From crude herbs to finished herbal products — the methods, techniques, dosage forms and the scientific studies that justify the traditional use of some of the world's best known medicinal plants.
What exactly are herbal medicines?
Herbal medicines are not a single category of product. According to the World Health Organization (WHO), the term covers a broad spectrum of materials and preparations — from crude plant parts to fully formulated finished products sold to consumers.
This breadth is precisely what makes herbal medicines so difficult to regulate and standardise. It is often difficult to ascertain the conditions to which the starting materials have been subjected, the composition and properties of the final product may vary considerably, and the quality control of herbal medicines is fundamentally different from that of conventional pharmaceutical products.
A herbal medicine is defined as much by how it was produced as by what plant it came from. Identity, processing and formulation all shape the final product.
Herbs
Herbs are crude materials which may be derived from lichen, algae, fungi or higher plants. The plant parts used commonly include leaves, flowers, stems, roots, barks, seeds and fruits.
They may be presented entire, fragmented or powdered, depending on the intended preparation.
Herbal materials
Herbal materials are the processed or naturally occurring substances obtained from herbs. They include:
These materials may be further processed by steaming, roasting or stir-baking in alcoholic beverages and other materials.
Herbal preparations
Herbal preparations form the basis for finished herbal products. They include herbal materials, extracts, tinctures and fatty oils of herbal materials, produced by physical or biological processes such as extraction.
They also include preparations made by steeping or heating herbal materials in alcoholic beverages, in honey, or in other suitable materials.
Finished herbal products
Finished herbal products are obtained by subjecting herbal substances to treatments such as extraction, distillation, expression, fractionation, purification, concentration and fermentation.
A product containing more than one herb may be called a mixed herbal product. In such preparations, one herb (or two) may be the only active pharmaceutical ingredient, while the others act as excipients that enhance the activity of the active ingredient. Finished products may also contain excipients in addition to the active ingredients.
Important distinction: the addition of chemically defined substances — whether synthetic or of herbal origin — makes the product a non-herbal product.
Forms of herbal medicines
Herbal medicine is dispensed in a wide range of dosage forms. The form chosen depends on the plant material, the intended route of administration, the required shelf life and the preference of the patient or practitioner.
Herbal powders and pills
Unique formulations available as a single herb or as a combination of herbal powders. They may be added to food and drinks, can be used externally as dusting powders, and retain potency for about a year if stored in airtight containers.
Single or combinations of vegetable, mineral or animal drugs. They can be used for up to two years, and indefinitely when minerals are included. They do not lose their original colour, form or taste on standing, and should be kept away from moisture if they contain salt or sugar.
Herbal tablets and capsules
Hard compressed medication in round, oval or spherical shape. They may include excipients such as binders, glidants, lubricants and disintegrants. A coating may be added to mask or hide a bitter taste.
Contain drug extract, with or without fillers, or dried powdered herbal material or granules in hard shells. Soft gelatin shells are used for herbal oils or herbal ingredients suspended in oils.
Herbal soaps and pastes
Made by saponification of a fatty acid (usually oils) with caustic soda or a suitable base, with the herb of choice incorporated. They have antifungal and antimicrobial properties and are used for eczema, dandruff, ringworms and boils.
Less greasy than ointments and contain about 50% herbal powder dispersed or dissolved in a base. A fatty base is used for the skin; an aqueous stiff base is used as a toothpaste.
Ointments, balms and medicated butters
Creams, suppositories and pessaries
Herbal oils, poultices and plasters
Herbal oils may be infused (macerated) oils such as coconut oil, aromatic oils such as lemongrass or lavender oil obtained by distillation, or medicated oils in which a fine paste of the drug is combined with oil in a ratio of 1:4 and taken internally with warm water and milk.
Poultices are made by mashing fresh herbs, wrapping them in gauze and applying to the affected area of the skin once the temperature is suitable. An example is golden leather fern applied to wounds. Plasters are prepared in a similar spirit for external application.
Lozenges, oxymel and syrups
Herbal teas and decoctions
Herbal teas are infusions or preparations taken as tea. They may come as tea bags or powdered herbal material, and may also be boiled in water as a decoction. For a fermented infusion, a boiled sugar solution is added and allowed to stand without becoming sour.
Decoctions are made by boiling the herb in water for a period of time to extract soluble constituents. For a fermented decoction, sugar is added to the decoction and boiled, then allowed to stand — again, not to the point of becoming sour.
