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In this study we purified and characterized a Protease Inhibitor (PI) from the seeds of Hibiscus acetosella (HAPI). The inhibitor was purified using ammonium sulphate fractionation, Fast Protein Liquid Chromatography using anion exchanger UNOsphere Q column and trypsin affinity chromatography. The HAPI has a subunit molecular weight of 20 kDa and inhibited trypsin to the extent of 89.81 ± 0.61% and larval gut protease activity of Spodoptera litura to the extent of 84.61 ± 0.97%. The purified inhibitor showed 5690.00 U/mg specific inhibition activity with a fold purity of 158.10 and yield of 2.2 µg per gram of seed. The HAPI was quite stable in the range of pH 7–9 with a maximum activity around pH 8–9, the pH range in the gut of lepidopteran larvae. The inhibitor was found to be stable up to a temperature of 50 C and retained an inhibition of 73.54 ± 0.83% even at 70 °C but declined beyond 80 °C. Further, detergents, oxidizing agents and reducing agents altered the inhibition activity of HAPI. The kinetic analysis revealed that HAPI is a non-competitive inhibitor of trypsin with a Ki of 52 nM. Feeding experiments on S. litura larvae with 1.16 µg of the purified inhibitor twice daily resulted in only 5.5% of the larvae emerged as adults from the treated group as against 97% the larvae emerged as adults from control group indicating its potential in pest control. [ABSTRACT FROM AUTHOR]

Abstract The objective of this work was to evaluate the performance of okra grafted onto Hibiscus spp. in the presence and absence of three root knot nematode species. The experimental design was completely randomized in a 4x4 factorial arrangement with ten replicates. The first factor consisted of the following four rootstocks: kenaf (Hibiscus cannabinus), false roselle (Hibiscus acetosella), self-grafted, and non-grafted. The second factor was the inoculation of 5,000 eggs and second-stage juveniles of Meloidogyne incognita, Meloidogyne javanica, and Meloidogyne enterolobii in okra plants, plus an uninoculated control. Vegetative development, agronomic performance, and nematode reproduction were evaluated. The grafting of okra onto Hibiscus spp. in the presence of root-knot nematodes provided a greater plant height, scion length, fresh shoot mass, number of fruits, and yield, when compared with self-grafted and non-grafted plants. The averages of the root-knot nematode reproduction factor were low in the plants grafted onto Hibiscus spp., indicating that grafting in the presence of root-knot nematodes is capable of maintaining okra vegetative development and yield.

[Display omitted] • Spray drying is the main technique to encapsulate bioactive compounds of Hibiscus. • H. acetosella , H. sabdariffa and H. cannabinus are the only exploited species. • Anthocyanins from H. sabdariffa calyces are the main encapsulated compounds. • Encapsulated extracts of Hibiscus plants increased stability of food formulations. • Researches on biological effects of encapsulated extracts of Hibiscus are missing. The genus Hibiscus includes more than 250 species, and many studies showed that these plants contain bioactive compounds with technological potential to be used in the development of functional foods. However, the instability of these compounds during typical food processing conditions, such as exposure to high temperatures, pH changes and presence of light and oxygen have stimulated the use of encapsulation techniques to increase their stability and applicability. Among the existing Hibiscus species, only H. sabdariffa , H. cannabinus , and H. acetosella have been investigated in encapsulation studies, being spray drying the most common method approached. Considering the high technological potential offered by the incorporation of encapsulated bioactive compounds from plants of the genus Hibiscus in food formulations, this review discusses key information of selected encapsulation techniques, which represents promising alternatives to increase food systems' stability and stimulate the design of new functional foods. Relevant gaps in the literature were also noticed, mainly the lack of systematic studies regarding the composition of bioactive compounds after encapsulation, instead of total determinations, and biological activities in different analytical systems, such as antioxidant, antimicrobial and anti-inflammatory properties as well as bioaccessibility and bioavailability. [ABSTRACT FROM AUTHOR]