Meroterpenoids are secondary metabolites formed due to mixed biosynthetic pathways which are produced in part from a terpenoid co-substrate. These mixed biosynthetically hybrid compounds are widely produced by bacteria, algae, plants, and animals. Notably amazing chemical diversity is generated among meroterpenoids via a combination of terpenoid scaffolds with polyketides, alkaloids, phenols, and amino acids. This review deals with the isolation, chemical diversity, and biological effects of 452 new meroterpenoids reported from natural sources from January 2016 to December 2020. Most of the meroterpenoids possess antimicrobial, cytotoxic, antioxidant, anti-inflammatory, antiviral, enzyme inhibitory, and immunosupressive effects.

Objectives: Owing to extraordinary healing power, Terminalia species have been used in traditional medicine systems to treat various diseases. Many folklore uses of Terminalia neotaliala (Madagascar’s almond) included treating arterial hypertension, diabetes, diarrhea, dysentery, colic, oral and digestive candidiasis, intestinal parasitic infections, inflammatory skin conditions, postpartum care, and mycotic infections but nevertheless scientifically explored for its medicinal and pharmacological importance. Therefore, the current study intended to prepare methanolic extract and its fractionation with hexane, chloroform, and butanol followed by evaluation of their polyphenolic content, biological activities, and LCMS analysis. The biological study included antioxidant activity and enzyme inhibition assay i.e., α-glucosidase and urease. The insight study of biologically active secondary metabolites of butanol fraction (BUAE) was performed through LCMS. Methods: The total phenolic content (TPC) and total flavonoid content (TFC) of hydroalcoholic and its fractions were estimated using the Folin-Ciocalteu and aluminum chloride method. The total tannin content (TTC) was determined using the Folin-Denis spectrophotometric method. Similarly, the antioxidant potential of HAAE, HEAE, CFAE, and BUAE was determined using four methods as DPPH (1,1-diphenyl-2-picrylhydrazyl), 2,2-azinobis(3-ethylbenothiazoline)-6-sulfonic acid, cupric reducing antioxidant capacity (CUPRAC), and ferric reducing antioxidant power (FRAP). The sample extracts were also evaluated against two clinically important enzymes i.e., α-glucosidase and urease. Results: The BUAE (butanol aerial fraction) showed the highest TPC (234.79 ± 0.12 mg.GAE.g^-1 DE), TFC (320.75 ± 12.50 mg.QE.g^-1 DE), and TTC (143.36 ± 4.32 mg.TA.Eq.g^-1 DE). The BUAE also showed the highest scavenging potential determined by DPPH (642.65 ± 1.11 mg.TEq.g^-1 DE) and ABTS (543.17 ± 1.11 mg.TEq.g^-1 DE), and the metal-reducing capacity determined by CUPRAC (1510.41 ± 4.45 mg.TEq.g^-1 DE) and FRAP (739.81 ± 19.32 mg.TEq.g^-1 DE). The LCMS of BUAE identified 18 different biologically active phytoconstituents validating a rich source of hydrolyzable tannins including ellagitannins and gallitannins. Conclusion: The present study concluded that T. neotaliala is a rich source of polyphenols capable of neutralizing the damage caused by free radical accumulation in the cells and tissues. The significant antioxidant results and identification of high molecular weight hydrolyzable tannins enlightened the medicinal importance of T. neotaliala.

Psidium guajava L. (guava) is a small tree known for its fruit flavor that is cultivated almost around the globe in tropical areas. Its fruit is amazingly rich in antioxidants, vitamin C, potassium, and dietary fiber. In different parts of the world, this plant holds a special place with respect to fruit and nutritional items. Pharmacological research has shown that this plant has more potential than just a fruit source; it also has beneficial effects against a variety of chronic diseases due to its rich nutritional and phytochemical profile. The primary goal of this document is to provide an updated overview of Psidium guajava L. and its bioactive secondary metabolites, as well as their availability for further study, with a focus on the health benefits and potential industrial applications. There have been several studies conducted on Psidium guajava L. in relation to its use in the pharmaceutical industry. However, its clinical efficacy and applications are still debatable. Therefore, in this review a detailed study with respect to phytochemistry of the plant through modern instruments such as GC and LC-MS has been discussed. The biological activities of secondary metabolites isolated from this plant have been extensively discussed. In order to perform long-term clinical trials to learn more about their effectiveness as drugs and applications for various health benefits, a structure activity relationship has been established. Based on the literature, it is concluded that this plant has a wide variety of biopharmaceutical applications. As a whole, this article calls for long-term clinical trials to obtain a greater understanding of how it can be used to treat different diseases.

Roots of Rondeletia odorata are a rich source of phytochemicals with high antioxidant potential and thus may possess health benefits. This study used the LC-MS technique to identify phytoconstituents in R. odorata roots extract/fractions. Results revealed that n-butanol fraction and ethanolic extract contained total phenolic and flavonoid contents with values of 155.64 ± 0.66 mgGAE/g DE and 194.94 ± 0.98 mgQE/g DE, respectively. Significant potential of antioxidants was observed by DPPH, CUPRAC and FRAP methods while the ABTS method showed moderate antioxidant potential. Maximum % inhibition for urease, tyrosinase and carbonic anhydrase was shown by ethanolic extract (73.39 ± 1.11%), n-butanol soluble fraction (80.26 ± 1.59%) and ethyl acetate soluble fraction (76.50 ± 0.67%) which were comparable with thiourea (standard) (98.07 ± 0.74%), kojic acid (standard) (98.59 ± 0.92%) and acetazolamide (standard) (95.51 ± 1.29%), respectively, while all other extract/fractions showed moderate inhibition activity against these three enzymes. Hemolytic activity was also observed to range from 18.80 ± 0.42 to 3.48 ± 0.69% using the standard (triton X-100) method. In total, 28 and 20 compounds were identified tentatively by LC-MS analysis of ethanolic extract and n-butanol soluble fraction, respectively. Furthermore, molecular docking was undertaken for major compounds identified by LC-MS for determining binding affinity between enzymes (urease, tyrosinase and carbonic anhydrase) and ligands. It was concluded that active phytochemicals were present in roots of R. odorata with potential for multiple pharmacological applications and as a latent source of pharmaceutically important compounds. This should be further explored to isolate important constituents that could be used in treating different diseases.