Cat's whiskers

Orthosiphon stamineus (of the family Lamiaceae^[1] and synonymous with Orthosiphon aristatus) is a plant that originates from eastern Asian countries such as Vietnam, Thailand, Indonesia and Malaysia but was introduced to the West in the early 20^th century where it was consumed as a tea known as 'Java' (not to be confused with the variant of 'Java coffee' coming from the island of Java)^[2] with other common names (Misai kucing, Kumis kucing or cats whiskers) referring to the plant's wispy appearance.^[3] The plant comes in two varieties, one with white flowers and the other with light purple flowers, where the purple variety seems to have a greater quantity of the same bioactives.^[1]

Various other names for this plant include moustaches de chat (French for Cat's Whiskers), yaa nuat maeo, rau meo, cay bac (all Thailand), and Remujung (Indonesia).^[4]

It appears to have medicinal usage for the treatment of atherosclerosis, nephritis, kidney stones, diabetes,^[5] inflammatory disorders (fever, cold, rheumatism),^[3] STIs (gonorrhea and syphilis),^[6] and hepatic disorders such as jaundice and hepatitis;^[1] it also appears to possess a 'strong' diuretic effect.^[1]

Orthosiphon stamineus is a plant whose leaves are used to make a health tea, and beyond the obvious diuretic effect of this tea is appears to be traditionally used for mostly inflammatory and urinary disorders. It is known as Java, but does not refer to nor is related to the coffee known as Java

The contents of __ (leaves unless otherwise specified) include:

• Eupatorin (3′,5-dihydroxy-4′,6,7-trimethoxyflavone)^[2] at 0.34-3.37% (average of 1.24%) of the leaf dry weight^[6]
• Sinensetin (3',4',5,6,7-pentamethoxyflavone)^[2][7] at 0.22-1.76% (average of 0.73%) of the leaf dry weight^[6]
• Heptamethoxyflavone (3',4',3,5,6,7,8-heptamethoxyflavone)^[7]
• Tangeritin (4',5,6,7,8-pentamethoxyflavone)^[7]
• Tetramethylscutellarein or Scutellarein tetramethylether (4',5,6,7-tetramethoxyflavone);^[7][8] a variant of the flavonoid found in Scutellaria baicalensis
• Salvigenin (5-Hydroxy-6,7,4'-trimethoxyflavone) and Ladanein (5,6-dihydroxy-7,4'-dimethoxyflavone)^[5]
• 3'-hydroxy-5,6,7,4'-tetramethoxyflavonone^[6][7] at 0.1-0.63% of the leaf dry weight^[6]
• 5-hydroxy-6,7,3',4'-tetramethoxyflavone^[5] and 6-hydroxy-5,7,4'-trimethoxyflavone^[5]
• 7,3',4'-trimethylluteolin^[5]
• Rosmarinic Acid^[2][9] (5.3-29.9% dry leave weight; average of 12.4%^[6]) and related structures Aurantiamide acetate^[5] and Cichoric acid (0.07% in 50-70% ethanolic extracts^[9])^[9]
• Diterpene structures including Orthisiphols A-Z (Isopimarane type),^{[5][8][10][11][12][13]} Staminols A-B (novel 'staminane' backbone), staminolactone A-B, norstaminol A (highly oxygenated staminanes),^[5] secoorthosiphols A-C^[10][14]
• 13-epi-orthosiphol N^[15]
• Siphonols A-E^[16]
• Vomifoliol^[5]
• Oleanolic acid, betulinic acid (2.25-3.70mg/g dry weight depending on extract^[17]), and ursolic acid^[5]
• Caffeic acid (0.01-0.03mg/mL in 50-70% ethanolic extracts) and^[2][5] 2,3-dicaffeoyltartaric acid^[18]
• β-sitosterol^[5]

There is also a polysaccharide present in the leaves that is involved in the urogenital health effects, 95.6% carbohydrate by weight (preliminarily named OSAP).^[19] There are also detectable glycosaponin and protein structures in the ethanolic extracts.^[20]

