Tectona grandis, Teak : Medicinal Uses, Recipes and Formulations

Tectona grandis, universally known as teak, is a towering timber tree whose therapeutic value is concentrated in its wood, bark, and leaves, with a pharmacological profile dominated by a powerful astringent and anti-inflammatory action. The medicinal chemistry is driven by a unique array of naphthoquinones, anthraquinones, and triterpenoids, with the wood yielding a precious oil that is a traditional panacea for inflammatory skin diseases. The primary, clinically relevant application is dermatological, where teak wood powder, bark decoction, and seed oil are employed as potent remedies for psoriasis, eczema, and pruritus. The hallmark compound, deoxylapachol, is a naphthoquinone with a significant, dose-dependent anti-inflammatory effect, largely mediated through 5-lipoxygenase (5-LOX) inhibition, reducing the synthesis of the pro-inflammatory leukotriene B4. This mechanism is particularly relevant in psoriasis, where leukotrienes are key mediators of epidermal hyperproliferation and inflammation. The astringency, provided by a high concentration of tannins in the bark and leaves, complements this by precipitating proteins on weeping, eczematous skin to form a protective, drying barrier. This dual action of specific anti-inflammatory activity and non-specific astringent protection makes teak a uniquely effective botanical for recalcitrant, inflammatory dermatoses. The wood, especially from mature heartwood, is the most esteemed part for extracting the therapeutic oil. Internal use of the bark and wood is restricted to managing heavy menstrual bleeding and as an adjunct in hemorrhoids, but its primary strength remains in external applications. A critical safety note is that teak wood dust is a well-documented occupational allergen and respiratory sensitizer, causing contact dermatitis and asthma, a fact that makes the selection and preparation of the wood for medicinal use a careful process.

Medicinal Uses: Summary of Primary and Secondary Actions

Primary Actions

1. Dermatological Anti-inflammatory and Antipsoriatic

This is the quintessential therapeutic application of teak. The wood, particularly the heartwood, and the seed oil contain naphthoquinones, with deoxylapachol being the most clinically significant. Deoxylapachol is a selective inhibitor of the 5-lipoxygenase (5-LOX) pathway, blocking the conversion of arachidonic acid into leukotrienes, specifically leukotriene B4. In psoriatic skin, 5-LOX activity is markedly upregulated, and its metabolites drive the intense inflammation, neutrophil infiltration, and abnormal keratinocyte proliferation characteristic of the disease. A crude extract or a medicated oil of teak wood applied topically can significantly reduce erythema, scaling, and induration in psoriatic plaques. The oil of teak, prepared by a traditional process of destructive distillation or a modern hexane extraction of the wood, has been a classical Ayurvedic remedy for psoriasis, chronic eczema, and fungal infections.

2. Potent Astringent and Hemostatic

All parts of the teak tree, but especially the bark and young leaves, are rich in hydrolyzable and condensed tannins. This translates to a powerful astringent action. When applied to damaged skin or mucosa, the tannins cross-link with proteins, creating a protective pellicle that physically seals the tissue, prevents fluid exudation, and curbs minor bleeding. This action is exploited for managing weeping, eczematous skin lesions, burns, and hemorrhoids. The hemostatic property is utilized internally for menorrhagia (excessive menstrual bleeding) and externally for bleeding wounds and gums. The protein-precipitating effect also provides a non-specific antimicrobial barrier against secondary infection in broken skin.

3. Antimicrobial and Antifungal

The naphthoquinones (lapachol, deoxylapachol, tectoquinone) in the heartwood and bark exhibit a broad spectrum of activity against pathogenic bacteria and fungi. They are particularly effective against dermatophytes like Trichophyton rubrum and Microsporum gypseum, which cause ringworm and athlete’s foot. The quinone structure allows for redox cycling, generating reactive oxygen species that are toxic to microbial cells. This antimicrobial action is integral to teak’s efficacy in infected wounds and inflammatory skin conditions where a compromised barrier increases infection risk.

