, the rats in the preventive regimen also showed good response to the ethanol extract at 300mg/kg. The findings suggest that the ethanol extract of Aerva lanata possesses marked nephroprotective activity with minimal toxicity and could offer a promising role in the treatment of acute renal failure caused by nephrotoxins like cisplatin & gentamicin.

2 PROTECTIVE EFFECT OF Pongamia pinnata FLOWERS AGAINST CISPLATIN & GENTAMICIN INDUCED NEHROTOXICITY IN RATS¹⁸

When ethanolic extract of flowers of Pongamia pinnata (300 &600mg/kg) was administered orally in rats followed by cisplatin (5mg/kg ip), toxicity of cisplatin as measured by loss of body weight, elevated blood urea & serum creatinine declined significantly. Similarly in gentamicin (40mg/kg sc) induced renal injury, the extract 600mg/kg normalized the raised blood levels of urea & serum creatinine levels. Reversal of cisplatin & gentamicin renal cell damage was confirmed on histopathological examination. The results suggested that the protective effects is through antioxidant property of two flavonoids kaempferol and 3,5,6,7,8-penta methoxy flavone.

3 Salviae radix EXTRACT PREVENTS CISPLATIN INDUCED ACUTE RENAL FAILURE IN RABBITS¹⁹

The present study was carried out to determine if Salviae radix extract (SRE) exerts a beneficial effect against cisplatin induced renalfailure in rabbits. Rabbits were pretreated with SRE orally followed by cisplatin injection (5mg/kg ip). Cisplatin injection caused a reduction in GFR, which was accompanied by an increase in serum creatinine levels. The fractional Na⁺ excretion and lipid peroxidation were also increased. All these changes were prevented by SRE pretreatment. Cisplatin treatment invitro in renal cortical slices increased LDH release and lipid peroxidation, which were prevented by SRE and its effect may be attributed to its antioxidant action.

4 PROTECTIVE EFFECT OF GYCYRRHIZIN ON GENTAMICIN INDUCED ACUTE RENAL FAILURE IN RATS²⁰

The effects of glycyrrhizin (200 mg/kg/day) on renal function in association with the regulation of aquaporin 2 water channel in rats with gentamicin (100 mg/kg/day)-induced acute renal failure was investigated. Polyuria in rats with gentamicin-induced acute renal failure was associated with down-regulation of renal aquaporin 2 in the inner and outer renal medulla, and cortex. Glycyrrhizin administration restored the expression of aquaporin 2 with paralleled changes in urine output. Changes in renal functional parameters, such as creatinine clearance, urinary osmolality, and solute-free reabsorption, accompanying acute renal failure were also partially restored after administration of glycyrrhizin. Histological changes in rats with gentamicin-induced acute renal failure were also abrogated by glycyrrhizin treatment. The above results suggest that glycyrrhizin treatment could ameliorate renal defects in rats with acute renal failure induced by gentamicin.

5
Ginkgo biloba EXTRACT AMELIORATES GM INDUCED NEPHROTOXICITY IN RATS²¹

The effect of Ginkgo biloba (EGb), a plant extract with an antioxidant effect, has been studied on gentamicin-induced nephrotoxicity in male wistar rats. Ginkgo biloba extract (300 mg/kg BW) was administered orally concurrently with gentamicin (80 mg/kg BW). Estimations of urine creatinine, glucose, blood urea, serum creatinine, plasma and kidney tissue MDA were carried out after gentamicin treatment. Kidneys were examined using histological techniques. Blood urea and serum creatinine were increased with gentamicin. Creatinine clearance was significantly decreased with gentamicin. Changes in blood urea, serum creatinine and creatinine clearance induced by gentamicin were significantly prevented by Ginkgo biloba extract. There was a rise in plasma and kidney tissue MDA with gentamicin, which were significantly reduced to normal with Ginkgo biloba extract. Histomorphology showed necrosis and desquamation of tubular epithelial cells in renal cortex with gentamicin, while it was normal with Ginkgo biloba extract. These data suggest that supplementation of Ginkgo biloba extract may be helpful to reduce gentamicin nephrotoxicity.

6 EFFECT OF Cassia auriculata ROOT EXTRACT ON CISPLATIN & GM INDUCED RENAL INJURY²²

The ethanol extract of the roots of Cassia auriculata was studied for its nephroprotective activity in cisplatin- and gentamicin-induced renal injury in male albino rats. In the cisplatin model, the extract at doses of 300 and 600 mg/kg body wt. reduced elevated blood urea and serum creatinine and normalized the histopathological changes in the curative regimen. In the gentamicin model, the ethanol extract at a dose of 600 mg/kg body wt. reduced blood urea and serum creatinine effectively in both the curative and the preventive regimen. The extract had a marked nitric oxide free-radical-scavenging effect. The findings suggest that the probable mechanism of nephroprotection by C.auriculata against cisplatin- and gentamicin-induced renal injury could be due to its antioxidant and free-radical-scavenging property.

