Cytotoxic effects of plant extracts from the families Fabaceae, Oleaceae, Philadelphaceae, Rosaceae and Staphyleaceae

A human transformed line of HeLa cells was treated with extracts prepared from Gymnocladus dioicus, Holodiscus discolor, Stephanandra tanakae, Ligustrum delavayanum, Ligustrum vulgare and Staphylea pinnata. The study evaluating the influence of the active extracts on HeLa cell division also reveals their acute, delayed and combined effect. A 35% degradation of HeLa cells was found after 72 h treatment with 62.5 microg/mL of the extract isolated from Stephanandra tanakae. A 100% lysis of HeLa cells was observed after 72 h treatment with a 125 microg/mL concentration of the extract prepared from Gymnocladus dioicus. The extracts from Ligustrum devayanum and Ligustrum vulgare were specifically effective only with HeLa cells. On the other hand, the extract prepared from Gymnocladus dioicus was effective on the bacteria and on the HeLa cells.     

Bioactivity-guided isolation of antiproliferative compounds from Centaurea arenaria

The antiproliferative effects of n-hexane, chloroform and aqueous methanol extracts prepared from the whole plant of Centaurea arenaria M.B. ex Willd. were investigated against cervix adenocarcinoma (HeLa), breast adenocarcinoma (MCF7) and skin epidermoid carcinoma (A431) cells, using the MTT assay. The chloroform extract displayed high tumour cell proliferation inhibitory activity (higher than 85% at 10 μg/mL concentration), and was therefore subjected to a bioassay-guided multistep separation procedure. Flavonoids (eupatilin, eupatorin, 3'-methyleupatorin, apigenin and isokaempferid), lignans (arctigenin, arctiin and matairesinol), the sesquiterpene cnicin, serotonin conjugates (moschamine and cis-moschamine), β-amyrin and β-sitosterin-β-D-glycopyranoside, identified by means of UV, MS and NMR spectroscopy, were obtained for the first time from this species. The isolated compounds were also evaluated for their tumour cell growth inhibitory activities on HeLa, MCF7 and A431 cells, and different types of secondary metabolites were found to be responsible for the antitumour effects of the extracts; in addition to moderately active compounds (isokaempferid and moschamine), especially apigenin, eupatorin, arctigenin, arctiin, matairesinol and cnicin exert marked antitumour effects against these cell lines.     

龙葵生物碱体外抑制肿瘤细胞增殖作用的实验研究

目的:研究龙葵生物碱提取物对人肺癌A549细胞株增殖的抑制作用。方法:采用盐酸-乙醇混合溶剂加热回流法从龙葵中提取分离生物碱。以MTT法考察龙葵生物碱不同浓度对人肺癌A549细胞株增殖的抑制作用,采用倒置显微镜观察药物对肿瘤细胞株形态的影响。结果:龙葵生物碱提取物对人肺癌A549细胞株具有显著的细胞增殖抑制作用,且呈剂量依赖关系,并可使肿瘤细胞形态发生显著变化。结论:龙葵生物碱具有对肺癌细胞的抑制作用。     

Antiproliferative and apoptosis inducing activity of Markhamia tomentosa leaf extract on HeLa cells

Ethnopharmacological relevance

Markhamia tomentosa (Benth) K. Schum ex. Engl. (Bignoniaceae), a tree widely dispersed in West Tropical Africa, is used traditionally to treat various diseases as it possesses antimicrobial, antioxidant, analgesic, anticancer and anti-inflammatory activities.

Materials and methods

This study evaluates the cytotoxic effect and underlying mechanisms of the ethanolic extract of Markhamia tomentosa on HeLa and MCF-7 cancer cell lines and non-cancerous Vero cell line. Brine shrimp lethality test was used for preliminary screening. Cytotoxicity was determined using the MTT assay and IC₅₀ was calculated. Effect of Markhamia tomentosa on the cell cycle was monitored by flow cytometry and the apoptosis-induction capability confirmed by exposure of phosphatidylserine to the outer leaflet of the plasma membrane. Loss of mitochondrial membrane potential was analysed by flow cytometry using JC-1.