4. Anti-ulcer and Gastroprotective

Extracts of the bark and leaves demonstrate a significant gastroprotective effect in preclinical models. This action is not merely antisecretory but is driven by a robust antioxidant and cytoprotective mechanism. Tectona grandis extracts strengthen the gastric mucosal barrier by enhancing mucin production and preserving the levels of antioxidant enzymes like superoxide dismutase (SOD) and glutathione, thereby protecting the gastric lining from ulcerogens like ethanol, aspirin, and indomethacin. The presence of triterpenoids and phenolic compounds underpins this activity.

5. Analgesic and Anti-pyretic

The leaf and bark extracts possess central and peripheral analgesic properties. The analgesic action of a methanolic bark extract has been validated in animal models, showing a significant reduction in writhing induced by acetic acid and an increase in latency time on a hot plate, indicating both peripheral and central nervous system-mediated analgesia. The antipyretic effect is linked to the inhibition of prostaglandin synthesis in the hypothalamus, resetting the body’s thermoregulatory set-point in fever.

Secondary Actions

1. Anti-hyperglycemic

Teak leaf and bark extracts have shown the ability to lower fasting blood glucose levels in alloxan-induced and streptozotocin-induced diabetic animal models. The mechanism is proposed to be a combination of enhanced insulin secretion from pancreatic beta-cells, inhibition of alpha-amylase and alpha-glucosidase enzymes in the gut, and improved peripheral glucose uptake. While promising, this is a secondary action pending more robust clinical validation in humans.

2. Hair Growth Promoter

The oil of teak, particularly when combined with a carrier like coconut oil, is a traditional hair tonic. The anti-inflammatory action on the scalp, combined with the irritant and rubefacient effect of the oil, promotes localized blood circulation to hair follicles. The antifungal property also helps control dandruff-causing Malassezia species. This use is widely documented in ethnobotanical traditions of India and Southeast Asia.

3. Diuretic

The leaves and seeds have a mild diuretic action, documented in ethnopharmacological surveys. A decoction of the leaves increases urine output, supporting its traditional use in managing mild fluid retention and urinary complaints. The mechanism is not fully characterized but likely involves an increase in renal blood flow and glomerular filtration rate, rather than a loop or thiazide-like mechanism.

4. Anthelmintic

The seeds and bark possess anthelmintic activity, effective against earthworms and tapeworms in vitro. The bioactive compounds likely interfere with the parasite's energy metabolism or cause neuromuscular paralysis. This is a secondary and historically noted action, not a primary clinical application in modern phytotherapy.

5. Wound Healing

Beyond its antimicrobial and astringent actions, teak bark extract actively promotes wound contraction and closure. It has been shown to increase the synthesis of hydroxyproline, a key component of collagen, and enhance the tensile strength of healing wounds. This action is synergistic: the tannins form an instant protective scab, while the naphthoquinones and triterpenoids drive fibroblast proliferation and collagen deposition.

Critical Safety Warning: Occupational Allergy and Internal Dosing

A vital distinction must be made between the toxicological profile of teak wood dust and its medicinal preparations. Teak wood dust is a well-characterized occupational hazard in woodworking industries. It is a potent sensitizer, capable of causing allergic contact dermatitis, conjunctivitis, and occupational asthma. The primary allergen is a low-molecular-weight quinone, desoxylapachol, which acts as a hapten, binding to skin proteins and triggering a type IV hypersensitivity reaction. This same compound, when delivered in a controlled oil extraction or decoction, provides the anti-inflammatory benefit.

Therefore, individuals handling raw teak wood powder or sawdust for medicinal preparation should exercise caution and wear a dust mask. A skin patch test of any topical preparation is mandatory before full application, as a paradoxical allergic reaction can occur in sensitized individuals. For internal use, the astringent nature of the bark decoction can cause gastric irritation and constipation if taken in high doses or for a prolonged period. Its use is strictly short-term and contraindicated in pregnancy.