7 AGED GARLIC EXTRACT ATTENUATES GM INDUCED RENAL DAMAGE AND OXIDATIVE STRESS IN RATS²³

Aged garlic extract (AGE), an antioxidant, has a protective role in this experimental model of male Wistar rats were studied. AGE was given at a dose of (1.2 mL/kg/12 hours) followed by GM (70 mg/kg/12 hours). Nephrotoxicity was made evident by:

1) the increase in blood urea nitrogen and plasma creatinine

2) the decrease in plasma glutathione peroxidase (GPx) activity and the urinary increase in N-acetyl-beta-D-glucosaminidase activity and total protein

3) necrosis of proximal tubular cells

4)increase in the renal levels of oxidative stress markers: nitrotyrosine and protein carbonyl groups and the decrease in manganese superoxide dismutase (Mn-SOD), GPx, and glutathione reductase (GR) activities.

These alterations were prevented or ameliorated by AGE treatment. Furthermore, AGE prevented the GM-induced The protective effect of AGE was associated with the decrease in the oxidative stress and the preservation of Mn-SOD, GPx, and GR activities in renal cortex. These data suggest that AGE may be a useful agent for the prevention of GM-nephrotoxicity.

8 THE EFFECTS OF Nigella sativa OIL ON GM NEPHROTOXICITY IN RATS²⁴

In this work, tested whether oral treatment of rats with N. sativa oil (0.5, 1.0 or 2.0 ml/kg/day) would ameliorate nephrotoxicity of GM (80 mg/kg/day im) concomitantly with the oil. Nephrotoxicity was evaluated histopathologically and by measurement of concentrations of urea, creatinine and total antioxidant status (TAS) in plasma and reduced glutathione (GSH) and TAS in kidney cortex. The results indicated that GM treatment caused moderate proximal tubular damage, significantly increased the concentrations of creatinine and urea, and decreased that of TAS and GSH. Treatment with N. sativa oil produced a dose-dependent amelioration of the biochemical and histological indices of GM nephrotoxicity that was significant at the two higher doses used, and it increased GSH and TAS concentrations in renal cortex and enhanced growth. The results suggest that N. sativa may be useful in ameliorating signs of GM nephrotoxicity in rats.

9 FLAVONOID OF Drynaria fortunei PROTECTS AGAINST ARF²⁵

The flavonoid fraction (FF) from Drynaria fortunei was investigated to determine its biological activity expression in three acute renal failure animal models Guinea pigs & mercuric chloride treated mice. Guinea pigs received 100 mg/kg of gentamicin & 10 mg/kg of FF. FF treatment prevented the GM toxicity, ie; the increase in BUN and creatinine levels. Mice were treated once with 6 mg/kg of mercuric chloride, followed by 10 mg/kg of FF. BUN and creatinine levels were found to be significantly higher on the mercuric chloride treatment and is ameliorated by FF treatment. In conclusion, the present study suggests that FF prevents nephrotoxicity, improves kidney function and promotes kidney primary epithelial tubular cell regeneration.

10
THE ROLE OF GINSENOID-Rd IN CISPLATIN INDUCED ARF²⁶

Ginsenoside-Rd has been proved to decrease the severity of renal injury induced by cisplatin, in which proximal urinaferous tubules represent the main site of injury. When ginsenoside-Rd was given orally at a dose of 1 or 5 mg/kg body weight/day prior to cisplatin injection, the activities of the antioxidation enzymes superoxide dismutase and catalase were higher, while malondialdehyde levels in serum and renal tissue were lower in the treated rats than in the controls. The levels of urea nitrogen and creatinine in serum were decreased in rats given ginsenoside-Rd. Decreased urinary levels of glucose, sodium and potassium reflected a protective action against the renal dysfunction caused by cisplatin. In addition, it was demonstrated that ginsenoside-Rd affected cultured proximal tubule cells exposed to cisplatin.

11 NEPHROPROTECTIVE ACTION OF Tribulus terrestris AND Crataeva nurvala IN ALBINO RATS²⁷

Nephrotoxic model was developed in male albino rats by administering GM. The aqueous extract of fruits of T.terrestris (65 or 130mg/kg) and C.nurvala (70 or 145mg/kg) after GM administration. Urine was examined for sugar, albumin, RBC & epithelial cells. Histopathological changes were also noted. The drug showed a dose dependant nephroprotective action against GM toxicity. The results indicate that the two indigenous plants would ameliorate renal effects in albino rats with acute renal failure induced by GM.