Results

Markhamia tomentosa was toxic to brine shrimps with LD₅₀ of 31.62 µg/ml. Cell viability and growth of HeLa cells was inhibited by the extract with an IC₅₀ of 189.1±1.76 µg/ml at 24 h post treatment. However, no cytotoxic effect was observed in MCF-7 and Vero cell lines. The extract induced cell cycle arrest in HeLa cells in the G₀/G₁ phase resulting in cell death after 24 h exposure. Induction of apoptosis in HeLa cells was substantiated by Annexin V-FITC/PI double staining showing phosphatidylserine translocation and depolarisation of the mitochondrial membrane potential by flow cytometry of JC-1 stained cells.

Conclusion

The ethanolic extract of Markhamia tomentosa induces G₀/G₁ in HeLa cells followed by induction of the intrinsic pathway of apoptosis.     

A novel function of bamboo extract in relieving lipotoxicity

Lipotoxicity is closely related to the etiology and complications of type 2 diabetes mellitus. This study investigated the protective effect of an extract from bamboo Phyllostachys edulis against palmitic acid (PA)-induced lipoapoptosis. The lipo-detoxification function of the bamboo extract (BEX) was evaluated using cell culture models. Cell viability was measured by MTT assay and cell apoptosis was monitored by Annexin V staining. Cellular uptake of fluorescent free fatty acid (FFA) analog was measured by flow cytometry. Protein levels of total protein kinase B (Akt) and phosphorylated Akt (p-Akt) were measured by western blotting. The results show that co-incubating BEX with mouse myoblast C2C12 cells had no effect on the cellular uptake of FFA, but dramatically decreased PA-induced cell apoptosis and protected cell viability. A similar antilipotoxicity effect of BEX was observed in other mammalian cells. BEX significantly decreased the protein levels of both Akt and p-Akt in C2C12 cells under normal cell culture conditions but not under lipotoxic conditions, indicating the regulatory effect of BEX on cell signaling pathways and its response to a high FFA environment. This study demonstrated a novel function of bamboo extract in preventing lipotoxicity in mammalian cells, implicating a promising phytotherapeutic approach for lipo-detoxification.     

The effect of seasonal variation on the antineoplastic activity of Alstonia scholaris R. Br. in HeLa cells

In order to evaluate the seasonal variation as well as cytotoxicity of different fractions of Alstonia scholaris R. Br. (ASE), the HeLa cells were treated with different doses of various fractions of ASE collected in monsoon, winter and summer. The exposure of HeLa cells to different extracts prepared from the stem bark collected in monsoon, winter and summer seasons resulted in a dose dependent increase in the cell killing effect of ASE and the highest cell killing effect was observed for the extract prepared from the summer collections. Similarly, treatment of HeLa cells with different doses of various fractions of the Alstonia scholaris extract viz. residue (ASERS), steroidal (ASEST), chloroform (ASECH), petroleum ether (ASEPE), diethyl ether (ASEDE), ethyl acetate (ASEEA), n-butanol (ASENB), aqueous (ASEAQ) and echitamine chloride (ECL) also resulted in a dose dependent decline in the cell viability, where the greatest cytotoxic effect was observed for residue (ASERS), followed by the whole extract (ASE) and chloroform (ASECH) fraction, while the least activity was observed for the steroidal (ASEST) fraction. The cytotoxicity declined ASERS > ASE > ASECH >ECL > ASEEA > ASEDE > ASEPE > ASENB > ASEAQ > ASEST in order. Our study demonstrates that the extract prepared from the summer collection, and the fractions containing the alkaloids were highly effective in cell killing. The extract of ASE was more powerful than the active principle echitamine present in ASE.     

蟾酥提取工艺优化与提取物体外抗肿瘤活性研究

目的优化蟾酥中脂溶性成分华蟾酥毒基及酯蟾毒配基的提取工艺,并探讨蟾酥提取物对人宫颈癌HeLa细胞和卵巢癌SKOV-3细胞的增殖及细胞周期的影响。方法采用U5（54）均匀设计,考察酒精浓度、酒精用量、提取时间等因素对指标性成分提取的影响;MTT法检测蟾酥提取物对HeLa与SKOV-3细胞增殖的影响;流式细胞技术检测细胞周期变化;倒置显微镜下观察HeLa和SKOV-3细胞形态变化。结果以100倍量95%酒精加热回流提取2次,每次2.5 h,两种指标性成分转移率最大,为（117.20±3.52）%;蟾酥提取物呈时间和剂量依赖性地抑制HeLa和SKOV-3细胞增殖;随着蟾酥提取物剂量的增加,HeLa细胞出现S期和G2/M期阻滞,SKOV-3细胞出现G0/G1期阻滞,两种细胞均出现空泡样变性。结论均匀设计法优选蟾酥有效成分的提取工艺合理可行;蟾酥提取物可显著抑制HeLa和SKOV-3细胞的增殖,使细胞出现空泡样变性,并阻滞细胞周期。     