Production of herbal medicines
When producing herbal medicines, several considerations must be made at every stage. These determine whether the final product is safe, effective and reproducible.
Key production considerations
Quality
The identity, purity and potency of the starting material and the finished product must be established.
Quantity
Accurate measurement of raw materials and extracts ensures a consistent dose in every unit.
Presentation
The dosage form, packaging and labelling influence patient acceptance and correct use.
Safety
Toxicological considerations, contamination and adulteration must be ruled out before release.
Consistency
Batch-to-batch reproducibility is one of the greatest challenges in herbal manufacture.
Efficacy and storage
The product must retain its activity through its shelf life under the recommended storage conditions.
Fresh or dried plant material
Production begins with fresh or dried medically practised plants or plant parts. The active ingredients are usually not completely isolated; they are extracted together with other naturally occurring components of the plant. Those other components are believed to influence the efficacy of the active ingredient — a concept that sits at the heart of herbal therapeutics.
Steps in the production process
Planning and developing a new herbal product
Bringing a new herbal product to market follows a structured pathway from idea to regular production:
- Market analysis and literature review
- Formulation of the phytopreparation recipe
- Laboratory testing on raw materials and extractive preparation
- Phytopreparation production and definition of packaging
- Phytopreparation quality control
- Technology and registration documentation
- Protection of intellectual property
- Introduction of the final product into regular production
Challenges and limiting factors
Herbal medicine production faces a distinct set of scientific, regulatory and practical obstacles — many of which do not apply to conventional pharmaceuticals.
Challenges in production
The hard problems
- Management within ranges of risk and communication of uncertainty
- Pharmacological, toxicological and clinical documentation
- Pharmacovigilance and post-market surveillance
- Accessing conflicting toxicological, epidemiological and other data
- Verification of the herbal medicines actually used by patients
- Understanding why the addition of harmful additives occurs
- Evaluating drug–herb interactions
- Constraints with clinical trials and available participants
- Standardisation of complex multi-component products
- Safety and efficacy assessment
Factors affecting production
Limiting factors in herbal medicine processing
- Indiscriminate harvesting and poor post-harvest treatment practices
- Lack of research and development
- Poor agricultural and propagation methods
- Inefficient processing technology leading to low yields and poor quality products
- Poor quality control procedures
- Difficulties in marketing
- Lack of trained personnel and equipment
- Lack of facilities to fabricate equipment locally
- Lack of access to the latest technology and market information
- Packaging limitations
- Cost of production
- Adulteration of crude drugs
Scientific evidence justifying herbal remedies
The use of herbal medicines continues to rise, largely driven by dissatisfaction with conventional medicine in some settings. Yet the evidence base for herbal medicines remains generally very limited. Many people find them helpful, but their use tends to rest on traditional knowledge rather than on scientific research.
The objective of this type of research is not to search for new drug leads, but to determine whether remedies used traditionally have a scientific basis — particularly where affordable orthodox medicines with high activity and low toxicity already exist.
Why justify the use of herbal remedies?
Such research may involve in vivo and in vitro preclinical studies as well as clinical trials in humans — especially in the form in which the remedies are traditionally used or taken.
Antihypertensive remedies
Generally recommended ethnomedicinally for cardiovascular disease. Hippocrates (459–370 BC) mentioned garlic as a remedy against intestinal parasites, a laxative and a diuretic. A number of preclinical and clinical studies report a hypotensive effect, which appears more consistent in animal studies than in clinical studies. Dhawan and Jain observed an antihypertensive effect in 20 hypertensive patients compared with 20 normotensive patients receiving garlic pearl preparations for two months; blood pressure decreased. Allicin and other garlic compounds have hypocholesterolemic, hypolipidemic and antihypertensive activity, although the precise mechanism of blood pressure lowering is not known.
Known as the “miracle tree” because it has been used traditionally as food and medicine to treat anaemia, diabetes, infectious and cardiovascular diseases. In vivo and in vitro investigations have confirmed antihypertensive properties. It contains N,α-L-rhamnopyranosyl vincosamide, isoquercetin, quercetin, quercetrin and isothiocyanate, which help prevent the thickening of arteries. Quercetin decreases stress on the heart and helps stabilise blood pressure. Leaf extract showed ACE inhibitory activity attributable to quercetin-3-O-glucoside and kaempferol-3-O-glucoside — activity even higher than captopril used as positive control.