The unique bioactives in the leaves appear to be the methylated flavonoids, similar to Kaempferia Parviflora; this plant appears to have more methyl groups on their flavonoids though, yet the most prominent bioactive is just a hefty dose of rosmarinic acid

When looking at the phenolics (50% methanolic extract), the majority (67%) belong to the class of phenolic acids including caffeic acid and 2,3-dicaffeoyltartaric acid or their oligomers (rosmarinic and cichoric acids as well as Aurantiamide acetate)^[18] and this majority increases to 94.5% when using a hot water extract.^[18] Overall though, there is the greatest extraction of rosmarinic acid seen with the 50% methanolic extract^[21][22] and the various extraction techniques tend to result in:

• 50% methanolic extract has a total extractable content of 275.66mg/g, total phenolic content of 189.073+/-49.15mg/g (GAE; gallic acid equivalents), and total flavonoid content of 17.56+/-5.5mg/g (RE; rutin equivalents)^[22] with noted contents of eupatorin (0.34%), sinensetin (0.2%), and 3'-hydroxy-5,6,7,4'-tetramethoxyflavone (0.24%) with a large content of rosmarinic acid (7.58%)^[4]
• 50% ethanolic (around 8.1% yields^[23]) extracts accumulate eupatorin (1.01-3.03%), sinensetin (3.76%), and 3′hydroxy-5,6,7,4′-tetramethoxyflavone (1.01-3.03%)^[4] and 100% ethanolic extracts have higher levels of eupatorin (19.9%), sinensetin (19.2%), and 3′hydroxy-5,6,7,4′-tetramethoxyflavone (5.4%) as well as 3.70mg/g betulinic acid^[17][24] and 25% ethanolic extracts lower values of eupatorin (0.97%), sinensetin (1.14%), and 3′hydroxy-5,6,7,4′-tetramethoxyflavone (0.38%);^[24] rosmarinic acid varies from 0.091-0.117mg/mL depending on the ethanolic content (50-70% range)^[9]
• Hot water extract has 178.34mg/g total extractables (a usual yield of 7.6%^[23]), of which 160.327+/-15.552mg/g are phenolics (GAE) and 13.20+/-4.2mg/g flavonoids (RE)^[22] but have a low content of both eupatorin (0.00035%) and sinensetin (0.00056%) sometimes being undetectable^[24][25] due to being 94.5% caffeic acid phenolics (like rosmarinic acid); the water extracts do have betulinic acid (2.25-2.43mg/g dry weight)^[17]
• n-hexane extract has 4.02mg/g of total extractables and 35.507+/-1.420mg/g (GAE) phenolics, with a flavonoid content of 24.52+/-2.5mg/g (RE)^[22]
• n-butanol has 72.93mg/g total extractables with 183.250+/-14.110mg/g (GAE) being phenolics and 14.94+/-1.9mg/g (RE) being flavonoids^[22] with detectable sinensetin (0.07%) and 3′hydroxy-5,6,7,4′-tetramethoxyflavone (0.17%) but not eupatorin^[24]
• Chloroform extract has 7.75mg/g total extractables and a phenolic content of 139.813+/-12.164mg/g (GAE); flavonoids are measured at 58.11+/-9.5mg/g (RE)^[22] and there is a detectable eupatorin (22.5%), sinensetin (14.5%), and 3′hydroxy-5,6,7,4′-tetramethoxyflavone (5.7%)^[24]
• Dichloromethane extracts contain eupatorin (0.95%) and sinensetin (0.47%)^[25]
• Ethyl acetate with total extractables at 12.62mg/g; phenolics at 222.927+/-7.580mg/g (GAE) and flavonoids at 28.83+/-4.1mg/g (RE)^[22] with detectable levels of eupatorin (1.48%), sinensetin (1.41%), and 3′hydroxy-5,6,7,4′-tetramethoxyflavone (1.6%)^[24]
• Petroleum ether extracts have been ntoed to accumulate eupatorin (1.82%) over sinensetin (0.21%)^[25]

