Skin aging is a natural process that involves a decline in hydration, circulation, and elasticity of the skin, leading to wrinkle formation and skin laxity. There is also a reduction in collagen content due to both an upregulation of matrix metalloproteinases (MMPs) and a decrease in collagen synthesis, contributing to the appearance of aging skin.⁷⁸ Over recent decades, numerous products and procedures have been developed as part of the new generation of anti-aging solutions. However, for millennia in the Ayurvedic tradition, species of the genus Terminalia, namely T. arjuna and T. chebula, in addition to Phyllanthus emblica, have been studied and recognized for their anti-aging properties.

Terminalia chebula in particular has shown consistent anti-aging activity across both in vitro and clinical studies. In vitro, T. chebula is associated with upregulation of proteoglycans, collagen, and genes related to cutaneous blood vessel development and water homeostasis, as well as inhibition of hyaluronidase, elastase, and MMP-1, -2, -3, -9, and -12.^23,24,28,29 Two studies found that expression of senescence-associated secretory phenotype (SASP) genes, including IL-1β, IL-6, IL-8, CXCL1, CSF3, and MAP4K2, was reduced in human dermal fibroblasts following incubation with T. chebula extract.^25,26 Four clinical trials, with sample sizes ranging from 11 to 26, examined anti-aging properties of topical T. chebula, which found increases in skin elasticity, hydration, radiance, firmness, and decreases in skin roughness after eight to 12 weeks of treatment.^19,21,22,27 Concentrations of T. chebula extract ranged from 0.5% to 5%, with one study not reporting concentration used. In that study, a combination formulation of T. chebula, niacinamide, and retinol was investigated.²²

One randomized controlled trial has been conducted exploring the anti-aging properties of an oral supplement containing T. chebula extract. Subjects treated with the supplement experienced a 4.3% reduction in wrinkles after eight weeks, while the control group saw an increase in wrinkle severity of 3.9% (P < 0.05).²⁰

Phyllanthus emblica has a similar amount of evidence supporting its anti-aging properties. In vitro analyses reveal stimulation of keratinocyte growth, upregulation of collagen, and inhibition of hyaluronidase, elastase, collagenase, and MMP-1 and -2.^{31–34,36–38} Two controlled clinical trials (n=20-60) investigated the anti-aging benefits of topical P. emblica, which demonstrated increases in elasticity and hydration and decreases in wrinkle volume and roughness after 14 to 84 days of application.^34,35 One of these trials explored a combination product of P. emblica, Centella asiatica, and Momordica cochinchinensis extracts.³⁵ In another study, an oral concoction consisting of emblica and lingonberry extracts was administered to 99 human subjects. Twelve weeks of intake was associated with increased stratum corneum water content and reduced wrinkles.³⁰

Only one study investigated the anti-aging effects of Terminalia arjuna. The researchers observed an increase in skin hydration, elasticity, echogenicity, and blood microflow after treatment with arjuna extract in human subjects. An in vitro component of the study demonstrated downregulation of MMP-1 and upregulation of FGF-2 and VEGF in human skin fibroblasts and keratinocytes.¹⁸ Similarly, only one study explored the anti-aging properties of Triphala, which showed upregulation of elastin and collagen I in human dermal fibroblasts.³⁹

Antioxidants protect against cellular damage by scavenging free radicals. In this section, we discuss studies investigating the antioxidant activity of Terminalia and Phyllanthus species in skin.

Terminalia chebula was the most-studied species in regard to antioxidant properties. Five studies found that T. chebula extract exhibits free radical scavenging activity.^{28,29,41–43} One in vitro analysis found chebula extract to have stronger superoxide and hydroxyl scavenging capacities than ascorbic acid, a known powerful antioxidant.²⁹ When urban dust was used to induce oxidative damage in human keratinocytes in another study, treatment with T. chebula extract led to neutralization of reactive oxygen species (ROS).²⁷ In an animal study, mice topically treated with T. chebula extract demonstrated increased activity of catalase, glutathione reductase, and glutathione peroxidase.⁴⁴