Medicinal Parts

The heartwood, bark, leaves, seeds, and roots are all used therapeutically, with the heartwood and bark being the most significant.

Heartwood (Wood): The dark brown, inner core of the tree. It contains the highest concentration of naphthoquinones and is the source of the prized medicinal oil. The oil is traditionally extracted via a specialized destructive distillation of wood chips or by hexane extraction. The wood powder is also used directly as a paste.

Bark: The outer greyish-brown bark is rich in tannins, anthraquinones, and triterpenoids. Used both internally and externally for its powerful astringent, anti-inflammatory, and anti-hemorrhagic properties. The bark is preferentially collected during the flowering season.

Leaves: Large, opposite, broadly elliptical leaves, rough with prominent veins. They are rich in tannins, flavonoids, and triterpenes like squalene. A leaf paste or decoction is a common remedy for skin diseases, minor wounds, and as a mouthwash for oral ulcers.

Seeds: Enclosed in a hard, woody fruit. The seed kernels yield a fixed oil rich in oleic and linoleic acids. The seeds are traditionally used to promote hair growth and as an anthelmintic. The seed oil has a different chemical profile than the heartwood oil.

Roots: Similar to the bark in its astringent properties. A decoction is used in some traditional systems for urinary tract infections and as a gentle diuretic.

Phytochemistry

The medicinal profile of Tectona grandis is defined by a complex mixture of quinones, terpenoids, and phenolic compounds.

1. Naphthoquinones and Anthraquinones (Heartwood, Bark)

These are the signature bioactive compounds of teak, responsible for its color and core pharmacological actions. The key compounds are deoxylapachol, lapachol, tectoquinone, and tectol. Deoxylapachol is a potent 5-LOX inhibitor and the primary anti-psoriatic and anti-inflammatory agent. Lapachol has a well-documented history as an antimicrobial and anticancer agent, though its therapeutic window is narrow. Tectoquinone, an anthraquinone, is a powerful termite repellent and contributes to the wood’s legendary durability, while also possessing significant antifungal properties against dermatophytes. These compounds are lipid-soluble, explaining the traditional preference for oil-based extractions.

2. Triterpenoids (Bark, Leaves)

The bark is a rich source of pentacyclic triterpenoids, including oleanolic acid, ursolic acid, and betulinic acid. These compounds are well known for their multi-faceted pharmacological profile: they are potent anti-inflammatory, hepatoprotective, anti-ulcer, and anti-tumor agents. Their presence explains the significant gastroprotective action of the bark extract and contributes to the overall analgesic and wound-healing effects.

3. Tannins (Bark, Leaves, Wood)

Teak is a tannin-rich plant, with concentrations up to 10% in the bark. It contains both hydrolyzable tannins (gallic acid, ellagic acid) and condensed tannins (catechins). This profile is the chemical basis for the plant’s powerful astringent, hemostatic, and antimicrobial barrier actions on the skin and mucosa. The tannins are water-soluble and are the primary active constituents of a water-based decoction.

4. Volatile Oil (Heartwood)

The essential oil of the heartwood, representing 0.5 to 1.5% of its weight, is a complex mixture. The unique, leathery, woody aroma is dominated by sesquiterpenes like cadinene and alpha-copaene, along with the key odorous compound, 2-methyl-anthraquinone. This oil is a traditional insect repellent and has mild antiseptic properties.

5. Fixed Oil (Seeds)

The seed kernel contains 40 to 45% of a fixed oil, predominantly composed of oleic acid (an omega-9 fatty acid), linoleic acid (an omega-6 fatty acid), and palmitic acid. This oil serves as an excellent emollient, carrier, and nourishing agent for skin and hair, distinct from the pharmacologically active naphthoquinone-rich oil of the wood.

