Impact of Shodhana on Semecarpus anacardium Nuts

Semecarpus anacardium is classified in Ayurveda under the category of toxic plants. However, this toxic plant is reported to possess anti-inflammatory activity, anti-arthritic effect, antioxidant activity, antimicrobial activity, anti- carcinogenic activity, hypoglycemic activity, cardioprotective, hepatoprotective, neuroprotective, and hypolipidemic activity etc . All these activities are attributed to its various constituents like phenolic compounds, flavonoids, carbohydrates, alka-loids, steroids, etc. In Ayurveda, a series of pharmaceutical procedures which converts a poisonous drug into a safe and therapeutically effective medicine is termed as Shodhana. Shodhana improves the yield, decreases the phenolic and flavonoid content; and converts toxic urushiol into nontoxic anacardol derivative thereby reducing toxicity of nuts of Semecarpus anacardium . There are reports of alteration in pharmacology and phytochemistry of nuts of Semecarpus anacardium due to Shodhana.


Introduction
Ayurveda is proven to be the ancient traditional way of treatment in India, which is fully based on philosophical, experimental and practical concepts. It includes the use of indigenous drugs which have been preferred by many pharmaceutical industries towards a novel strategy for natural drug discovery. Ayurvedic proven concepts signifies more on human health and disease that recommend the use of herbal enriched compounds as special diets. However, some herbal compounds may have toxicity besides their therapeutic potential if used improperly [1].
There are so many plants which are identified as poisonous and semi-poisonous in Ayurveda. Plants like Atsanabha (Aconitum species), nux-vomica, Acorus calamus, Semecarpus anacardium, Strychnos, Abrus precatorius etc., are the most known examples of toxic plants. These plants are known for their hidden medicinal values and broadly accepted by the Indian Ayurvedic system of medicine. These plants are still used in Indian system of development of medicine for treatment. Aconite, strychnine, β-asarone, bhilawanols, abrin are some of the toxic components present in these plants [2].
Shodhana is the purificatory measure used in Ayurveda to purify toxic medicinal plants (upavishadravyas), by various pharmaceutical procedures like soaking, rubbing and washing etc. with specific medias like gomutra (cow's urine), godugdha (cow's milk) etc. Poisonous plants are subjected to shodhanasanskara (purification process), before their therapeutic use. This process reduces toxicity of poisonous plant considerably and keeps it at required optimum level. Physico-chemical changes and reduction of the toxic chemicals from the poisonous plants like strychnine, brucine in kupilu and scopolamine in dhattura have been reported [3].
Bhallataka (Semecarpus anacardium Linn; Anacardiaceae) fruit is one of the upavishadravyas (semi poisonous drugs). Its importance and utility is increasing day by day because of its therapeutic significance in many a diseases including cancer. Though the fruits of Bhallataka has many therapeutic values, pharmacies are scared to use this drug because of its irritant vesicating nature. If juice of Bhallataka (even in traces) comes in contact with body, produces severe daha (burning sensation), and Vrana (ulcer). When it comes in contact with face, it produces acute burning sensation with shotha (inflammation) and Visarpa (skin disease). The fruit contains tarry oil which causes contact dermatitis. Medically it is very well recognized as Urushiol induced contact dermatitis because the chemical Urushiol is responsible for dermatitis. If this vesicant nature is removed, the drug could be a good source for pharmaceutical industries in manufacturing many formulations containing Bhallataka as an ingredient [2,4].
Ayurveda advocates bhallataka after shodhana (purificatory procedures). Though there are different shodhana methods mentioned in Ayurveda, the shodhana method mentioned in the text Rasamrutam was adopted and quoted in (The Ayurvedic Pharmacopeia of India) (API) and the Ayurvedic formularly of India (AFD). The procedure is soaking the fruits in cow's urine, cow's milk and rubbing it in brick powder [5]. It is reported that R f values change in shodhita samples of Bhallataka when compared to raw bhallataka [3].

