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Secamone afzelii (Roem. & Schult.) K. Schum (family Asclepiadaceae) is a creeping woody climber used to treat ailments in many traditional medicine systems. The present study aims to examine the antioxidant and enzyme inhibition activities of S. afzelii leaf using different compositions of methanol–water mixture as an extraction solvent. The extracts were characterized by HPLC-ESI-MSn in terms of chemical compounds. The in silico results show that compound 23 (quercitrin) has the higher docking scores among the selected substances and the MD simulation revealed that the interactions with the enzymatic pocket are stable over the simulation time and strongly involve the tyrosinase catalytic Cu atoms. All together the results showed that both 80% and 100% methanolic extracts contained significantly (p < 0.05) the highest total phenolics content while the highest content of total flavonoids was significantly (p < 0.05) extracted by 100% methanol. About 26 compounds were tentatively identified by HPLC-ESI-MSn and 6 of them were quantified using standards. Results showed that the extracts were rich in flavonoids with a relatively high abundance of two kaempferol glycosides comprising 60% of quantified compounds. The 100% and 80% methanol extracts recorded significantly (p < 0.05) the highest total antioxidant, DPPH and ABTS activity as well as tyrosinase and ⍺-amylase inhibitory activities. The best significant (p < 0.05) cholinesterase inhibitory activity and reducing capacity of Fe+++ and Cu++ was recorded from the 80% methanolic extract while 100% ethanolic extract gave the highest significant (p < 0.05) butyrylcholinesterase inhibitory activity. The best glucosidase activity was observed in the 50% and 80% methanolic extracts. Although the water extract displayed the least total phenolics and flavonoids content and consequently the lowest antioxidant and enzyme inhibition activity, it displayed significantly (p < 0.05) the highest chelating power. In conclusion, these results demonstrated the richness of S. afzelii leaf as a potential source of bioactive compounds for the food industry, for the preparation of food supplements and functional foods. [ABSTRACT FROM AUTHOR]

Justicia secunda Vahl. is a traditional medicinal plant in tropical regions, including West Africa. The present study examined the chemical profiles and biological properties of J. secunda extracts obtained with different solvents (dichloromethane, ethyl acetate, methanolic and aqueous: macerated and infused). Chemical components were characterized by liquid chromatography-mass spectrometry (LC-MS), and over 50 compounds were identified, including flavonoids, phenolic acids, and alkaloids. Antioxidant, enzyme inhibitory, cytotoxic, and antiviral properties were selected as biological properties. Total phenolic and flavonoid contents in methanol (58.07 mg gallic acid equivalent (GAE)/g and 13.07 mg rutin equivalent (RE)/g) and water (infused) (36.34 mg GAE/g and 8.52 mg RE/g) were higher than in other extracts. Consistent with the levels of total bioactive components, the methanol and water extracts exhibited stronger antioxidant abilities. However, the dichloromethane and ethyl acetate extracts were more active on α-amylase and α-glucosidase than other extracts. Aqueous extracts exerted selective anticancer properties toward human pharyngeal cancer cell lines, whereas the methanolic extract decreased the human herpesvirus type-1 (HHV-1) infectious titer by 2.16 log and the viral load by 1.21 log. Overall, J. secunda could be considered a multifunctional bioactive raw material in the preparation of potent applications to manage diseases related to oxidative stress, including cancer, diabetes, and Alzheimer's. [ABSTRACT FROM AUTHOR]