Chloroform and ethanolic extracts seem to concentrate the flavonoids, while the methanolic has a decent dose of flavonoids but also a good rosmarinic acid content; the water extract is essentially just the rosmarinic acid and related caffeic acid phenolics (little to no flavonoids) and other extracts are unremarkable. Don't take the above values at face value (just note the trends)

If the essential oil fragment (aromatics) are separated from the leaves or stem, it includes:^[26]

• β-caryophyllene (24-35.1%)
• α-humulene (14.2-18.4%)
• β-elemene (8.5-11.1%)
• 1-octen-3-ol (7-8.2%)
• β-bourbonene (3-3.4%)
• β-pinene (1.7-2.1%)
• caryophyllene oxide (1.6-2.2%)
• camphene (1.3-1.6%)
• limonene (1.1-1.2%)
• α-pinene
• 1,8-cineol
• borneol
• linalool
• camphor
• eugenol
• p-cymene
• carvone
• bornyl acetate
• δ-cadinene

The essential oil fragment (not frequently used nor would it be found in the tea to a high degree) is mostly β-caryophyllene and α-humulene

Supplementation of an orthosiphon stamineus extract to rats (1g/kg oral intake of a 50% methanolic extract with 0.26% betulinic acid) resulted in a plasma betulinic acid content of 1.2+/-0.3μg/mL within an hour (T_max), with a three hour half life.^[27]

Lack of pharmacokinetic data on the main components of this plant (the methylated flavonoids)

In toxicity tests in mice, 4,000mg/kg of the water extract has failed to alter the enzyme activity of CYP1A and CYP2B9/10.^[28]

Orthosiphon stamineus appears to have inhibitory potential against the CYP2C19 enzyme with the petroleum ether extract (IC₅₀ of 67.1μg/mL) but not so much the dichloromethane (more than 250μg/mL), ethanolic (231.5μg/mL), nor water (835.5μg/mL) extracts.^[2] Isolated Eupatorin exerted mixed type inhibition with an IC₅₀ of 35.1μM; isolated Sinensetin was less inhibitory (IC₅₀ 192.3μM) and both caffeic acid and rosmarinic acid did not contribute^[2] and unlike CYP2C19, CYP2C9 does not appear to be significantly influenced by the major bioactives (most potent being rosmarinic acid at 318.9μM; water extract at 753.2μg/mL).^[25]

Eupatorin is able to potently inhibit CYP3A4 activity in a noncompetitive manner with an IC₅₀ of 14.5μM and CYP2D6 at 11μM in an uncompetitive manner;^[25] the water extract again being ineffective in inhibiting these enzymes significnatly (838.9μg/mL and 288.8μg/mL for CYP3A4 and CYP2D6).^[25]

While there is no in vivo evidence at this point in time, it is plausible that both CYP2C19 and CYP3A4 may be inhibited by consumption of this supplement

When assessing enzymes of glucuronidation in the range of 0.01-50μg/mL of orthosiphon stamineus (50% methanolic extract), inhibitory effects have been noted on UGT1A1 (24.65μg/mL), UGT1A6 (30.02μg/mL), UGT1A7 (10.83μg/mL), and UGT1A8 (43.39μg/mL) whereas the inhibition was not present (greater than 50μg/mL) for UGT1A3, UGT1A10, UGT1B7, and UGT1B15.^[3]

Known to interact with the enzymes of glucuronidation with unknown practical relevance; not as inhibitory as the other tested herb (andrographis paniculata)

Tetramethylscutellarein and sinensetin are known to interact with adenosine A₁ receptors with a pK_i of 5.4+/-0.1 and 5.5+/-0.1^[29] and are thought to be antagonistic;^[30] this is thought to underlie the diuretic effects of the herb, since A₁ receptor antagonists induce diuresis.^[31]

It is thought that the flavonoids may inhibit one of the adenosine receptors (not the same receptor that caffeine inhibits, which is A_2A), practical relevance of this information is not known