Four carotenoids from Pittosporum tobira protect primary cultured rat cortical cells from glutamate‐induced toxicity

We observed that an aqueous extract of this medicinal plant exhibited significant neuroprotection against glutamate‐induced toxicity in primary cultured rat cortical cells from methanol extracts of the seeds of P. tobira. To further clarify the underlying neuroprotective mechanism(s) of this observed effect, we isolated and identified various active fractions and components. By using such fractionation procedures, four known carotenoids compounds – tobiraxanthins A1, A2, A3, and B – were isolated from the n‐hexane fraction of methanol extracts from the seeds of P. tobira. Among these four compounds, tobiraxanthins B exhibited significant neuroprotective activity against glutamate‐induced neurotoxicity, as indicated by a cell viability of approximately 50%, at concentrations ranging from 0.1 μM to 10 μM. These findings indicate that, the neuroprotective effects of P. tobira might be due to the inhibition of glutamate‐induced toxicity by carotenoids present in the plant. Copyright © 2009 John Wiley & Sons, Ltd.     

Protective effects of methoxyflavone derivatives from black galingale against glutamate induced neurotoxicity in primary cultured rat cortical cells

To examine the neuroprotective effects of black galingale, its protection was tested against glutamate‐induced neurotoxicity in primary cortical cultured neurons. It was found that an aqueous extract of this medicinal plant exhibited significant protection against glutamate‐induced toxicity in primary cultured rat cortical cells. In order to clarify the neuroprotective mechanism(s) of this observed effect, isolation was performed to seek and identify active fractions and components. By such fractionation, bioactive methoxyflavone derivatives were isolated from the methanol extracts from the air‐dried rhizomes of black galingale. 5‐Hydroxy‐3,7,3′,4′‐tetramethoxyflavone exhibited significant neuroprotective activities against glutamate‐induced toxicity, exhibiting cell viability of about 60–70%, at concentrations ranging from 0.1 μm to 10 μm . Therefore, the neuroprotective effect of black galingale might be due to the inhibition of glutamate‐induced toxicity by the methoxyflavone derivatives it contains. Copyright © 2011 John Wiley & Sons, Ltd.     

Evaluation of anticancer activity of the alkaloid fraction of Alstonia scholaris (Sapthaparna) in vitro and in vivo

The anticancer effect of various doses of an alkaloid fraction of Sapthaparna, Alstonia scholaris (ASERS), was studied in vitro in cultured human neoplastic cell lines (HeLa, HepG(2), HL60, KB and MCF-7) and in Ehrlich ascites carcinoma bearing mice. Treatment of HeLa cells with 25 microg/mL ASERS resulted in a time dependent increase in the antineoplastic activity and the greatest activity was observed when the cells were exposed to ASERS for 24 h. However, exposure of cells to ASERS for 4 h resulted in 25% viable cells and hence this time interval was considered to be the optimum time for treatment and further studies were carried out using this time. Treatment of various cells with ASERS resulted in a concentration dependent decline in the viable cells and a nadir was reached at 200 microg/mL in all the cell lines studied. The IC50 was found to be 5.53, 25, 11.16, 10 and 29.76 microg/mL for HeLa, HePG2, HL60, KB and MCF-7 cells, respectively. Similarly, administration of ASERS, once daily for 9 consecutive days to the tumor bearing mice caused a dose dependent remission of the tumor up to 240 mg/kg body weight, where the greatest antitumor effect was observed. Since 240 mg/kg ASERS showed toxic manifestations, the next lower dose of 210 mg/kg was considered as the best effective dose, in which 20% of the animals survived up to 120 days post-tumor-cell inoculation as against no survivors in the saline treated control group. The ASERS treatment resulted in a dose dependent elevation in the median survival time (MST) and the average survival time (AST) up to 240 mg/kg ASERS and declined thereafter. The surviving animals were healthy and disease free. The effect of ASERS was better than cyclophosphamide, which was used as a positive control, where all the animals succumbed to death by 40 days and the MST and AST were 19.5 and 18.3 days, respectively. The effective dose of 210 mg of ASERS was 3/10 of the LD50 dose, which increased the MST and AST up to 54 and 49.5 days, respectively.     