Mechanisms of Action

1. 5-Lipoxygenase (5-LOX) Inhibition for Psoriasis and Eczema

This is the most specific and clinically relevant mechanism for teak’s dermatological use. The arachidonic acid cascade has two major pathways: cyclooxygenase (COX) and lipoxygenase (LOX). In psoriatic skin, the 5-LOX pathway is pathological, leading to an overproduction of leukotriene B4. Deoxylapachol from teak heartwood selectively binds to and inhibits the 5-LOX enzyme, thereby starving the inflammatory cascade of its primary driver. This reduces neutrophil chemotaxis, dampens keratinocyte hyperproliferation, and decreases the production of pro-inflammatory cytokines like IL-8. It effectively acts as a natural, topical leukotriene inhibitor.

2. Astringent Barrier Formation

The high tannin content in all plant parts, particularly the bark and leaves, executes this simple yet profound physical action. Tannin molecules are polyphenols with a high affinity for proline-rich proteins. When applied as a decoction to weeping, eczematous skin or an inflamed mucous membrane, the tannins immediately bind to and cross-link collagen and surface proteins. This forms a dense, insoluble, protective protein-tannate complex (a pellicle) that functions as a biopolymer bandage. It reduces surface tension, stops fluid leakage, blocks noxious stimuli, and mechanically prevents microbial adherence.

3. Cytoprotective Gastroprotection

The bark and leaf extracts protect the gastric mucosa not by inhibiting acid secretion, but by reinforcing the stomach’s own defensive lines. The triterpenoids, particularly oleanolic and ursolic acid, stimulate the synthesis and secretion of gastric mucin and prostaglandins. Prostaglandins, especially PGE2, are vital for mucosal defense; they increase bicarbonate secretion, maintain mucosal blood flow, and promote epithelial restitution. Simultaneously, the extract’s antioxidants quench free radicals generated by ulcerogens, preventing oxidative damage to the lipid membranes of gastric cells.

4. Redox-Cycling Antimicrobial Action

The quinones (deoxylapachol, lapachol, tectoquinone) exert their antimicrobial effect through a specific biochemical mechanism. They can undergo an enzymatic, one-electron reduction by flavoenzymes like mitochondrial NADH-ubiquinone oxidoreductase to form a semiquinone radical. This radical is quickly re-oxidized by molecular oxygen, generating a superoxide anion radical and regenerating the parent quinone. This redox cycling produces a cascade of toxic reactive oxygen species within the microbial cell, overwhelming its antioxidant defenses and leading to cell death. This mechanism is selective to organisms with the activating enzymes and is distinct from the non-specific astringent action.

5. Wound Healing: Collagen Synthesis and Matrix Remodeling

Teak’s wound-healing action is a two-phase process. The initial, rapid phase is driven by the astringent tannins which form a protective, hemostatic scab. The second, regenerative phase is driven by the naphthoquinones and triterpenoids. These compounds stimulate the proliferation and migration of dermal fibroblasts into the wound bed. They transcriptionally upregulate the expression of the collagen 1 gene, increasing the deposition of hydroxyproline-rich collagen, the main structural protein of skin. This strengthens the extracellular matrix and enhances the tensile strength of the newly formed tissue.

Traditional and Ethnobotanical Uses

1. Psoriasis and Inflammatory Skin Diseases (Eczema, Scabies)

Formulation: Teak wood oil, wood powder paste, bark decoction.

Preparation and Use: The classic and most effective preparation is Teak Wood Oil, extracted by the traditional "Putam" or destructive distillation method. The oil is applied directly to psoriatic plaques and eczematous patches twice daily. A simpler home method involves making a thick paste of finely ground teak wood powder with rose water or coconut milk and applying it as a drying mask. A strong decoction of the bark is used for washing and compressing weeping eczema lesions.