Spathodea campanulata is an important medicinal plant with traditional uses in the tropical zone. In the current work, we aimed to determine the chemical profiles and biological effects of extracts (methanolic and infusion (water)) from the leaves and stem bark of S. campanulata. The chemical components of the tested extracts were identified using LC-ESI-QTOF-MS. Biological effects were tested in terms of antioxidant (radical scavenging, reducing power, and metal chelating), enzyme inhibitory (cholinesterase, amylase, glucosidase, and tyrosinase), antineoplastic, and antiviral activities. Fifty-seven components were identified in the tested extracts, including iridoids, flavonoids, and phenolic acids as the main constituents. In general, the leaves-MeOH extract was the most active in the antioxidant assays (DPPH, ABTS, CUPRAC, FRAP, metal chelating, and phosphomolybdenum). Antineoplastic effects were tested in normal (VERO cell line) and cancer cell lines (FaDu, HeLa, and RKO). The leaf infusion, as well as the extracts obtained from stem bark, showed antineoplastic activity (CC50 119.03–222.07 µg/mL). Antiviral effects were tested against HHV-1 and CVB3, and the leaf methanolic extract (500 µg/mL) exerted antiviral activity towards HHV-1, inhibiting the viral-induced cytopathic effect and reducing the viral infectious titre by 5.11 log and viral load by 1.45 log. In addition, molecular docking was performed to understand the interactions between selected chemical components and viral targets (HSV-1 DNA polymerase, HSV-1 protease, and HSV-1 thymidine kinase). The results presented suggest that S. campanulata may be a bright spot in moving from natural sources to industrial applications, including novel drugs, cosmeceuticals, and nutraceuticals. [ABSTRACT FROM AUTHOR]

In the present study, two medicinal plants from Africa, namely Bersama abyssinica Fresen. and Scoparia dulcis L., were extracted using ethyl acetate, methanol, and water. The antioxidant, enzyme (α-amylase, α-glucosidase, acetyl- and butyrylcholinesterase, lipase, and tyrosinase) inhibitory action, and phytochemical profiles of extracts of Bersama abyssinica and Scoparia dulcis were determined. The aqueous (180.62 and 61.81 mg gallic acid equivalent/g extract, for B. abyssinica and S. dulcis respectively) and methanol (75.21 and 57.81 mg rutin equivalent/g extract, for B. abyssinica and S. dulcis, respectively) extracts contained high concentrations of phenolic and flavonoids, respectively. The ethyl acetate extracts of both plants were potent inhibitors of α-glucosidase and tyrosinase. Several phytochemical groups were determined by HPLC-MS/MS. The study tend to suggest that B. abyssinica and S. dulcis are potential candidates for the development of novel therapeutical agents. [ABSTRACT FROM AUTHOR]

In this study, we attempted for the first time to determine the phytochemical compositions and biopharmaceutical properties of the methanolic and aqueous extracts of Morinda morindoides fruits and seeds. Antioxidant propensities of the extracts were determined via free radical‐scavenging, phosphomolybdenum, metal chelating, and reducing power assays. Inhibitory activities against cholinesterases (acetylcholinesterase (AChE) and butyrylcholinesterase (BChE)), tyrosinase, α‐amylase, and α‐glucosidase were assessed. Moreover, the total phenolic and flavonoid contents were determined. High Performance Liquid Chromatography coupled to Electrospray Ionization Quadrupole Time‐of‐Flight Mass Spectrometry (HPLC‐ESI‐Q‐TOF‐MS) analysis was performed to establish the chemical profile of the investigated extracts. The tested extracts showed remarkable antioxidant abilities with aqueous fruit extract being most potent in all assays, except for ferrous ion chelating assay. Overall, the methanolic extracts were potent inhibitors of the tested enzymes. In conclusion, M. morindoides may be endorsed as promising sources of bioactive compounds and used for designing functional foods. Practical applications: In recent years, new compounds from plant sources have attracted great interest to design functional foods. Thus, we aimed to detect biological and chemical properties of Morinda morindoides fruits and seeds, a widely used as food with medicinal properties in Africa. Based on our findings, fruits extracts exhibited stronger activity when compared to seed extracts. Also, chemical identification was performed for each extracts. The presented findings could provide valuable information into the pool of scientific knowledge and may be basis for the design of novel functional applications from M. morindoides. [ABSTRACT FROM AUTHOR]