报告基因方法监测重金属汞及其化合物的早期毒性

目的：基于热休克信号响应和分泌型碱性磷酸酶（SEAP）报告基因,建立HSE-SEAP-HeLa细胞模型,预测重金属（汞及其化合物）的早期毒性。方法：将pHSE-SEAP质粒转染到人子宫颈癌HeLa细胞中,建立瞬时HSE-SEAP响应模型。热休克（42 ℃,1 h）或重金属化合物（CdCl₂,5 μmol·L^-1,4 h）处理后,在完全DMEM培养基中恢复48 h后,检测细胞上清液中的分泌型碱性磷酸酶的含量（表示该状态下细胞中的热休克蛋白表达量）,同时用MTT方法检测对应浓度下的细胞活性,以验证模型的有效性和重复性。并用亚致死浓度（由MTT实验确定）的无机和矿物汞（HgCl₂,HgS和朱砂）和柳硫汞钠处理细胞,检测诱导的细胞热休克响应。结果：热休克和CdCl₂作用HSE-SEAP-HeLa细胞模型后,细胞上清液中的分泌型碱性磷酸酶的含量显著升高；热休克蛋白表达早于Cd²⁺对细胞活性的降低。4种汞化合物在亚致死浓度均诱导细胞内热休克蛋白的变化,但4种化合物的作用时间和浓度效应不同,显示不同类型的汞化合物早期毒性存在差异。结论：HSE-SEAP-HeLa细胞模型可有效检测重金属诱导的热休克应激作用,并具有良好的重复性,可应用于重金属有关的早期毒性预测或药物毒性评估。     

Aged garlic extract induces proliferation and ameliorates gentamicin-induced toxicity in LLC-PK1 cells

Gentamicin (GM)-induced nephrotoxicity limits the use of this antibiotic. It has been shown that aged garlic extract (AGE) and S-allylcysteine (SAC), the most abundant organosulfur compound in AGE, ameliorate GM-induced nephrotoxicity in rats. The present communication evaluated the effect of AGE and SAC on proliferation and on GM-induced toxicity and genotoxicity of porcine kidney epithelial cell line (LLC-PK1 cells). The cells were preincubated with different concentrations of AGE or SAC for 12 h before incubation with 8 mm GM for an additional 72 h. At the end of this time, cell viability, genotoxicity and proliferation were evaluated. AGE stimulated cell proliferation and protected LLC-PK1 cells from GM-mediated toxicity and genotoxicity. SAC partially prevented only GM-induced genotoxicity. These results suggest that the stimulation of cell proliferation could possibly be one of the mechanisms involved in the in vitro protective effect of AGE in GM-induced toxicity of LLC-PK1 cells.     

Morphinane alkaloid dimers from Sinomenium acutum

Two new morphinane alkaloid dimers, 2,2'-disinomenine (1) and 7',8'-dihydro-1,1'-disinomenine (2), and known 1, 1'-disinomenine (3), were isolated from ethanol extracts of stems of Sinomenium acutum. Their structures were elucidated on the basis of spectroscopic methods. The absolute configuration of alkaloids 1-3 was determined by direct comparison of their CD spectra with the known alkaloid sinomenine. The isolated alkaloids were tested for cytotoxicity against A549, P388, and HeLa cell lines, and 1 and 3 showed weak inhibition against A549 and Hela cells.     

Antitumor activity of water extract of a mushroom,Inonotus obliquus,against HT‐29 human colon cancer cells

In the current study, it was demonstrated that the hot water extract of I. obliquus (IOWE) exerts inhibitory activity against the proliferation of human colon cancer cells (HT‐29). The inhibitory effect of IOWE on the growth of HT‐29 cancer cells was evaluated by treating cells with IOWE at concentrations of 0.25, 0.5 and 1.0 mg/mL for 24 or 48 h. The IOWE inhibited cell growth in a dose‐dependent manner, and this inhibition was accompanied by apoptotic cell death. The maximum inhibitory effect (56%) was observed when IOWE was treated at a concentration of 1.0 mg/mL for 48 h. The apoptotic effect of IOWE on HT‐29 cells was also confirmed by flow cytometric analysis. In addition, the apoptotic cell percentage was closely associated with down‐regulation of Bcl‐2 and up‐regulation of Bax and caspase‐3. The results suggest that IOWE would be useful as an antitumor agent via the induction of apoptosis and inhibition of the growth of cancer cells through up‐regulation of the expression of proapoptotic proteins and down‐regulation of antiapoptotic proteins. Copyright © 2009 John Wiley & Sons, Ltd.     