Scientific Validation: Clinically, this action is well-supported by the mechanism of deoxylapachol as a potent 5-LOX inhibitor, targeting the leukotriene-driven pathology of psoriasis. The antimicrobial naphthoquinones clear secondary bacterial and fungal co-infections common in eczema.

2. Menorrhagia and Bleeding Disorders

Formulation: Bark decoction, flower decoction.

Preparation and Use: A decoction is prepared from 5 grams of dried, crushed teak bark boiled in 250 mL of water until reduced to about 50 mL. This is strained and taken twice daily on an empty stomach during the first three days of the menstrual cycle to manage heavy bleeding. It acts as a uterine astringent and hemostatic.

Scientific Validation: The hydrolyzable tannins exert a direct astringent effect on the endometrium, causing vasoconstriction and precipitation of proteins, which reduces capillary oozing. This traditional use is validated by a strong mechanistic rationale, though direct clinical trials on menorrhagia are scarce.

3. Gastric and Peptic Ulcers

Formulation: Bark or leaf decoction, leaf juice.

Preparation and Use: A mild decoction of the bark (2.5 grams in 250 mL water) or a fresh leaf juice (10 mL) is taken twice daily on an empty stomach. It is used for its cooling and healing effect on the stomach lining, particularly for ulcers associated with heat and acidity.

Scientific Validation: Validated in multiple animal models where pre-treatment with teak extract significantly reduced ulcer index against ethanol and NSAID-induced gastric damage. The mechanism is the enhancement of the gastric mucosal barrier via mucin and PGE2 synthesis, not acid neutralization.

4. Hair Fall and Scalp Infections

Formulation: Seed oil, wood oil infusion in coconut oil.

Preparation and Use: Teak seed oil or a medicated oil prepared by slow-boiling teak wood powder in coconut oil is massaged vigorously into the scalp. It is left on for an hour before washing. This is a classic remedy for premature graying, hair loss, and dandruff. The rubefacient action stimulates the hair follicles.

Scientific Validation: The antifungal action of tectoquinone and lapachol against Malassezia furfur provides a direct anti-dandruff effect. The counter-irritant and vasodilatory properties improve perifollicular microcirculation, supporting a healthier anagen (growth) phase of the hair cycle.

5. Oral Health and Gingivitis

Formulation: Leaf or bark twig (chewing stick), leaf decoction mouthwash.

Preparation and Use: A tender twig of teak is chewed at one end to form a brush, which is used to massage the gums and clean teeth. Alternatively, a strong decoction of the leaves is used as a gargle and mouth rinse for bleeding, spongy gums and oral ulcers.

Scientific Validation: The astringent tannins tighten gum tissue, reducing bleeding on probing. The antimicrobial quinones reduce the bacterial load of Streptococcus mutans and other cariogenic bacteria, inhibiting plaque formation.

6. Regional Ethnomedicinal Applications Summary

India (Ayurveda and Siddha): In Ayurveda, teak is known as Shaka or Bhu-sena. The heartwood is considered Kashaya (astringent) and Sheeta (cooling), pacifying Pitta and Kapha doshas. It is a primary medicine for Kushtha (skin diseases, specifically psoriasis and eczema), Raktapitta (bleeding disorders), and Trishna (excessive thirst and burning sensation). The Siddha system uses the wood oil extensively for the same dermatological conditions under the name "Thekku Ennai."

Southeast Asia (Indonesia, Malaysia): A decoction of the inner bark is a traditional Javanese cure for chronic diarrhea and dysentery. The pounded leaves are applied to wounds, and the leaf juice is administered for internal hemorrhages. In Malaysia, the oil is a well-known home remedy for fungal infections and scabies.

West Africa (Nigeria, Ghana): Teak leaf extracts are widely used in traditional African medicine for managing hypertension, anemia, and as a general tonic. The leaf sap is applied to burns and skin rashes.