This study attempts to valorize the multiple pharmacological properties of Harungana madagascariensis Lam. ex Poir., also known as dragon's blood tree, with wide applications in African traditional medicine. The antioxidant and inhibitory activity of H. madagascariensis leaves and stem bark extracts (ethyl acetate, aqueous extracts, and methanol) against enzymes related to diabetes (α-glucosidase, α-amylase), epidermal hyperpigmentation problems (tyrosinase), and Alzheimer's disease (acetyl and butyryl cholinesterase) were evaluated. The phytochemical profiles of the extracts were studied by high-performance liquid chromatography with diode array detection and mass spectrometry (HPLC-DAD-MS), observing the presence of procyanidins and flavonoids, particularly in the leaves' extracts. The radical scavenging and reducing power of H. madagascariensis leaves' extracts were greater than the stem bark extracts. The methanol extracts of leaves (4.61 mg galantamine equivalent (GALAE)/g extract) and stem bark (4.68 mg galantamine (GALAE)/g extract) of H. madagascariensis inhibited acetyl cholinesterase. Methanol extracts (153.55 and 147.07 mg kojic acid equivalent (KAE)/g extract, for leaves and stem bark extracts, respectively) of H. madagascariensis showed high tyrosinase inhibition. Correlation and principal component analysis (PCA) were also performed. The observed pharmacological effects of H. madagascariensis support that this plant may be a promising candidate for the development of novel pharmacophores for the treatment of diabetes, epidermal hyperpigmentation problems, Alzheimer's disease, and other oxidative-stress-related complications. [ABSTRACT FROM AUTHOR]

Breynia retusa (Dennst.) Alston (also known as Cup Saucer plant) is a food plant with wide applications in traditional medicine, particularly in Ayurveda. Extracts obtained with four solvents (dichloromethane, methanol, ethyl acetate and water), from three plant parts, (fruit, leaf and bark) were obtained. Extracts were tested for total phenolic, flavonoid content and antioxidant activities using a battery of assays including 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing antioxidant power (FRAP), cupric reducing antioxidant capacity (CUPRAC), total antioxidant capacity (TAC) (phosphomolybdenum) and metal chelating. Enzyme inhibitory effects were investigated using acetylcholinesterase (AChE), butyrylcholinesterase (BChE), tyrosinase, α-amylase and α-glucosidase as target enzymes. Results showed that the methanolic bark extract exhibited significant radical scavenging activity (DPPH: 202.09 ± 0.15; ABTS: 490.12 ± 0.18 mg Trolox equivalent (TE)/g), reducing potential (FRAP: 325.86 ± 4.36: CUPRAC: 661.82 ± 0.40 mg TE/g) and possessed the highest TAC (3.33 ± 0.13 mmol TE/g). The methanolic extracts were subjected to LC-DAD-MSn and NMR analysis. A two-column LC method was developed to separate constituents, allowing to identify and quantify forty-four and fifteen constituents in bark and fruits, respectively. Main compound in bark was epicatechin-3-O-sulphate and isolation of compound was performed to confirm its identity. Bark extract contained catechins, procyanidins, gallic acid derivatives and the sulfur containing spiroketal named breynins. Aerial parts mostly contained flavonoid glycosides. Considering the bioassays, the methanolic bark extract resulted a potent tyrosinase (152.79 ± 0.27 mg kojic acid equivalent/g), α-amylase (0.99 ± 0.01 mmol acarbose equivalent ACAE/g) and α-glucosidase (2.16 ± 0.01 mmol ACAE/g) inhibitor. In conclusion, methanol is able to extract the efficiently the phytoconstituents of B. retusa and the bark is the most valuable source of compounds. [ABSTRACT FROM AUTHOR]