Phyllanthus emblica also exhibits robust antioxidant activity. Five in vitro analyses noted P. emblica to have significant free radical scavenging properties.^34–37,45 In one study, emblica had greater antioxidant capacity compared to ascorbic acid.³⁴

Only one study has investigated the antioxidant effects of Terminalia arjuna in skin, which found that emulsified formulations of the herb demonstrate free radical scavenging activity, although less than ascorbic acid.⁴⁰ Likewise, only one study to date exists on the antioxidant properties of Triphala. In that study, treatment of human dermal fibroblasts with Triphala led to a decrease in β-galactosidase, a marker of oxidative damage.³⁹

As these studies present solid evidence that Terminalia and Phyllanthus species have strong antioxidant activity, further research should focus on clinical applicability and address how to formulate topical products for maximal antioxidant effects.

It is well-known that UV exposure accelerates aging and increases risk of skin cancer by inducing cellular damage. In fact, the majority of cutaneous malignancies are a result of UV radiation rather than inherited or spontaneous mutations.⁷⁹ The studies outlined in this section explore the ability of Phyllanthus and Terminalia species to suppress molecular damage in irradiated skin.

Nearly all of the relevant literature to date pertains to Phyllanthus emblica. Molecular studies reveal that HaCaT (human immortalized) keratinocytes treated with P. emblica and exposed to UVB radiation show significant reductions in ROS generation and apoptosis, as well as increases in glutathione peroxidase, catalase, and superoxide dismutase activity compared to untreated cells.^38,45 In one study, HaCaT keratinocytes incubated with P. emblica extract prior to UVA and UVB irradiation demonstrated suppression of the MAPK/AP-1 pathway and activation of the ERK/TGF-β/Smad pathway, which normally stimulate cellular proliferation and inhibit tumorigenesis, respectively.⁴⁸ Additionally, other in vitro analyses showed that in human dermal fibroblasts treated with P. emblica extract and subsequently irradiated with UVB, collagen damage, and apoptosis is significantly lower compared to untreated, irradiated fibroblasts.^49,50 One animal study explored the UV-protective properties of P. emblica, finding that mice exposed to UVB radiation and treated with a combination of emblica and barley sprout powder showed reduced MMP-1, -2, -3, and -9 expression compared to untreated, UVB-exposed mice.⁴⁷

Terminalia chebula has also been investigated for photoprotective functions in skin. One study demonstrated that treatment of UVB-irradiated human keratinocytes with T. chebula is associated with a reduction in telomere shortening and increased cellular lifespan.⁴⁶ Another study found no significant difference in the amount of pro-collagen in human dermal fibroblasts irradiated with UVB after incubation with T. chebula extract compared to untreated cells.⁴³

Because the relevant studies evaluating the UV-protective properties of these herbs are mostly limited to in vitro analyses, further exploration of whether topical formulations can prevent UV damage in animals can be a future avenue for research.

The most common form of malignancy worldwide, some forms of skin cancer can be fatal if not detected early.⁸⁰ Though modern advances have improved the prognosis of skin cancer, patients may consider alternative approaches as a supplement to standard treatment. Animal studies have demonstrated significant reductions in cutaneous tumor volume and number, as well as decreased hyperplasia on tumor histology, in mice treated with Phyllanthus emblica or Terminalia chebula extract topically or orally.^44,51,52 Given that the tumors in these studies were chemically induced with carcinogenic agents, research involving the induction of tumors by UV radiation in animals may offer a more realistic representation of skin cancer as it occurs in humans.

Many common treatments for head lice, including malathion, permethrin, and pyrethrins, have sparked safety concerns as these compounds are also used as pesticides. In fact, carbaryl, an insecticide formerly used for lice, is no longer recommended due to its systemic toxicity.⁸¹ One study examined the efficacy of Phyllanthus emblica against head lice compared to conventional therapies. In that study, head lice were collected from children and applied to filter paper containing P. emblica shampoo. LT₅₀ was 48 seconds, in comparison to 6.5 and 65.9 minutes for carbaryl and malathion, respectively. In vivo testing of P. emblica was also performed, revealing a cure rate of 95% after one day and 100% after seven days. Comparatively, the cure rates for carbaryl and malathion were 85% and 72% after one day and 93% and 85% after seven days, respectively, although statistical significance in comparison to P. emblica was not reported.⁵³