Antidiabetic remedies
Widely used in Nigeria for both therapeutic and nutritional purposes, especially in the management of diabetes mellitus, hypertension and other metabolic diseases associated with the liver. Several preclinical studies using different in vivo and in vitro models of the roots and leaves validate the ethnomedicinal claims, as well as stabilising the biochemical and haematological abnormalities associated with diabetes. Saponins and flavonoids are suspected to be responsible for the hypoglycaemic effect by increasing pancreatic cell mass and enhancing proliferation of the β-cells of the islets of Langerhans; its mode of action is also similar to that of metformin. Even in combination with metformin it is safe, efficacious and additive in its effects.
Aloe vera has been used in the medicinal treatment of diabetes in India and the Arabian Peninsula. According to Vuskan and associates, the gel obtained from the inner portion of the leaves may contain glucomannan, a water-soluble fibre reportedly with hypoglycaemic and insulin-sensitising actions. Preclinical studies have reported inconsistent results; however, small-scale clinical trials suggested an improvement in fasting glucose levels with the extract. In a comprehensive review by Yeh and colleagues, it was concluded that preliminary data suggest a potential effect of Aloe vera in glycaemic control. Some patients also prefer to use orthodox and traditional remedies concurrently in managing diabetes.
Antimalarial remedies
Alcoholic extracts of the leaves, roots and barks have been used ethnomedicinally (orally) for centuries in the treatment of fevers and malaria. An in vitro study by Iroka in 1993 suggested that acetone/water neem leaf extract possessed better antimalarial properties than water extracts. In 2008, Gianotti et al. showed that the seed powder could be used as a vector control against the Anopheles larva. Studies have shown that azadirachtin and other limonoids in neem extracts are responsible for its antimalarial activity.
In malaria-endemic tropical Africa, M. lucida has found wide application in malaria treatment, used singly or with other plants. Practitioners of West African traditional medicine apply the leaves, stem bark and roots using different indigenous methods, mainly as a decoction. Several in vivo and in vitro studies on Plasmodium falciparum and P. berghei have substantiated the traditional claims. A synergy was observed when root and leaf extracts were combined. 3-hydroxy-2-hydroxymethylanthraquinone and damnacanthol, isolated from the root, exhibit significant antiplasmodial activity against chloroquine-susceptible (3D7) and chloroquine-resistant (K1) strains of P. falciparum with IC₅₀ values in the 20–45 μM range. It has shown lower efficacy than Artemisia annua but greater efficacy than bitter leaf.
Antibacterial remedies
Used traditionally in the treatment of sores, ulcers and skin eruptions, and possesses laxative, antioxidant and anti-inflammatory activities. Okpako and Ajibesin investigated and provided scientific evidence for its antibacterial activity in relation to skin eruptions and skin putrefaction. The leaf and root extracts possessed bacteristatic and bactericidal activities, while the stem extract possessed only the former. The fungicidal activity of the leaf extract against Candida albicans was also verified in the same study.
Antiviral remedies (HIV/AIDS)
A popular herb used in many forms (root, leaf and seed) for many centuries, as dated in Islamic and Christian history. Unscientific claims by herbal therapists on HIV led to research to determine the effectiveness of herbal remedies in HIV infection. The antiviral potential of N. sativa has been observed in many in vivo and in vitro studies, while previous studies confirmed its immunomodulatory effects. Various pilot studies and case reports have demonstrated that administration of N. sativa produced complete seroreversion of viral load in some HIV/AIDS patients. N. sativa could be used alone or in combination with HAART therapy, since no adverse drug interaction was observed in patients who used both concomitantly.
An important herb in the Ayurvedic and indigenous medical systems for over 4,000 years. It was observed in Uganda that people living with HIV had their health conditions improved with the intake of mango fruits. Mangiferin, isolated from mango fruit including the seed, skin and kernel, has been shown by in vitro methods to antagonise the cytopathic effects of HIV. The leaves have also been known to exhibit anti-HIV potential. Some Indian scientists have claimed that an isolate from mango leaves checks the growth of the AIDS virus, and trials of leaf isolates on AIDS patients at the National Institute of Healing in Washington found the isolates effective against HIV.