The stem bark (SB) of Piptadeniastrum africanum (PA) has been extensively used in African traditional medicinal systems. However, there is a dearth of scientific information regarding its possible activity in the management of type II diabetes, Alzheimer's disease, and skin hyperpigmentation disorders. This study therefore attempted to elucidate the in vitro inhibitory action of ethyl acetate, methanol, and water extracts of P. africanum stem bark (PA-SB) on α-amylase, α-glucosidase, acetylcholinesterase, butyrylcholinesterase, and tyrosinase. Cell viability, catecholamine, and 3-hydroxykynurenine levels of hypothalamic HypoE22 cells exposed to PA-SB extracts were also investigated. The phytochemical profiles of the extracts were determined by high performance liquid chromatography (HPLC) and antioxidant properties were investigated. Saponin (867.42 mg quillaja equivalent/g) and tannin (33.81 mg catechin equivalent/g) contents were higher in the methanol extract. Multiple dihydroxy-trimethoxy(iso)flavone isomers, loliolide, eriodictyol, naringenin, luteolin, chrysoeriol, apigenin, and liquiritigenin, were characterized from PA-SB extracts using HPLC. The methanol extract of PA-SB showed highest inhibitory activity against acetylcholinesterase (4.88 mg galantamine equivalent (GALAE)/g extract), butyrylcholinesterase (5.37 mg GALAE/g extract), and tyrosinase (154.86 mg kojic acid equivalent/g extract) while α-glucosidase was effectively inhibited by the ethyl acetate extract (15.22 mmol acarbose equivalent/g extract). The methanol extract of PA-SB also showed potent antioxidant properties (493.87, 818.12, 953.07, and 732.19 mg Trolox equivalent/g extract, for 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS), cupric reducing antioxidant capacity (CUPRAC), and ferric reducing antioxidant power (FRAP) assays, respectively). PA-SB extracts exhibited antioxidant activity and promising inhibition against key enzymes related to type II diabetes, Alzheimer's disease, and skin hyperpigmentation disorders. Additionally, all extracts were able to contrast hydrogen peroxide-induced oxidative stress, in HypoE22 cells, thus restoring basal catecholamine and 3-hydroxykinurenine levels, whereas only methanol and water extracts stimulated basal dopamine release. Overall, data from the present study contribute to the biological assessment of P. africanum that appears to be a promising source of natural compounds with protective and neuromodulatory effects. [ABSTRACT FROM AUTHOR]

In this study, ethyl acetate, methanol, and water extracts of Bersama abyssinica (Melianthaceae) stem bark were screened for enzyme inhibitory and antioxidant properties. The water extract possessed the highest concentration of phenols (230.83 mg gallic acid equivalent/g extract), while the methanol extract was rich in flavonoids (75.82 mg rutin equivalent/g extract), and the ethyl acetate extract possessed the highest amount of saponins (97.37 mg quillaja equivalent/g). The aim of this study was to investigate the antiproliferative effects against the human colon cancer HCT116 cell line challenged with serotonin (5-HT) as a stimulating-proliferation factor. The level of HCT116 cell-deriving pool of kynurenic acid (KA) was also assessed. The UHPLC results confirmed the presence of 58, 68, and 63 compounds in the ethyl acetate, methanol, and water extracts, respectively. Mangiferin, vitexin and its isomer isovitexin were tentatively identified in all extracts and KA (m/z 190.05042 [M−H]+) was also tentatively identified in the methanol and water extracts. The methanol extract (1464.08 mg Trolox equivalent [TE]/g extract) showed the highest activity in the CUPRAC assay, whereas the water extract (1063.70 mg TE/g extract) showed the highest activity with the FRAP technique. The ethyl acetate extract was the most active acetylcholinesterase (4.43 mg galantamine equivalent/g extract) and α-glucosidase (mmol acarbose equivalent /g extract) inhibitor. The water extract was able to inhibit 5-HT-stimulated viability of HCT116 cells, and blunt 5-HT-induced reduction of cell-deriving KA. The scientific data generated in this study provide baseline data regarding the biological properties of B. abyssinica stem bark, highlighting its potential use for the development of new pharmaceutic and cosmetic agents. [ABSTRACT FROM AUTHOR]

Bridelia species have been used in traditional African medicine for the management of diverse human ailments. In the current work, the detailed phytochemical profiles of the extracts of the stem bark of B. speciosa were evaluated and the antioxidant and enzyme inhibitory properties of the extracts were assessed. The anti-bacterial and anti-mycotic effects of the extracts were evaluated against selected pathogen strains. Additionally, the anti-proliferative effects were studied on the liver cancer HepG2 cell line. Finally, the putative protective effects were assessed on isolated rat liver that was challenged with lipopolysaccharide (LPS). The results revealed the presence of 36 compounds in the ethyl acetate extract, 44 in the methanol extract, and 38 in the water extract. Overall, the methanol extract showed the highest antioxidant activity, particularly in LPS-stimulated rat liver. Additionally, this extract exerted the highest antimycotic effect on C. albicans, whereas the water extract showed a promising anti-proliferative effect on liver cancer HepG2 cells. The methanol extract was also the most active as enzyme inhibitor, against acetylcholinesterase and butyrylcholinesterase. The current study appraises the antioxidant and enzyme inhibition properties of B. speciosa methanol extract and showed that this specie could be a promising source of biologically active phytochemicals, with potential health uses. [ABSTRACT FROM AUTHOR]

