Tuberculosis

Piperine is the one plant molecule that made it into a marketed TB drug, and it is a booster, not an antibiotic. Rifampicin’s bioavailability falls with chronic use, so an Indian fixed-dose combination, Risorine, pairs a reduced 200 mg rifampicin dose with isoniazid and 10 mg of piperine as a bio-enhancer. A randomised Phase III trial in 216 treatment-naïve, sputum-positive pulmonary TB patients found faster sputum conversion at 4 weeks (93% vs 84%), a higher cure rate at 24 weeks (92% vs 82%), and fewer liver-enzyme elevations (3 vs 9 patients) than conventional rifampicin ^{8Reference 8Patel et al. · 2017RCTA randomized, controlled, phase III clinical trial to evaluate the efficacy and tolerability of Risorine with conventional rifampicin in the treatment of newly diagnosed pulmonary tuberculosis patients — randomised controlled trialView study →}.

Supporting work: piperine showed protective efficacy against M. tuberculosis in vivo ^{9Reference 9Sharma et al. · 2014AnimalProtective efficacy of piperine against Mycobacterium tuberculosis — animal modelView study →}, and it potentiates anti-TB drugs in vitro ^{10,11Reference 10Hegeto et al. · 2019Systematic reviewPromising antituberculosis activity of piperine combined with antimicrobials — systematic review of preclinical studiesView study →Reference 11Hegeto et al. · 2018In vitroIn vitro combinatory activity of piperine and anti-tuberculosis drugs in Mycobacterium tuberculosis — in vitroView study →}.

The trial is evidence for a pharmaceutical formulation containing a measured dose of an isolated alkaloid alongside real antibiotics — not for black pepper, and emphatically not for pepper instead of drugs. Limits: a single trial, one country, ~25% dropout, and no independent replication.

Milk thistle targets the regimen’s actual weak point. A double-blind, placebo-controlled randomised trial found silymarin reduced the incidence of anti-tuberculosis drug-induced liver injury in patients starting standard therapy ^{12Reference 12Luangchosiri et al. · 2015RCTA double-blinded randomized controlled trial of silymarin for the prevention of antituberculosis drug-induced liver injury — randomised placebo-controlled trialView study →}. The value is indirect but substantial: hepatotoxicity is what forces treatment interruption, and interruption is what breeds resistance — so a liver protectant is, in effect, an adherence intervention.

Milk thistle is well tolerated, which matters when it is taken alongside four hepatotoxic drugs. The evidence is a single modest trial, not a replicated body of work, and guidelines do not yet recommend routine use. It prevents a drug side effect — it does nothing to the bacterium. Anyone on TB therapy should raise it with the clinician monitoring their liver enzymes rather than adding it unannounced.

Usnic acid inhibits M. tuberculosis in culture including drug-resistant strains, with no evidence that efflux drives innate resistance ^{13Reference 13Ramos et al. · 2010In vitroAntimycobacterial activity of usnic acid against resistant and susceptible strains of Mycobacterium tuberculosis and non-tuberculous mycobacteria — in vitroView study →}; among the lichen depsides, diffractaic acid was the most potent ^{14Reference 14Honda et al. · 2010In vitroAntimycobacterial activity of lichen substances — in vitroView study →}; and mechanistic work shows usnic acid alters the composition of the mycobacterial cell envelope and the organism’s redox status ^{15Reference 15Sieniawska et al. · 2021In vitroUsnic acid treatment changes the composition of Mycobacterium tuberculosis cell envelope and alters bacterial redox status — in vitro. mSystems. https://pubmed.ncbi.nlm.nih.gov/33947802/View study →} — a real mechanism against the waxy wall that makes TB so hard to kill.

A gap separates the concentrations that inhibit the organism from those tolerable to mammalian cells, and there is no animal efficacy work or clinical data to close it. Usnic acid is a drug lead rather than a treatment. The human liver injuries associated with it involved isolated compound concentrated into weight-loss products, not the whole lichen.

Cryptolepis is a West African antimalarial whose broad antimicrobial reach extends to mycobacteria. Cryptolepine hydrochloride is a potent antimycobacterial alkaloid active against several Mycobacterium species in vitro ^{16Reference 16Gibbons et al. · 2003In vitroCryptolepine hydrochloride: a potent antimycobacterial alkaloid derived from Cryptolepis sanguinolenta — in vitroView study →}, and the root’s aqueous extract was the most antimycobacterial of a panel of Ghanaian medicinal plants.

The evidence is in vitro only — no animal infection model and no human data for this indication. Cryptolepine is a DNA-intercalating alkaloid, which is part of why it is active against so many organisms and also why potency in a dish does not imply safety or efficacy in a person.