A 50% methanolic extract (125-1,000mg/kg) prior to hot plate failed to reduce pain and when given one hour prior to acetic acid, formalin, and tail flick latency tests only the highest dose was mildly effective, but routinely lost in potency to the reference drugs (9mg/kg morphine sulfate or 100mg/kg paracetamol).^[32]

May have very mild analgesic effects at the higher doses

Injections of orthosiphon stamineus (45-45,000mg/kg) intraperitoneally is able to increase the mRNA of POMC (hunger suppressing neuropeptide^[33]) with no dose dependency while the mRNA for neuropeptide Y (hunger inducing neuropeptide^[33]) decreased in a dose dependent fashion after two hours;^[34] these effects were confirmed with oral ingestion of 450mg/kg of a 70% ethanolic extract over two weeks, where a 58% increase in POMC expression and 20% reduction in NPY mRNA were noted.^[34] This is thought to be secondary due to serum increases in leptin (58-140% in lean rats, being attenuated with time; 80% in obese rats although POMC induction was not confirmed).

Secondary to an increase in leptin, there may be a suppression in appetite in rats

A 50% methanolic extract of orthosiphon stamineus at 125-1,000mg/kg given to mice infected with yeast (induces fever-like symptomology) was able to suppress the increaes in temperature in a dose-dependent manner; the highest dose being comparable to 150mg/kg paracetamol as reference;^[35] this is thought to be due to the anti-pyretic activities of rosmarinic acid.^[36]

There may be antipyretic (fever reducing) properties of this herb, with higher than normal doses being somewhat comparable to the reference drug (Acetominophen/Tylenol)

Methylripariochromene A (MRC A) appears to reduce blood pressure in spontaneously hypertensive rats (SHRs)^[37] and when testing a 50% methanolic extract and water extract of orthosiphon stamineus in SHRs (1,000mg/kg dietary intake for 14 days) the endothelium derived from these rats was able to reduce phenylephedrine induced contractions in a NOS-dependent manner that was enhanced by indomethacin (ex vivo) and did not augment acetylcholine induced relaxation (ex vivo).^[38]

One trial (single blind controlled) using orthosiphon stamineus at 100mg of an ethanolic extract (greater than 0.1% sinensetin) added in addition to a nutraceutical blend (berberine, monokolin K from red yeast rice, and policosanol at 500mg, 3mg, and 10mg respectively) was able to reduce blood pressure and glucose relative to baseline; its blood pressure reducing effects were less than the reference drug hydrochlorothiazide (12.5mg added to the same three nutraceuticals) and there was no significant difference in cardiovascular disease risk at the end of the trial.^[39]

Limited evidence on the topic of blood pressure, and nothing makes it appear to be a more respectable option than other supplemental options

A chloroform subfraction of the plant leaves (containing eupatorin at 1.48% and sinensetin at 2.26%) appears to inhibit glucose uptake in an ex vivo test of intestinal absorption at 500-2,000µg/mL.^[40] Elsewhere, it was shown that a 50% ethanolic extract of the leaves was able to inhibit α-glucosidase (IC₅₀ of 4.63mg/mL) and α-amylase (IC₅₀ of 36.70mg/mL) which was thought to be due to the sinensetin content which had an IC₅₀ of 0.66g/mL and maximum inhibition of 89% (2.5mg/mL) on α-glucosidase and an IC₅₀ of 1.13mg/mL and maximum inhibition of 85.8% (2.5mg/mL) on α-amylase;^[4] this study noted that sinensetin outperformed the reference drug acarbose.

One study using 200-1,000mg/kg of the water extract in normal rats has noted that only the higher dose was associated with reliable reductions in blood glucose in response to an oral glucose tolerance test (OGTT); the reductions over the next 210 minutes being in the range of 19-35% (no time dependence).^[41] This did not occur overly reliable at any dose in diabetic rats, although at 90 and 210 minutes after ingestion there were reductions at all tested dose.^[41]

A potential usage of this plant could be the inhibition of glucose uptake, which seems pretty respectable and isn't something that needs extensive pharmacological studies on (since the active components do not need to be absorbed); it may occur in rats, although the OGTT may not be the best model since there are some peripheral actions of this herb (see next sections)

