Components of marketable herbal feed supplements are primarily evaluated based on their efficacy and safety to ensure quality. Nevertheless, as complex mixtures of different groups of primary and secondary metabolites, retention of overall phytochemical consistency with permissible levels of contaminants is critical to their efficacy and safety of herbal feed supplements. Herbs sourced from right geography, collected in the right season, authenticated appropriately and processed with stringent systems of manufacturing are serious factors to sustain efficacy with the consistency of phytochemicals inorder to manufacture herbal feed supplements. To ensure overall quality of herbal feed supplements through application of good agricultural and collection practice (GACP), good plant authentication and identification practice (GPAIP), good manufacturing practice (GMP) and good laboratory practice (GLP) in analysis are inevitable. In this communication, Natural Remedies Pvt. Ltd., recommends and adopts three steps process (HerbSecure) such as ensuring genuinity, safety, and efficacy to achieve the consistent quality of the herbal feed supplements to animal health industry.
1. Ensuring Genuinity
Quality of herbs used in the formulation of feed supplements start with sourcing. Sourcing should comply with Good Agricultural and Collection Practices (GACP). Main objectives of GACP are 1. Contribute to the quality assurance of plant materials used as the source for herbal feed supplements 2. To encourage and support the sustainable cultivation and collection of plants of good quality in ways that respect and support the conservation of herbs and the environment in general. 3. To provide traceability of the ingredients used in the formulation.
Good agricultural and collection practice starts with creating standard operating procedures (SOPs) for collection, post-harvest treatments like drying and maintaining traceability. Drawing a representative sample and equating with plant voucher herbarium specimens is the primary step in authenticity. Collected samples must be equated with a reference (standard) voucher specimens species-defining characters to ascertain the authenticity. An expert taxonomist is required to certify this step.
Other methods for plant authentication are macroscopic, microscopic character sets and their phytochemical (secondary metabolites) profiles. It is not unusual that most pharmacopeial monographs initiate the identification of herbs based on morphological and anatomical characters of dried and sorted plant parts (2). In phytochemical profile method, the chromatographic finger print of the sample developed using a validated analytical method is compared with a botanical reference material of the same species. The similarity of the finger printing of the sample to the reference material confirms the identity. Apart from that, presence of marker compounds which are specific to particular species also confirms identity (Figure 1).
Phytochemical profiling is extensively used for species and plant part specific identification since macroscopic and microscopic characters in dried or processed plant, parts are disturbed and creating authentication difficult. Phytochemical profiling chiefly employs high-performance thin-layer chromatography (HPTLC) and high-performance liquid chromatography in addition to gas chromatography (GC) (2, 4, 5). Among these techniques, thin-layer chromatography (TLC) and high-performance thin-layer chromatography (HPTLC) are widely used at Natural remedies Pvt. Ltd., for the generation of chemical fingerprints. In addition to above conventional methods, modern methods based on genomic profiling and DNA barcoding are complementary techniques to classical systematic approaches to plant authentication, which can be used for the unequivocal identification of plant species (6).
Figure 1. Methods used to determine the genuinity of herbs
2. Ensuring Safety:
Guaranteeing authentic medicinal herb with permissible impurities is the next important step towards accomplishing excellency in herbal products. Impurities include heavy metal, pesticide residues, and aflatoxins/mycotoxins. Heavy metal in plant species are accumulated from contaminated soils. More than 500 plant species are identified to store high levels of heavy metals, and in some cases, heavy metal occurrence in aerial parts exceed life-threatening toxicity levels to animals (2). Heavy metals (Pb, Hg, As, and Cd) are tested on herbal products using sophisticated techniques like atomic absorption spectroscopy (AAS), inductively coupled plasma mass spectrometry (ICP-MS) (Figure 2). The allowable limits for the heavy metals and metalloids in herb starting materials and preparations are prescribed by feed standard, WHO and individual herbal monographs of British and US pharmacopoeias (2).
Pesticide residues in medicinal herbs ascend from crop protection practices in cultivation. Pesticides broadly categorized to fungicides, insecticides, and weedicides. Multiple classes of pesticides like organochlorines, organophosphorus, carbamates, benzimidazoles, dithiocarbamates, and amino acid herbicides are used in plant cultivation. Quality driven herbal companies took the challenges of testing all the broad groups of pesticides using acceptable methods.
Other major contaminant that pose threat to safety of herbal products is mycotoxins. Out of hundreds of known mycotoxins, aflatoxins (Figure 2), ochratoxin A, fumonisins, zearalenone, and deoxynivalenol are the key ones. Mycotoxins are known to have neurotoxic, carcinogenic, immunotoxic, and teratogenic. Country specific feed standards, pharmacopoeias prescribe safe limits of aflatoxins and ochratoxin A in their documents. A number of validated methods of mycotoxin analysis including LC MS/MS GCMSMS (Figure 2) in the plant matrix are reported (7). Due to safety issues, it is critical to check fungal infection and prove that the herbal material is free of mycotoxin contamination especially after harvest and storage.
Figure 2. Detection of heavy metals and pesticide residues
In spite of the growing market demand on herbal products, there are still concerns associated with their safety. Surprisingly, not more than 10% of herbal products in the global market are actually standardized to known active components and strict quality control measures are not always wisely complied (8). For majority of these products in use, very little is known about their active and/or toxic constituents. This raises apprehension on their safety and consequences for their use as supplements. Toxicity testing using harmonized guidelines (Eg. ICH, OECD, schedule Y) in a Good Laboratory Practice (GLP) lab can divulge about risks which are associated with use of such herbs, consequently evading possible detrimental effects (9).
3. Ensuring Efficacy:
The success of modern analytical chemistry methods often conceals the problem since increasing amount of analytical data does not necessarily give more insight to biological effect. As alternative approaches, bioactivity-based detection of marker(s) can deliver valuable information about phytochemicals responsible for biological effects of complex materials such as herbal feed supplements. Effect directed analysis tries to interconnect instrumental analytical techniques with a biological/biochemical entity, which identifies or isolates substances of biological relevance (Figure 3). The connection of biological effects with the identification and quantification of phytochemicals leads to relevant answers to many questions (10).
It is utmost important to establish the synergy or additvity wherever more than one herb used in the supplement for the desired biological activity. Also, to confirm the efficacy it is vital that herbal product to undergo different levels of efficacy studies as mentioned in Figure 4. Once the bioactive molecule(s) identified as mentioned above it is important to determine the same in herbal products using qualitative and quantitative methods as it is equally important to verify the consistency across each batch using single or combination of analytical chemistry techniques (Figure 5) in the final product.
Figure 3. Bio-assay guided fractionation of plant (11).
Figure 4. Frame work of biological studies to develop herbal product
Figure 5. Verification of consistency between batches of poly herbal formulation
In conclusion, experience and knowledge on traditional and modern systems of herbal usage, infrastructure with sophisticated instruments, bioassays and able scientists, certified excellent process (GACP, GPAI, GMP, NABL, GLP, KOSHER, FAMIQS) would lead to delivering consistent, safe and cost effective herbal products to animal health industry. The herbal feed supplements produced in Natural Remedies undergoes the fore said systems to ensure quality.
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