Anogeissus leiocarpus (DC.) Guill. & Perr. (Combretaceae) has a long history of use by folk populations for the management of multiple human ailments. Based on the published literature, there has been no attempt to conduct a comparative assessment of the biological activity and the phytochemical profiles of the leaves and stem bark of A. leiocarpus extracted using methanol, ethyl acetate, and water. By high-performance liquid chromatography with electrospray ionization mass spectrometric detection (HPLC-ESI-MSn) analysis, quinic, shikimic, gallic, and protocatechuic acids were tentatively identified from all the extracts, while chlorogenic, caffeic, ferulic, and dodecanedioic acids were only characterised from the leaves extracts. Additionally, a pharmacological study was carried out to evaluate potential protective effects that are induced by the extracts in rat colon and colon cancer HCT116 cell line. In general, the methanol and water extracts of A. leiocarpus leaves and stem bark showed potent radical scavenging and reducing properties. It was noted that the stem bark extracts were more potent antioxidants as compared to the leaves extracts. The methanol extract of A. leiocarpus leaves showed the highest acetyl (4.68 mg galantamine equivalent/g) and butyryl (4.0 mg galantamine equivalent/g) cholinesterase inhibition. Among ethyl acetate extracts, the pharmacological investigation suggested stem bark ethyl acetate extracts to be the most promising. This extract revealed ability to protect rat colon from lipopolysaccharide-induced oxidative stress, without exerting promoting effects on HCT116 cell line viability and migration. As a conclusion, A. leiocarpus represents a potential source of bioactive compounds in the development of novel therapeutic agents. [ABSTRACT FROM AUTHOR]

• The stem barks and seeds of Ricinodendron heudelotii was tested. • Antioxidant and enzyme inhibitory assays were done. • Catechin and gallic acid derivatives are main components in stem barks. • Stem bark extracts exhibited significant biological activities. • The current study could provide new sources of biologically-active compounds. Ricinodendron heudelotii (Baill.) Heckle is used as food ingredient and in the African traditional medicine. In the present study inhibitory activity on α-amylase, α-glucosidase, acetylcholinesterase, butyrylcholinesterase, and tyrosinase of ethyl acetate, methanol, and water extracts of R. heudelotii seeds and stem bark were assessed. Stem bark extracts exhibited significant antioxidant properties. Ethyl acetate extract of seed had great inhibitory potential against α-glucosidase, acetylcholinesterase, and butyrylcholinesterase. Nuclear magnetic resonance (NMR) and high-performance liquid chromatography with electrospray ionization mass spectrometry (HPLC-DAD-ESI-MSn) analysis revealed the presence of catechin and gallic acid derivatives in bark while fatty acid in seeds. Multivariate analysis of obtained data was performed showing a clear separation between seed and stem bark. Obtained results indicate R. heudelotii stem bark as new starting materials for the development of novel pharmaceutical formulations. [ABSTRACT FROM AUTHOR]