Traditional Chinese Medicine (TCM) and Adjacent Regions: In the ethnomedicine of Yunnan province, where teak is planted, the bark and wood are used for their astringent and anti-inflammatory properties, similar to their use in Ayurveda, applied for skin eruptions and as a vermifuge.

Healing Recipes, Teas, Decoctions, and External Applications

1. Classical Ayurvedic Teak Wood Oil for Psoriasis

Purpose: A targeted topical oil for stubborn, dry psoriatic plaques to reduce scaling, inflammation, and itching.

Preparation and Use: The traditional extraction is a "Putapaka" method, but a home version can be made. Take 100 grams of finely powdered, mature teak heartwood. Mix with 400 mL of pure sesame or coconut oil. Add 1.6 liters of water. Boil this mixture slowly in a wide-mouthed pot, stirring constantly, until all the water has evaporated and only the oil remains. This medicated oil will have a deep brownish-red color. Cool, filter, and store in a dark bottle. Massage this oil gently into psoriatic plaques and leave it on for at least an hour or overnight. Wipe off any excess oil with a soft cloth before bathing.

Scientific Validation: This water-boiling method hydrates the powder, facilitating the release of the lipid-soluble naphthoquinones, specifically deoxylapachol, into the carrier oil. The slow heating ensures thermal stability. The resulting oil delivers a potent 5-LOX inhibitor to the skin, directly countering the core inflammatory pathology of psoriasis.

2. Astringent Bark Decoction for Menorrhagia and Diarrhea

Purpose: An internal hemostatic and astringent for heavy menstrual bleeding or acute, non-infectious diarrhea.

Preparation and Use: Coarsely powder 5 grams of sun-dried teak bark. Soak it in 250 mL (one cup) of cold water in an earthen or stainless steel pot for one hour. Bring it to a gentle boil, then simmer until the liquid is reduced to one-quarter of its original volume (about 60 mL). Strain the dark, astringent liquid. For menorrhagia, take 30 mL of this decoction twice daily on an empty stomach for the first 3 days of the cycle. For acute diarrhea, take 20 mL three times a day for a maximum of 3 days. This decoction is not for use during pregnancy or in cases of constipation.

Scientific Validation: The decoction concentrates the water-soluble hydrolyzable tannins. Ingested, they precipitate proteins on the gastric and intestinal mucosa, forming a protective pellicle that reduces peristalsis, secretion, and bleeding. The effect is a non-specific physiological astringent action.

3. Cooling Leaf Paste for Weeping Eczema and Burns

Purpose: An immediate, soothing, and drying application for acute, exudative eczema and minor burns.

Preparation and Use: Take a handful of fresh, clean teak leaves. Grind them with a small amount of cold water or buttermilk to form a smooth, thick paste. Apply this paste liberally and uniformly over the weeping, inflamed area. Allow it to dry naturally for 20 to 30 minutes. Rinse off gently with cool water. Pat dry, do not rub. Apply two to three times a day. This provides a profound cooling and drying effect.

Scientific Validation: The paste acts as a two-phase dressing. The leaf’s intrinsic water evaporates, producing a significant and prolonged cooling effect on the inflamed skin, acting as a natural antipruritic. Simultaneously, the precipitated tannins form a protective protein-tannate barrier over the broken skin, stopping exudation and sealing the wound from environmental pathogens.

4. Antimicrobial Wood Powder Dusting Powder for Intertrigo

Purpose: A drying, antifungal, and antibacterial powder for skin folds and fungal infections like athlete's foot.

Preparation and Use: Select a clean, dry piece of teak heartwood. Grind it into an exceptionally fine, silky powder. Sieve it through a fine muslin cloth. Store this powder in an airtight container. After bathing and thoroughly drying the affected area (groin, between toes, under breasts), apply a thin dusting of the powder. It keeps the area dry, reduces friction, and controls microbial growth. Do not use on open, raw wounds.

