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====== ''Rasa'' ======

====== ''Rasa'' ======

Acharya Priya Vrat Sharma has discussed concept of ''rasa'' based on the physicochemical constitution of ''dravyas'' as follows:  ''madhura'' (sugar, fat, and amino acids), ''amla'' (acids), ''lavana'' (salts), ''katu'' (essential oils, phenols), ''tikta'' (certain alkaloids and glycosides), and ''kashaya'' (tannins). According to his hypothesis, carbohydrates and proteins are present in ''madhura rasa dravyas''; all the ''amla rasa dravyas'' show acidic properties and all the drugs in ''lavana varga'' contain sodium chloride (NaCl). All the ''dravyas'' of ''katu varga'' contain essential oils while half of all ''katu dravyas'' contain alkaloids or glycosides or phenols. All the ''tikta dravyas'' contain alkaloids, and only 10% of ''dravyas'' contain glycosides. Many of the ''kashaya'' ''rasas'' contain tannin1.

Acharya Priya Vrat Sharma has discussed concept of ''rasa'' based on the physicochemical constitution of ''dravyas'' as follows:  ''madhura'' (sugar, fat, and amino acids), ''amla'' (acids), ''lavana'' (salts), ''katu'' (essential oils, phenols), ''tikta'' (certain alkaloids and glycosides), and ''kashaya'' (tannins). According to his hypothesis, carbohydrates and proteins are present in ''madhura rasa dravyas''; all the ''amla rasa dravyas'' show acidic properties and all the drugs in ''lavana varga'' contain sodium chloride (NaCl). All the ''dravyas'' of ''katu varga'' contain essential oils while half of all ''katu dravyas'' contain alkaloids or glycosides or phenols. All the ''tikta dravyas'' contain alkaloids, and only 10% of ''dravyas'' contain glycosides. Many of the ''kashaya'' ''rasas'' contain tannin<ref>K. Nishteswar, Basic concepts of ayurvedic pharmacology, Chaukhamba Sanskrit series office, Varanasi,2008,pp:xii </ref>.

====== Guna ======

====== Guna ======

In recent years, some effort has been made to refine the objective parameters used for assessing ''snigdha-ruksha'' and ''sheeta-ushna gunas'' by employing animal experimentation. Absolute evaluation of one ''guna'' is not possible in a living body since there are infinite factors related to each and every biological event. Metabolic study (''dipana pachana'' experiment), intestinal secretion and motility test, and swimming stress test (swimming induced hypothermia) have been employed to assess the effects of various drugs having ''snigdha-ruksha'' and ''sheeta- ushna gunas''. ''Sheeta'' and ''snigdha guna'' drugs have shown an increase in body weight in metabolic experiments compared to ''ushna'' and ''ruksha guna'' drugs. ''Snigdha guna'' drugs alleviated stress-induced hypothermia whereas ''ruksha guna'' drugs aggravated it 2,3.

In recent years, some effort has been made to refine the objective parameters used for assessing ''snigdha-ruksha'' and ''sheeta-ushna gunas'' by employing animal experimentation. Absolute evaluation of one ''guna'' is not possible in a living body since there are infinite factors related to each and every biological event. Metabolic study (''dipana pachana'' experiment), intestinal secretion and motility test, and swimming stress test (swimming induced hypothermia) have been employed to assess the effects of various drugs having ''snigdha-ruksha'' and ''sheeta- ushna gunas''. ''Sheeta'' and ''snigdha guna'' drugs have shown an increase in body weight in metabolic experiments compared to ''ushna'' and ''ruksha guna'' drugs. ''Snigdha guna'' drugs alleviated stress-induced hypothermia whereas ''ruksha guna'' drugs aggravated it<ref>Supriya. S. Balerao A comprehensive study of gunas and evolution of some ojective parameters  in the context of snigdha and ruksha gunas Thesis, IPGT&RA, Gujarat Ayurved University, Jamnagar,1998 </ref>  <ref>Santosh Mane Evolution and evaluation of some objective parameters for ushna and sita gunas based on panchabhoutik theory and experiments. Thesis,IPGT&RA, Gujarat Ayurved University, Jamnagar,2008. </ref>

====== ''Veerya'' ======

====== ''Veerya'' ======

An attempt has been made to assess the effects of ''sheeta'' and ''ushna veerya'' drugs (''samana pratyayarabdha dravyas'') on basal metabolic rate (BMR). Two ''sheeta veerya'' drugs, namely, ''yashtimadhu'' (Glycyrrhiza glabra) and ''shatavari'' (Asparagus racemosus) and two ''ushna veerya'' drugs, namely, ''chitraka'' (Plumbago zeylanica) and ''jatiphala'' (Myristica fragrans) were considered for this study. In healthy volunteers, initial BMR was recorded with McKesson metabolizer. Then the drug was administered three times a day (''chitraka'' and ''jatiphala'' 2gm each and ''yashtimadhu'' and ''shatavari'' 5gm each). A significant increase (p<0.05) was observed with ''yashti'', while the increase in BMR with ''shatavari'' was not very significant. ''Chitraka'' and ''jatiphala'' brought about a significant decrease in BMR(p<0.05). Therefore, ''sheetaveerya'' and ''ushnaveerya'' drugs which represent the ''saumyatva'' and ''agneyatva'' of a drug or food may be responsible for synthesizing or metabolizing the ''dhatus'' due to their ''santarpaka'' or ''apatarpaka'' actions4.