Flow cytometric estimation on cytotoxic activity of leaf extracts from seashore plants in subtropical Japan: isolation,quantification and cytotoxic action of (-)-deoxypodophyllotoxin

The cytotoxic activity of methanol extracts of leaves collected from 39 seashore plants in Iriomote Island, subtropical Japan was examined on human leukaemia cells (K562 cells) using a flow cytometer with two fluorescent probes, ethidium bromide and annexin V-FITC. Five extracts (10 microg/mL) from Hernandia nymphaeaefolia, Cerbera manghas, Pongamia pinnata, Morus australis var. glabra and Thespesia populnea greatly inhibited the growth of K562 cells. When the concentration was decreased to 1 microg/mL, only one extract from H. nymphaeaefolia still inhibited the cell growth. A cytotoxic compound was isolated from the leaves by bioassay-guided fractionation and was identified as (-)-deoxypodophyllotoxin (DPT). The fresh leaves of H. nymphaeaefolia contained a remarkably high amount of DPT (0.21 +/- 0.07% of fresh leaf weight), being clarified by a quantitative HPLC analysis. DPT at 70-80 pM started to inhibit the growth of K562 cells in an all-or-none fashion and at 100 pM or more it produced complete inhibition in all cases. Therefore, the slope of the dose-response curve was very steep. DPT at 100 pM or more decreased the cell viability to 50%-60% and increased the number of cells undergoing apoptosis (annexin V-positive cells). The results indicate that DPT contributes to the cytotoxic action of the extract from the leaves of H. nymphaeaefolia on K562 cells.     

The neuromuscular blockade produced by pure alkaloid,mitragynine and methanol extract of kratom leaves (Mitragyna speciosa Korth.)

Aim of the study

The effects of pure alkaloid, mitragynine and a methanolic extract of kratom leaves were investigated on neuromuscular junction and compound nerve action potential.

Materials and methods

Wistar rats were killed by cervical dislocation and decapitated. The phrenic nerve–hemidiaphragms, hemidiaphragms and sciatic nerve were isolated.

Results

Kratom methanolic extract present at 0.1–1 mg/mL and mitragynine (0.0156 mg/mL) decreased the muscle twitch on the isolated phrenic nerve–hemidiaphragm and hemidiaphragm preparation. Muscle relaxation caused by kratom extract (1 mg/mL) was greater than the effect of mitragynine. Pancuronium and succinylcholine potentiated the effect of kratom extract. It also had a direct relaxation effect on the hemidiaphragm muscle. The muscle relaxation caused by kratom extract was not antagonized by neostigmine, tetraethylammonium and calcium chloride. High concentrations of kratom extract (10–40 mg/mL) and mitragynine (2 mg/mL) blocked the nerve conduction, amplitude and duration of compound nerve action potential.

Conclusions

The mechanism of action of kratom extract might not act as a competitive antagonist of acetylcholine yet its dominant effect was at the neuromuscular junction and not at the skeletal muscle or somatic nerve.     

小檗碱对HeLa细胞凋亡及其凋亡相关蛋白表达的影响

目的 研究小檗碱对人宫颈癌HeLa细胞株增殖及凋亡的影响及其发生机制.方法 采用MTT法观察小檗碱对HeLa细胞增殖的影响,DNA ladder、流式细胞仪等方法进行细胞凋亡检测,用Western blotting方法检测凋亡过程中相关蛋白Bel-2和Bax表达的变化.结果 小檗碱在体外试验中能明显抑制HeLa细胞的增殖,在一定的时间、剂量范围内呈时间-剂量依赖关系.20、40 mg/L小檗碱作用48 h后,细胞DNA片段分析可看到凋亡时降解形成的梯带,流式细胞仪检测到了细胞凋亡峰,各组的凋亡率分别是(16.7±2.8)%、(29.6±4.4)%,与对照组(1.9±0.6)%和5 mg/L小檗碱组(2.3±0.8)%相比差异显著(P＜0.01).在凋亡过程中,Bax蛋白表达明显增高,而Bcl-2蛋白表达下凋.结论 小檗碱体外能抑制HeLa细胞增殖并诱导其发生凋亡,其机制可能与Bax蛋白表达明显增高,而Bcl-2蛋白表达下调有关.     