When tested in vitro, a water extract does not stimulate insulin secretion.^[41] In vivo tests using a chloroform subfraction of the plant leaves (containing eupatorin at 1.48% and sinensetin at 2.26%) at 500-1,000mg/kg twice daily for 14 days does not appear to stimulate insulin secretion in diabetic rats^[40] and elsewhere was noted to suppress insulin release in response to a subcutaneous glucose load^[42] and oral glucose test.^[41]

In otherwise normal rats given 450mg/kg of an ethanolic extract, there does not appear to be any alterations in fasting insulin (nor glucose) after two weeks relative to control.^[34]

There does not appear to be any stimulatory effect on insulin secretion, and in response to glucose-stimulated insulin release there may be a slightl suppressive effect

A chloroform extract (1.48% eupatorin and 2.26% sinensetin) is able to increase glucose uptake into diaphragm muscles at the concentration of 2mg/mL in a manner not complementary with insulin, but not at 0.5-1mg/mL.^[40]

Possible uptake of glucose into muscle cells; has not yet been applied to skeletal muscle (voluntary contractile muscle) which is the largest body of muscle in the body

It appears that orthosiphon stamineus is a relatively popular antidiabetic alterantive medicine in the region from which it originated, with its 24.2% usage (among those who do use alternativ medicine) being less than Momordica Charantia (30.4%) but more than garlic (13.3%).^[43]

In streptozotocin diabetic rats, a chloroform subfraction of the plant leaves (containing eupatorin at 1.48% and sinensetin at 2.26%, as well as some terpenoids) at 500-1,000mg/kg oral intake twice daily for 14 days was able to slightly reduce blood glucose; the potency was significantly less than the reference drug 500mg/kg Metformin.^[40] This has been noted to occur with the water extract as well over 14 days, reaching a 13% reduction in fasting blood glucose and being less effective than the reference drug glibenclamide.^[41]

Acutely, this same dose and extract is able to reduce blood glucose from a subcutaneous glucose tolerance test yet was unable to induce hypoglycemia.^[42]

May have some potential in diabetes for acutely reducing blood glucose (seen with both oral and subcutaneous glucose loads, which means the intestines are not the only factor at play) but to a lesser degree than reference drugs. The inability to induce hypoglycemia suggests that AMPK is related to the mechanisms of action (Metformin's target)

In isolated 3T3-LI adipocytes, the ethanolic and n-butanolic extracts (not not water, n-hexane, nor ethylacetate) increased leptin mRNA in the range of 50-100µg/mL, with efficacy at 10µg/mL in the n-butanolic extract^[34] and these results being replicated with little to no difference between 100µg/mL and 1,000µg/mL of the ethanolic extract.^[44]

In normal weight rats, 70% ethanolic extract of orthosiphon stamineus leaves at 450mg/kg oral ingestion for two weeks appears to induce leptin secretion as it was measured 140% higher than control after two weeks.^[34] This has been replicated elsewhere over eight weeks in lean (58% only) and obese (80% relative to obese control) mice with a 70% ethanolic extract (around 38-58mg/kg and 33-58mg/kg in lean and obese), although in the obese and leptin resistant rats it was not met with weight loss nor appetite reduction alone.^[44]

Something in the ethanolic extract of orthosiphon stamineus appears to induce leptin production in fat cells. This has been confirmed in rodents and may occur at low enough doses to be relevant to oral supplementation

In normal weight mice, 450mg/kg of a 70% ethanolic extract over two weeks is able to reduce body weight (weight gain over two weeks was attenuated 41%) and fat mass (63% of control) associated with reductions in food intake (45%) and increases in serum leptin (140% more than control).^[34] Elsewhere, the weight loss seen in lean mice with of the 70% ethanolic extract (1mg overall; but about 38-58mg/kg) over eight weeks was not highly significant relative to control.^[44]