Tuberculosis remedies
Used for treating sexually transmitted infections, hernias, coughs, fever, ascariasis, constipation, headaches, rheumatism, stomach ache, tuberculosis, pain, epilepsy, pneumonia and skin infections; the leaves and root are used in the management of TB. In vitro assays using the n-hexane root extract were effective against Mycobacterium tuberculosis (H37Ra) and M. bovis BCG, giving credence to its ethnomedical use. However, the n-hexane root extracts did not give credible evidence against M. tuberculosis (H37Rv), M. avium DSM and M. smegmatis.
In Nigeria it is used for the treatment of diabetes, leprosy and tuberculosis. In vitro studies of the leaf extract have shown that it is moderately active against M. tuberculosis strain H37Rv but has no activity against Mycobacterium bovis BCG.
The seeds have been commonly used in the management of tuberculosis, but in vitro studies involving M. tuberculosis strain H37Rv and Mycobacterium bovis BCG revealed no substantial evidence to corroborate the ethnomedicinal claims. It is, however, effective for cough: in vivo assays by Ray Ozolua and associates in 2016 using male Wistar rats and hydroethanolic seed extracts provided scientific validation for its antitussive effects.
Cough remedies
The bulb is used ethnomedicinally in the management of cough, asthma and tuberculosis. There is no substantial scientific evidence to verify these claims, although inferences are made that since it is an effective antimicrobial agent it might be effective against coughs arising from microbial infections.
Used to treat inflammatory and infectious processes such as dysentery, cholera, gastric ulcers, urinary diseases, and ear and pulmonary infections. It was found scientifically using in vivo assays that the ethanolic extract of the leaves possesses antiasthmatic and antitussive properties, verifying its claim for the treatment of pulmonary infections that can be associated with bouts of cough.
Peptic ulcer remedies
Unripe plantain has a sticky gum which our forefathers recognised as having the power to cover up wounds or sores in the intestine. Various preparations of dried unripe plantain banana were found to be anti-ulcerogenic against aspirin-induced ulceration in the rat, and were effective both as prophylactic treatment and in healing ulcers already induced by aspirin. Ripe fruit bananas were inactive. This study was carried out by Best et al. in 1984.
In Nigeria, the young leaves are prescribed as a common anti-ulcer remedy. A few leaves chewed and swallowed three times for 4–8 weeks are believed to produce a complete cure of ulcer. An in vivo study carried out by Akah et al. in 1998 revealed that they elicited anti-ulcerogenic properties in a dose-dependent way. They protected rats from aspirin-induced ulcerogenesis, delayed intestinal transit, increased the pH, and decreased both the volume and acidity of gastric secretion — providing scientific evidence validating the ethnomedicinal use of the plant.
The use of chewing sticks for cleaning teeth
In many homes in Nigeria, the root and slim stem of certain plants are used to clean the teeth in the morning by chewing them until they acquire brush-like ends. Though some are tough and penetrate the gum during use, causing discomfort, scientific investigations have revealed that they possess antimicrobial activity against oral microbes. They are therefore bifunctional — acting as both toothpaste and toothbrush.
Hydrolysable tannins and related compounds have been isolated from chewing stick extracts and may be considered as lead antimicrobial agents.
Antiproliferative and anticancer remedies
A commonly used plant in Sokoto for the management of cancers. Evaluation of its extract against Dalton's ascitic lymphoma (DAL) induced solid and ascitic tumours in BALB/c mice by Sakthivel et al. in 2012 showed its protective influence by increasing lifespan and restoring total white blood cell count and haemoglobin content. It also significantly decreased the levels of serum aspartate transaminase (SGPT), alanine transaminase (SGOT), alkaline phosphatase (ALP), gamma glutamyl transferase (GGT) and nitric oxide (NO).
An annual herb used in folklore for managing a wide range of diseases including cancer. The cytotoxicity of the ethylacetate extract on A549 (lung carcinoma) and P388 (leukaemia) cell lines in humans and mouse respectively has been reported. The leaf extract also inhibited the proliferation of SF-767, LNCaP, PC-3 and SF-763 cancer cell lines. The anticancer effect is attributed to the presence of kaempferol, oxygenated terpenes, sesquiterpene hydrocarbons and monoterpene hydrocarbons.
Antipsychotic remedies
The bark is used in popular medicine for treating inflammatory processes, for healing wounds, as a cure for diarrhoea, and in Nigeria for psychosis. The ethanolic extract was found to reduce the feeding and locomotor activity of Wistar albino rats in a dose-dependent manner in amphetamine-induced psychosis.