Kaempferitrin induces apoptosis via intrinsic pathway in HeLa cells and exerts antitumor effects

Ethnopharmacological relevance

Justicia spicigera is used for the empirical treatment of cervical cancer in Mexico. Recently, we showed that Justicia spicigera extracts exerted cytotoxic and antitumoral effects and the major component of this extract was kaempferitrin (KM).

Materials and methods

The cytotoxic and apoptotic effect of KM on human cancer cells and human nontumorigenic cells were evaluated using MTT and TUNEL assays, and Annexin V/Propidium iodide detection by flow cytometry. The effect of KM on cell cycle was analyzed by flow cytometry with propidium iodide. The apoptotic and cell cycle effects were also evaluated by western blot analysis. Also, different doses of KM were injected intraperitoneally daily into athymic mice bearing tumors of HeLa cells during 32 days. The growth and weight of tumors were measured.

Results

KM induces high cytotoxic effects in vitro and in vivo against HeLa cells. The general mechanisms by which KM induces cytotoxic effects include: cell cycle arrest in G1 phase and apoptosis via intrinsic pathway in a caspase dependent pathway. Also, KM exerts chemopreventive and antitumor effects.

Conclusion

KM exerts cytotoxic and antitumor effects against HeLa cells.     

Stimulation of glucose uptake by triterpenoids from Weigela subsessilis

Four ursane‐type triterpenoids, corosolic acid (1), ilekudinol B (2), ursolic acid (3) and pomolic acid (4), were isolated from an EtOAc‐soluble extract of the leaves of Weigela subsessilis. These bioactive compounds were evaluated for their glucose uptake activity and produced moderate to strong enhancement both in basal‐ and insulin‐stimulated L6 muscle cells. In particular, corosolic acid exhibited the most potent activity, increasing uptake by basal‐ and insulin‐stimulated myotubes by 2.63‐ and 3.33‐fold, respectively; ilekudinol B produced 1.6‐ and 2.9‐fold, ursolic acid produced 1.84‐ and 2.64‐fold, and pomolic acid produced 1.6‐ and 2.8‐fold increases. No cytotoxicities were observed for corosolic acid, ursolic acid and ilekudinol B in myoblasts, while pomolic acid at doses of 25 and 50 µm reduced cell viability by 19% and 21.8% upon 24 h treatment and by 48.6% and 54.1% upon 48 h treatment, respectively. These results suggest that ursane‐type triterpenoids from W. subsessilis might enhance glucose uptake by acting as insulin mimics and as insulin sensitizers and that they could be useful as nontoxic diabetes treatment agents. Copyright © 2009 John Wiley & Sons, Ltd.     

Effect of a Garcinia gardneriana (Planchon and Triana) Zappi hydroalcoholic extract on melanogenesis in B16F10 melanoma cells

Ethnopharmacology relevance

Garcinia gardneriana (Planchon and Triana) Zappi (Clusiaceae) is popularly called “bacopari” in southern Brazil. The leaves of this plant are traditionally used to treat skin disorders.

Aim of study

This study evaluated the effects of a hydroalcoholic extract of Garcinia gardneriana leaves (HEGG) on B16F10 murine melanoma cells in order to search for new depigmenting agents.

Materials and methods

The effects of HEGG were assessed in melanin content assays in B16F10 melanoma cells compared with the reference drug kojic acid (500 mM). Melanin content was measured after spontaneous melanogenesis, UVB-induced melanogenesis and melanogenesis induced by α-MSH. At the same time, cell viability assays were conducted. Intracellular and mushroom tyrosinase activity assays were employed to evaluate the effect of HEGG on tyrosinase activity.

Results

HEGG decreased the level of melanin under all three experimental conditions of melanin content evaluation without reducing cell viability. In intracellular tyrosinase assays, the enzyme's activity was reduced about 19% with extract concentrations ranging 0.1–10 µg/mL. In the mushroom tyrosinase activity assay a maximal inhibition of 35% (1000 µg/mL) was observed.

Conclusion

These results suggest that HEGG inhibition relates to its tyrosinase activity. Therefore, the hydroalcoholic extract of Garcinia gardneriana shows great potential for use as a depigmenting agent in hyperpigmentation disorders.