In high fat fed obese mice given orthosiphon stamineus alongside a larger dose of betulinic acid (500µg; around 16-29mg/kg) than normally found in orthosiphon stamineus (due to PTP1B inhibition,^[45] which is thought to be theapeutic in the leptin resistance since PTP1B negatively regulates leptin signalling^[46] and occurs in the hypothalamus^[47] where appetite is regulated) is able to reduce weight synergistically; orthosiphon alone was effective in lean but not obese mice (betulinic acid being the opposite) while the combination was synergistic in obese mice only and showed minor additive effects in lean rats.^[44]

Due to inducing leptin, orthisiphon appears to reduce weight in normal rats but not leptin resistant obese rats. PTP1B inhibition (betulinic acid being used, but ursolic acid and berberine both having this property) works in obese rats but not lean rats, and the combination is synergistic in obese rats only

In a rat model of Carrageenan induced edema, 125-1,000mg/kg of a 50% methanolic extract was able to reduce edema at only the higher doses of 500-1,000mg/kg (17-27%) and was less potent than the reference drug of 10mg/kg Indomethacin.^[32]

Antiinflammatory potential against joint inflammation is mild at best

Siphonols A-E show inhibitory activity on macrophage activation (induced by LPS) with IC₅₀ values in the range of 10.6-22.9µM with most potency from siphonol A.^[16] Orthosiphol U can inhibit this process with an IC₅₀ of 6.4μM (with most orthosiphols in the range of 20-60μM),^[13] and some other diterpenes have an IC₅₀ in the range of 10.8-25.5μM.^[12]

Eupatorin and Sinensetin have also demonstrated antiinflammatory actions in the same type of macrophage study (IC₅₀ values of 5.2µM and 9.2µM) with slightly more effective inhibition of PGE₂ release and TNF-α secretion (IC₅₀ values of 5.0µM and 2.7µM);^[48] both flavonoids were found to inhibit STAT1α activation from LPS.^[48]

The diterpenes have moderately potent antiinflammatory activities on macrophage activation while the flavonoids are slightly more potent; the IC₅₀ value of sinensetin is low enough that it may be biologically relevant despite its low concentration in ethanolic/methanolic extracts

In human PBMCs, the ethanolic and water extracts of orthosiphon stamineus at a concentraiton of 100µg/mL (12.5-50µg/mL ineffective) have stimulated proliferation of these cells by 149.75% and 256.39% respectively.^[23]

May have a potential immunostimulatory property

In vitro, the water and ethanolic extracts have failed to significantly reduce the growth of the Escherichia coli and Klebsilla pneumonia bacteria while there was inhibition of grwoth against Staphylococcus aureus and Streptococcus agalactiae;^[23] only the water extract established MIC values, which were 1.56mg/mL (MIC against Staphylococcus aureus) and 3.13g/mL (MIC against Streptococcus agalactiae 3.13).^[23]

May have inhibitory effects against gram positive bacteria, but not gram negative

The methanolic extracts appears to have an antioxidant potential comparable to pure quercetin or butylated hydroxylanisole (BHA) in an in vitro antioxidant test (β-carotene and linoleic acid oxidation) when said methanolic extracts contain a phenolic content of 6.69-10.1mg/g dry weight (caffeic acid equivalents);^[6] this same study has been published elsewhere under another title^[21] but replicated elsewhere with the water extract having an IC₅₀ (DPPH assay) of 9.6+/-0.021µg/mL and the ethanolic extract 21.4+/-0.1µg/mL relative to that of Vitamin C (4.6µg/mL) and BHT (21.1µg/mL).^[23]

In a DPPH assay investigating extracts of the leaf, there appeared to be least potent with the n-hexane extract (IC₅₀ of 126.2+/-23μg/mL) and gradually more potency was seen when assessing the chloroform extract (31.25+/-1.2μg/mL), water extract (23.0+/-3.2μg/mL), 50% methanolic extract (16.66+/-1.5 μg/mL) ethyl acetate (15.25+/-2.3μg/mL) and n-butanol (13.56+/-1.9μg/mL).^[22] In a β-carotene oxidation test, the n-butanol extract seemed most potent yet did not outperform BHA as reference.^[22]