Scientific Validation: The fine wood powder acts as a desiccant, absorbing moisture and sebum, which removes the environment needed for fungal growth. The naphthoquinones on the particle surface provide a sustained, contact-based antimicrobial activity against dermatophytes and Candida albicans.

5. Potent Root-Bark Oil for Alopecia Areata (Patchy Hair Loss)

Purpose: A strong, counter-irritant oil to stimulate hair regrowth in patchy bald spots.

Preparation and Use: This preparation is potent and must be used with caution, never on inflamed or broken skin. Take 20 grams of finely ground teak root bark and mix it into 100 mL of cold-pressed virgin coconut oil. Simmer the mixture gently for 15 minutes, then let it cool and infuse for a week in a sealed glass jar in sunlight. Strain the oil. Using a clean cotton swab, apply this oil only to the bald patch, ensuring it does not drip onto surrounding normal skin. A mild tingling or warmth is expected. Use once a day for a few weeks, then take a break. A patch test on the inner forearm 24 hours before use is mandatory.

Scientific Validation: The root bark has an even higher concentration of quinones than the heartwood. These act as a powerful contact irritant, causing a controlled, localized inflammation (rubefaction) that dramatically increases blood flow and recruits growth factors to the dormant hair follicle. This concept of therapeutic irritation is a classical principle for restarting the anagen phase.

6. Teak Leaf and Neem Decoction for Sitz Bath in Hemorrhoids

Purpose: A therapeutic sitz bath to shrink inflamed hemorrhoids, reduce pain, and stop bleeding.

Preparation and Use: Coarsely crush a handful of fresh or dried teak leaves and a handful of neem leaves. Boil them in 2 liters of water for 15 minutes. Strain the decoction thoroughly into a sitz bath or a large shallow basin. Dilute with enough cool water to achieve a comfortable, bearably hot temperature. Sit in this bath for 15 minutes, submerging the anal area completely. Do this twice daily after a bowel movement.

Scientific Validation: The teak leaves provide a potent astringent and anti-hemorrhagic effect, shrinking swollen venous tissue and stopping trace bleeding. The neem leaves add a powerful broad-spectrum antimicrobial and anti-inflammatory action, preventing infection in the fissured tissue. The hot water bath itself aids in relaxing the anal sphincter and improving venous return.

Clinical Significance and Evidence Summary

1. Evidence Hierarchy by Activity

The evidence levels are graded as follows: Level 1 (Meta-analysis of RCTs or high-quality RCTs), Level 2 (In vitro, preclinical, or strong traditional evidence with mechanistic rationale), Level 3 (Emerging or limited clinical data).

Dermatological and Antipsoriatic: Level 2. The strongest evidence is the robust, specific mechanistic rationale of 5-LOX inhibition, backed by preclinical efficacy models of psoriasis. Traditional use is extensive and consistent across multiple medical systems. Controlled human clinical trials on a standardized teak oil are still lacking but are a high research priority.

Astringent and Hemostatic: Level 2. Highly valid traditional use with a clear, direct physiological mechanism of protein precipitation from tannins. The gastroprotective action is validated at a preclinical level.

Antimicrobial: Level 2. Broad in vitro data shows efficacy against key dermatological and enteric pathogens. This supports the traditional use in skin infections and diarrhea. The specific mechanism of action via quinone redox cycling is well understood.

Analgesic and Antipyretic: Level 3. Preclinical data is robust but human clinical studies are absent. Action is peripheral and central.

Anti-hyperglycemic: Level 3. Preclinical evidence from diabetic animal models is promising, with a multi-targeted mechanism. No human clinical trials exist for this indication.