Vitiligo is a common skin condition with a reported worldwide prevalence of up to 2%.⁸² In one study, 65 patients with vitiligo were administered a tablet containing 100 mg Phyllanthus emblica extract, 4.7 mg carotenoids, and 10 mg vitamin E three times daily for six months. At the same time, these patients were also treated with phototherapy and/or topical therapy. A control group (n=65) was treated with phototherapy and/or topical therapy alone. New or enlarging depigmented macules were observed after six months in approximately 60% of the control group compared to 35% of patients treated with the tablet (P < 0.05).⁵⁴ Because the frequent dosing may be limiting for patients, a future study could examine whether twice or once daily dosing has the same effect.

Excess seborrhea increases susceptibility to seborrheic dermatitis, a chronic inflammatory skin condition characterized by greasy scale affecting the scalp, eyebrows, and ears.⁸³ Patients with scalp seborrhea in one placebo-controlled study received an oral prebiotic containing 1 g Triphala twice daily for two months. Scalp sebum levels were measured at the conclusion of the trial. Subjects given Triphala experienced a 25% reduction in sebum level from baseline, while those who received placebo showed a 24% increase (P = 0.047). Though the result is statistically significant, seborrheic dermatitis is not directly quantified in the study; rather, only scalp sebum levels are measured.⁵⁵

As psoriasis can have a marked impact on quality of life and is often difficult to treat, herbal remedies may offer promise as adjuncts to conventional therapy. A study by An et al found that following two days’ challenge with a mixture of cytokines designed to mimic the inflammation produced in psoriasis, HaCaT keratinocytes treated with Terminalia chebula showed a decrease in IL-17A, IL-23, and TNF-α. Keratinocyte proliferation was also decreased. Additionally, in the same study, imiquimod was used to induce psoriatic lesions in mice. Following intragastric administration of T. chebula, mice experienced a significant decrease in scale and erythema.⁵⁶ No human studies have yet explored the effect of Terminalia or Phyllanthus species on psoriasis.

Melasma, which presents as hyperpigmented macules or patches on the face, is another condition that can cause significant psychosocial impact. Costa et al recruited 23 participants with melasma to apply a combination product of Phyllanthus emblica extract, licorice, and Belides twice daily. Twenty-seven control patients applied hydroquinone 2% cream nightly. After 60 days, both groups experienced a significant quantitative reduction in melasma; however, there was no difference between the groups.⁵⁸ Similarly, in a study by Kheirieh et al, 15 participants applied Terminalia chebula cream while 15 participants applied hydroquinone 2% cream nightly for 12 weeks. Modified Melasma Area and Severity Index (mMASI) scores were decreased in the T. chebula group at 4, 8, and 12 weeks and in the hydroquinone group at 8 and 12 weeks.⁵⁷ Given the findings in both studies, Phyllanthus emblica and Terminalia chebula may be helpful for melasma, similar to the current standard of using hydroquinone.

In recent decades, there has been an increase in the global prevalence of atopic dermatitis.⁸⁴ In one study, mice were treated with Terminalia chebula extract following induction of an atopic dermatitis-like state with 2,4-dinitrofluorobenzene (DNFB). IL-31 and MMP-9 expression was found to be lower in mice treated with T. chebula extract compared to controls treated with DNFB alone. Skin of mice treated with T. chebula also showed fewer eosinophils on histology.⁵⁹ Though these results suggest T. chebula may reduce the inflammation associated with atopic dermatitis, induction with DNFB likely does not fully reproduce the complex pathophysiology of this condition.