12 EFFECT OF Ocimum sanctum AQUEOUS LEAF EXTRACT ON GM INDUCED NEPHROTOXICITY IN RATS²⁸

Nephrotoxicity was induced in rats by GM (180mg/kg/day ip). O.sanctum aqueous leaf extract (OS) was given orally at a dose of 100 mg/kg/day along with GM. Concurrent administration of OS significantly prevented rise in levels of serum creatinine, blood urea & plasma MDA which elevated by GM. It also significantly prevented the histological damage caused by GM. The results suggested that OS probably by virtue of its antioxidant property prevented GM induced nephrotoxicity in rats.

13 THE EFFECT OF TREATMENT WITH THE MEDICINAL PLANT Rhazya stricta ON GM INDUCED NEPHROTOXICITY²⁹

Crude water extract of R. Stricta leaves (0.25, 0.5 and 1 g/Kg) was given orally to rats and thereafter, concomitantly with GM (80 mg/Kg/day). Nephrotoxicity was evaluated histopathologically and biochemically by measuring the concentrations of urea and creatinine in serum, reduced glutathione (GSH), lipid peroxidation and superoxide dismutase (SOD) activity in kidney cortex. The results suggested that a dose-related amelioration in the indices of toxicity was noted when the two higher doses of the plant extract were given. The two higher doses, significantly and dose-dependently increased SOD activity and GSH concentration, and decreased that of lipid peroxides in the kidney cortex. These results suggest that R. stricta water extract may contain compounds that could potentially ameliorate GM nephrotoxicity in rats.

14 RENOPROTECTIVE EFFECT OF GRAPE SEED EXTACT IN ETHYLENE

GLYCOL INDUCED NEPHROTOXIC MICE³⁰

Grape seed extract in ethylene glycol (EG) induced nephrotoxicity in mice was studied for its nephroprotective activity. Mice received grape seed extract 100mg/kg BW was given after EG (2ml/kg BW po) administration. Grape seed extract in mice produced significant reduction of urinary LDH, blood urea, creatinine & dilated tubules lined by normal intact epithelium indicating recovery. The results suggest that the renoprotective effect of Vitis vinifera seed extract is due to improvement in antioxidant status.

15
CYTOPROTECTIVE ROLE OF Solanum nigrum AGAINST GM INDUCED KIDNEYCELL (VERO CELL) DAMAGE INVITRO³¹

The 50% ethanol extract of the whole plant of Solanum nigrum was tested in vitro for its cytoprotection against gentamicin-induced toxicity on Vero cells. Cytotoxicity was significantly inhibited as assessed by the Trypan blue exclusion assay and mitochondrial dehydrogenase activity (MTT) assay. The test extract also exhibited significant hydroxyl radical scavenging potential, thus suggesting its probable mechanism of cytoprotection.

16 EVALUATION OF NEPHROPROTECTIVE EFFECT OF INDIAN MEDICINAL PLANS (IMPs) IN EXPERIMENTAL GM INDUCED NEPHROTPXICITY³²

The effect of administration of IMPs, Withania somnifera, Emblica officinalis, Glycyrrhiza glabra on BUN, serum creatinine, bodyweight MDA, renal histopathology were evaluated with administration of GM (150mg/kg/day) in female rats. Concurrent administration of IMPs & alpha lipoic acid prevented the rise in BUN, serum creatinine, kidney MDA to varying degrees. Thus IMPs show promise as protective agents against experimental nephrotoxicity.

DISCUSSION

This study was conducted to establish the nephroprotective activity of plants. Various models have been used to substantiate the nephroprotective activity of herbals. They were GM in albino rats, cisplatin in rabbits, mercuric chloride in mice, ethylene glycol in mice etc. These nephrotoxic agents caused nephropathy mainly due to their free radical generation in kidney tissues. And the kidney damage was indicated by changes in renal function parameters like creatinine, BUN, and the enzymes suchn as GPx, SOD and was also confirmed histopathologically. Above works certified that, by ameliorating all the allied effects, mainly due to antioxidant property the plants like A.lanata, P.pinnata, C.auriculata, S.radix, G.glabra, G.biloba, N.sativa, D.fortunei, T.terrestris, C.nurvala, O.sanctum, S.nigrum, V.vinifera have nephroprotective activity.

CONCLUSION

As we gone through various studies on treatment of kidney disorders, we can conclude that herbal plants play a unique role in medicine. There is no synthetic drug which relieve overall insufficiency of kidney. But indigenous plants possess tissue rejuvenator property which is anyway unavoidable. To Indians, who are brought upon Indian food, soul & climate with Indian habits of life and environment, Indian drugs naturally suit better and safer than European constitution built upon their peculiar food, climate, habits and manner of life. This may perhaps be the reason why in numerous cases,where synthetic medicines fails, Indiginous system of medication succeed.

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Cite this: Moona A Latheef Madhukkal, Sithara Ravindran, "NEPHROPROTECTIVE PLANTS", B. Pharm Projects and Review Articles, Vol. 1, pp. 700-745, 2006. (http://farmacists.blogspot.in/)