The in vitro cytotoxicity against human melanoma cells, tyrosinase inhibition and antioxidant activity of Grewia tenax leaves extracts / La citotoxicidad in vitro contra las células de melanoma humano, inhibición de la tirosinasa y actividad antioxidante de los extractos de hojas de Grewia tenax

Grewia tenax (Forssk.) Fiori (Malvaceae) grows in the Arabian Peninsula and is used for several medicinal purposes. To characterize the dermatological bioactivities of G. tenax in terms of its antimelanoma, antityrosinase and antioxidant activities. Cytotoxicity was assessed by cell proliferation and mitochondrial viability assays. Ability to inhibit mushroom tyrosinase and scavenge free radicals were evaluated by an enzymatic and DPPH scavenging microtiter assay, respectively. Phytochemical analyses were carried out using TLC, HPLC-UV and NMR. The chloroform extract shown significant cytotoxic activity in terms of mitochondrial viability (43 ± 14 µg/mL). We identified lupeol and b-sitosterol as the main active components for the tyrosinase inhibitory activity of the hexane extract. Scavenging activity of the DPPH· radical was confined to the water extract. Extracts from this plant have the potential to be used as a base in the development of cosmeceutical products intended to whiten skin or to combat radical-induced physiopathological processes.

Grewia tenax (Forssk.) Fiori (Malvaceae) crece en la Península Arábiga y se utiliza con varios fines medicinales. Para caracterizar las bioactividades dermatológicas de G. tenax en cuanto a sus actividades antimelanoma, antitirosinasa y antioxidante; la citotoxicidad se evaluó mediante ensayos de proliferación celular y viabilidad mitocondrial. La capacidad para inhibir la tirosinasa de hongo y eliminar los radicales libres se evaluó mediante un ensayo de microtitulación enzimático y de eliminación de DPPH, respectivamente. Los análisis fitoquímicos se realizaron mediante TLC, HPLC-UV y NMR. El extracto de cloroformo mostró una actividad citotóxica significativa en términos de viabilidad mitocondrial (43 ± 14 µg/mL). Identificamos lupeol y b-sitosterol como los principales componentes activos para la actividad inhibitoria de tirosinasa del extracto de hexano. La actividad depuradora del radical DPPH· se limitó al extracto acuoso. Los extractos de esta planta tienen potencial para ser utilizados como base en el desarrollo de productos cosmecéuticos destinados a blanquear la piel o combatir procesos fisiopatológicos inducidos por radicales.

TLC separation and antioxidant activity of flavonoids from Carissa bispinosa, Ficus sycomorus, and Grewia bicolar fruits

BACKGROUND: Carissa bispinosa, Ficus sycomorus, and Grewia bicolar are edible fruit plants that grow in the wild. The plants produce yellow-, red-, and purple-colored fruits and thus can be good sources of flavonoids for fighting oxidative reactions in humans, food, and the pharmaceutical industry. The present study aimed at isolating flavonoids from C.bispinosa, F. sycomorus, and G. bicolar fruits and determining their antioxidant activity using the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and 2, 2-azino-bis 3-ethylbenz-thiaz-oline-6-sulfonic acid (ABTS) model radical assays. METHODS: Analytical and preparative thin-layer chromatography was used to isolate flavonoids from the fruits using methanol/chloroform/hexane (7:2:1,v/v/v) as a mobile phase system. The ABTS and DPPH radical scavenging methods were used to test for the antioxidant activity of the samples, using quercetin and catechin as reference standards. RESULTS:Thin-layer chromatographic profiling revealed two different types of flavonoids from each plant.C. bispinosa yielded two flavonoid bands, Rfvalues 0.11 and 0.38;G. bicolaryielded two flavonoid bands,Rfvalues 0.63 and 0.81; andF.sycomorus also yielded two types of flavonoids, Rfvalues 0.094 and 0.81. All the extracted flavonoids exhibited significant antioxidant activity of over 80% at a concentration of 200 mg/L. The order of radical scavenging activity for the 200-mg/Lsamples is G. bicolar Rf(0.81) >C. bispinosa Rf(0.113) >F. sycomorus Rf(0.094) >F. sycomorus Rf(0.047) >C. bispinosa Rf(0.38) >G. bicolar Rf(0.63).G. bicolar(Rf= 0.81) exhibited antioxidant activitythat was superior to that of catechin. CONCLUSION:The present study results show that C. bispinosa,F. sycomorus,and G. bicolar contain different flavonoid types with significant antioxidant activity of over 80% at a concentration of 200 mg/L. Therefore, the fruits can be used as a source of natural antioxidants which can be used as nutraceuticals to promote health, as preservatives to delay peroxidation of foods, and as flavoring for packed foods.

Biological screening of selected flora of Pakistan.

Methanolic extracts of different parts of five medicinal plants, Ferula assafoetidaL. resin, Grewia asiaticaL. leaves, Ipomoea hederaceaJacq. seeds, Lepidium sativumL. seeds and Terminalia chebulaRetz. fruits were tested in vitrofor their cytotoxic, phytotoxic, insecticidal, nematicidal and anthelmintic activities. Ipomoea hederaceashowed very significant phytotoxic and cytotoxic activity, with 100% inhibition of Lemna minorgrowth and 100% death of Artemia salinaat concentrations of 1000 and 100 µg mL-1. Grewia asiaticaexhibited very weak activities while Lepidium sativumand Ferula assafoetidashowed moderate to good potential in all three bioassays. The results suggest screening of Ipomoea hederaceaseeds further for isolation of bioactive compounds that may be responsible for its toxic potential.

Biological screening of selected flora of Pakistan

Methanolic extracts of different parts of five medicinal plants, Ferula assafoetidaL. resin, Grewia asiaticaL. leaves, Ipomoea hederaceaJacq. seeds, Lepidium sativumL. seeds and Terminalia chebulaRetz. fruits were tested in vitrofor their cytotoxic, phytotoxic, insecticidal, nematicidal and anthelmintic activities. Ipomoea hederaceashowed very significant phytotoxic and cytotoxic activity, with 100% inhibition of Lemna minorgrowth and 100% death of Artemia salinaat concentrations of 1000 and 100 µg mL-1. Grewia asiaticaexhibited very weak activities while Lepidium sativumand Ferula assafoetidashowed moderate to good potential in all three bioassays. The results suggest screening of Ipomoea hederaceaseeds further for isolation of bioactive compounds that may be responsible for its toxic potential.