Tinea corporis, colloquially known as ringworm, is a superficial skin infection caused by dermatophytes in the genera Trichophyton, Microsporum, and Epidermophyton. As an effort to explore alternatives to standard treatment, Singh et al applied an ointment containing apigenin extracted from Terminalia chebula to the skin of mice infected with Trichophyton mentagrophytes and compared its efficacy to topical terbinafine. By the twelfth day of treatment, all mice treated with apigenin showed complete cure, defined by both clinical resolution of skin lesions and clearance of fungal burden on tissue culture. Notably, terbinafine also produced full cure in all mice by day 12. The study did not examine whether T. chebula in combination with terbinafine could potentiate anti-fungal activity.⁶⁰

Wound healing is complex and involves the coordinated action of several processes including fibrin clot formation, cell growth and proliferation, matrix remodeling, and immune responses aimed at eliminating invading microbes.⁸⁵ Evidence suggests that Terminalia arjuna, when administered in oral or topical form, improves tensile strength of wounds in rats by increasing hydroxyproline content.^61,62 Additionally, topical Terminalia chebula has been associated with increased tensile strength, decreased size, and shorter epithelialization period of wounds in rats.^63,65,66 These findings may be explained by T. chebula’s ability to increase collagen, uronic acid, hexosamine, VEGF, and HIF-1α in wounds, as well as its antimicrobial activity.^64–66

Wound healing properties of Phyllanthus emblica have been explored in rat studies involving application of combination topicals (P. emblica with Shorea robusta, Yashada bhasma, flax seed oil, and cow ghee, or P. emblica with Vitex negundo and Tridax procumbens). Wounds treated with these topicals demonstrated increased collagen, hydroxyproline, and hexosamine content and improved wound contraction compared to untreated wounds.^67,68

Only one study investigated Triphala in wound healing, which found that in infected full-thickness wounds in rats treated with Triphala ointment, compared to vehicle, MMP expression and bacterial counts were reduced, while collagen, uronic acid, and hexosamine levels were increased.⁶⁹

For people of all ages and backgrounds, hair can be an integral component of self-esteem and identity. Research investigating the effects of Phyllanthus emblica on hair has varying results. In an animal study, application of an oil containing emblica extract did not lead to significant differences in hair growth in rabbits or sheep after four weeks.⁷⁵ However, two clinical trials demonstrated benefit for hair.^73,74 In the first, a topical product containing emblica extract, selenium, and freeze-dried coconut water was associated with decreased hair loss.⁷⁴ The other trial investigated oral P. emblica syrup, which was shown to lead to an increased percentage of hairs in anagen compared to placebo.⁷³ The potential benefits of P. emblica on hair may be explained by in vitro analyses demonstrating the herb’s ability to induce VEGF, IGF-1, and HGF and inhibit 5α-reductase in keratinocytes.^76,77

Terminalia bellerica may also have benefits for hair as mouse studies have revealed downregulation of 5α-reductase and hair regrowth in testosterone-induced alopecia to be superior to that of minoxidil or finasteride.^70,71 One study found that treatment of human dermal papilla cells with Terminalia chebula has no effect on cellular proliferation.⁷²

PL reports being on the speaker’s bureau for AbbVie, Arcutis, Eli Lilly, Galderma, Hyphens Pharma, Incyte, La Roche-Posay/L’Oréal, Pfizer, Pierre-Fabre Dermatologie, Regeneron/Sanofi Genzyme, Verrica; reports consulting/advisory boards for Alphyn Biologics, AbbVie, Almirall, Amyris, Apogee, Arcutis, ASLAN, Astria Therapeutics, Boston Skin Science, Bristol-Myers Squibb, Burt’s Bees, Castle Biosciences, Codex Labs, Concerto Biosci, Dermavant, Eli Lilly, Galderma, Kenvue, LEO Pharma, Lipidor, L’Oréal, Merck, Micreos, MyOR Diagnostics, Pelthos Therapeutics, Phyla, Regeneron/Sanofi Genzyme, Sibel Health, Skinfix, Soteri Skin, Stratum Biosciences, Sun Pharma, Theraplex, Thimble Health, UCB, Unilever, Verdant Scientific, Verrica, Yobee Care. Stock options with Alphyn Labs, Codex Labs, Concerto Biosci, Soteri Skin, Stratum Biosciences, Thimble, Yobee Care, Verdant Scientific. In addition, Dr. Lio has a patent pending for a Theraplex product with royalties paid and is a Board member and Scientific Advisory Committee Member emeritus of the National Eczema Association.

AK reports no relevant disclosures.