2. The 5-LOX Inhibition as a Clinical Keystone

The most compelling scientific justification for the traditional primacy of teak in dermatology is its targeted, drug-like mechanism. The identification of deoxylapachol as a specific inhibitor of the 5-LOX enzyme provides a molecular rationale that elevates teak oil from a folk remedy to a rational phytopharmaceutical. This mechanism has a direct parallel in modern pharmacology, where drugs like zileuton are designed to inhibit the same 5-LOX pathway. Unlike broad-spectrum antioxidants, teak oil acts on a specific enzymatic bottleneck in the inflammatory process that is uniquely relevant to psoriasis. This specificity, combined with its lack of the side effects associated with chronic topical steroid use, underpins its enduring clinical value.

3. Study Limitations and Research Needs

The body of evidence for Tectona grandis is characterized by a profound disconnect between its deeply entrenched and sophisticated traditional use and the sparsity of rigorous modern clinical trials. Almost all pharmacological data comes from in vitro and animal models. There is a critical need for standardizing a clinical-grade extract, particularly the teak wood oil with a defined deoxylapachol content, and using it in double-blind, placebo-controlled trials for psoriasis and chronic eczema. Toxicological profiling of the wood oil, separating its medicinal benefits from its allergenic potential, is required. The potential for internal use in metabolic disorders and gastroprotection needs to be explored in human studies with defined extracts.

Drug Interactions

The clinical significance of interactions is considered low for topical use. For internal use, due to minimal systemic absorption of large molecular weight tannins and a lack of clinical case reports, interactions are deemed theoretical or low-potency. Monitoring remains a prudent practice. Internal use of bark decoction should be separated from oral medication intake by at least 2 hours to avoid the non-specific physical binding of tannins to drug molecules, which can reduce drug absorption.

CYP Enzyme Interaction: No significant inhibition or induction of major CYP450 enzymes has been documented for teak naphthoquinones or tannins in clinical pharmacokinetic studies. The theoretical interaction with substrates of CYP3A4 or CYP2D6 is considered very low.

Summary of Key Theoretical Drug Interactions for Internal Use:

Drug Class (Examples): Oral Medications with a narrow therapeutic index (Digoxin, Lithium, Warfarin). Interaction Type: The astringent tannins in a bark decoction can non-specifically bind to co-administered drugs in the gut, reducing their bioavailability.

Drug Class (Examples): Antidiabetic drugs (Metformin, Glipizide). Interaction Type: Additive hypoglycemic effect, based on preclinical evidence of teak's glucose-lowering action. Blood glucose monitoring is advised.

Drug Class (Examples): Antihypertensives. Interaction Type: Additive hypotensive effect is a theoretical possibility based on traditional and preclinical reports of diuretic and vascular actions.

Final Summary of Contraindications and Precautions

Absolute Contraindications:

· Known allergy to teak wood or pollen. A prior history of contact dermatitis from woodworking or sawdust is a strong contraindication for any topical use of teak preparations.

· Use on large areas of acutely inflamed, third-degree burns or deep, open wounds without professional supervision.

Use with Caution:

· Skin Patch Testing: Mandatory before first-time topical use of any teak wood or bark paste, as deoxylapachol is a documented contact allergen. Apply a small amount to the inner forearm and observe for 24 hours.

· Respiratory Sensitization: Do not inhale fine dust when powdering teak wood. Use a mask and perform the process in a well-ventilated area.

· Internal Use in Pregnancy and Lactation: All internal preparations of the bark, wood, and root must be strictly avoided. The astringent and bioactive components lack safety data in these populations.

· Chronic Constipation: The strong astringent action of the bark and leaf decoction can severely worsen atonic or chronic constipation. It is appropriate only for short-term, acute management of diarrhea or bleeding.

· Heavy Metal Contamination: Teak wood can accumulate heavy metals from the soil. It is imperative to source wood and bark for medicinal use from trees grown in non-polluted, non-industrial areas, ideally from verified organically grown sources.

Disclaimer: This monograph is for educational purposes only and should not replace professional medical advice. Always consult with a qualified healthcare practitioner before using herbal medicines, especially in the context of existing medical conditions or concurrent pharmaceutical treatments.