An attempt has been made to assess the effects of ''sheeta'' and ''ushna veerya'' drugs (''samana pratyayarabdha dravyas'') on basal metabolic rate (BMR). Two ''sheeta veerya'' drugs, namely, ''yashtimadhu'' (Glycyrrhiza glabra) and ''shatavari'' (Asparagus racemosus) and two ''ushna veerya'' drugs, namely, ''chitraka'' (Plumbago zeylanica) and ''jatiphala'' (Myristica fragrans) were considered for this study. In healthy volunteers, initial BMR was recorded with McKesson metabolizer. Then the drug was administered three times a day (''chitraka'' and ''jatiphala'' 2gm each and ''yashtimadhu'' and ''shatavari'' 5gm each). A significant increase (p<0.05) was observed with ''yashti'', while the increase in BMR with ''shatavari'' was not very significant. ''Chitraka'' and ''jatiphala'' brought about a significant decrease in BMR(p<0.05). Therefore, ''sheetaveerya'' and ''ushnaveerya'' drugs which represent the ''saumyatva'' and ''agneyatva'' of a drug or food may be responsible for synthesizing or metabolizing the ''dhatus'' due to their ''santarpaka'' or ''apatarpaka'' actions<ref>K Nishteswar, Basic concepts of Ayurvedic pharmacology, Choukhambha Sanskrit Series office, Varanasi,2009 pp-109-114 </ref>.

====== ''Vipaka'' ======

====== ''Vipaka'' ======

An attempt has been made to assess ''vipaka'' of certain drugs by their effect on ''malas'' (feces and urine) and ''doshas'' (''vata, pitta,'' and ''kapha''). Drugs, namely ''bala'' and ''shatavari'' (''madhura vipaka''), ''vrikshamla'' and ''amalaki'' (''amla vipaka'' and ''madhura vipaka''), ''maricha'' and ''pippali'' (''katu vipaka'' and ''madhura vipaka''), ''kushtha'' and ''nimba'' (katu vipaka), and lodhra and Ashoka (katu vipaka) were taken up for the study. The study was done for six days. For the first two days, kapardika bhasma (250 mg., thrice a day) as placebo was administered and from the third day onwards the trial drug, in decoction form, (96 ml, twice a day) was given to healthy volunteers for two days. The remaining two days were used for following up. The influence of these drugs on doshas and malas were assessed using a structured proforma. Madhura and Amla vipaka drugs increased the quantity of urine and stool. Madhura vipaka drugs increased kapha dosha while Amla vipaka drugs increased pitta dosha.  Katu vipaka drugs decreased the urine and stool output and increased vata dosha5.

An attempt has been made to assess ''vipaka'' of certain drugs by their effect on ''malas'' (feces and urine) and ''doshas'' (''vata, pitta,'' and ''kapha''). Drugs, namely ''bala'' and ''shatavari'' (''madhura vipaka''), ''vrikshamla'' and ''amalaki'' (''amla vipaka'' and ''madhura vipaka''), ''maricha'' and ''pippali'' (''katu vipaka'' and ''madhura vipaka''), ''kushtha'' and ''nimba'' (katu vipaka), and lodhra and Ashoka (katu vipaka) were taken up for the study. The study was done for six days. For the first two days, kapardika bhasma (250 mg., thrice a day) as placebo was administered and from the third day onwards the trial drug, in decoction form, (96 ml, twice a day) was given to healthy volunteers for two days. The remaining two days were used for following up. The influence of these drugs on doshas and malas were assessed using a structured proforma. Madhura and Amla vipaka drugs increased the quantity of urine and stool. Madhura vipaka drugs increased kapha dosha while Amla vipaka drugs increased pitta dosha.  Katu vipaka drugs decreased the urine and stool output and increased vata dosha<ref>Naveen H. Dave, Vipaka karmanishtaya Thesis, IPGT&RA, Gujarat Ayurved University, Jamnagar,1998 </ref>.

====== ''Prabhava'' ======

====== ''Prabhava'' ======

It is quite apparent that the ''acharyas'' formulated the hypothesis that explained the workings of drugs after observing various activities. In the context of the failure of the hypothetical principles to explain the drug action in a rational way, the concept of ''prabhava'' was formulated which may be interpreted as an empirical principle. Drugs with similar chemical structure should have similar actions. But it is not possible to predict the activity of a drug entirely by its chemical structure. Drugs with similar structures but having entirely different effects are known as isomers, for example, Antazoline and Tolazoline appear chemically similar but former is an antihistamine and the latter is an adrenergic blocking agent. Conversely, many dissimilar chemical agents have similar action, for example, phenobarbitone, chloralhydrate, and paraldehyde are all depressants of the central nervous system. The concept of ''prabhava'' may be interpreted using the concept of isomerism6.

It is quite apparent that the ''acharyas'' formulated the hypothesis that explained the workings of drugs after observing various activities. In the context of the failure of the hypothetical principles to explain the drug action in a rational way, the concept of ''prabhava'' was formulated which may be interpreted as an empirical principle. Drugs with similar chemical structure should have similar actions. But it is not possible to predict the activity of a drug entirely by its chemical structure. Drugs with similar structures but having entirely different effects are known as isomers, for example, Antazoline and Tolazoline appear chemically similar but former is an antihistamine and the latter is an adrenergic blocking agent. Conversely, many dissimilar chemical agents have similar action, for example, phenobarbitone, chloralhydrate, and paraldehyde are all depressants of the central nervous system. The concept of ''prabhava'' may be interpreted using the concept of isomerism<ref>Dwarkanath C.,The Fundemental Principles of Ayurveda, Chaukhambha Sanskrit Series, Varanasi; 2009: pp-180 </ref>.

=== References ===

=== References ===