The root decoction was an Indigenous North American tuberculosis medicine, and the antimycobacterial activity has been reported independently by three groups and tracked by bioassay-guided fractionation to a specific molecule — the polyacetylene falcarindiol, alongside furanocoumarins ^{17,18Reference 17O’Neill et al. · 2013In vitroThe Canadian medicinal plant Heracleum maximum contains antimycobacterial diynes and furanocoumarins — in vitroView study →Reference 18Webster et al. · 2010In vitroAntimycobacterial screening of traditional medicinal plants using the microplate resazurin assay — in vitroView study →}. Traditional indication → replicated screening hit → named active constituent is a tighter chain than most ethnobotanical claims achieve.

The testing used the avirulent laboratory strain H37Ra rather than a virulent clinical isolate, and most potency data come from methanolic extracts even though the aqueous infusion is the traditional — and the bioassay-validated — preparation. It is in vitro throughout, without animal or human data.

The plant carries a serious separate hazard: its furanocoumarins cause phytophotodermatitis — handling the sap and then going into sunlight produces genuine chemical burns.

Dioscorides described agarikon in the first century, and the dried conk stayed in European practice for centuries for consumption, fevers and night sweats. The modern finding is specific: chlorinated coumarins isolated from F. officinalis are active against M. tuberculosis in vitro ^{19Reference 19Hwang et al. · 2013In vitroChlorinated coumarins from the polypore mushroom Fomitopsis officinalis and their activity against Mycobacterium tuberculosis — in vitroView study →}.

The chemistry does not sit where tradition looked — the anti-TB coumarins concentrate in cultured mycelium, not in the conk that historical practice used. Agaric acid makes the fungus a drastic purgative. No monopreparation has ever been tested in a person.

A single but well-characterised study identified the antimycobacterial polyynes of devil’s club root and stem bark — falcarinol-type molecules including falcarindiol and oplopandiol — consistent with its long traditional use for infections ^{20Reference 20Kobaisy et al. · 1997In vitroAntimycobacterial polyynes of devil’s club (Oplopanax horridus), a North American native medicinal plant — in vitroView study →}. This is the same polyyne class that carries cow parsnip’s activity, from an unrelated plant family, which makes the class more interesting than either plant alone. One in-vitro paper, no in vivo work. Devil’s club’s better-supported research direction is antiproliferative, not antimycobacterial.

A respiratory herb whose antimycobacterial evidence belongs, strictly speaking, to a relative. Aralia nudicaulis — wild sarsaparilla, used by Iroquois and Algonquin peoples as a cough and tuberculosis remedy — yielded two C17 polyacetylene diynes, falcarinol and panaxydol, on antimycobacterial screening ^{18,21Reference 18Webster et al. · 2010In vitroAntimycobacterial screening of traditional medicinal plants using the microplate resazurin assay — in vitroView study →Reference 21Li et al. · 2012In vitroAnti-mycobacterial diynes from the Canadian medicinal plant Aralia nudicaulis — in vitroView study →}. Again the same polyyne chemistry. The studied species is a congener, and A. racemosa itself has not been shown to do this. The traditional respiratory use and the family chemistry are consistent, but for A. racemosa that is inference, not evidence.

Mexico’s most widely used medicinal plant, with antimycobacterial activity documented alongside its cytotoxic and anti-inflammatory profile ^{22Reference 22Gálvez Romero et al. · 2022In vitroAntimycobacterial, cytotoxic, and anti-inflammatory activities of Artemisia ludoviciana — in vitro / animal modelView study →}. The finding comes from a broad antibacterial screen; estafiate is not a dedicated TB remedy, and its better-supported directions are gastrointestinal and antiparasitic. In vitro, with MICs in the mg/mL range: high concentrations, no in-vivo cure, no standardised preparation.

Haritaki shares milk thistle’s hepatoprotective rationale, with weaker evidence. A T. chebula fruit extract prevented liver toxicity from sub-chronic administration of rifampicin, isoniazid and pyrazinamide in combination — the exact triple regimen that causes anti-TB drug-induced liver injury — in an animal model ^{23Reference 23Tasduq et al. · 2006AnimalTerminalia chebula (fruit) prevents liver toxicity caused by sub-chronic administration of rifampicin, isoniazid and pyrazinamide in combination — animal modelView study →}. Directly on target, and consistent with the herb’s broader replicated liver-protective record across several distinct insults.

The evidence is animal only; there is no human trial of haritaki for this purpose, which is precisely the gap silymarin has filled. Haritaki is also a laxative at higher doses, which is an unhelpful property in someone already losing weight.

The resinous root was decocted for coughs, colds, fevers and tuberculosis across the Interior Plateau and Great Basin, chewed for sore throat, and used as an antimicrobial poultice — the poultice being the best-attested application. No antimycobacterial testing exists for this plant at all. It is what people used before there was a cure, in an era when TB killed roughly half of those it sickened regardless of what they took.