• Chemical profiles of Chrysophyllum perpulchrum extracts were investigated. • Different parameters for biological profiles were detected. • The stem bark extracts had more activity than leaves extracts. • Flavan-3-ols were main components in the methanol extracts. • Chrysophyllum perpulchrum is as source of phyto-pharmaceutics. Chrysophyllum perpulchrum Mildbr. ex Hutch. & Dalziel has been reported to possess several therapeutic properties in African traditional medicine. However, its pharmacological properties have not been fully studied. Herein, we focused on the evaluation of the antioxidant, enzyme inhibitory, antimicrobial and cytotoxic effects of three solvent extracts (ethyl acetate, methanol, and water) of the stem bark and leaves. Polyphenolic components of the extracts were also identified by high-performance liquid chromatography with electrospray ionization mass spectrometric detection (HPLC-ESI-MSn). The methanolic stem bark extract possess the highest DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging, ferric and molybdenum (VI) reducing, and the highest inhibitory effect against acetylcholinesterase and butyrylcholinesterase. The aqueous stem bark extract displayed the highest ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)) scavenging and cupric reducing power. In contrast, the leaf ethyl acetate extract was the most effective metal chelator and α-amylase inhibitor while the leaf methanolic extract exhibited the highest tyrosinase and α-glucosidase inhibition. The highest total phenolic content (131.58 mg GAE/g extract) was recorded from the methanolic stem bark extract while the leaf methanolic extract was the richest in total flavonoid content (30.43 mg RE/g extract). Flavan-3-ols were main group in the methanol extracts. The minimum inhibitiory concentration values for the methanolic stem bark extract against Gram positive and negative bacteria strains ranged between 62.5–125 μg / ml. Bark extracts of C. perpulchrum were very effective against Salmonella kentucky , Proteus vulgaris and Staphylococcus aureus at 62.5 μg / ml. In addition, cytotoxic activity of stem bark samples was evident at lower concentration than those of leaf extracts. Stem bark extracts displayed the highest prevention against to HeLa cell line (IC 50 = 264 μg/mL after 48 h). In light of the above, C. perpulchrum might provide health benefits against oxidative stress and the associated chronic diseases. Nonetheless, the detailed mechanism of action is yet to be further investigated. [ABSTRACT FROM AUTHOR]

• Different extracts from Khaya senegalensis stem barks and leaves were investigated. • Chemical characterization for each extract was performed with HPLC-ESI-TOF-MS. • Stem bark extracts exhibited the best antioxidant abilities. • ADMET predictions and network analysis was performed for limonoids. • K. senegalensis could be considered as a promising source of bioactive compounds for novel nutraceuticals. Khaya senegalensis A. Juss (Meliaceae) is a popular medicinal plant, widely used in the management of various ailments in the African traditional medicine. This study attempts to investigate into the different extraction methods (homogenizer-assisted extraction (HAE), maceration (MAC), infusion and Soxhlet (SE) extraction) on the pharmacological properties and chemical profiles of K. senegalensis. Antioxidant properties and inhibitory potential against key enzymes were assessed and bioinformatics analysis was conducted on selected limonoids to predict putative pharmacokinetics and protein targets underlying the pharmacological effects. Overall, the leaf extracts showed notable flavonoid (20.59–104.43 mg RE/g) content and the stem barks extracts displayed the highest total phenolic (87.69–46.28 mg GAE/g), phenolic acid (62.96–107.22 mg CE/g), flavanol (3.60–135.40 mg CAE/g) contents. All extracts showed remarkable antioxidant activities, with the MAC-Water leaf extract being most active in all the assays. Regarding stem bark, the MAC-MeOH extract exerted the highest free radical scavenging abilities, while HAE and MAC extracts were better sources of reducing agent and metal chelators. The HAE-MeOH, MAC-Water, and SE extracts showed noteworthy inhibitory activity against AChE, BChE (only stem barks), tyrosinase and α-glucosidase (only stem barks). All extracts displayed moderate inhibitory activities against α-amylase. The bioinformatics approach showed that khayanoside A and C interacted with multiple isoforms of metalloproteinase, while humilin B and khayanone interacted with opioid receptors. To sum up, the chemical profiles and biological activities of K. senegalensis were closely dependent on the extraction methods. Results amassed from this study showed that K. senegalensis is a potent source of bioactive compounds which could be explored as a functional food. [ABSTRACT FROM AUTHOR]