Outside of the body, it appears to be an antioxidant compound with a potency comparable to Vitamin C and isolated Quercetin; requires some pharmacokinetic data to see if this applies to the body after oral ingestion since the main class of molecules (methylated flavonoids) can be summed up as being poorly absorbed (flavonoids) but enhanced (methylated) making their relevance unpredictable

125-1,000mg/kg of the 50% methanolic extract of orthosiphon stamineus leaves orally to rats an hour before an ulcer producing dose of alcohol is able to reduce the subsequent ulcer index, with 500-1,000mg/kg (67.56-86.93% inhibition) being of comparable potency as 30mg/kg omeprazole (79.13%);^[49] this inhibitory effect was dose-dependent and associated with reductions in lipid peroxidaiton.^[49]

Appears to reduce ulceration from alcohol. Higher doses are quite respectable in potency, and this appears to be directly tied into the antioxidant properties of the herb

General hepatoprotective effects were initally noted against CCl₄ toxicity^[50] and subsequently a 95% ethanolic extract of orthosiphon stamineus at 100-200mg/kg daily for two months alongside the known hepatoxin thioacetamide (TAA) thrice weekly was associated with dose-dependent protective effects that were only significant at the higher dose, yet still less potent than the relative drug of silymarins (50mg/kg) from Milk thistle.^[51]

General liver protective effects, but these are not better than the herbal reference of milk thistle

In rats given calcium oxalate induced nephrolithiasis (calcium based kidney stones), 80-160mg/kg of various extracts of the leaves noted that while the flavonoids (Ethyl acetate) were able to increase urinary calcium and oxalate excretion that a polysaccharide reduced CaO crystal nucleation and aggregation; observed effects were dose dependent.^[19]

There is a potential reduction in the synthesis of calcium based stones in the kidneys

250-2,000mg/kg of the 50% methanolic leaf extract in hyperuricemic rats is able to decrease serum urate at six hours after measurement (but not eight) and was significantly less potent than the reference drug allopurinol (50mg/kg).^[52] Urinary uric acid has been noted to be increased with 50-70% ethanolic extracts in rats as well.^[9]

Appears to increase the bodily elimination of uric acid, which may underlie anti-gout properties

Supplementation of a single 2,000mg/kg dose of a 50% or 100% methanolic extract of orthosiphon stamineus leaves to rats is able to promote diuresis over 24 hours (less potent than the reference drug hydrochlorothiazide) while increasing urinary pH from 8.0 to around 8.7-8.9 associated with increased urinary potassium and sodium.^[52] When the dose was reduced to 500mg/kg and the time frame increased to a week, there appeared to be time-dependent increases in cumulative urine output starting at day three^[52] and diuresis has been replicated in rats elsewhere with a 50% ethanolic extract being less potent than furosemide^[9] and a water extract but still with less potent than both furosemide and hydrochlorothiazide although it was dose dependent at 5-10mg/kg;^[53] this lower dose did not alter urinary sodium nor chloride, but increased urinary potassium.^[53]

Ethanolic extracts (50-70% extracts) noted that only the 50% ethanolic was effective.^[9] This is thought to either be due to methylripariochromene A (MRC A) which itself has diuretic properties^[37] or due to methylated flavonoids (Tetramethylscutellarein and sinensetin) which are probably adenosine A1 receptor antagonists^[29][30] and this mechanism is known to induce diuresis.^[31]

There appears to be a diuretic property of the leaf extracts, and this is thought to either be due to MRC A (shown to have diuretic properties) or some of the methylated flavonoids (known to possess a mechanism that is known to promote diuresis); the potency is less than reference drugs, but reportedly greater than other herbs

When tested in humans, supplementation of 10 grams of the dry leaves of Orthosiphon stamineus for four days alongside a standardized diet and fluid intake (1.21 L of fluid) failed to increase 24 hour urine output relative to control.^[54]