A common herb used traditionally for psychiatric management in Nigeria. The aqueous root extract has high potential as an antipsychotic agent and elicited better activity than the standard drug (chlorpromazine) at the tested doses. The presence of indole alkaloids such as yohimbine, reserpine, rescinnamine, raucaffricine, ajmaline and ajmalicine is reported to be responsible for the antipsychotic activity.
Justifying traditional practices scientifically
Beyond individual remedies, many traditional practices surrounding how plants are handled — from collection to preparation to the route of administration — can also be examined scientifically. This covers every process from the point of collection, through preparation of the plant material, to its use, without disregarding the route of administration employed.
Night collection of plants
Traditional medicine practitioners often recommend the collection of certain plants at a specific time of the night — for example Chromolaena odoratum (L.) R.M.King & H.Rob. (Asteraceae) — for it to have its desired efficacy. Two scientific explanations may account for this:
However, there is currently no scientific explanation for the collection of Ageratum conyzoides L. (Asteraceae), goatweed, at night as recommended by some traditional medicine practitioners.
State or age of the leaves
Radiations
Some plants have been known to emit certain radiations characteristic of each plant, possessing their own energy pattern. These radiations are said to be detectable by psychic eyes — especially experienced clairvoyant herbalists who could analyse the energy pattern of a leaf and tell whether its collection at a particular time of day for medicinal use will be beneficial or not.
With the aid of powerful microscopes and high-frequency generators, interesting photographs of such radiations have been made. Such radiation around the patient is observed by some traditional medicine practitioners to diagnose disease. These claims remain outside the current framework of scientific evidence.
Preparation of plant extracts
Physostigma venenosum — the ordeal bean
Physostigma venenosum Balf. (Fabaceae), otherwise known as ordeal beans, is used traditionally in the detection of witchcraft. It contains a toxic compound, eserine, which is degraded to eseroline — a less toxic compound — by boiling.
It is assumed that a hot decoction of the plant is given by the practitioner to the individual presumed innocent, and a cold infusion to the one presumed guilty. It is also assumed that a guilty individual will take the preparation more slowly than an innocent one, resulting in gradual and steady absorption of eserine leading to death by asphyxia. The innocent person, on the other hand, may simply experience irritation of the gastric lining and vomiting before the drug has time to be absorbed.
Route of administration
Arrow poisons, when spread on the spiny fruits of Tribulus macropterus Boiss. (Zygophyllaceae), enter the bloodstream directly on contact with the foot of an unsuspecting victim — a parenteral route — leading to lethal effects associated with the cardiac glycosides they contain.
When these same arrow poisons are taken by the oral route, an attack of dysentery is experienced instead. Caution should therefore be employed during preparation so that the poison does not come into contact with open wounds.
What this means in practice
Herbal medicine sits at the intersection of tradition, pharmacology and public health. The evidence reviewed here shows that many traditional remedies have a genuine scientific basis — while others do not.
Formulation matters
The same plant can become a powder, decoction, tincture, ointment or capsule — each with different stability, dosing and bioavailability.
Quality control is the hardest problem
Identity, adulteration, substitution with exhausted drugs and variable composition remain the greatest threats to herbal product quality.
Some claims are well supported
Moringa oleifera, Vernonia amygdalina, Morinda lucida, Ficus exasperata and Rauvolfia vomitoria all have credible preclinical or clinical support.
Some claims are not
Garcinia kola failed to show activity against M. tuberculosis in vitro, and Crinum jagus lacks substantial verification for its cough and asthma claims.
Traditional practice can be rational
Diurnal variation in volatile oils, the phenolic richness of fallen leaves and the degradation of eserine by boiling all offer plausible scientific explanations for long-standing traditional practice.
Important: information published here is for general educational purposes only. It is not a substitute for professional medical, pharmacy or healthcare advice. Always consult a qualified healthcare professional before using any herbal remedy, particularly if you are taking prescription medicines.
Tradition is a starting point. Evidence is the destination.
From the maceration of a leaf to the quality control of a finished product, herbal medicine deserves the same rigour we apply to any other therapeutic intervention — clear methods, honest evidence and responsible presentation.
This article is drawn from lecture material in Pharmacognosy and Herbal Medicine, and is published as a study resource for students and curious readers.
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