1H-NMR and LC-MS Based Metabolomics Analysis of Wild and Cultivated Amaranthus spp.

Amaranthus crops are important for their use as food and nutritional sources, as well as for their medicinal properties. They are mostly harvested from the wild, and cultivation of Amaranthus species is still rare, and therefore, attempts are being made to commercialize and market this important crop. This research investigated the effect of cultivation and environment on the chemical profile of both cultivated and wild A. cruentus and A. hybridus by multivariate statistical analysis of spectral data deduced by Nuclear Magnetic Resonance (NMR). Furthermore, wild samples of A. cruentus and A. hybridus were subjected to Liquid Chromatography-Mass Spectrometry (LC-MS) for further analysis. Through NMR analysis, it was found that maltose and sucrose increased in both cultivated A. cruentus and A. hybridus. Moreover, the amino acid, proline was present in cultivated A. cruentus in high quantity whereas, proline and leucine were prominent in A. hybridus. Other compounds that were found in both wild and cultivated A. cruentus and A. hybridus are trehalose, trigonelline, lactulose, betaine, valine, alanine, fumarate, formate and kynurenine. LC-MS analysis revealed the presence of rutin, 2-phenylethenamine and amaranthussaponin I in both wild A. cruentus and A. hybridus, while chlorogenic acid was identified only in cultivated A. hybridus. On the contrary, L-tryptophan, kaempferol, phenylalanine and quercetin were detected only in wild A. cruentus. Amaranth is not only rich in macro and micronutrients, but the leaves also contain phytochemicals that vary between species and cultivated plants, and might, therefore, affect the medicinal properties of the material.

Three new α-glucosidase inhibitors from guggul, the oleogum resin of Commiphora wightii.

Three new compounds; epi-mukulin, (Z)-Δ(1,2) dehydroguggulsterone and Δ(6,7)dehydro-20-hydroxygugglsterone were isolated from the n-hexane-soluble fraction (HSF) of the methanol extract of guggul, the oleogum resin of Commiphora wightii together with six known compounds: diasesartemin, (+)-epi-magnolin, (+)-diayangambin, gugglsterol I, (E)-guggulsterone and (Z)-guggulsterone. Their structures were elucidated on the basis of different spectroscopic data. α-Glucosidase inhibitory effects of HSF and the isolated compounds were evaluated calorimetrically. The HSF showed significant α-glucosidase inhibitory effect [IC(50) value of 140 µg mL(-1) (p < 0.05)]. Under the assay conditions, diasesartemin (IC(50) = 60.6 ± 0.01 µM) was found to be more potent than the positive control, acarbose (IC(50) = 92.94 ± 0.01 µM); a known α-glucosidase inhibitor (p < 0.05). The IC(50) values of epi-mukulin and (Z)-guggulsterone were found to be 159.33 and 132.14 µM, respectively. Other compounds showed weak α-glucosidase inhibitory effects, <30% inhibition of the enzyme activity at 0.1 mg mL(-1).

Antidiabetic activity of Terminalia sericea constituents.

Diabetes mellitus is an endocrine disorder that affects more than 100 million people worldwide. South African plants namely Terminalia sericea, Euclea natalensis, Warbugia salutaris, Aloe ferox, Artemisia afra, Sclerocarya birrea, Spirostachys africana and Psidium guajava were investigated for their in vitro alpha-glucosidase and alpha-amylase properties, and antioxidant activities. Terminalia sericea stem bark extract showed the best results against alpha-glucosidase and alpha-amylase enzymes. Bioassay-guided fractionation of an acetone extract of T. sericea stem bark led to the isolation of four known compounds namely beta-sitosterol (1), beta-sitosterol-3-acetate (2), lupeol (3), and stigma-4-ene-3-one (4), in addition to two inseparable sets of mixtures of isomers [epicatechin-catechin (M1), and gallocatechin-epigallocatechin (M2). 1 and 3 showed the best inhibitory activity on alpha-glucosidase (IC50:54.5 and 66.5 microM). Bio-evaluation of the inhibitory activity of the purified compounds on alpha-amylase showed that 3 and 1 exhibited IC50 values of 140.7 and 216.02 microM, respectively against alpha-amylase. Compounds 2, M1, 3 and M2 were found to be non-toxic to Vero cells. This study is the first to report alpha-glucosidase and alpha-amylase activity of M1, M2, 2 and 4 isolated from T. sericea, which validated the traditional use of the bark of T. sericea for diabetes in South Africa.