Semecarpus anacardium
This is a native of India. It is known as bhallatak in India and "marking nut" by Europeans. Semecarpus anacardium plant (Figure 1) is widely available in sub-Himalayan province, tropical and central part of our country India. It is known as a deciduous tree; medium in size. Height of the tree is normally 12-15 m. Leaves are large and simple about 60 cm long and 30 cm wide. The color of bark is deep brown and is quite rough in structure. The flowers are dull greenish in color [6]. Abundantly the plant is found in Odisha, Chittagong, central India and Northern Australia [7]. The color of fruit is black when ripe as well as smooth and shiny in texture (Figure 2). The fruit is generally categorized as toxic and the integral part of the fruit i.e. nut is about 1 inch long in size [8].

Uses of Semecarpus anacardium
It has been reported for wide arena of ethno-pharmacological activities. Researchers have identified SA nuts extracts for potent pharmacological actions. Most of these studies are pre-clinical studies. Their clinical efficacy is yet to be reported. The list of health disorders against which Semecarpus anacardium has a potential to be used is given in Table 3. The possible mechanism of action is also described.

Analgesic and anti-inflammatory effect
There are reports of analgesic [20] and anti-inflammatory [21,22] activity by Semecarpus anacardium. Biflavonoid like tetrahydroamentoflavone (THA) showed significant COX-1 and COX-2 inhibition in vitro. THA may be responsible for its  analgesic and anti-inflammatory activity [23]. SA extracts were studied for their antiinflammatory activities in vitro using synovial fluid and blood of healthy individuals and rheumatoid arthritis patients. SA inhibited proinflammatory cytokine production like IL-1 beta and IL-12P40 without affecting IL-6 and TNF-alpha production [24].

Anticancer activity
Nut extracts of Semecarpus anacardium showed efficacy against human breast cancer cell line (T47D) [25] and mammary carcinoma in rats [26]. It also showed efficacy against leukemic cells in mice [27]. SA extracts have energy restoration, tumor marker regulation and membrane stabilization effect against hepato-cellular carcinoma [28]. Semecarpus anacardium may have a protective as well as therapeutic contribution against Mitomycin-C induced mutagenicity [29]. Semecarpus anacardium showed significant cytotoxicity having LC50 29.5 μg in brine shrimp lethality test [30]. The mechanism of cytotoxicity is by inducing apoptosis following caspase 3 pathway [31].

Cardioprotective effect
S. anacardium nuts prevented isoproterenol (ISO) induced myocardial damage in rats [32]. S. anacardium (1 mg/100 g body weight) reduced serum cholesterol levels and raised HDL levels in rats fed with atherogenic diet [33]. The process of atherogenesis triggered by lipid peroxidation can be inhibited by Semecarpus anacardium [34].

Nootropic effect
Semecarpus anacardium effectively inhibits acetyl choline esterase which in turn prolongs the half-life of acetylcholine. Hence, SA has been shown to be useful in improving cognitive ability [35][36][37].  Table 3. Potential uses of Semecarpus anacardium with possible mechanism of action.

Hepatoprotective effect
S. anacardium decreased the levels of the marker enzymes induced by lead acetate in liver [38]. This hepatoprotective action may be attributed to its anti-oxidant action [39].

Antimicrobial activity
The flavonoid present in S. anacardium showed antifungal activity at 400 mg/ml concentration [40]. Furthermore, the oil possessed anti-microbial activity against both Gram positive (B. subtilis, S. aureus) and Gram negative (P. vulgaris, E. coli) organisms [41]. The petroleum ether and aqueous extracts of SA inhibit the growth of Staphylococcus aureus and Shigella flexneri. However, chloroform and ethanol extracts showed inhibition against Bacillus licheniformis and Pseudomonas aeruginosa respectively [42]. The alcoholic extract of SA was found to be bactericidal against Gram positive (E. coli, S. Typhi and P. vulgaris) and Gram negative (S aureus and C diphtheria) strains [43]. Water extract showed potential with MIC 6.25 μg/ml against M. tuberculosis during in vitro bioassay [44].

Aphrodisiac and spermicidal activity
Semecarpus anacardium significantly improved both mounting and mating performance of male mice [45]. However, there are reports of spermicidal activity including spermatogenic arrest in male rats. There is also decrease in density and motility of sperms [36,46,47].