In various cancer cells (breast, myeloma, leukemia, adenocarcinoma) the chloroform extract (0.53+/-0.08% eupatorin) and eupatorin itself were able to reduce proliferation with eupatorin having an IC₅₀ value in the range of 4.29-16.61µM; there was no effect of eupatorin on noncancerous BJ or HUVEC cells (greater than 50µM) and eupatorin was weaker than the reference of Alvocidib in all cell lines.^[55]

In HCT 116 cancer cells exposed to the 50% ethanolic extract (3.625-100μg/mL) for 48 hours, orthosiphon stamineus is able to reduce VEGF content in cells by 18-45% (25-50μg/mL) while there was no significant reduction in noncancerous HUVEC cells up to 100μg/mL.^[20] The extract can inhibit VEGFR2 phosphorylation induced by VEGF (concentration dependent), and in vitro after a scratch wound in HUVEC cells migration was reduced 76.8-97.33% over 12 hours with 25μg/mL.^[20]

Appears to be quite antiproliferative in isolated cells associated with suppressing the formation of new blood vessels

When tested in vitro in colonic 26-L5 cancer cells, the leaf methanolic extract demonstrated cytotoxicity (ED₅₀ of 73.6µg/mL) which was thought to be due to eupatorin (EC₅₀ of 11.3µg/mL).^[5]

100-200mg/kg of a 50% ethanolic extract of orthosiphon stamineus (in mice bearing HCT 116 colorectal tumors) once daily for four weeks was able to reduce blood vessel formation in the excised tumors and dose-dependently reduce tumor size .^[20] VEGF expression in the excised tumors appeared to be reduced by 17-33% relative to tumor bearing controls, and tumor growth (calculated by ΔT/ΔC) was 13.6% (100mg/kg) and less than 1.45% (200mg/kg) after three weeks while both doses more than halved tumor volume;^[20] a ΔT/ΔC less than 42% growth is considered significant anti-tumor activity.^[56]

Preclinical evidence suggests quite a respectable therapeutic effect against colon cancer, which begets more studies on this topic

In skin explants from donors, 2% orthosiphon stamineus at 10mg/mL was able to reduce the mRNA content of 5α-reductase type 1 and caused 64% inhibition of this enzyme; the reference drug, 1% zinc gluconate at the same concnetration, reached 56% inhibition of enzyme activity.^[57]

In women with self-reported oily skin given a 2% orthosiphon stamineus cream to apply twice daily over 28 days, the herb appeared to outperform 1% zinc gluconate when it came to reducing visible pore size, skin shininess, and oiliness while it was also more effective at improving evenness, radiance, and was associated with better self-reported in both skin texture and appearance.^[57]

Preliminary evidence suggests that orthosiphon stamineus improves skin quality to a level greater than the reference drug

In high fat fed mice given orthosiphon stamineus alongside a larger dose of betulinic acid (due to PTP1B inhibition,^[45] which is thought to be theapeutic in the leptin resistance since PTP1B negatively regulates leptin signalling^[46] and occurs in the hypothalamus^[47] where appetite is regulated) is able to reduce weight synergistically; orthosiphon alone was effective in lean but not obese rats (betulinic acid being the opposite) while the combination was synergistic in obese rats only and showed minor additive effects in lean rats.^[44]

Due to inducing leptin, orthisiphon appears to reduce weight in normal rats but not leptin resistant obese rats. PTP1B inhibition (betulinic acid being used, but ursolic acid and berberine both having this property) works in obese rats but not lean rats, and the combination is synergistic in obese rats only

The LD₅₀ of orthosiphon stamineus appears to be greater than 5,000mg/kg in this study that noted no apparent toxicity there was a seemingly benign increase in liver weight (a reduction in serum enzymes)^[58] and this lack of toxicity at this dose has been replicated acutely^[59] and over a period of 28 days with the 50% ethanolic extract.^[60]

The water extract has failed to show genotoxic effects in Salmonella/microsome assays, and doses up to 4,000mg/kg in mice failed to exert genotoxic effects in a bone marrow test.^[28]

At this moment in time this herb does not appear to be toxic nor genotoxic, with the doses tested being 5-10 times higher than the supplemented doses