• Cola caricifolia and Crotalaria retusa extracts were tested. • Phytochemical fingerprinting was obtained using analytical approaches. • Three new flavonoid glycosides were isolated from Crotalaria retusa. • The presented results might be useful for development novel bioactive products. Cola caricifolia (G.Don) K. Schum and Crotalaria retusa L. are important plants in African traditional medicine used against a plethora of human ailments. In this study, phytochemical characterization and enzyme inhibitory assays were performed to assess the potential usefulness of C. caricifolia and C. retusa leaves extracts as source of bioactive constituents for potential industrial applications. The flavonoid content of C. caricifolia (22.27 mg rutin equivalent (RE)/g) was significantly higher (p< 0.05) than C. retusa (12.45 mg RE/g) methanol extract. Inhibitory activity against acetylcholinesterase, butyrylcholinesterase, and tyrosinase were evaluated for all the extracts (ethyl acetate, methanol, and water), whereby the best activity recorded for the methanol extracts. Additionally, the methanol extracts of C. caricifolia and C. retusa showed significant antioxidant activity in the phosphomolybdenum, metal chelating, reducing power, and radical scavenging assays. Flavonoid glycosides and caffeoyl derivatives were the most abundant constituents in C. caricifolia. Crotalaria retusa contained several flavonoid glycosides with structures not described previously. One new compound, kaempferol-6-C-β-glucopyranoside-3-O-β-glucopyranosil-6-O-caffeoyl ester has been elucidated using spectroscopic method in the current study. Derivatives present in minor amount were tentatively identified as kaempferol glycosides. Overall phytochemical investigations allowed the identification of flavonoid O and C glycosides, caffeic acid derivatives, and phytosterols from both plant extracts while pyrrolizidine alkaloids were identified in C. retusa. Structural characteristics of the new isolated compounds along with the most abundant constituents of the two extracts were elucidated allowing the observation of some structural moieties related to the observed activity. These observations highlighted the potential use of these plants as a source of multi-directional biological agents that could lead to bioproducts development. [ABSTRACT FROM AUTHOR]

The stem bark (SB) of Piptadeniastrum africanum (PA) has been extensively used in African traditional medicinal systems. However, there is a dearth of scientific information regarding its possible activity in the management of type II diabetes, Alzheimer's disease, and skin hyperpigmentation disorders. This study therefore attempted to elucidate the in vitro inhibitory action of ethyl acetate, methanol, and water extracts of P. africanum stem bark (PA-SB) on α-amylase, α-glucosidase, acetylcholinesterase, butyrylcholinesterase, and tyrosinase. Cell viability, catecholamine, and 3-hydroxykynurenine levels of hypothalamic HypoE22 cells exposed to PA-SB extracts were also investigated. The phytochemical profiles of the extracts were determined by high performance liquid chromatography (HPLC) and antioxidant properties were investigated. Saponin (867.42 mg quillaja equivalent/g) and tannin (33.81 mg catechin equivalent/g) contents were higher in the methanol extract. Multiple dihydroxy-trimethoxy(iso)flavone isomers, loliolide, eriodictyol, naringenin, luteolin, chrysoeriol, apigenin, and liquiritigenin, were characterized from PA-SB extracts using HPLC. The methanol extract of PA-SB showed highest inhibitory activity against acetylcholinesterase (4.88 mg galantamine equivalent (GALAE)/g extract), butyrylcholinesterase (5.37 mg GALAE/g extract), and tyrosinase (154.86 mg kojic acid equivalent/g extract) while α-glucosidase was effectively inhibited by the ethyl acetate extract (15.22 mmol acarbose equivalent/g extract). The methanol extract of PA-SB also showed potent antioxidant properties (493.87, 818.12, 953.07, and 732.19 mg Trolox equivalent/g extract, for 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS), cupric reducing antioxidant capacity (CUPRAC), and ferric reducing antioxidant power (FRAP) assays, respectively). PA-SB extracts exhibited antioxidant activity and promising inhibition against key enzymes related to type II diabetes, Alzheimer's disease, and skin hyperpigmentation disorders. Additionally, all extracts were able to contrast hydrogen peroxide-induced oxidative stress, in HypoE22 cells, thus restoring basal catecholamine and 3-hydroxykinurenine levels, whereas only methanol and water extracts stimulated basal dopamine release. Overall, data from the present study contribute to the biological assessment of P. africanum that appears to be a promising source of natural compounds with protective and neuromodulatory effects., Competing Interests: The authors declare no conflict of interest.