Hypoglycemic effect
Ethanolic extract of SA (100 mg/kg) reduced blood glucose level in normoglycemic rats. However, no effect was observed in case of hyperglycemic rats [49,50].

Toxicity of Semecarpus anacardium
Use of Bhallataka needs adequate precaution due to its extreme hot and sharp attributes. It should be kept away from pregnant women, old aged person and also children. Individual persons showing allergic reactions like rash, itching and swelling to it should avoid its use. Furthermore, it is highly recommended to keep away from direct exposure to sunlight, heat and extreme sex during the course of Bhallataka treatment. The oily portion of nut should be removed for its safe use which can lead to nephropathy. Fewer antidotes like coconut oil, coriander leaves pulp and ghee is useful in case of allergic reactions [51]. The traditional way of administration with peanut oil was proven to be safe up to 25 mg/kg/day for 9 day [52].
Bhallataka nut oil extracts in male albino rats is reported to decrease hemoglobin count as well as erythrocytes indicating anemia. It exhibited an alteration in kidney enzyme level leading to nephrotoxicity during acute and subchronic toxicity [53].
Hence, it is necessary to undertake Shodhana sanskara of Bhallataka with precaution before using it in medicine to avoid toxic effects of Ashuddha (impure) Bhallataka [54].

Shodhana of Semecarpus anacardium nuts
The process Shodhana, which is also known as detoxification or purification process signifies the conversion of any poisonous drug into beneficial, non-poisonous/nontoxic drug. Shodhana process involves sequential steps to purify and reduce the extreme toxicity levels/principles and also sometimes may result in enhancing the therapeutic efficacy. Shodhana is essential because higher concentrated chemicals may contribute towards adverse episodes on human body. There are 2 types of Shodhana i.e. Samanyashodhana and visheshshodhana which purifies toxic drugs. Furthermore, shodhana limits toxicity by removing the visible and invisible impurities, heterogeneous substances and toxic substances [55].
As per Ayurvedic texts shodhana can be done for SA nuts (Figure 3). The thalamus part of the fruit is removed with a steel knife. Then, the nuts are subjected to fresh cow urine daily for 7 days followed by cow milk daily for 7 days followed by rubbing thoroughly with brick powder for 3 days. During the treatment with cow urine and cow milk, the nuts are washed with water before adding fresh cow urine or milk. On the final day (18th day), the nuts are washed with hot water to remove the brick powder. This shodhana procedure is repeated three times [35,[56][57][58].
Shodhana improves the yield in methanolic extract, but decreases the phenolic and flavonoid content [31]. Shodhana decreases cytotoxicity without affecting anticancer activity significantly. The reduction in cytotoxicity may be attributed to reduction in oxidative stress [59]. Shodhana of the nuts reduce nootropic activity   [35]. So shodhana not only reduces toxicity but also alters its pharmacological activities.

Conclusion
Semecarpus anacardium is classified in Ayurveda under the category of toxic plants. There are reports of anti-inflammatory activity, anti-arthritic effect, antioxidant activity, antimicrobial activity, anti-carcinogenic activity, hypoglycemic activity, cardioprotective, hepatoprotective, neuroprotective, and hypolipidemic activity etc. shown by Semecarpus anacardium. Shodhana of nuts of Semecarpus anacardium can be done as per method given in Ayurvedic Pharmacopeia of India. Shodhana improves the yield, decreases the phenolic and flavonoid content; and converts toxic urushiol into nontoxic anacardol derivative thereby reducing toxicity. Shodhana not only reduces toxicity but also alters its pharmacological activities. Shodhana decreases cytotoxicity without affecting anticancer activity significantly. Shodhana also reduces nootropic activity.

Future scope
The effect of Shodhana on other pharmacological activities of Semecarpus anacardium can be studied in future. This work can also be extended to other poisonous and semi poisonous plants for which shodhana method is described in Ayurvedic Pharmacopeia of India.

Conflict of interest
The authors declare that they have no conflict of interest.

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