ANALYSIS OF ESSENTIAL TRACE ELEMENTS IN MEDICINAL HERBS BY RADIOCHEMICAL METHODS

Abstract

Herbs are nature's pharmacy and knowledge of its medicinal importance is recognized in most civilizations of world. However, it is more prevalent in Asia, Africa, Egypt, China, Latin America, Malaysia, Turkey etc. Indian society with strong cultural heritage and rich biodiversity attained this knowledge in a well organized form, systematically recorded and employed as a traditional health care system called Ayurveda (Ayu =life, Veda =knowledge) meaning Science of Life. It encompasses medicinal, psychological, cultural, religious and philosophical concepts with holistic approach towards long, healthy and disease free happy life. Present work was undertaken as a part of the Board of Research in Nuclear Sciences (BRNS) sponsored project on the Development of Radiochemical Methods for the Analysis of Trace Elements in Medicinal Herbs. In recent years, antioxidant properties of dietary constituents and herbal products have created much interest. Many medicinal plants are reported to be rich source of antioxidants, which neutralize free radicals generated by certain biochemical reactions. Therefore, these have attracted attention of health professionals as well as of basic scientists interested in biomedical research. Thesis is divided into six chapters dealing with following aspects: Ch I on Radiochemical Methods introduces the general aspects of radioanalytical methods including principle, classification and applications of NAA in various fields. Role of elements in life processes and its analytical importance is emphasized. Abrief introduction of Indian medicinal system Ayurveda and its present status in global context is dealt. Importance of the availability of trace elements in biocompatible form and easy assimilability has been emphasized. Ch II on Experimental Methodology deals with the sampling methods, its preparation and instrumentation used in NAA and AAS. Also details of data processing and bioassay studies are included. An important aspect of this work was the establishment of high resolution y-ray spectrometry facility with lead shielding, associated hardware and software. Ch III deals with our results on the analysis of 25 elements in 15 medicinal herbs commonly used in Indian household. In most cases Kcontent is higher than Na by almost an order of magnitude. Similarly Ca and Mg are 09 found in much higher concentrations in some herbs. Fe contents in all the samples are > 200 jag/g though bakuchi (P. corylifolia) seeds and jatamansi {N. jatamansi) show much higher amounts of 923±123 and 1210±200 p.g/g respectively. Jatamansi is particularly enriched in Cr (8.19±0.04 ug/g), Mn (474±5 ng/g), Fe (1210±200 jag/g), Cu (36.8 ug/g) and Zn (60.0+6.3 ug/g). According to Ayurveda it is recommended as antibacterial, antipyretic and heart tonic. K/P ratio was found to vary in a wide range of 2.07-24.2. Fe & Mn and Zn & Cr were linearly correlated in some herbs. Ch IVdeals with the analysis of two herbal formulations; Trifala and Pragyapeya. Former is the most popular herbal formulation widely used as effective laxative, powerful antioxidant and antibacterial with anticancer properties. We have analysed 9 brands of Trifala including its 3 constituents, amalaki (Embilica officinalis), bibhitaki (Terminalia bellirica) and haritaki (T. chebula) for 29 elements. A perusal of elemental contents suggests that trifala as whole is enriched in K (12.6±1.1 mg/g), Mg (0.91±0.34 mg/g), Ca (4.88±7.62 mg/g), Fe (1.01±0.23 mg/g) and Zn (41.1±14.9 \ig/g), though Se is also present in significant amounts (104±34 ng/g). Also gallic acid was separated by column chromatography and further confirmed by ir, NMR and GC-MS studies. Pragya-peya, another herbal formulation from Shantikunj, Haridwar is a mixture of 12 herbs; aagya-ghas, arjuna, bay leaves, brahmi, dalchini, fennel, nagarmotha, red sandal, shankhpushpi, sharpunkha, tulsi and yastimadhu, widely recommended for cold and cough, as a nervine tonic and stimulant. It is especially enriched in several nutrient elements such as Ca (23.9±1.3 mg/g), K (9.37±0.92 mg/g), Mg (2.23±0.41 mg/g), P (1.20±0.04 mg/g), Mn (87.8±10.9 ug/g), Fe (676±176 ug/g), Cu (14.7±0.8 ug/g), Cr (1.56±0.24 ug/g), Co (0.62±0.09 ug/g) and Zn (34.5±4.0 |ag/g). Aagya ghas is particularly enriched in Cr, Fe, Cu and Zn whereas fennel seeds are enriched in K, Mg, P and Se. It is possible that some metals exist as complex with macromolecules thus enhancing their bioavailability. Some toxic heavy metals such as Hg, Sb, Cd and Pb are also present but these are within WHO permissible limits. Fe is correlated with Fe/Zn and Co in all the herbs. It suggests that the concentration levels of many elements in the herbs are strongly affected by characteristics of plant, soil as well as environmental conditions. On) Ch Vdescribes analysis of Bhasmas; the unique metallic-herbal preparations known in Indian subcontinent for several thousand years. Use of metals in medicine is often associated with the question of toxicity. These are believed to be biologically produced nano-particles, which enter in the blood stream enhancing their efficacy as medicine. Twenty bhasmas based on Ca, Fe, Zn, Hg, Ag, K, As, Cu, Sn and gemstones were analysed for up to 21 elements including C, H, Nand S. Besides the major constituent elements, several other essential elements such as Na, K, Ca, Mg, V, Mn, Fe, Cu, Zn, etc, have also been found in significant amounts. These are derived from herbs and seem to remain chelated with organic macromolecules acting as ligands. The bhasmas are taken along with milk, butter, honey or ghee (milk preparation) and thus make these elements easily digestible, eliminating their harmful effects and enhancing their biocompatibility. Siddhamakaradhwaja, and swet parpati correspond to the stoichiometry of HgS and KNO3 respectively. K/P was found to vary in a wide range (0.23 to 12) though for most bhasmas (n=12) it lies in a close range of 2.3 ± 1.2. Further, Fe/Mn is linearly correlated (r = 0.96) with iron in 9 non-iron containing bhasmas. Ch VI deals with the bioassay studies of brahmi (Bacopa monnieri) extracts in aqueous-methanol (BAM) for DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging, DNA strand break, antilipid peroxidation, superoxide anion scavenging, H202 scavenging activity and total phenol content. It also showed protective effect of y-ray induced DNA damage. Elemental contents in respective extracts were also determined. It is observed that elemental contents of Na, K, CI, Co and Zn were higher in the BAM extract. In general, it is observed that no single herb is enriched in all the essential nutrients. However, some herbs are particularly enriched in elements such as Fe, Mn, Co, Cu, Zn, Se and Vessential for various enzymatic processes and play a vital role in its pharmacological/curative properties. Also some elements in various medicinal herbs represent synergistic or antagonistic effects suggesting usefulness of herbal formulations.