BAHD acetyltransferase contributes to wound-induced biosynthesis of oleo-gum resin triterpenes in Boswellia.

Triterpenes (30-carbon isoprene compounds) represent a large and highly diverse class of natural products that play various physiological functions in plants. The triterpene biosynthetic enzymes, particularly those catalyzing the late-stage regio-selective modifications are not well characterized. The bark of select Boswellia trees, e.g., B. serrata exudes specialized oleo-gum resin in response to wounding, which is enriched with boswellic acids (BAs), a unique class of C3α-epimeric pentacyclic triterpenes with medicinal properties. The bark possesses a network of resin secretory structures comprised of vertical and horizontal resin canals, and amount of BAs in bark increases considerably in response to wounding. To investigate BA biosynthetic enzymes, we conducted tissue-specific transcriptome profiling and identified a wound-responsive BAHD acetyltransferase (BsAT1) of B. serrata catalyzing the late-stage C3α-O-acetylation reactions in the BA biosynthetic pathway. BsAT1 catalyzed C3α-O-acetylation of αBA, ßBA, and 11-keto-ßBA in vitro and in planta assays to produce all the major C3α-O-acetyl-BAs (3-acetyl-αBA, 3-acetyl-ßBA, and 3-acetyl-11-keto-ßBA) found in B. serrata bark and oleo-gum resin. BsAT1 showed strict specificity for BA scaffold, whereas it did not acetylate the more common C3ß-epimeric pentacyclic triterpenes. The analysis of steady-state kinetics using various BAs revealed distinct substrate affinity and catalytic efficiency. BsAT1 transcript expression coincides with increased levels of C3α-O-acetyl-BAs in bark in response to wounding, suggesting a role of BsAT1 in wound-induced biosynthesis of C3α-O-acetyl-BAs. Overall, the results provide new insights into the biosynthesis of principal chemical constituents of Boswellia oleo-gum resin.

Afrostyrax lepidophyllus extracts exhibit in vitro free radical scavenging, antioxidant potential and protective properties against liver enzymes ion mediated oxidative damage.

BACKGROUND: Several studies described the phytochemical constituents of plants in relation with the free radical scavenging property and inhibition of lipid peroxidation. This study investigated the in vitro antioxidant property, and the protective effects of ethanolic and aqueous ethanol extract of the leaves and barks of Afrostyrax lepidophyllus (Huaceae) against ion mediated oxidative damages. METHODS: Four extracts (ethanol and aqueous-ethanol) from the leaves and barks of A. lepidophyllus were used in this study. The total phenols content, the antiradical and antioxidant properties were determined using standard colorimetric methods. RESULTS: The plant extracts had a significant scavenging potential on the 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl (OH), nitrite oxide (NO) and 2,2-azinobis (3-ethylbenzthiazoline)-6-sulfonic acid (ABTS) radicals with the IC50 varied between 47 and 200 µg/mL depending on the part of plant and the type of extract. The ethanol extract of A. lepidophyllus bark (GEE) showed the highest polyphenolic (35.33 ± 0.29) and flavonoid (12.00 ± 0.14) content. All the tested extracts demonstrated a high protective potential with the increased of superoxide dismutase, catalase and peroxidase activities. CONCLUSION: Afrostyrax lepidophyllus extracts exhibited higher antioxidant potential and significant protective potential on liver enzymes.

Evaluation of Indian sacred tree Crataeva magna (Lour.) DC. for antioxidant activity and inhibition of key enzymes relevant to hyperglycemia.

In the present investigation, leaf and stem bark of Crataeva magna are evaluated for their antioxidant activity and inhibition of key enzymes relevant to hyperglycemia. Both the parts exhibited significant antioxidant and anti-α-glucosidase activity. The results will lead in favor of the use of this plant as a potential additive/nutraceutical antioxidant compound.

Scots pine (Pinus sylvestris) bark composition and degradation by fungi: potential substrate for bioremediation.

The composition of Scots pine bark, its degradation, and the production of hydrolytic and ligninolytic enzymes were evaluated during 90 days of incubation with Phanerochaete velutina and Stropharia rugosoannulata. The aim was to evaluate if pine bark can be a suitable fungal substrate for bioremediation applications. The original pine bark contained 45% lignin, 25% cellulose, and 15% hemicellulose. Resin acids were the most predominant lipophilic extractives, followed by sitosterol and unsaturated fatty acids, such as linoleic and oleic acids. Both fungi degraded all main components of bark, specially cellulose (79% loss by P. velutina). During cultivation on pine bark, fungi also degraded sitosterol, produced malic acid, and oxidated unsaturated fatty acids. The most predominant enzymes produced by both fungi were cellulase and manganese peroxidase. The results indicate that Scots pine bark supports enzyme production and provides nutrients to fungi, thus pine bark may be suitable fungal substrate for bioremediation.